Heavy rain will create flash flood threatMay 9th, 2012 at 6:59 pm by Jim Spencer under Weather
Rain and thunderstorms are expected to increase across the area Thursday night into Friday morning. A few severe thunderstorms are also possible. The latest projections from computer models and the National Weather Service have decreased slightly the forecast rainfall totals to 2-3″, with isolated 4-6 inch amounts.
The upper level storm system bringing the rainfall is now tracking across northern Mexico, and won’t move away from our area until Saturday, so some lingering showers could continue into the weekend, though the heaviest rain should end by Friday night.
A strong upper level disturbance will begin to impact the area on Thursday and continue through Friday…with the potential for severe thunderstorms and flooding rains. The main severe weather threat will be Thursday afternoon and evening along and south of a line from Karnes City to San Antonio to Del Rio. The main threats will be large hail and damaging winds. The other threat will be flash flooding. Widespread rainfall is expected. Rainfall amounts will average 2 to 4 inches, with isolated amounts over 4 inches possible. A flash flood watch is in effect for the Hill Country and South Central Texas, from 6 PM Thursday to Noon Friday.
FLOOD WATCH NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX THU MAY 10 2012 ...A FLASH FLOOD WATCH REMAINS IN EFFECT FOR ALL OF SOUTH CENTRAL TEXAS FROM 6 PM THIS EVENING UNTIL NOON FRIDAY... .AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS NORTHERN MEXICO WILL MOVE EASTWARD ACROSS TEXAS THROUGH FRIDAY. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH THIS AFTERNOON AND INTO THE EARLY MORNING HOURS FRIDAY. RAIN CHANCES ARE EXPECTED TO DECREASE FROM WEST TO EAST DURING THE DAY FRIDAY.
WITH SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS EXPECTED THROUGHOUT THE DAY TODAY AND THROUGH THE OVERNIGHT HOURS. AVERAGE RAINFALL TOTALS THROUGH FRIDAY MORNING ARE EXPECTED TO BE 2 TO 4 INCHES...WITH ISOLATED TOTALS IN EXCESS OF 4 INCHES POSSIBLE. SINCE SOILS OVER SOUTH CENTRAL TEXAS HAVE ALREADY BEEN MOISTENED FROM RAINFALL EARLIER THIS WEEK...THE HEAVY RAINS SHOULD PRODUCE FASTER RUNOFF AND AN INCREASED POTENTIAL FOR FLASH FLOODING...AS WELL AS FLOODING OF SMALL CREEKS AND STREAMS. ...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 6 PM CDT THIS EVENING THROUGH FRIDAY MORNING... THE FLASH FLOOD WATCH CONTINUES FOR * THE FOLLOWING COUNTIES IN SOUTH CENTRAL TEXAS...ATASCOSA... BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL... COMAL...DEWITT...DIMMIT...EDWARDS...FAYETTE...FRIO... GILLESPIE...GONZALES...GUADALUPE...HAYS...KARNES...KENDALL... KERR...KINNEY...LAVACA...LEE...LLANO...MAVERICK...MEDINA... REAL...TRAVIS...UVALDE...VAL VERDE...WILLIAMSON...WILSON AND ZAVALA. * FROM 6 PM CDT THIS EVENING THROUGH FRIDAY MORNING * AVERAGE STORM TOTAL RAINFALL AMOUNTS OF 2 TO 4 INCHES WITH ISOLATED TOTALS HIGHER THAN 4 INCHES POSSIBLE. * PERIODS OF RAIN...HEAVY AT TIMES...WILL PRODUCE FLASH FLOODING OF NORMALLY DRY CREEK BEDS...POOR DRAINAGE AREAS AND LOW WATER CROSSINGS. URBANIZED AREAS INCLUDING LOCATIONS IN AND AROUND THE AUSTIN AND SAN ANTONIO METRO AREAS CAN EXPECT RUNOFF TO MAKE SOME ROADWAYS IMPASSABLE. THE FLASH FLOOD IMPACT WILL BE HIGHEST THIS EVENING INTO FRIDAY MORNING. PRECAUTIONARY/PREPAREDNESS ACTIONS... A FLASH FLOOD WATCH MEANS FLASH FLOODING IS POSSIBLE IN OR NEAR THE WATCH AREA. IF YOU ARE IN THE WATCH AREA...PLAN NOW FOR WHAT YOU WILL DO IF FLASH FLOODING DEVELOPS. STAY INFORMED AND BE READY TO ACT IF YOU SEE FLOODING OR IF A FLASH FLOOD WARNING IS ISSUED.