Austin / Travis County and South Central Texas Weather Statement #1
Prepared by UT University/Incident Meteorologist Troy Kimmel
900am CT – Wednesday / 15 April 2015
Severe Thunderstorm Risk for Tomorrow and Tomorrow Night ..
NWS WATCHES / ADVISORIES / WARNINGS:
At this time, there are no watches/advisories/warnings that include the greater
Austin metro area or the IH35 corridor counties of Travis.. Hays and Williamson.
At the very least tomorrow, I expect the NWS/Austin-San Antonio to issue
Significant Weather Advisories (SPSEWX), Airport Weather Warnings
for Austin Bergstrom International Airport (AWWAUS) as well as the
possibility of Urban and Small Stream Flood Advisories (FLSEWX).
SYNOPTIC/FORECAST REASONING:
On the surface weather maps, a weakening front is along the Texas coast with
another cold front extending south from western Colorado into northwest New
Mexico and Arizona. In the upper part of the atmosphere, a strong upper air
low pressure disturbance is located just southeast of the Great Salt Lake.
As the front off the Texas continues to wash out and return northward as a
warm front today into tonight, a return south southeasterly surface wind flow
becomes reestablished over most of Texas. As the surface front and the strong
upper air low pressure area.. both out west.. advances slowly eastward, we’ll see a
the atmosphere locally become much more moist and unstable tomorrow through
Friday.
Atmospheric lift will increase by mid to late morning tomorrow with scattered
rain showers and thunderstorms developing and becoming more numerous late
tomorrow afternoon into tomorrow night and even into early Friday. Even though
the main part of the upper level low will remain to our west northwest, disturbances –
like spokes on a bicycle wheel – will rotate northeastward over our area into the
counterclockwise flow around the upper air low itself. When these disturbances
move through and by the area, this will greatly increase upward lift and will trigger
waves of rain showers and thunderstorms and the attendant risk of severe weather
as well as periods of heavier rain.
At this point, while we could see localized urban and low water water crossing effects,
I’m not as concerned with the flood/flash flood threat as I much as I am with the
overall threat of severe weather as outlooked by the NWS/Storm Prediction Center.
The risk of rainfall exceeding flash flood guidance over the next few days should be
confined to areas along the middle and upper Texas coast.
The cold front will move through the area on Friday with the severe risk and the
overall rain and thunderstorm chances decreasing, but not dropping from the forecast
completely, for Friday night into Saturday. Deadly cloud-to-ground lightning will
continue, of course, to be a threat as long as thunderstorms are in the forecast.
THREAT(S) FOR AUSTIN METRO AND IH35 CORRIDOR COUNTIES:
NWS/Storm Prediction Center “Slight” to “Enhanced” Risk of Severe Thunderstorms
Threats: Larger hail.. damaging straight line thunderstorm winds as well as the
presence of deadly cloud-to-ground lightning. Any risk of any tornadoes appears to
be greatest to the south through southeast of the Austin area.
Geographic area: All of the area
Time Period: Mid morning through midnight Thursday night and perhaps into the
predawn hours Friday morning.
MY FORECAST CONFIDENCE:
Weather system evolution: High to very high
Precipitation chances: Increasing to high by mid morning tomorrow through early Friday
Liquid precipitation (rain) chances: Increasing to high by mid morning tomorrow through early Friday
Freezing precipitation (freezing rain/freezing drizzle) chances: NONE
Frozen precipitation (snow/ice pellets-sleet) chances: NONE
Thunderstorm/lightning chances: Very high tomorrow mid morning through early Friday
Severe thunderstorm chances: Up to moderate
Flood/Flash Flood chances: Low (perhaps some localized urban/low water crossing flooding)
AVIATION INFORMATION FOR THE AUSTIN/BERGSTROM
INTERNATIONAL AIRPORT (KAUS) AERODROME:
According to the NWS/Storm Prediction Center, the possibility of severe thunderstorms exists
for much of Texas Thursday into Thursday night. Main risks for ABIA aerodrome includes
larger hail along with strong straight line thunderstorm wind and the occurrence of deadly
cloud-to-ground lightning. There is also a smaller risk of tornadoes mainly south through
southeast of the area. Airport weather warnings (AWWAUS) will likely be issued by the
NWS/Austin-San Antonio tomorrow.. tomorrow night into early Friday as thunderstorms
develop over or move over the aerodrome.
Current KAUS Terminal Aerodrome Forecast (TAF) – Issued 151140z ..
KAUS 151140Z 1512/1618 VRB03KT P6SM BKN035
TEMPO 1512/1514 5SM BR BKN030
FM152000 15007KT P6SM SCT050
FM160400 16008KT P6SM BKN020=
. For Our DAL/DFW Hub Aerodromes ..
There is a “marginal” risk of severe thunderstorms for the DAL/DFW aerodromes.
When and if thunderstorms develop or move over the aerodromes tomorrow through
tomorrow night, expect delays and perhaps some diversions.
For Our HOU/IAH Hub Aerodromes ..
There is a “slight” to “enhanced” risk of severe thunderstorms for the HOU/IAH
aerodromes.. this is a higher risk than the marginal risk. When and if thunderstorms
develop or move over the aerodromes tomorrow through tomorrow night, expect
delays and perhaps some diversions.
Current FAA National Airspace Status
CALL TO ACTION:
Please remain “weather aware” and listen for the latest weather statements,
advisories, watches and warnings from the National Weather Service.
Today is the day to make sure that your NOAA All Hazards Weather Radios are
operational and are set to alarm in case of severe and inclement weather watches
and/or warnings.