Austin / Travis County and South Central Texas Weather Update #3
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
1030pm CDT – Tuesday / 19 March 2013
… Severe Weather Risk Locally Slowly Diminishing …
Please see this SPC/Storm Prediction Center mesoscale discussion just issued for an update of our severe thunderstorm watch…
http://www.spc.noaa.gov/products/md/md0288.html
At 1030pm… Doppler weather radars indicated scattered rain showers and thunderstorms over parts of Llano.. Burnet.. Blanco and Gillespie counties.. but no severe weather has been indicated in the last few hours. A few of the stronger thunderstorms may contain hail up to 3/4 to 1 inch in diameter.
As a result, while we may indeed see some additional rain shower and thunderstorm development and some small hail may result, I feel as though the overall severe weather risk is diminishing. Remember, though, the the NWS Severe Thunderstorm Watch remains officially in effect until midnight or until officially canceled by the NWS.
This is my last statement regarding this weather situation.
tk
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Austin / Travis County and South Central Texas Weather Update #2
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
815pm CDT – Tuesday / 19 March 2013
… Cold Front Moving Southward Through the Austin Area …
… SPC Mesoscale Discussion Issued for Area (Update on Severe Thunderstorm Watch) …
At 815pm.. a cold front is moving through the Austin area. It passed through northwest Austin at 802pm and winds picked up from the northeast and the dew point temperature has fallen about 4 degrees since then. This wind shift line will continue to move southward through the remainder of the Austin metro area through 9pm. It is well depicted by a fine line in base reflectivity WSR88D data from Granger (KGRK) radar data.
At 815pm.. the nearest thunderstorm activity is located just southwest of Burnet /Burnet County/ and just northwest of Florence /Williamson County/.
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NWS / Storm Prediction Center has issued a mesoscale discussion updating us on the severe thunderstorm watch (until 12 midnight). You can see it here…
http://www.spc.noaa.gov/products/md/md0287.html
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I will continue to keep you informed…. tk
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Austin / Travis County and South Central Texas Weather Update #1
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
555pm CDT – Tuesday / 19 March 2013
… SPC Mesoscale Discussion Issued …
… SPC Severe Thunderstorm Watch Issued for All of Area …
For SPC Mesoscale Discussion, please see… http://www.spc.noaa.gov/products/md/md0285.html
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… Authority / NWS Storm Prediction Center …
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 56
NWS STORM PREDICTION CENTER NORMAN OK
545 PM CDT TUE MAR 19 2013
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
PARTS OF CENTRAL AND SOUTHEAST TEXAS
EFFECTIVE THIS TUESDAY AFTERNOON FROM 545 PM UNTIL MIDNIGHT CDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 125 MILES WEST
NORTHWEST OF AUSTIN TEXAS TO 30 MILES SOUTH SOUTHEAST OF COLLEGE
STATION TEXAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).
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THIS WATCH INCLUDES TRAVIS COUNTY AND ALL SURROUNDING COUNTIES
AND INCLUDES THE GEORGETOWN-ROUND ROCK-AUSTIN-SAN MARCOS IH35
METRO AREA...
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REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
DISCUSSION...THUNDERSTORM DEVELOPMENT IS UNDERWAY ACROSS CENTRAL TX
NEAR THE INTERSECTION OF A DIFFUSE TROUGH/DRYLINE AND WNW-ESE
ORIENTED SURFACE FRONT. THE AIR MASS S OF THE FRONT IS MODERATELY
UNSTABLE WITH BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 50S AND
TEMPERATURES IN THE LOW-MID 80S...WHICH IS DRIVING MLCAPE AROUND
1500 J/KG. MEANWHILE...WATER VAPOR IMAGERY SHOWS THE APPROACH OF A
MID-UPPER JET STREAK MOVING FROM NM INTO W CENTRAL TX...AND ASCENT
IN THE EXIT REGION OF THIS JET STREAK WILL OVERSPREAD CENTRAL TX
THIS EVENING. THUS...THUNDERSTORMS ARE EXPECTED TO INCREASE IN
COVERAGE/INTENSITY THIS EVENING...IN AN ENVIRONMENT WITH SUFFICIENT
DEEP-LAYER VERTICAL SHEAR FOR SUPERCELLS. LARGE HAIL WILL BE THE
PRIMARY SEVERE THREAT WITH THE INITIAL SUPERCELLS...AND THE RISK FOR
A FEW DAMAGING GUSTS WILL DEPEND MORE ON UPSCALE GROWTH INTO A
CLUSTER THROUGH STORM MERGERS.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 30025.
