Majority of Rain with Tropical Disturbance will Remain East of the Metro...

Scattered showers and isolated thunderstorms will continue across the area today. It won't rain all of the time, nor is rain likely to be particularly widespread at any given time. Locally heavy downpours of rain are possible at times with any scattered heavier showers and/or any isolated thunderstorms.

As we've been forecasting throughout this event, we do not expect any significant and/or widespread flooding concerns across the local area with this event. If heavier showers happen to impact a particularly troublesome low water crossing across a specific portion of the area more than once in a short time period, localized/isolated issues may develop at that specific location. Otherwise, the type of activity we're expecting, along with the scattered coverage of that activity, suggest that any local impacts will likely be zero to minimal overall.

Please note that shower and thunderstorm activity will be more widespread, and heavier, further to the East of the local area today, over east-central and southeast Texas.

For the local area, scattered activity is expected to decrease in number after Sunset today, and then end during the pre-dawn hours of Thursday morning, in association with this fetch of tropical moisture anyway.

Scattered Showers & T-Storms Are Possible Tonight/Pre-Dawn Thursday

Scattered to numerous showers and scattered thunderstorms are possible after 10pm this evening (and more likely toward/after Midnight tonight) into the pre-dawn and early morning hours on Thursday.

Locally heavy downpours of rain and lightning are possible with any scattered thunderstorms tonight/pre-dawn Thursday.

While we cannot completely rule out an isolated stronger thunderstorm with strong, gusty winds and/or spotty hail during the overnight hours tonight and/or the pre-dawn hours of Thursday morning, widespread and/or organized severe weather appears unlikely for the local area at this time, as the activity will likely be undergoing a weakening trend due to the time of night.

The activity is expected to shift East/Southeast out of the area by around 6-7am on Thursday morning, based on present indications.

Scattered thunderstorms are possible across the area this afternoon...

...Synopsis...
An area of showers and thunderstorms currently over west-central and northwest Texas will continue moving Eastward and Northeastward throughout the day today. If we were to consider only the present location and movement of this activity, all of it would remain to the North of the local area, with no local impacts of any kind. However, a boundary associated with this activity will move East/Southeast into the local area between the hours of 12 Noon and 6pm this afternoon. The potential exists for at least scattered thunderstorm development in association with the passage of this boundary during the above mentioned time period.

...Local Forecast...
There are 3 possible scenarios that could unfold for the local area at this time, all of which would occur sometime (as indicated below) during the 12 Noon-6pm time frame:

1. With the majority of the energy associated with the parent storm system passing to the North of the local area, thunderstorms are unable to develop locally, and all of the thunderstorm activity remains to the North of the local area. Probability of occurrence: 30 percent.

2. Scattered thunderstorms develop across the area between 12 Noon and 6pm this afternoon. Probability of occurrence: 60 percent. Please note: this doesn't mean that 60 percent of the area will have thunderstorms, but rather, there's a 60 percent chance of scattered thunderstorms across the local area. Some locations may receive rain and/or a thunderstorm while others, possibly very nearby, do not. Based on present indications, under this scenario we would place the probability of a thunderstorm impacting any given location at about 40 percent.

3. A line of thunderstorms moves from West/Northwest to East/Southeast across the area between 12 Noon and 3pm, with scattered activity behind it through 6pm this afternoon. Probability of occurrence: 10 percent.

With the above in mind, we currently expect scattered showers and thunderstorms from around or shortly after 12 Noon through about 6pm this afternoon. Locally heavy downpours of rain and lightning can be expected with any scattered thunderstorms, and an isolated to scattered stronger thunderstorm may also produce strong, gusty winds and/or hail in the affected portion(s) of the area. Present indications suggest the activity will be more numerous, and heavier, to the immediate North of the local area during the period.

...Locally Heavy Rainfall...
Although widespread, heavy rainfall does not currently appear likely across the local area, any isolated to scattered concentrations of heavier downpours could result in minor, mostly localized flooding of low lying and poor drainage areas in the affected portion(s) of the region. The potential for more numerous issues will likely increase as you move further to the North of the local area.



We will continue monitoring the situation and issue updates and/or specific alerts/warnings as conditions warrant.

Details on the Blanco River in southern Hays County....

A Flood Warning continues for the Blanco River in Hays County.  Details by location are as follows:


...At Fischer...
Current stage: 12.3 ft
Flood stage: 17.0 ft

The river is expected to crest just above flood stage later this evening, then recede overnight, falling just below flood stage during the pre-dawn hours on Thursday.

Applicable flood guidance based on previous history (note that guidance for 1 level above the current forecast crest is provided for precautionary/preparedness purposes):

At 23 feet: Lowest homes are threatened. Water begins to cut off secondary roadways near the river.

At 17 feet: Roadways and low bridges along the river are flooded. Vehicles cannot pass. Livestock can be stranded.

At 12 feet: Overbank conditions may cut off livestock in low areas.



...At Wimberley...
Current stage: 8.7 ft
Flood stage: 13.0 ft

The river is expected to crest near 20 feet later this evening, then recede overnight into pre-dawn Thursday. The river is expected to drop just below flood stage near dawn on Thursday.

