Austin / Travis County and South Central Texas Weather Update #3
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
445pm CDT – Friday / 22 November 2013

.. Weather Update #3 ..

New NWS watches/advisories/warnings have been issued or updated:

NWS/Austin-San Antonio has issued a WINTER WEATHER ADVISORY for the Texas
Hill Country.. including Blanco, Burnet, Gillespie and Llano Counties.. now until 12 noon
Saturday. At 12 noon Saturday through 12 noon Monday, a WINTER STORM WATCH
will go into effect for these same counties.

NWS/San Angelo continues a WINTER WEATHER ADVISORY for Mason County
until 6am Saturday with a WINTER STORM WATCH going in effect at that time
and remaining in effect until 6am Monday.

Although not in our immediate area, you should also be aware that the NWS/Fort Worth
has issued a WINTER STORM WATCH which goes into effect for the northwestern half
of north Texas.. including all of the DFW Metroplex.. beginning at 6am Sunday morning
and continuing until 12 noon Monday.

Temperatures continue to slowly fall across the area as a cold modified arctic air mass
builds into the area. About 4,000 to 4,500 feet above the ground and upward from there,
southerly and southwesterly winds are bringing moisture northward and overrunning it over the
colder surface air. Over the next few days, a series of upper air low pressure disturbances
will move across the area (west to east) creating atmospheric lift and keeping us in clouds
and  precipitation chances.

The critical issue is  (1) how cold the surface air is becoming and will become this weekend
and, in addition, (2) the depth or “thickness” of the surface based cold air (this is an
important complex factor in determining winter precipitation types – where it occurs).

I still do not believe that the numerical forecast models have a good handle on the
forecast temperatures within this air mass locally (temperature performance so far leaves a bit
to be desired). As I mentioned yesterday, I continue to become increasingly concerned that this
developing winter storm.. particularly the passage of the major upper level low Sunday into Monday..
could have more effect into the Austin area than we’re currently thinking.  Precipitation is
not the question here.. it will occur. Temperature is the question and my thinking, at this
point, is that temperatures may be at or even slightly below freezing Sunday night into Monday
morning (especially west through north of Austin. If that verifies, we could expect to see problems
given that at least some of the the models are squeezing out up to 1/2 inch of rain or more between
12 noon Sunday into 6pm Monday evening.

I urge you to remain in close touch with the latest forecasts and the latest NWS watches/advisories
and/or warnings that are expanded and/or issued over the next few days as the effects of this
potential winter storm across Texas become more focused.

I’ll continue to keep you informed… tk