Austin / Travis County and South Central Texas Weather Statement #3
Prepared by UT University/Incident Meteorologist Troy Kimmel
855am CT – Wednesday / 31 December 2014
.. Arctic Air Holds with Precipitation Chances Later Today into New Years Day and Friday ..
.. NWS Upgrades Winter Storm Watch to Winter Storm Warning for Texas Hill Country ..
.. Winter Weather Threat Remains to the West Northwest of Austin/IH35 Corridor ..
NWS WATCHES / ADVISORIES / WARNINGS:
NWS / Winter Storm Warming (Valid 6pm Wed/31Dec2014 until 12noon Thu/01Jan2014)
Counties Included.. Blanco.. Burnet and counties westward through the hill country
Ice accumulations to 1/10th inch.. with isolated sleet/ice accumulations to 1/4 inch possible.
At this time, this DOES NOT include the greater Austin metro area or the IH35 corridor
counties of Travis.. Hays and Williamson.
SYNOPTIC/FORECAST REASONING:
The center of arctic high pressure.. currently centered over Kansas with a surface pressure of 1042mb..
continues to slide south southeastward into the southern plains and lower Mississippi valley. The coldest
air will be settling over our area by late tonight into New Years Day morning. By tomorrow evening into
the overnight hours tomorrow night, the enter of the high pressure ridge, 1025mb surface pressure, will
extend from western Oklahoma eastward into western Tennessee.
The shallow wedge of colder arctic air continues overhead of the IH35 corridor counties of south central
Texas with surface air temperatures ranging from the mid to upper 30s and with a shallow surface colder
depth to about 3,000 feet above ground level. Above this layer, a pronounced south southwesterly wind
flow exists.
With the approach of several upper air disturbances from the west and southwest, we’re already seeing an
overrunning pattern develop with moisture gliding north and northeastward over the layer of surface based
arctic air and resulting in our overcast cloud layer. Light overrunning precipitation will develop over the area
today as the afternoon progresses with precipitation continuing through tonight and New Years Day as well as
Friday. As advertised, surface air temperature is going to be the key factor on whether we simply see, at any
given location, a cold rain/drizzle or whether we could see the possibility of freezing rain and freezing drizzle.
At this point, my confidence of seeing freezing precipitation for the Austin metro area and the IH35 corridor
counties remains quite low. Based on forecast atmospheric soundings, sleet/ice pellets may be a factor in hill
country areas further west and northwest of Austin.
Even with the low confidence forecast, I still believe that the main time of concern around the western parts of
south central Texas area are in a window from 6pm today through 12 noon on Thursday /New Years Day/. Although
the main risk area is expected to remain to the west and northwest of the Austin metro area/IH corridor, it still
could be too close for comfort. Needless to say, all areas from the Austin metro area/IH35 corridor counties
of Williamson, Travis and Hays counties westward through the hill country should remain alert to the latest
watch/advisory/warning issuances from the National Weather Service Austin-San Antonio.
The main dynamic part of the upper air low pressure disturbance will cross the area by late tomorrow night into
Friday night with the best chance of rain and even a few thunderstorms across our area. It would appear that surface
temperatures will have warmed a few degrees by then with temperatures above critical freezing levels. A reminder,
though, that models have a tendency to dislodge arctic cold based surface air too quickly so let’s watch this closely.
With the passage of the upper air low pressure disturbance, rain chances will end locally with clouds
breaking/clearing by midday into early afternoon Saturday.
THREAT(S) FOR AUSTIN METRO AND IH35 CORRIDOR COUNTIES:
Low probability – Freezing drizzle / freezing rain (some sleet/ice pellets)
Geographic area: Far western border areas of Travis, Williamson and Hays counties
Time Period: Possible in the 6pm today (31 Dec) through 12 noon Thursday (1 Jan 2015) time period.
MY FORECAST CONFIDENCE:
Weather system evolution: Very high
Precipitation chances: Increasing to very high by tomorrow through Friday and Friday night
Liquid precipitation (rain) chances: Increasing to very high by tomorrow through Friday and Friday night
Freezing precipitation (freezing rain/freezing drizzle) chances: Low
Frozen precipitation (snow/ice pellets-sleet) chances: None to very low
Thunderstorm/lightning chances: Moderate to high Thursday night through early Saturday morning
Severe thunderstorm chances: None
AVIATION INFORMATION FOR THE AUSTIN/BERGSTROM
INTERNATIONAL AIRPORT (KAUS) AERODROME:
The chance of freezing precipitation at ABIA appears very low. However, if it did occur, it
would have major impacts and all airport interests are urged to continue to closely monitor
this situation through midday tomorrow (01 January 2015).
. Current KAUS Terminal Aerodrome Forecast (TAF) – Issued 311144z ..
KAUS 311144Z 3112/0118 02017KT P6SM SCT015 OVC050
FM311800 02015KT P6SM -DZ OVC050
FM010000 01011KT P6SM -DZ BKN020 OVC045
FM011200 01008KT 6SM -DZ BKN015 OVC035
FM011700 02006KT 6SM -RA BKN015 OVC030
. For Our DAL/DFW Hub Aerodromes ..
Current NWS public forecasts continues a possible rain and freezing rain mix for the
Dallas/Fort Worth area for late tonight into tomorrow time period… precipitation
probabilities increase from 40% tonight to 80% for tomorrow.
. For Our HOU/IAH Hub Aerodromes ..
Current NWS public forecasts do not have any freezing or frozen precipitation
for the New Years Eve/New Years Day forecast period. Isolated thunderstorms
are mentioned for the Friday.. Friday night and early Saturday time period with
precipitation probabilities of 70% for Friday and Friday night.
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.
Make sure that your NOAA All Hazards Weather Radio is operational and are
set to alarm in case of severe and inclement weather watches and/or warnings.
FOLLOWUP STATEMENTS:
I will continue to keep you informed regarding this severe/inclement weather
event. Any questions, please let me know at tkimmel@austin.utexas.edu
GENERAL WEATHER INFORMATION LINKS:
NWS/Austin-San Antonio Current Statements/Advisory/Watches/Warnings
NWS/Austin-San Antonio Web Page
NWS/Storm Prediction Center (Outlooks)
NWS/Storm Prediction Center (Mesoscale Discussions – Severe Weather & Snow)
NWS/Storm Prediction Center (Severe Thunderstorm/Tornado Watches)
NWS/Weather Prediction Center (Mesoscale Discussions – Heavy Rain & Flooding)
NWS/National Hurricane Center
tk