Applicable flood guidance based on previous history (note that guidance for 1 level above the current forecast crest is provided for precautionary/preparedness purposes):

At 21 feet: Water recreation is very dangerous above Blanco to the San Marcos River confluence, including John Knox Camp and Dudley Johnson Park at Five Mile Dam above San Marcos.  Secondary roads and bridges in the flood plain are very dangerous to motorists. Hydraulic jumps behind low dams are dangerous to canoeists and kayakers as they may become trapped.

At 17 feet: Water recreation in the Blanco river is dangerous from above Blanco to the San Marcos river confluence. Secondary roads and bridges in the flood plain are flooded and dangerous. Much of Dudley Johnson park at Five Mile Dam is flooded.

At 13 feet: Minor lowland flooding reaches secondary roads. Low bridges and crossings from the headwaters to the San Marcos River confluence near San Marcos flood and are dangerous. Property in low lying areas of the Blanco and San Marcos Rivers should be moved to higher ground. Swimming and tubing are life threatening due to turbulence. Hydraulic jumps behind low water dams can trap canoeists and kayakers between the dam and the hydraulic jump and can be life threatening.

At 10 feet: A fast moving rise down the Blanco River can make swimming and canoeing dangerous above Blanco to below San Marcos. Especially in areas where steep banks make getting out of the river dangerous. Low dams create hydraulic jumps which can trap canoeists and kayakers between the dam and the jump.

At 7 feet: Overbank conditions begin to threaten swimmers and tubers in recreation areas above Blanco to the San Marcos River confluence below San Marcos.

At 6 feet: Low lying areas and crossings of secondary roads flood near and below Blanco to below Wimberley including Farm to Market 178 just above Wimberley.



...At San Marcos...
Current stage: 10.32 ft
Flood stage: 18.0 ft

The river is expected to crest near 22.5 feet during the pre-dawn hours of Thursday morning, then recede during the daytime hours on Thursday, falling just below flood stage near 12 Noon.

Applicable flood guidance based on previous history (note that guidance for 1 level above the current forecast crest is provided for precautionary/preparedness purposes):

At 24 feet: Lowest homes are threatened. Water beings to cut off secondary roads near the river.

At 18 feet: Roadways and low bridges along the river are flooded. Vehicles cannot pass. Livestock can be stranded.

At 13 feet: Overbank conditions may cut off livestock and low bridges near the river.



***PLEASE NOTE: ALL of the above forecasts are based on current conditions and short term forecast information. Should additional heavy rainfall occur upstream earlier or in greater quantity than currently expected, the forecast levels and timing could change. We will continue to monitor the situation and issue additional updates as warranted.

Also, additional heavy rainfall later this week will result in additional and/or renewed flooding issues at times across the area through this coming weekend.  We will continue monitoring the situation and issue updates as conditions warrant.

Scattered Heavy Downpours Possible Beginning Today, Increasing Through the Week....

Expected impacts:

• Periods of showers and thunderstorms will produce locally heavy rainfall at times from this afternoon through midday Saturday
• With ground conditions already saturated and stream levels running high across the region, flooding will likely result at least at times during the Watch period
• Initially, the typical problem low water crossings and other typically flood prone areas will be the primary concern, with stream and river flooding then possible over time as we move through the period
• On average, rainfall of 4-6 inches is expected for much of the area mainly from this afternoon through midday Saturday
• Locally higher amounts are possible in spots depending upon exactly where the heaviest rainfall recurs during the period

Discussion:
Periods of showers and thunderstorms will produce locally heavy rainfall at times across the area from this afternoon through midday Saturday. With ground conditions already saturated and stream levels running high across the region, flooding will likely result at least at times during the period. Initially, the typical problem low water crossings and other typically flood prone areas will be the primary concern, with stream and river flooding then possible in parts of the area over time as we move through the period. Please see below for a general overview of our present thinking for each day during the period:

...Today...
Scattered showers are possible this morning, becoming more numerous at times this afternoon into early this evening. Scattered thunderstorms are likely this afternoon into early this evening. The activity is expected to decrease near Sunset.
Low Water Crossing Flood Risk: Low to Moderate (Not widespread, but localized depending upon specific locations of thunderstorms)
River/Stream Flood Risk: Low

...Wednesday...
Scattered to numerous showers and thunderstorms. The activity appears likely to be most numerous during the midday and afternoon hours.
Low Water Crossing Flood Risk: Moderate to High (mainly p.m.)
River/Stream Flood Risk: Low to Moderate (mainly later p.m.)

...Thursday...
Scattered to at times numerous showers and thunderstorms. The activity appears likely to be most numerous during the afternoon and evening hours.
Low Water Crossing Flood Risk: High
River/Stream Flood Risk: Moderate to High on a localized basis

...Friday...
Scattered to at times numerous showers and thunderstorms.
Low Water Crossing Flood Risk: High
River/Stream Flood Risk: Moderate to High on a localized basis

...Saturday...
Scattered to at times numerous showers and scattered thunderstorms. The activity appears likely to be most numerous during the pre-dawn and morning hours.
Low Water Crossing Flood Risk: High (especially a.m.)
River/Stream Flood Risk: Moderate to High on a localized basis

...Expected Rainfall Amounts...
In general, rainfall of 4-6 inches appears probable for most of the area on average throughout the period from this afternoon through midday Saturday. A few locations that receive particularly frequent bouts of heavier rain could see greater than 6 inches, while a few locations that don't receive as many heavy downpours could see less than 4 inches. It is also important to remember that ground conditions are already saturated going into this event, and stream/river levels are already running above normal levels across many parts of the area. Both of those factors indicate that it will take less rain than normal to cause flooding issues across the area.
We will continue monitoring the situation and issue updates as conditions warrant.

