SYNOPTIC/FORECAST REASONING:
A large center of arctic high pressure.. currently centered over west Canada with a surface pressure
of 1056mb.. will slide south southeastward along and to the east of the Rockies into the plains states
beginning late tonight into tomorrow with the coldest air will settling over our area by New Years Eve into
New Years Day. The enter of the high pressure, 1028mb surface pressure by then, is forecast to be over
Arkansas by daybreak on New Years Day.

As the shallow layer of cold arctic air, forecast to be only a few thousand feet deep locally, is overrun by
moisture beginning late tomorrow into tomorrow night through New Years Day and Friday, light overrunning
rain will develop over the area. Surface air temperature is going to be the key factor on whether we simply
see a cold rain or whether we could see the possibility of freezing rain and freezing drizzle. Sleet/ice pellets
and snow will not be a factor based on the forecast of very shallow surface based cold air. Even though, at
this point, I have a low confidence of any freezing precipitation, I believe that the main times of concern
around the south central Texas area are in a brief window 5am to 10am Wednesday morning and again from
6pm Wednesday through 10am on Thursday /New Years Day/. The main risk area may remain over the hill
country areas to our northwest and west. Even though it is not anticipated at this time, please note that if the
air is colder than expected or if the colder air remains in place into Thursday night and early Friday and
doesn’t warm as guidance suggests, this threat area and period could be expanded.

The main part of the upper air low pressure disturbance will cross the area by Thursday night into Friday
night with the best chance of rain and thunderstorms across our area. Even though this needs to be monitored
closely, it would appear that surface temperatures will have warmed a few degrees by then with temperatures
well above critical freezing levels.  With the passage of the upper air low pressure disturbance, rain chances
will end locally with clouds breaking/clearing by midday Saturday.

MY FORECAST CONFIDENCE:
Weather system evolution: High to very high
Precipitation chances: Very high
Liquid precipitation (rain) chances: Very high
Freezing precipitation (freezing rain/freezing drizzle) chances: Low
Frozen precipitation (snow/ice pellets-sleet) chances: None
Thunderstorm/lightning chances: High to Very High
Severe thunderstorm chances: None

AVIATION INFORMATION FOR THE AUSTIN/BERGSTROM
INTERNATIONAL AIRPORT (KAUS) AERODROME:
Any freezing precipitation occurring at ABIA would have impacts and all airport
interests should closely monitor this situation over the next 24 to 36 hours.

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