Troy Kimmel Weather

Forecasting Austin and South Central Texas Weather Since 1984

TK’s Weather Discussion

…. SPECIAL UPDATE ….

Austin / Travis County and South Central Texas Weather Update #1
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
100pm CDT – Tuesday / 21 May 2013

.. Severe Weather Threat Continues …

At 1pm… there’s not much new to report. The NWS/Storm Prediction Center threat areas
(slight and moderate) generally cover the same areas. A TORNADO WATCH continues for
counties to our north (Bell and Milam) until 7pm CT.

I have been talking about thunderstorms over north Texas moving eastward and some
“back building” (southwestward) into our area. The latest guidance is also suggesting that I
pay a little more attention to areas to our west (western Hill Country) for development this
afternoon that, as it moves eastward, would impact our area from the west later this afternoon
into tonight. Latest visible satellite data suggests some cloud enhancement in these areas. As a
result, let’s continue to monitor all areas to our west and southwest through the northwest and
north this afternoon into tonight for thunderstorms that could potential affect our area later.

One interesting factor at midday that we’ve noticed is the persistence of low level cloudiness
over the area which is keeping us from getting as warm as we might otherwise be. This factor
would make the atmosphere not as unstable  as it might otherwise be. Just something to keep
in mind..

The severe weather risk continues locally with the biggest risk being large, damaging hail as well
as damaging straight line thunderstorm winds. In addition, especially north and east of Austin.. there
is an attendant tornado threat as well. Everyone should be weather aware now through the midnight
hour tonight and be ready to take action in case the NWS issues additional watches/advisories/warnings
as we go into the late afternoon and evening hours.

Remember.. check that NOAA All Hazards (Weather) Radio NOW and make sure it’s ready
to alarm in case those watches and/or warnings start to be issued by the NWS.

NWS/Austin-San Antonio webpage…
http://www.srh.noaa.gov/ewx/

I’ll continue to monitor..  tk

Austin / Travis County and South Central Texas Weather Update
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
900am CDT – Tuesday / 21 May 2013

.. Severe Thunderstorm Outbreak Expected Across Texas Later Today into Tonight …

.. Synoptic / Forecast Discussion …
On this Tuesday morning… a trough.. or line.. of upper air low pressure is over the central
plains of the USA. Within the counterclockwise flow of this upper air low.. a strong disturbance
is over eastern New Mexico. At the surface, a cold front extends southwestward from northeastern
Oklahoma across the Red River around Wichita Falls into far west Texas near El Paso.

By later today into tonight.. intense daytime heating will combine with available moisture and
increased atmospheric instability as well as the southeastward movement of the weakening cold front
and  the strong upper level low pressure disturbance to create a very unstable and dynamic
atmosphere. As the best lift in the atmosphere passes locally.. in the 3pm to 10pm this afternoon
and tonight.. thunderstorms will develop to the north and northwest of our area initially in the
mid and late afternoon hours and then sweep eastward as the upper air disturbance moves
eastward. The real key to the forecast for this period will be how far these thunderstorms
“back build” south and southwestward into our area for the late afternoon into the evening
hours today.  To me it is clear that the highest risk of severe thunderstorms.. along with a threat
of stronger tornadoes and significantly damaging straight line thunderstorm winds.. will be to our
north and east, however, this threat is not real far from our area so we must remain weather aware
for the afternoon and nighttime hours today.

GENERAL WEATHER THREATS LATER TODAY INTO TONIGHT…

The NWS/Storm Prediction Center (SPC) is forecasting a SLIGHT RISK of severe
thunderstorms for all of our local area later this afternoon into tonight. There is a MODERATE
RISK of severe weather to the north.. northeast and east of the Temple.. Belton. Killeen area
into the ArkLaTex region of northeast Texas.. northwestern Louisiana and southwestern Arkansas.

Main threats locally are very large hail and damaging straight line thunderstorm wind along with
an attendant tornado threat especially in areas north through northeast of Austin.

You can see the day one severe weather outlook from the SPC at…
http://www.spc.noaa.gov/products/outlook/day1otlk.html

Please remember, as usual, during the potential severe/inclement weather episode, please
consult the NWS / Storm Prediction Center website regularly at..
http://www.spc.noaa.gov/products/md/ ..
for the latest mesoscale convective updates as these are usually the “heads up” on impending
severe weather watches.