Periods of locally heavy rainfall may result in new/renewed flooding this week....

Expected impacts:

• Periods of showers and thunderstorms will produce locally heavy rainfall at several different times mainly from Tuesday afternoon through Saturday morning
• With ground conditions already saturated and stream levels running high across the region, flooding will likely result at least at times during the period
• Initially, the typical problem low water crossings and other typically flood prone areas will be the primary concern, with stream and river flooding then possible in parts of the area over time
• On average, rainfall of 4-6 inches is expected for much of the area from mainly Tuesday afternoon through early Saturday morning
• Locally higher (and in some cases, lower) amounts are possible in spots depending upon exactly where the heavier thunderstorms track throughout the period

Discussion:
Periods of showers and thunderstorms will produce locally heavy rainfall at several different times across the area from Tuesday afternoon through Saturday morning. With ground conditions already saturated and stream levels running high across the region, flooding will likely result at least at times during the period. Initially, the typical problem low water crossings and other typically flood prone areas will be the primary concern, with stream and river flooding then possible in parts of the area over time. Please see below for a general overview of our present thinking for each day during the period:

...Today...
There is a chance for an isolated or widely spaced shower or thunderstorm across some portions of the local area mainly this afternoon or early this evening. While any such activity is expected to be isolated in nature at this time, if locally heavy downpours with an isolated thunderstorm occur in just the wrong place, then some mostly minor flooding issues could result in the adjacent low lying areas. Present indications suggest activity is more likely to occur to the immediate South of the local area today, but we'll continue to monitor trends closely.

...Tuesday...
Scattered to at times numerous showers and scattered thunderstorms. The activity appears likely to be most numerous during the afternoon hours, from 12 Noon to 6pm.
Low Water Crossing Flood Risk: Moderate
River/Stream Flood Risk: Low

...Wednesday...
Scattered to numerous showers and thunderstorms. The activity appears likely to be most numerous during the midday and afternoon hours.
Low Water Crossing Flood Risk: High
River/Stream Flood Risk: Moderate

...Thursday...
Scattered to at times numerous showers and thunderstorms. The activity appears likely to be most numerous during the afternoon and evening hours.
Low Water Crossing Flood Risk: High
River/Stream Flood Risk: Moderate to High on a localized basis

...Friday...
Scattered to at times numerous showers and thunderstorms. The activity appears likely to be most numerous during the morning hours.
Low Water Crossing Flood Risk: High
River/Stream Flood Risk: Moderate to High on a localized basis

...Saturday...
Scattered to at times numerous showers and scattered thunderstorms. The activity appears likely to be most numerous during the pre-dawn and early morning hours.
Low Water Crossing Flood Risk: High (pre-dawn/early a.m.)
River/Stream Flood Risk: Moderate to High on a localized basis

...Expected Rainfall Amounts...
In general --to repeat-- in general, rainfall of 4-6 inches appears probable for most of the area on average throughout the period Tuesday (mainly afternoon) through Saturday morning. We emphasized the "in general" detail because of the fact that actual amounts will widely vary based on thunderstorm tracks throughout the period. A few locations that receive particularly frequent bouts of heavier rain could see greater than 6 inches, while a few locations that don't receive as many heavy downpours could see less than 4 inches. It is also important to remember that ground conditions are already saturated going into this event, and stream/river levels are already running above normal levels across many parts of the area. Both of those factors indicate it will take less rain than normal to cause flooding issues at least at times across the area.
We will continue monitoring the situation and issue specific updates, alerts and/or warnings as conditions warrant.

More potential for locally heavy rainfall beginning Tuesday and then each day thereafter this week...

...Synopsis...
We are continuing to closely monitor a developing weather situation for the period Monday afternoon into Tuesday. While some specific details (as to exact rainfall amounts, etc.) are yet to be worked out, it appears probable that locally heavy rainfall can be expected at times across at least some portions of the area mainly during the day on Tuesday, which could lead to flooding of low lying and poor drainage areas at times. This will be the first of several rain events to impact the area this week, each of which will carry a risk for locally heavy rainfall.

...Forecast...
There is a chance for an isolated or widely scattered shower or thunderstorm on Monday afternoon or Monday evening, but present indications suggest the majority of the area will remain dry during that time period. Showers and thunderstorms are likely to begin developing near dawn on Tuesday and then increase into much of the daytime hours, ending by around 6pm Tuesday. Locally heavy rainfall and lightning can be expected at times with thunderstorms, most numerous at times during the day on Tuesday.

...Flood Risk...
Due to recent heavy rainfall and saturated ground conditions, there will be a higher than normal risk of low land flooding throughout the period in the affected portions of the area, to include probable impacts at times on at least some low water crossings, etc. Present trends suggest that any issue on Monday afternoon or evening would be very isolated. The primary concern is expected to occur during the day on Tuesday especially by the afternoon transportation period, the extent to which will become more clear in later updates.

...A Note About the Remainder of This Week...
Please also be aware that additional periods of shower and thunderstorm activity are likely at various times from Wednesday through Saturday of this week. An elevated risk of low land flooding will continue throughout the week due to recent heavy rainfall, saturated grounds, and the probability of additional heavy rain at times in at least some portions of the local area each day (generally except for Monday).

