Friday Severe Threat

Weather Set Up

A potent and far southward-digging upper level storm system (trough of low pressure) and its attendant surface cold front will approach and move across the state of Texas on Friday. Ahead of this strong storm system, strong south southeasterly winds have developed. Those winds off of the Gulf of Mexico are pumping in lots of Gulf of Mexico moisture for the approaching storm system to work with to generate thunderstorms, some of which are likely to be strong/severe, Friday afternoon/evening/night across central, south central, north, southeast and east Texas. 

Threat Level by City

Austin Threat Level: Enhanced

San Antonio Threat Level: Slight

Houston Threat Level: Enhanced

Dallas/Fort Worth Threat Level: Enhanced

Central Texas Severe Outlook

Graphic courtesy of Meteorologist Avery Tomasco at CBS Austin News

Texas Severe Outlook

What does an enhanced risk of severe storms mean? Let’s take a look – plus I've added our threat levels for Friday's forecast

   

Numerous severe storms possible. The severe storms that develop will be more persistent and/or widespread and a few may be intense

      A few tornadoes possible – LOW THREAT

Several reports of wind damage – MODERATE THREAT

 Damaging hail 1-2 inches in diameter – LOW THREAT

***Widespread severe weather is NOT expected, however, there is the potential for some areas to receive some severe weather

Friday Weather Timeline

As it looks right now, passing showers and perhaps a thundershower will be possible Friday morning through early afternoon across central Texas (I think a lot of that activity will be limited by a layer of warmer air aloft) with the more organized activity developing late afternoon into Friday evening along and just west of the I-35 corridor as the main upper level energy and a cold front begin to move in. Based on the latest high resolution forecast model data, it appears that there is the potential for a rapidly developing squall line (line of thunderstorms) to initiate along and possibly just west of the I-35 corridor between 4-8 p.m. CST Friday evening. The greatest severe threat from these developing storms will be damaging winds in excess of 60-75 mph. Once this line of storms initiates, it will continue to march east with the cold front and upper level storm system. The severe threat looks to ramp up once the line of storms pushes east of the I-35 corridor.

Tornadoes??
There is a low-end tornado threat across the area tomorrow evening, however, the best dynamics for tornadoes appears to remain east and especially well to the northeast of the I-35 corridor into east Texas and northeast Texas (red shaded area on the Texas map above). Damaging wind gusts still appear to be the biggest threat from storms that develop locally. Additionally, all storms that develop will have the potential to produce brief heavy downpours and dangerous cloud to ground lightning.

I do need to mention that if the forecast line of storms remains broken (rain free areas in between the forecast line of storms) and if isolated storms are able to develop ahead of the forecast line of storms, those discrete thunderstorm cells will have the best potential to rotate and perhaps produce a tornado. This will need to be watched closely and it is by no means likely or a sure thing. 

Along with all that I’ve mentioned above, it’s possible that we only see garden variety showers and storms in Austin with the worst of the weather potentially staying off to our east.

Rainfall Accumulation
A quick 0.5-1.5 inches of rain will be possible...some may receive more and some may receive less. Rainfall is very welcome at this time and flash flooding does NOT look to be an issue on Friday.

With all that noted, we will all need to remain weather aware Friday afternoon/evening. With the potential for severe weather, it is always a good idea to turn on emergency alert notifications on your cell phone.

How to enable emergency alerts on iPhone

Open settings à notifications à scroll down to the bottom of notifications tab to where it says “Government Alerts” and turn on “Emergency Alerts”

Should and if a tornado or flash flood warning were to be issued, you would receive notification on your phone

What to Expect behind the Storms & the Weekend

Behind the line of storms, lingering showers and thundershowers may persist for 2-3 hours before conditions rapidly clear from west to east behind the storm system as a much drier and cooler air mass infiltrates the region.

Highs Saturday despite a sunny sky will only manage the 50s to lower 60s (near normal for this time of year) with a breezy northwest wind. As winds relax Saturday evening under a clear sky, temperatures will plummet into the 20s to middle 30s across the area by early Sunday morning. Low-lying, out-lying locations will likely receive a freeze with areas like downtown Austin staying a few degrees above 32°F.

Sunny and near perfect conditions expected for your Sunday with highs rebounding into the lower 60s under a mainly sunny sky.