Flash Flood Watch/Severe Weather Risk

Hello, folks! The fourth storm system this month has its eyes set on Texas and we're already feeling its effects. The upper level low is currently located in northern Mexico south of Arizona and is pushing disturbances across the state of Texas out ahead of it. These disturbances generate lift in our atmosphere. That lift helps to promote the development of showers and thunderstorms.

Image above courtesy of earth wind map and is depicting upper level winds over Mexico and the United States

Gulf moisture has already made a big return to the area as of Wednesday afternoon as evidenced by dew point temperatures in the upper 60s. At the surface a cold front is currently draped along the I-20 corridor across West Texas and is the focus for thunderstorm development this afternoon. Yellow shaded area north west of south central Texas is under a SEVERE THUNDERSTORM WATCH until 11pm CDT this evening. The storms outlined in red boxes are severe.

Texas Radar Update as of 5:20 pm CDT Tuesday evening

What should we expect in central Texas?

This evening/overnight:Widespread shower and thunderstorm activity will remain well to the north and west of our region tonight. A few thunderstorms may try and creep into northwestern areas of the Hill Country, but the storms will hold off for the I-35 corridor until Wednesday and especially Wednesday afternoon and evening. With that being said, a brief passing shower or downpour cannot be ruled out overnight and early Wednesday morning. Lows tonight will only manage the 60s area wide thanks to a persistent moist southerly breeze off of the Gulf of Mexico.

Wednesday Morning: Showers and storms may be ongoing across portions of the northwestern Hill Country and a large portion of west Texas slowly spreading south and east into the Hill Country during the early afternoon hours.

Wednesday afternoon/evening: Scattered showers and thunderstorms will begin to pop up along the I-35 corridor, becoming more widespread as a line of storms develops across the Hill Country and pushes slowly east through the I-35 corridor during the early evening hours. This is when the worst of the storms are expected in Austin/IH-35 corridor. In addition to the threat of locally heavy rainfall and dangerous cloud to ground lightning, the Storm Prediction Center based in Norman, Oklahoma has placed a large swath of central, south central, south, and southeast Texas under a SLIGHT RISK area for potential severe weather on Wednesday. This is a threat level 2 out of 5 and indicates that scattered severe storms will be possible, but the severe storms that develop will be short-lived and/or not widespread; however, an isolated intense storm or two is possible.

Forecast Radar Graphic (this is what one model believes the radar will look like at different times of the day on Wednesday)

Wednesday Severe Weather Threats

Flash Flood Watch (counties shaded in green)
in effect for the following counties: Travis, Williamson, Hays, Burnet, Blanco, Llano, and Gillespie from 7 am CDT Wednesday until midnight Thursday. Widespread amounts of 2-4 inches of rain will be possible in these locations with isolated higher amounts of up to 6 inches possible.

Images above courtesy of the Austin/San Antonio National Weather Service Forecast Office

Please remember, IF YOU COME ACROSS A FLOODED ROADWAY, TURN AROUND, DON'T DROWN!!!

Storms Likely Tonight

Forecast Discussion
A potent upper level storm system currently located over New Mexico will be bringing us the opportunity for thunderstorms late this evening and overnight. Out ahead of this storm system, sticky Gulf of Mexico moisture has infiltrated the region and combined with the approaching storm system and a surface dry line and cold front will be the fuel for a few isolated thunderstorms this afternoon and early evening (predominately for areas north and west of the Austin Area) and then widespread thunderstorms late evening into the early morning hours of Thursday for all of central and south central Texas. Storms that are able to develop this afternoon and early evening will have the potential to produce very large hail, damaging winds and isolated tornadoes. The most likely areas for this type of weather will be for areas north and west of the Dallas/Fort Worth Metroplex. I'm expecting quiet conditions across south central Texas until after 10 pm.

What to expect
Given the potent nature of this approaching storm system, severe weather will be possible across the area late this evening into early Thursday morning (pre-dawn). The Storm Prediction Center out of Norman, Oklahoma has placed a large swatch of north, central and south central Texas under an ENHANCED RISK for severe weather today/tonight. An enhanced risk is a level 3 out of 5 severe weather threat. The Storm Prediction Center defines an enhanced risk as "numerous severe storms possible" and the storms that develop will be "more persistent and/or widespread, a few intense."

Severe Weather Threat: Enhanced Risk (Orange shaded areas)
All modes of severe weather will be possible tonight (large hail, damaging winds, and perhaps an isolated spin-up tornado). I believe the greatest risks for the I-35 corridor will be the potential for some larger hail (potentially up to the size of golf balls) & some damaging wind gusts. Frequent and dangerous cloud to ground lightning and heavy rain will accompany all storms that develop.

Areas surrounding the enhanced risk area are in a slight risk (yellow shaded areas) category (threat level 2 out of 5)

What makes a thunderstorm severe?
A thunderstorm is considered to be severe by the National Weather Service if it's producing:

1. hail of at least of one inch in diameter or greater (quarter-sized)
2. and/or winds in excess of 58 mph or greater
3. and/or a tornado

Storm Timeline (High Resolution Rapid Refresh Model Imagery)

*times below are an estimate, line of storms will arrive along the I-35 corridor between 11:30 pm to 1:30 am

9 pm | Line of storms develops across the far western Hill Country 

11 pm | Line of storms pushing through the Hill Country (still west of the Hwy 281 corridor)

1 am | Line of storms overtakes the I-35 corridor

3 am | Residual light to moderate rains continue across the I-35 corridor; heaviest storms pushing through Lee & Fayette County

7 am | Line of storms pushing through east and southeast Texas 

How much rain can we expect?

On average 0.5 - 1.5 inches of rain...some areas out west will see less than that and some areas along and east of the I-35 corridor may see more than that. Flash flooding is not expected to be a concern at this time, but short-lived heavy downpours may result in minor street flooding late tonight/early Thursday. 

Thursday/Easter Weekend Outlook
All of this activity will quickly push east of the area by sunrise Thursday as high pressure builds in from the west leaving us with a sunny, gusty, and cooler day with highs in the 70s. Highs rebound into the 80s by the weekend with more cloud cover returning each day. No rain is expected.

***Please remain weather aware this evening and overnight and have a way to receive watches/warnings. It would be a good idea to have a flash light handy and your cell phones fully charged by midnight tonight just in case power goes out in your area.

Storm Chances Increasing

Thursday's Record Heat

The temperature soared to 92°F at Austin's Camp Mabry Thursday afternoon beating the previous record high of 89°F set back in 2017. Austin Bergstrom International Airport missed their record high of 92°F set back in 1958 by one degree. Abundant sunshine, abnormally dry conditions, and a down-sloping westerly component to the wind on Thursday allowed temperatures to soar. Keep in mind the average high temperature for this time of year is closer to 77°F.

Weekend Storm Chances

A series of upper level disturbances will be passing through the state of Texas this weekend and each disturbance will bring us a chance for showers and thunderstorms. A few of which will have the potential to be on the strong/severe side with large hail & damaging winds being the primary threats. The best chance for widespread showers and thunderstorms will come on Saturday (especially Saturday morning into early Saturday afternoon), but rain chances will begin to increase late tonight (most likely after 11 pm).

Severe Weather Risk: SLIGHT 

Given the potential for some isolated to scattered severe weather, the Storm Prediction Center out of Norman, Oklahoma has placed a large portion of central and east Texas under the SLIGHT RISK area for potential severe weather on Saturday and shifted the SLIGHT RISK area for potential severe weather farther east for Sunday. The severe weather threat will stay west of the area today. See outlooks below. 

Friday Severe Weather Risk Area

Saturday Severe Weather Risk Area

Sunday Severe Weather Risk Area

Understanding Severe Weather Risk Outlooks

Forecast Rainfall Accumulation

Between late Friday night through Sunday afternoon, 1-2 inches of rain may fall across central Texas with some areas potentially seeing more and some areas potentially seeing less. Areas west of the IH-35 corridor may see less than areas east. Flash flooding does NOT look to be a concern at this point in time, but if things do change always remember TURN AROUND, DON'T DROWN.

NWS Forecast Rainfall Accumulation (1-3 Day Outlook)

valid now through early Monday AM