We will continue monitoring the situation and issue updates as conditions warrant.

Locally Heavy Rainfall Expected Again Monday-Tuesday; Additional activity possible later next week...

Expected impacts:

• Showers and thunderstorms are expected from Monday afternoon into Monday night and pre-dawn Tuesday
• Locally heavy rainfall (and lightning) can be expected at times with some of this activity
• Due to recent heavy rainfall and saturated ground conditions there will be a higher than normal risk of low land flooding throughout the period

Discussion:
...Synopsis...
We are closely monitoring a developing weather situation for the period Monday afternoon into Tuesday morning. While some specific details (as to exact rainfall amounts, etc.) are yet to be worked out, it appears probable that locally heavy rainfall can be expected at times across at least some portions of the area during the period, which could lead to flooding of low lying and poor drainage areas at times during the period.

...Forecast...
Showers and thunderstorms are expected to develop on Monday afternoon, initially on a scattered basis. The activity is expected to increase in coverage by Monday evening and continue at times into pre-dawn Tuesday. Locally heavy rainfall (and lightning) can be expected at times with some of this activity. The activity is then expected to decrease in coverage on Tuesday morning.

...Flood Risk...
Due to recent heavy rainfall and saturated ground conditions there will be a higher than normal risk of low land flooding throughout the period in the affected portions of the area, to include probable impacts on low water crossings, etc. Please note that both the Monday afternoon transportation period and the Tuesday morning transportation period would be impacted by this activity, the extent to which will become more clear in later updates.

The reason that the Advisory extends until 12 Noon Tuesday, yet we expect the rain to end pre-dawn Tuesday, is because runoff from earlier rainfall would likely continue well into the morning hours, after the falling rain has ended. If present trends continue, a Flood Watch will likely be required for all or part of the period in later updates.

...A Note About the Remainder of Next Week...
Please also be aware that additional periods of shower and thunderstorm activity appear probable at times from Wednesday through Friday of next week. An elevated low land flood risk is likely to continue throughout the week due to recent heavy rainfall, saturated grounds, and the probability of additional heavy rain at times in at least some portions of the local area. We will issue additional advisories, watches, etc., for specific time periods as the day-to-day situation becomes more clear.

We will continue monitoring the situation and issue updates as conditions warrant.

Update on showers and thunderstorms for late afternoon/evening...

Scattered showers and thunderstorms are likely across the local area from now into the evening hours. When shower and thunderstorm activity are present, they are likely to move from the Southwest to the Northeast across the area in general, though some erratic movement is possible at times with some of the activity.

Locally heavy downpours of rain and lightning can be expected at times with any thunderstorms. The activity will tend to move slowly - likely at 10-15 mph on average. This could result in minor flooding of low lying and poor drainage areas (such as low water crossings, etc.) at times in the affected areas, especially in those parts of the area that received heavier downpours yesterday and/or early this morning.

The atmosphere has destabilized somewhat since the rain from earlier today but it is not, however, highly unstable. Therefore, the risk of any significant and/or organized "severe" weather this evening appears low for the local area. An isolated stronger thunderstorm could produce gusty winds and/or spotty, mostly smaller size hail in mainly isolated portions of the area. The risk of strong to severe thunderstorm activity will be higher (and the activity likely more numerous) to the South of the local area, based on present indications.

We will continue monitoring the situation and issue updates as conditions warrant.

Update for northern Travis and Williamson Counties...

Expected impacts:

• Showers and thunderstorms will overspread the area from the West through 5pm, and continue into the 5 and likely the 6 o'clock hours
• Locally heavy downpours of rain and lightning can be expected at times with some of this activity
• Locally heavy downpours over some of the same areas could result in localized minor flooding of low lying and poor drainage areas at times this evening

Discussion:
Showers and thunderstorms will overspread the area from the West through 5pm, and continue into the 5 and likely the 6 o'clock hours.

Locally heavy downpours of rain and lightning can be expected at times with some of this activity. Should locally heavy downpours occur repeatedly over some of the same areas, it could result in localized minor flooding of low lying and poor drainage areas at times this evening.

We will continue monitoring the situation and issue updates and/or specific alerts/warnings as conditions warrant.

Update for Southern Travis and Hays Counties...

Expected impacts:

• Scattered showers and thunderstorms will continue across the area from now into the evening hours
• Locally heavy downpours of rain and lightning are possible at times with any thunderstorms
• Any slow moving thunderstorms with heavy downpours of rain could produce minor flooding in low lying and poor drainage areas at times this evening
• An isolated stronger thunderstorm may also produce gusty winds and/or spotty hail in some parts of the area
• Present trends suggest that conditions will be more favorable for strong to severe thunderstorms to the South of the local area this evening

Discussion:
Scattered showers and thunderstorms will continue across the area from now into the evening hours. Locally heavy downpours of rain and lightning are possible at times with any thunderstorms.

Any slow moving thunderstorms with heavy downpours of rain could produce minor flooding in low lying and poor drainage areas at times this evening, and there's a slight chance that an isolated stronger thunderstorm may also produce gusty winds and/or spotty hail in some parts of the area.

Present trends suggest that conditions will be more favorable for strong to severe thunderstorms (i.e., with large hail, damaging winds, etc.) to the South of the local area this evening.