...THOMPSON
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Austin / Travis County and South Central Texas Weather Update
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
830am CDT – Tuesday / 19 March 2013
.. NWS/Storm Prediction Center Posts “Slight Risk” of Severe Thunderstorms for Area …
In their latest outlook issued in the last hour, the NWS/Storm Prediction Center has placed
all of south central Texas in a “slight risk” area for severe thunderstorms later this afternoon into tonight with main risk being larger hail. You can see this day one outlook at… http://www.spc.noaa.gov/products/outlook/day1otlk.html
An upper air disturbance, over the southwestern USA, will continue east southeastward toward Texas by tonight with the front to the south.. that moved through our area yesterday afternoon.. and the associated moisture to its south returning back northward as a result. As the upper air disturbance moves overhead tonight, there will be abundant atmospheric lift and instability and the question, I think, is how efficiently moisture will return to the area in advance of the system and exactly how much will be available as the system passes.
This is one of these cases where I think the strong lift and instability will compensate for any lack of moisture across the area. As a result, we’ll likely see widely scattered to scattered thunderstorms develop out to our west (over the hill country) by late afternoon and then progress eastward tonight as the upper air disturbance moves eastward across the area. Stronger thunderstorms may produce larger hail in excess of 1 inch in diameter locally for the 6pm to 12 midnight time frame. Once the upper disturbance moves eastward across the IH35 corridor, a cold front will move through the area with rain chances decreasing thereafter.
I’ll continue to keep you informed regarding the evolving severe weather (large hail) threat.
tk
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Updated 845am CDT Tuesday / 19 March 2013
A Weakening Cold Front Over Far South and West Texas ….
Upper Air Disturbance to Move Overhead with Associated Cold Front Tonight ….
More Clouds Due Late Week as a Stronger Cold Front Moves Through Friday ….
On this Tuesday… a weakening cold front extends from a surface low over central Georgia southwestward across the Florida panhandle through the north central and northwestern Gulf of Mexico into south Texas north of Brownsville into northeastern Mexico then into a developing surface low over southwest Texas and southern New Mexico. The cold front extends westward from the developing surface low through southern New Mexico. Given this surface pressure pattern, surface winds are light north northeasterly across our area of Texas.
In the upper levels of the atmosphere, a broad upper air trough.. or line.. is located over the eastern 2/3rds of the USA. Within this broad flow, a disturbance is located over the southwestern USA. As a result of this upper air wind flow, our upper level winds are light to moderate west northwesterly with winds over Austin at about 18,500 feet blowing about 35 to 45 mph.
The surface cold front.. which moved across our area yesterday afternoon.. has weakened and settled to our distant south.
The upper air disturbance, to the west of us, will continue east southeastward toward Texas by tonight with the front to the south and the associated moisture to its south trying to return back northward as a result. As the upper air disturbance moves overhead tonight, there will be abundant atmospheric lift and instability and the question is how much moisture will be available. This is one of these cases where I think the strong lift and instability will compensate for any lack of moisture across the area. As a result, we’ll likely see widely scattered to scattered thunderstorms develop out to our west (over the hill country) by late afternoon and then progress eastward tonight as the upper air disturbance moves eastward across the area. Stronger thunderstorms may produce larger hail in excess of 1 inch in diameter for the 6pm to 12 midnight time frame. Once the upper disturbance moves eastward across the IH35 corridor, a cold front will move through the area with rain chances decreasing thereafter.
A partly cloudy sky will prevail in the wake of the overnight system tomorrow into tomorrow night with temperatures at or slightly below average.
By Thursday into Thursday night, surface winds turn more south southeasterly and surface moisture will be on the increase with clouds increasing as well. As the atmosphere becomes more moist and unstable, we’ll see a slight chance of rain ahead of a stronger cold front due in the area by late afternoon on Friday.
Much cooler and drier air will move into the area Friday night through the weekend with overnight lows falling into the 30s in the outlying and low lying areas and 40s elsewhere over the weekend. Daytime high will be well below average with highs in the 60s to near 70 with a partly cloudy sky prevailing.
Have a good Tuesday night and Wednesday…
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel