Rain and storms expected through Wednesday morning

January 8th, 2013 at 3:00 pm by under Weather

A strong upper level low pressure storm system will move across South Central Texas on Wednesday and to North Texas and Oklahoma Wednesday night. The storm system in combination with rich tropical moisture from the Gulf of Mexico and eastern Pacific, will produce widespread shower and thunderstorm activity through Wednesday. Some of these storms could become strong to severe this evening and tonight with damaging winds, hail, and heavy rainfall possible. Some isolated tornadoes are also possible mainly near and south of I-10 and east of I-37. Rainfall totals could range from one half to one inch west of highway 83, one to two inches from east of highway 83 to highway 281, from 2 to 3 inches from Highway 281 to a line from Georgetown and Austin to Yorktown and 3 to 6 inches along and east of a line from Georgetown and Austin to Yorktown. (National Weather Service)

There is a slight risk of severe thunderstorms through Wednesday morning south and east of a line from Lexington to Lakeway to Helotes to Carrizo Springs. The main threat will be damaging winds however isolated tornadoes will be possible across our southeast counties…generally south of I-10 and east of I-37. A flash flood watch is in effect through noon Wednesday for the following counties, Bastrop, Caldwell, Dewitt, Fayette, Gonzales, Lavaca. Lee, Travis and Williamson. Rainfall totals of 3 to 6 inches are possible across the watch area which may result in flooding. (National Weather Service)
Here is a message from Paul Yura, the Warning Coordination Meteorologist at our local National Weather Service:
…Heavy rain and thunderstorms tonight and Wednesday.  Severe Weather and Flash Flooding possible…

An upper level storm moving across northern Mexico is causing scattered showers and thunderstorms to form this afternoon across many sections of South Central Texas.  A Flash Flood Watch has been issued for Williamson….Travis…Lee…Bastrop…Caldwell…Fayette…Gonzales…Lavaca…and DeWitt Counties until Noon on Wednesday as rains are expected to become more widespread over the next 24 hours and could total 3 to 6 inches.   Severe weather chances will increase during the late afternoon and evening…but be mainly confined to east of I-35.    Main impact time of possible flooding and severe weather will be from 8pm Tuesday to Noon on Wednesday.  Isolated tornadoes are possible….mainly south of I-10 and east of I-37 and east of I-35.

Tuesday afternoon

As the upper low approaches Texas from the west during the next 24 hours, rains will become more widespread across South Central Texas.  Brief heavy downpours are expected with the showers and storms through late afternoon although dont expect any major problems expect some minor urban type street flooding.  The storms are moving fairly fast so it will take a lot of training to produce high rain totals.  A few spots may receive 1 inch by early this evening but those totals should be isolated.  Severe risk is low this afternoon.

Tuesday Night/Early Wednesday
Heavy rainfall is expected across most of South Central Texas.  A large complex of showers and storms will likely form and move to the east and northeast across the I-35 corridor.  Rainfall totals will increase as you head to the east.  I have attached a graphic showing the latest forecast rain totals and threats.  Storm total rainfall amounts of up to 1 inch along the Rio Grande from Del Rio to Eagle Pass…1-2 inches over most of Hill Country….2-3 inches along the I-35 Corridor from Austin to San Antonio…and 3-6 inches mainly east of I-35 as you head along I-10 and Highway 290 toward Houston.

This evening and overnight, there will be a severe risk although it will be fairly isolated.  Could have a few spots with wind damage and even an isolated tornado.  We had several small tornadoes with an event in January 2012.    The highest severe risk will be south and east of I-35.  Would expect most severe reports to be along or near the Texas Coast….but cant rule it out over South Central Texas.

Event Ending on Wednesday afternoon:
The weather system will start to push east out of South Central Texas by Wednesday afternoon.  Rains should generally end from west to east starting Wednesday morning while significant rains should end over the eastern sections by Wednesday afternoon.  The large upper low will still be over the central part of the state late Wednesday but overall weather threats will have ended.

Rainfall Impacts
Heavy rainfall will lead to increased flows of creeks and low water crossings. Urban flooding in the Austin and San Antonio metro areas appears likely given the expected rainfall amounts. Due to the ongoing drought, area lake, reservoir and river levels are low. At this time, flooding of main stem rivers is not expected, although river levels will likely rise given the expected rainfall amounts.  Always remember that the majority of flash flood deaths occur at nighttime.  Since we are expecting heavy rains late Tonight into early Wednesday, remember…Turn Around Dont Drown.

Please continue to monitor our website at weather.gov/austin for the latest information and forecasts on this weather system.

Paul Yura
National Weather Service Austin-San Antonio TX

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