We will continue monitoring the situation and issue updates and/or specific alerts/warnings as conditions warrant.

Better chance of showers and t-storms across the area today/this evening...

Expected impacts:

• Isolated to widely scattered rain showers are possible this morning, mainly before 10am
• Scattered showers and thunderstorms are possible mainly toward/after 2-3pm and are expected to increase toward/after 5-6pm and into this evening
• Locally heavy downpours of rain and lightning are likely at times with any thunderstorms
• A few stronger thunderstorms could also produce strong, gusty winds and/or hail in some parts of the area mainly after 3pm, into parts of this evening
• If thunderstorms with heavy rain occur more than one time in the same part(s) of the area, minor flooding of low lying and poor drainage areas could result at times, especially this evening

Discussion:
...Synopsis...
An outflow boundary from thunderstorms in north Texas last night is moving into the local area at this time. There are scattered showers along this boundary, but most are light, and this type of activity will continue through mid-morning before dissipating. This boundary, along with a disturbance approaching from the West, are expected to serve as a focus for new thunderstorm development later this afternoon and into this evening.

...This Morning...
Isolated to widely scattered rain showers are possible, mainly before 10am.

...This Afternoon and Evening...
Scattered showers and thunderstorms are possible mainly toward/after 2-3pm and are expected to increase in number especially toward/after 5-6pm and into the evening hours. The activity will likely decrease and/or move East out of the area by Midnight tonight.

...Potential Hazards with Thunderstorms Later This Afternoon and Evening...
Locally heavy downpours of rain and lightning are likely at times with any thunderstorms this afternoon and/or evening. If clusters of heavy downpours occur more than one time over the same portions of the area, this could lead to mostly minor flooding at times, mainly in low lying and poor drainage areas this evening into tonight (as runoff continues). In addition, a few stronger thunderstorms could also produce strong, gusty winds and/or hail in some parts of the area mainly after 3pm, into parts of this evening hours.

We will continue monitoring the situation and issue updates as conditions warrant.

At this time we expect majority of t-storm activity to continue to remain to our North...

Expected impacts:

• There is a slight chance of an isolated shower or thunderstorm this afternoon and evening, but the majority of the area will likely remain dry based on present indications
• Depending on the evolution of thunderstorm activity to our North and Northwest later this evening, showers and thunderstorms could move into some parts of the local area during the pre-dawn hours of Thursday
• Should thunderstorms occur later tonight, locally heavy downpours of rain and lightning can be expected in the affected areas

Discussion:
...Synopsis...
So far today, thunderstorm development has remained along the Red River and into extreme Northwest parts of Texas - well to the North of the local region. This is due to the fact that the surface boundary that we discussed in the morning update has remained nearly stationary, focusing the activity in that region. Present indications suggest that trend will continue in the near term.

Depending upon how the activity in northwest and north Texas evolves later this evening, we could see at least some parts of the local area impacted by shower and thunderstorm activity mainly toward/after Midnight tonight, into the pre-dawn hours of Thursday, but this remains a very uncertain proposition at this time. We will need to continue monitoring thunderstorm trends into the evening hours to see if any congealment and Southward motion begins to take place. Right now, all of the referenced activity is moving Northeastward across northern portions of Texas.

Please see below for current thinking on the local forecast concerns.

...This Afternoon and Evening (Now thru Midnight) - Confidence: Moderate to High...
There is a slight chance of an isolated shower or thunderstorm, but the majority of the area will likely remain dry. While the chance of a thunderstorm locally currently appears to be remote at best during the period, if a thunderstorm is able to develop it could produce strong, possibly damaging wind gusts and large hail in the impacted portion of the area.

...Tonight/Pre-Dawn Thursday (Midnight to 6am) - Confidence: Moderate...
The forecast for this period continues to be highly dependent upon what, if anything, occurs to our North and Northwest this evening. Present indications suggest that if any parts of the local area were to be impacted by shower or thunderstorm activity, it would most likely be after Midnight tonight, into the pre-dawn hours of Thursday morning. Locally heavy downpours of rain and lightning would be likely with any such activity. However, there are considerable factors that currently suggest that all of the activity may remain to the North of the local area, even into the overnight hours.  We will continue to monitor storm trends and issue further updates as the situation evolves.


We will continue monitoring the situation and issue updates as conditions warrant.

Update on Thunderstorm Potential Later Today/Tonight...

Expected impacts:

• There is a slight chance of an isolated shower or thunderstorm this afternoon, but the majority of the area will likely remain dry
• There is a chance of scattered shower and thunderstorm activity this evening into early tonight but the more widespread activity is likely to remain further to the North of the local area
• Should any thunderstorm activity occur, locally heavy downpours of rain are possible at times in the affected portions of the area
• Should any thunderstorm activity occur, an isolated stronger thunderstorm could produce strong, gusty winds and/or hail in the affected portions of the area
• The extent of any local activity this evening/tonight will heavily depend upon what occurs further to our North and Northwest during the day today; please monitor for future updates to this Advisory

Discussion:

...Synopsis...
A frontal boundary is located along the Red River to the North of the Dallas/Ft. Worth area early this morning. The movement of this boundary during the day today will play a critical role in determining how far South thunderstorm activity will occur later in the day and this evening/tonight. At this time we expect the boundary to stall in north Texas for much of the day, keeping the primary focus for widespread shower and heavy thunderstorm activity to the North of the local area from later this morning into the afternoon hours.

