Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 080104
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
704 PM CST Thu Dec 7 2017

.AVIATION.../00Z_TAFS/
MVFR ceilings currently exist at all of our TAF sites with light snow
and sleet being reported at or in the vicinity of all of our sites.
There is a band of heavier snowfall from UVA to 5C1 (just north of
SAT) to AUS that is reducing visibilities as low as 1 SM, and this
band will continue to slowly push to the south and east as individual
elements move to the northeast. Evaporational cooling will allow for
brief accumulations at these sites up to one inch, but this should
mainly be in the form of slush as ground temperatures at the TAF
sites should remain above freezing. Although there is a large model
ensemble spread, we do expect that the heavier band of snowfall
should clear the I-35 TAF sites by 2Z and snowfall in general should
end between 3-6Z. Although isentropic ascent will continue above 600
mb beyond this time, dry air and isentropic descent below 600-700 mb
should keep snow from reaching the surface after 6Z if not earlier.

Once the snow ends from northwest to southeast and MVFR ceilings give
way to VFR conditions around 4-5Z at the I-35 sites and 9Z at DRT,
the main impacts to aviation will be freezing temperatures tonight
lasting through 14-15Z. Northerly winds will remain around 5-10 knots
overnight before becoming more westerly late tomorrow morning. Winds
will increase tomorrow afternoon to 10-15 knots with gusts to 20
knots possible.

&&

.PREV DISCUSSION... /ISSUED 258 PM CST Thu Dec 7 2017/

SHORT TERM (Tonight through Friday Night)...
A deep upper level disturbance extending from the Southern Plains
southwestward into the four corners region is expected to push to the
southeast and into our area tonight. A cold airmass is forecast to
spread across South Central Texas tonight into the overnight hours
with cold rain expected mainly along and south of Highway 90 before
temperatures drop down into the lower 30s. There are some HiRes
models that suggest few snow flurries across the Hill Country
tonight as a pulse of energy moves across the area. Therefore, even
though is not mentioned for the tonight weather forecast period,
don`t be surprised if you see some flurries this evening. No snow
accumulation expected. Talking about flurries, the far southeast part
of South Central Texas especially east of Schulenburg to Floresville
to Derby line has a slight chance to observe light snow overnight as
temperatures reach the freezing mark. Limited to no snow
accumulation expected. One thing that should be brought up is the
possibility of black ice resulting in slippery roads due wet
surfaces from earlier rains that may still be around.

Due to the coldest temperatures so far this season across the area,
a Special Weather Statement was issued for the entire area to
address the cold temperatures and chances for snow flurries.

Also, a Freeze Warning has been issued for all areas beginning at
midnight tonight through 9 am Friday with the exception of the Hill
Country (Edwards/Real/Kerr/Gillespie and Llano counties since they
already reached the freezing mark once earlier in the season) as
temperatures are expected to drop to the upper 20s and lower 30s.

A warm up is expected on Friday after a cold start with highs in the
low to mid 50s. A clear night is in store for Friday into Saturday
morning with minimum temperatures dropping down to the upper 20s
across the Hill Country to low and mid 30s elsewhere.

LONG TERM (Saturday through Thursday)...
An upper level ridge will dominate through the extended forecast
period with dry and warmer temperatures later into the weekend
continuing next week as surface winds come from the west and
southwest.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              29  54  35  65  36 /  40   0   0   0   0
Austin Bergstrom Intl Airport  29  54  32  64  33 /  40   0   0   0   0
New Braunfels Muni Airport     29  55  33  65  34 /  50  -    0   0   0
Burnet Muni Airport            26  53  31  61  33 /  20   0   0   0   0
Del Rio Intl Airport           31  52  32  62  33 /  40   0   0   0   0
Georgetown Muni Airport        28  53  33  63  34 /  30   0   0   0   0
Hondo Muni Airport             27  56  29  67  32 /  40   0   0   0   0
San Marcos Muni Airport        29  53  33  64  34 /  50   0   0   0   0
La Grange - Fayette Regional   30  51  32  62  34 /  50  -    0   0   0
San Antonio Intl Airport       32  56  35  66  36 /  40   0   0   0   0
Stinson Muni Airport           32  55  33  65  35 /  50  -    0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from midnight tonight to 9 AM CST Friday for the
following counties: Atascosa...Bandera...Bastrop...Bexar...Blanco...
Burnet...Caldwell...Comal...De Witt...Dimmit...Fayette...Frio...
Gonzales...Guadalupe...Hays...Karnes...Kendall...Kinney...Lavaca...
Lee...Maverick...Medina...Travis...Uvalde...Val Verde...
Williamson...Wilson...Zavala.

&&

$$

Mesoscale/Aviation...LH
Synoptic/Grids...24
Public Service/Data Collection...Williams



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