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

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FXUS64 KEWX 102304
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
504 PM CST Sun Dec 10 2017

.AVIATION...
One line TAFs are in the forecast as light southerly winds continue.
There will be some passing high clouds, but VFR conditions are
expected through the period.

&&

.PREV DISCUSSION... /ISSUED 235 PM CST Sun Dec 10 2017/

SHORT TERM (Tonight through Monday Night)...
Other than some high clouds and dry air mixing down to the surface
resulting in very low afternoon RH values, not much else of note in
the short term forecast. A closed low off the western coast of Baja
California is pumping moisture across Mexico and the western half of
Texas per water vapor imagery. With the continued pattern of ridging
across the western CONUS and a longwave trough in the east, South
Central Texas will be under a rather stagnant pattern, allowing highs
to warm into the mid 70s Monday after starting cold in the morning.
High pressure at the surface will also keep winds light and generally
out of the west. Forecast soundings again indicate dry air aloft
will be allowed to mix back down to the surface similar to today and
likely bring RH values again down into the 15-25 percent range in the
afternoon.

LONG TERM (Tuesday through Sunday)...
Not too much of note in the foreseeable future as well. A series of
cold fronts are expected over the course of the next week, with the
first arriving early Tuesday and doing little more than shifting
winds northerly and dropping temperatures back to more seasonal
normals. High pressure will settle over South Central Texas Wednesday
morning, allowing lows to dip back into the 30s.

The next front is expected late Thursday night, but still likely
without any rain associated with it as low level wind fields ahead of
the front are progged out of the west, cutting off any return
moisture flux and keeping things dry.

Model outcomes begin to diverge at this point, especially with the
handling of moisture advection into the region by the weak low
meandering off the west coast of Mexico. Deterministic 12Z GFS pulls
this moisture across Texas due to high pressure over the Gulf of
Mexico, whereas the 12Z ECMWF more intuitively halts that moisture
advection at the Serranias Del Burros. Thus, feel the GFS QPF
generation is likely overdone. The ECMWF also produces a stronger,
southward diving shortwave across the Central Plains, and thus a more
potent cold front. Will need to monitor this with further runs as it
would require increasing wind potential and dropping temps for
Saturday. For now, given the model disagreement, went with the
typical consensus blends until more confidence can be given to the
ECMWF.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              42  74  44  63  38 /   0   0   0   0   0
Austin Bergstrom Intl Airport  33  74  41  62  34 /   0   0   0   0   0
New Braunfels Muni Airport     36  75  42  63  35 /   0   0   0   0   0
Burnet Muni Airport            36  72  40  61  35 /   0   0   0   0   0
Del Rio Intl Airport           38  72  42  67  39 /   0   0   0   0   0
Georgetown Muni Airport        37  74  40  60  36 /   0   0   0   0   0
Hondo Muni Airport             34  73  40  66  34 /   0   0   0   0   0
San Marcos Muni Airport        38  75  42  62  36 /   0   0   0   0   0
La Grange - Fayette Regional   40  72  43  62  35 /   0   0   0   0   0
San Antonio Intl Airport       39  74  43  65  37 /   0   0   0   0   0
Stinson Muni Airport           37  73  43  65  37 /   0   0   0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Mesoscale/Aviation...Hampshire
Synoptic/Grids...17
Public Service/Data Collection...33


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