Depending upon how far South that particular activity builds this afternoon, and depending upon whether or not any thunderstorm generated boundaries may develop and drift Southward this afternoon, there will be a chance for isolated to scattered shower and thunderstorm activity across at least some portions of the local area by this evening and into early tonight. If the majority of the afternoon activity and associated boundaries are held even further North than currently expected, then we will see less of a chance of any local activity this evening and early tonight. On the other hand, if more of the activity and associated boundaries move further South than currently expected during the day, then we would see an increase in the chance for local activity this evening and early tonight.

With the above in mind, it will be important to monitor the progression of thunderstorm activity and associated boundaries to our North throughout the day today so as to determine (or adjust) the precise degree of any potential local impacts this evening or tonight. The forecast below is based on present thinking, and is subject to change, as noted above.

...This Afternoon (12 Noon to 6pm) - Confidence: High...
There is a slight chance of an isolated shower or thunderstorm this afternoon, but the majority of the area will likely remain dry.

...This Evening (6pm to Midnight) - Confidence: Moderate...
There is a chance of scattered shower and thunderstorm activity this evening, but present indications suggest that the more widespread activity is likely to remain further to the North of the local area. This is subject to change based on trends during the afternoon hours today, so please monitor for future updates as the situation becomes more clear today. Should any thunderstorm activity occur, locally heavy downpours of rain are possible at times in the affected portions of the area, and an isolated stronger thunderstorm could produce strong, gusty winds and/or hail in the affected portions of the area.

...Tonight/Pre-Dawn Thursday (Midnight to 6am) - Confidence: Moderate...
The forecast for this period is highly dependent upon what, if anything, occurs on Wednesday evening. Present indications suggest that if scattered shower and thunderstorm activity does occur in parts of the local area on Wednesday evening, it should move out of the area by 2am on Thursday morning. Any shifts in timing of the evening activity on Wednesday could result in shifts in expected conditions during this time period as well, so please monitor for further updates.

...Updates as Per Trends...
Please continue to monitor for updates to this Advisory throughout the day today as storm trends are identified and become more clear further to our North.

We will continue monitoring the situation and issue updates and/or specific alerts/warnings as conditions warrant.

The latest on the forecast, and underlying uncertainties, for this evening through pre-dawn Thursday...

Expected impacts:

• There is a slight chance of an isolated shower or thunderstorm this evening or early tonight, but the majority of the area will likely remain dry
• There is a chance of an isolated shower or thunderstorm on Wednesday afternoon or Wednesday evening, but the more widespread activity is likely to remain further to the North of the local area
• Scattered showers and thunderstorms are possible from Wednesday night into the pre-dawn hours of Thursday morning
• Locally heavy downpours of rain are possible at times with any thunderstorms in the affected portions of the area

Discussion:
We know that you depend on us to provide the most accurate, dependable weather forecasts that we possibly can, and that's indeed what we strive to do on a daily basis. However, we are, after all, talking about predicting the future, and sometimes that's just downright difficult to do. This certainly applies to the next 24-36 hour period across the local area.

At this time we are unable to be as confident as we would like to be regarding the forecast, particularly for the Wednesday afternoon and evening into Wednesday night time period. This is because there are numerous variables in play - many more than usual - which will determine the eventual outcome of the local situation. We will continue to closely monitor these variables, utilizing all of the tools, technology and experience that we have available, and issue appropriate updates as the situation evolves. This is one of those situations where you want to continue monitoring our updates for the latest thinking and trends as they occur. Right now, our best efforts have produced the below, and we submit it for your review:

...This Evening and Tonight - Confidence: Moderate to High...
There is a slight chance of an isolated shower or thunderstorm this evening into early tonight, but the vast majority of the local area is likely to remain dry.

...Wednesday Afternoon and Wednesday Evening - Confidence: Moderate...
There is a chance of an isolated shower or thunderstorm on Wednesday afternoon or Wednesday evening, however at this time, the majority of the more numerous to widespread activity is expected to remain to the North of the local area during this time period. If a thunderstorm is able to develop during the Wednesday afternoon or evening time period, it could produce hail and/or strong, gusty winds in the affected parts of the area. There is still a moderate amount of uncertainty with regard to the Wednesday afternoon and evening time period at this time, and we'll continue to attempt to better identify local thunderstorm potential for any necessary later updates.

...Wednesday Night/Pre-Dawn Thursday - Confidence: Low to Moderate...
Scattered showers and thunderstorms are possible from Wednesday night into the pre-dawn hours of Thursday morning, assuming that some of the activity which forms to the West during the afternoon and evening on Wednesday organizes and moves East/Southeast into the local area. Please be aware that this is far from certain, as there are numerous indicators that suggest the activity will once again remain to the North of the local area during the Wednesday night to pre-dawn Thursday time period. We will continue monitoring for any changes in trends during this time period.

...Expectations with any Thunderstorms During any of the Above Time Periods - Confidence: High...
Regardless as to the coverage of any thunderstorm activity during the above mentioned time periods, locally heavy downpours of rain are possible at times with any thunderstorms in the affected portions of the area. Also, as noted above, any thunderstorm that manages to form on Wednesday afternoon or evening could also produce hail and/or strong, gusty winds in the affected portions of the area.

