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

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FXUS64 KEWX 191124
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
524 AM CST Thu Jan 19 2017

.UPDATE...
12Z Aviation Update Below.

&&

.AVIATION...
Band of RA and embedded TSRAs east of I-35 will continue to move east
and exit the region mid morning. Radiation fog has developed out
west where skies have cleared, and the fog is beginning to become
dense. LIFR visibility and ceiling in FG will persist at DRT through
15Z then quickly lift. Along the I-35 corridor, IFR ceilings being
reported. There is a chance the ceilings could briefly dip into LIFR
and visibility drop into IFR to MVFR 13Z-15Z as BR develops. Skies
will then quickly clear along the I-35 corridor sites 15Z-17Z. VFR
conditions prevail this afternoon and evening across the region with
a 5-10 kt SW to W wind developing.

&&

.PREV DISCUSSION... /ISSUED 342 AM CST Thu Jan 19 2017/

SHORT TERM (Today through Friday)...

The final round of showers and storms are moving across South-central
TX early this morning and should be retreating from the area by 15Z.
Some patchy fog is expected for the first couple hours of the day;
then wake subsidence and westerly winds should hasten the break-up
of low level clouds and bring fast rising temperatures by midday.
Soaked soils east of I-35 and the delayed removal of clouds should
mean high temperature should be about 5 degrees cooler over eastern
counties versus western counties. The surface winds are not forecast
to be that strong, so the mixing of dewpoints over areas east of I-35
should be temporary with dewpoints rebounding and patchy fog
developing by late tonight.

A progressive pattern aloft keeps surface troughing intact over NW
TX with a N-S pressure gradient to keep low level winds westerly on
Friday. Warmer temperatures should thus expand farther east although
there could be some stubborn clouds again over eastern counties where
moisture pooling remains. Broad upper troughing over TX could enable
an embedded subtle shortwave activity to generate convection over
parts of the Coastal Prairies, but am not confident in sufficient
moisture will be available for deep convection in our inland
counties, with models showing better moisture pooling over the
Coastal Bend.

LONG TERM (Friday Night through Wednesday)...

After two days of westerly wind mixing, will assume enough low level
drying to leave out the mention of potential patchy fog for daybreak
Saturday. Strong upper jet dynamics continues to carve troughing
upstream from TX and a new progressive upper low is forecast to take
shape over N TX late Saturday. Some elevated dynamic lift may be
enough to generate convection over the Hill Country and Central TX,
but with limited moisture and most of the PVA passing to the north,
will keep the wording over our area as showers. The passage of the
deepening upper low to the north Saturday night means a warm west
wind will stay up for much of the night and keep dew points dry. W/NW
winds at 850 mbs between 06Z and 12Z Sunday are forecast by the GFS
to be 60-70 knots over the area and those strong winds are expected
to mix to the surface by late morning. Daytime peak winds at 5000 ft
are now forecast to trend downward during the middle of the day, as
the 00z model runs have accelerated the forward movement of the upper
low. This should help minimize the potential for High Wind Warning
criteria as feared from yesterdays runs. However, conditions will
remain favorable for a no-brainer wind advisory day with some gusts
to 45 mph expected once adiabatic heating enhances mixing. The strong
winds, plus humidities dropping into the teens to around 20 percent
for much of the western counties means near critical fire weather
conditions are still in play.

The progressive zonal pattern aloft continues in the wake of the wind
producing low pressure system, and Monday into early Tuesday continue
to be influenced by low level westerly wind components to have above
normal daytime temps. By Tuesday evening, a cold front should arrives
to curb temperatures for Wednesday with reinforcing cold air to
arrive Wednesday night. Thursday temperatures should finally return
to late January normals and a prolonged meridional flow pattern aloft
by both the GFS/ECM runs suggests a sustained cool period lasting
into next weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              74  53  78  54  75 /  20   0  20  20  20
Austin Bergstrom Intl Airport  74  51  78  53  75 /  20  -   20  20  20
New Braunfels Muni Airport     73  51  76  55  77 /  30   0  20  10  10
Burnet Muni Airport            73  48  75  48  72 /  10   0  10  10  20
Del Rio Intl Airport           75  46  76  50  78 /   0   0   0  -   10
Georgetown Muni Airport        73  50  76  52  73 /  20   0  20  20  20
Hondo Muni Airport             74  48  79  49  79 /  10   0  10  -   -
San Marcos Muni Airport        73  51  78  55  75 /  30  -   20  20  20
La Grange - Fayette Regional   71  55  77  58  74 /  40  -   20  20  20
San Antonio Intl Airport       74  52  78  54  77 /  20   0  20  10  10
Stinson Muni Airport           74  52  79  54  78 /  20   0  20  10  -

&&

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

&&

$$

Mesoscale/Aviation...Runyen
Synoptic/Grids...Oaks
AVIATION (......


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