Latest national NWS QPF guidance suggests that rainfall will be only in the 1/4 to 1/2 inch range
with isolated totals up to 1  to 1 1/2 inch in heavier thunderstorms. Given the current drought
conditions along with the progressive (fast forward movement) nature of the thunderstorms expected
later today, flooding should not be a major problem.

Even though flooding is not expected, you should always remember.. “Turn Around, Don’t Drown”..
which is the National Weather Service safety campaign to get people to recognize flood
dangers and to avoid low water crossings when they are flooded.

As in all anticipated severe/inclement weather events, no matter where you are, please continue
to stay “weather aware” and please check to make sure that your NOAA All Hazard Weather Radios
are operational and are set to alarm in case of severe and inclement weather watches and/or warnings.

AVIATION INFORMATION…

.. FOR THE AUSTIN BERGSTROM INTERNATIONAL (AUS) AIRPORT AERODROME …
Scattered thunderstorms are forecast to build north and northwest of our area by mid and late
afternoon today and then “back build” into the area from the north northeast by evening. Where
thunderstorms develop.. severe weather is quite likely with large hail and damaging straight line
thunderstorm winds possible along with an attendant tornado threat. The thunderstorm chances
will decrease after 10pm to 12 midnight tonight.
NWS issued Airport Weather Warnings are possible as / if thunderstorms develop over or
approach the ABIA aerodrome.

..AUS Terminal Aerodrome Forecast (TAF).. Issued by the NWS at 1134z…

KAUS 211134Z 2112/2218 16012KT P6SM SCT013 BKN021
TEMPO 2112/2114 BKN013
FM211500 15012KT P6SM BKN025
FM211700 18015KT P6SM BKN035
FM220000 15010KT P6SM SCT050 BKN120
TEMPO 2201/2204 VRB30G40KT 1SM +TSRA OVC010CB
FM220800 36007KT P6SM BKN025 OVC250
FM221500 06005KT P6SM FEW050 SCT250=

.. FOR OUR DAL/DFW HUB AERODROMES …
While the strongest afternoon and evening thunderstorms will be south and southeast of the DFW
aerodromes later today.. thunderstorms between now and mid and late afternoon may produce
some severe weather with hail and strong winds at these airports. Delays.. diversions and FAA traffic
management programs are likely today and into tonight as the thunderstorms impact the individual
aerodromes and, of course, the FAA/Fort Worth center airspace as a whole.

.. FOR OUR HOU/IAH HUB AERODROMES …
The greatest risk of severe weather later today into tonight will generally remain north and northwest
of these aerodromes. Some delays and FAA traffic management programs as well as diversions are
possible with thunderstorms later tonight into the predawn hours on Wednesday as thunderstorms
affect the northernmost areas of the FAA/Houston Center airspace.

FAA National Airspace Status can always be found at…
http://www.fly.faa.gov/ois/

FOLLOWUP STATEMENTS…

I will continue to keep you informed of this severe/inclement weather threat event.
Any questions, please let me know at tkimmel@austin.utexas.edu .

GENERAL WEATHER INFORMATION LINKS…

NWS web sites…
Austin area… http://www.srh.noaa.gov/ewx/
Bryan – College Station area… http://www.srh.noaa.gov/hgx/

To see all current real time weather warnings/statements for all NWS offices, please see…
http://kamala.cod.edu/svr/
For the Austin and LaGrange areas, it’s the “NWS/Austin-San Antonio office”… for the
Bryan/College Station area, it’s the “NWS/Houston-Galveston office.”
The list is national in scope and the bulletins are all listed in chronological order with the most recent
statements/warnings at the top (you scroll down to go back in time). Click on the NWS Office name
to see the warning… and click on the the four letter ID after that to see any follow up statements to
the warnings. This web page “auto refreshes” every two (2) minutes.

As in all anticipated severe/inclement weather events, no matter where you are, please continue
to stay “weather aware” and please check to make sure that your NOAA All Hazard Weather Radios
are operational and are set to alarm in case of severe and inclement weather watches and/or warnings.

tk