Update on Thunderstorm Trends for the Midday and Afternoon Hours Today...

Expected impacts:

• Scattered showers and isolated thunderstorms are possible through 2pm
• Showers and thunderstorms are expected to become more numerous toward/after 2pm, on into the early to mid-evening hours
• Locally heavy rainfall is likely at times with thunderstorms especially later this afternoon into early this evening, which could produce flooding at times in low lying and poor drainage areas
• Storm total rainfall of 2-3 inches is expected across most of the area, with localized amounts of 3-4 inches possible in some spots
• A few strong to severe thunderstorms could also produce strong, gusty winds and/or hail in at least some parts of the area later this afternoon into early this evening

Discussion:
...Near Term Update and Forecast...
The shower and thunderstorm activity that moved through the area this morning continues to shift off to the South and East of the area at this time, and has formed into a solid line from near San Antonio to Seguin to Bastrop. This activity has effectively cut-off the flow of moisture into the area from the Southeast, and has, at least temporarily, resulted in a significant stabilization of the local atmosphere (note the cool, North breeze across the area at this time).

The above mentioned boundary now to the South of us, called an outflow boundary, is expected to stall soon as Southerly winds increase in Deep South Texas. One of two things will then happen this afternoon: 1). The boundary will hold nearly stationary to the South of the area through the afternoon, thereby keeping the highest risk of strong to severe thunderstorm activity to the South of the local area where the air is more unstable or 2). the boundary could start lifting back Northward and reach at least some portions of the local area later this afternoon. If scenario 2 were to occur, it would most likely be into southern portions of the area (i.e., Hays County), with decreasing probability as you move Northward.

If scenario 2 occurs, then there will be a risk of strong to severe thunderstorm activity, with hail and/or strong, possibly damaging wind gusts in the affected areas, as well as very heavy downpours of rain and of course, lightning. This would occur mainly from toward/after 2-3pm through about 7-8pm. If scenario 1 occurs, then we can expect scattered to numerous showers and scattered thunderstorms, some of which could produce small hail in some parts of the area, as well as locally heavy downpours of rain, this afternoon into early this evening.

Regardless as to which of the above scenarios takes place, all shower and thunderstorm activity should move East out of the area by around 8-9pm this evening, based on present trends.

We will continue monitoring the progress and/or return of the outflow boundary during the midday and afternoon hours and issue additional updates as trends become identified.

...Expected Rainfall and Possible Low Land Flood Risk...
Regardless as to which of the above scenarios takes place, locally heavy downpours of rain will be likely again at times in many parts of the area during the afternoon (especially toward/after 2-3pm) into the early evening hours. Heavy rain will be more widespread if scenario 2 occurs, and less widespread (more scattered to regional in nature) if scenario 1 occurs.

Any periods of heavy rainfall this afternoon into early this evening may result in mostly minor flooding of low lying and poor drainage areas, such as low water crossings and similar areas. If scenario 2 above occurs, and the heavier rain is more widespread, runoff may continue well into the late evening and overnight hours, well after the falling rain has ended, in the affected areas.

We will continue monitoring the situation and issue updates and/or specific alerts/warnings as conditions warrant.

Locally Heavy Rainfall Likely Especially this Afternoon/Early Evening...

Expected impacts:

• Scattered to numerous showers and isolated thunderstorms are likely this morning
• Showers and thunderstorms are likely this afternoon into early-mid evening
• Locally heavy rainfall is likely at times with thunderstorms especially this afternoon/early evening, which could lead to flooding at times, especially in low lying and poor drainage areas
• Present indications suggest that rainfall is likely to average 2-3 inches across most of the area, with localized amounts of 3-4 inches possible in some spots
• A few strong to severe thunderstorms could produce strong, gusty winds and/or hail this afternoon; a more organized line of strong to severe t-storms is possible mainly from 4pm-7pm

Discussion:
...This Morning...
Scattered to numerous showers and isolated thunderstorms will continue across the area this morning. Outside of any isolated thunderstorms, most of the rain this morning is expected to be light to moderate in intensity for the most part. Any isolated thunderstorms could produce locally heavy downpours of rain in the affected portions of the area.

...This Afternoon and Evening...
Showers and thunderstorms are expected to increase in number and intensity during the afternoon hours today and continue until about 7-8pm this evening. Locally heavy rainfall is likely at times with some of this activity, which could lead to flooding at times in at least some parts of the area, especially in low lying and poor drainage areas such as low water crossings and similar parts of the area. In addition, a few stronger thunderstorms could produce strong, gusty winds and/or hail in some parts of the area this afternoon into early this evening.

It is also possible that a more organized line of thunderstorm activity could move into the area late this afternoon/early this evening, especially between 4pm and 7pm. If this occurs, an enhanced possibility of strong, possibly damaging wind gusts could result, and isolated spin-up type tornadoes sometimes occur with such activity as well. The reason we're saying "could move into the area" is that there is uncertainty at this time as to whether the line will develop to the immediate West of the local area and then move East across the area, or whether the line will not form until the associated frontal boundary moves to the immediate East of I-35 during the 4-7pm time period. This aspect of the situation should become more clear around midday today or early this afternoon, and we'll provide additional information as the situation unfolds.

...Expected Rainfall and Possible Low Land Flood Risk...
Present indications suggest that rainfall is likely to average 2-3 inches across most of the area, with localized amounts of 3-4 inches possible in some spots. About 25 percent of that amount is expected to occur this morning, with the majority of the remainder likely to occur this afternoon into early this evening.

