Austin / Travis County and South Central Texas Weather Update #2
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
745am CDT – Thursday / 5  December 2013

.. Weather Update #2 ..

NWS watches/advisories/warnings that have been issued as of 730am CT:

NWS/Austin-San Antonio… a WINTER WEATHER ADVISORY will be in effect for the Texas
Hill Country and IH35 corridor.. including Williamson, Travis and Hays Counties.. from 12
midnight tonight through 12 noon Friday for possible ice accumulations (mainly exposed bridges
and overpasses).

NWS/San Angelo… a WINTER WEATHER ADVISORY will be in effect for Mason County
from 6pm Thursday evening to 12 noon Friday for possible ice/sleet accumulations of 1/10th
to 1/4 inch.

NWS/Fort Worth… a WINTER STORM WARNING will be in effect 6pm tonight until
6pm Friday for areas northwest of a line from Goldthwaite to Canton line for the likelihood
of significant ice/sleet accumulations (1/4 to 1/2 inch ice/sleet accumulations)
with downed trees and power lines possible with lengthy power outages possible.
A WINTER WEATHER ADVISORY will be in effect 6am Friday until 6pm Friday for the area
southeast of the warning above and to include Bell and McLennan counties.. including
the Killeen.. Belton.. Temple and Waco areas for the possibility of ice/sleet accumulations of less
than 1/4 inch.

DISCUSSION

…. Little Change ….

Another very cold arctic air mass continues to slide southward out of Canada into the through the
western two thirds of the USA. As this cold air continues to move southeastward through Texas, it, as
usual, is in a relative shallow layer close to the ground. This is combining with an active subtropical
jet stream to cause moisture to overrun the cold air and then upper air disturbances embedded in the
subtropical jet stream to move by between now and Sunday, create lift in the atmosphere and, as a result,
cause precipitation.

The front arrived in the Austin area about 4 to 5am this morning with rain showers and light rain and
falling temperatures into the 30s by afternoon with a gusty north wind. Tonight’s lows will be around
freezing with temperatures holding in the 30s.. and even below freezing at times.. for the period tomorrow
and Saturday into Saturday night and early Sunday.

Again, with this episode, please understand that precipitation will most likely occur.. especially today
into Friday night and early Saturday. The surface temperatures and the temperature of the air aloft in
the shallow layer of cold air will continue to be the player as far as the prospect of getting rain or the
likely possibility of getting freezing or frozen precipitation. In comparison with the cold air outbreak
and precipitation one to two weeks ago, this arctic air mass appears to be a bit colder.

Unfortunately, it may be more “last minute” as whether we have potential effects (ice accumulations) from
this system.. we’ll need to watch the 12 midnight tonight to 12 noon (morning rush hour) on Friday for the potential
for freezing rain. The NWS has already issued a WINTER WEATHER ADVISORY for the Austin metro area
for tomorrow for this likelihood.

Another winter weather risk exists for the local area for late tomorrow afternoon into tomorrow night into
Saturday and again for late Saturday afternoon and night into early Sunday morning time period.. these time
periods will be dealt with by the NWS with possible later watches/advisories/warnings.

A continued reminder to let you know of the potentially widespread and dangerous winter weather (ice storm)
situation that map develop to our north over north Texas, Oklahoma into adjoining Arkansas where
WINTER STORM and ICE STORM WARNINGS are already in effect. This could cause widespread
and long lasting power outages in north and northeast Texas.. including the Dallas/Fort Worth metroplex
as well as the Longview/Tyler/Kilgore as well as Texarkana areas over the coming days.

Another note… this cold arctic air will continue to be reinforced from the north through the weekend and
into next week. Based on the guidance I’m seeing now, I would be surprised if we’re back above
50 degrees F for high temperatures until about 7 or 8 days from now. More importantly, overnight lows
next week, assuming a clearing sky, will result in hard freezes in the overnight areas with some areas to
around 20 degrees F for overnight lows on Monday/Tuesday/Wednesday nights of next week. The good news..
at this time.. is that no precipitation is expected for this time period.

In conclusion, there is still much uncertainty about this potential winter weather event locally for our south
central Texas area even for tomorrow morning. On the other hand, please understand the very high impact that
this system could have on our area with very little notice if temperatures turn out being even slightly colder over
our area than we’re currently forecasting now. It is very important that all interests pay close attention to the latest
weather conditions over the coming days and for the latest NWS watches/advisories and/or warnings that may be
issued.

I’ll continue to monitor this situation.

tk