Present indications suggest the primary time of concern for possible low land flooding to develop will be from around 2-3pm through about 8-9pm this afternoon/evening. Depending upon the coverage and amount of heavy rain, a low land (i.e., low water crossing, etc.), a flood condition could linger into the pre-dawn hours of Thursday, well after the falling rain has ended (as runoff from earlier rain will continue). If the heavier rain does in fact exit the region by 7-8pm this evening as is currently expected, then any flood condition of low water crossings, etc., should decrease during the pre-dawn hours of Thursday, before the morning rush period begins, but again, this will depend on the extent of the afternoon/early evening activity overall.

...Strong to Severe Thunderstorm Risk this Afternoon/Early this Evening...
A few stronger thunderstorms could produce strong, gusty winds and/or hail in some parts of the area this afternoon into early this evening. It is also possible that a more organized line of thunderstorm activity could move into the area late this afternoon/early this evening, especially between 4pm and 7pm. If this occurs, an enhanced possibility of strong, possibly damaging wind gusts could result, and isolated spin-up type tornadoes sometimes occur with such activity as well. Details on this possibility should become more clear during the midday/early afternoon hours as activity evolves.

Locally Heavy Rainfall Likely at Times for Most of the Area on Wednesday...

Expected impacts:

• Scattered showers and thunderstorms are expected to develop just before dawn on Wednesday, and then increase into the daytime and evening hours on Wednesday
• Present indications suggest that locally heavy rainfall is likely at times with this activity across much of the local area
• Periods of heavy rainfall may lead to flooding at times, especially in low lying and poor drainage areas, which could extend beyond the time the rainfall ends, into early Thursday morning
• Present indications suggest that rainfall is likely to average 2-4 inches across most of the area, with localized amounts of 4-6 inches possible in some spots on Wednesday
• In addition to the threat of locally heavy rainfall, a few of the thunderstorms could also produce strong, gusty winds and/or hail in some parts of the area during the day on Wednesday

Discussion:
Scattered showers and thunderstorms are expected to develop just before dawn on Wednesday, and then increase in number and intensity into the daytime and evening hours on Wednesday. Present indications suggest that locally heavy rainfall is likely at times with some of this activity, potentially across large portions of the area.

Present indications suggest that rainfall is likely to average 2-4 inches across most of the area, with localized amounts of 4-6 inches possible in some spots. The majority of the rainfall is expected to occur during the period 6am on Wednesday morning to 12 Midnight on Wednesday night.

Periods of locally heavy rainfall may lead to flooding at times, especially in low lying and poor drainage areas, which could extend beyond the time the rainfall ends, into early Thursday morning. While present indications suggest that the rain itself will end around Midnight on Wednesday night, runoff will likely continue into the pre-dawn and early morning hours of Thursday, which could cause a low land flood risk to extend into the Thursday morning rush period. The extent to which this occurs will obviously be highly dependent upon the exact amount and coverage of rainfall on Wednesday/Wednesday evening.

Impacts from low land flooding are possible both for the afternoon/evening rush period on Wednesday, as well as the morning rush period on Thursday. As the precipitation is currently expected to be more in the developmental stages early on Wednesday morning, significant impacts appear unlikely for the Wednesday morning rush time period, but that could change in future updates if significant shifts in timing occur.

In addition to the threat of locally heavy rainfall, a few of the thunderstorms could also produce strong, gusty winds and/or spotty hail in some parts of the area during the day on Wednesday, especially during the afternoon and early evening hours.

We will continue monitoring the situation and issue updates as conditions warrant.

Forecaster Confidence (Low/Moderate/High):

Moderate to High

Cold Rain Likely Wednesday into Thursday Morning; Some Minor Flooding Possible...

With this update we are shifting the focus from wintry precipitation (although that is still possible briefly on Thursday morning but without consequences locally), to the potential for locally heavy rainfall which appears increasingly likely locally on Wednesday. Please see below for all details:

Rain will develop around or shortly after Midnight tonight and increase into the day on Wednesday, likely falling moderately to heavily at times on Wednesday. While moderate to heavy downpours will be possible at times anytime during the day on Wednesday, there may be an extended period of concentrated locally heavy rainfall at times particularly from around 10 or 11am to about 3 or 4pm on Wednesday.

With ground conditions remaining saturated across the area from recent rains, any prolonged periods of moderate to heavy rainfall may result in mostly minor flooding of low lying and poor drainage areas at times in some parts of the area on Wednesday into Wednesday evening. Low water crossings and similar flood prone areas would be the primary concern in this scenario.

Periods of rain will continue Wednesday night and into pre-dawn Thursday, then diminish by around 10am on Thursday. Storm total rainfall of 1-2 inches is likely on a widespread basis (from after Midnight tonight to 10am Thursday), with some 2-3 inch amounts possible in spots.

Throughout the duration of the rainfall, temperatures will be cold - generally in the 30s - however present indications suggest that we will not reach freezing at the surface level across the local area during the period. Temperatures will reach the mid 30s on Thursday morning, and we cannot completely rule out that some sleet or light snow could mix in at times with the rain as it ends on Thursday morning, but no accumulation will occur locally.

We will continue monitoring the situation and issue updates as conditions warrant.