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

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631
FXUS64 KEWX 202358 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
558 PM CST Tue Feb 20 2018

.AVIATION.../00Z TAF CYCLE/

Widespread MVFR conditions are occurring for the eastern 2/3rd of
south central-Texas and impacting KAUS/KSAT/KSSF while KDRT is VFR.
-SHRA continues for KAUS/KSAT/KSSF this evening and this will persist
 overnight into Wednesday morning. Greater coverage of TSRA is
 expected to occur and have continued previous forecast of TSRA this
 evening and overnight. Moved up timing of storms near KDRT given
 current radar trends of activity in Mexico slowly shifting
 northeast. Heavier showers will lead to lower visibilities and
 ceilings with IFR and LIFR likely Wednesday morning. Winds are
 southeast at 0 to 15 knots with gusts to 25 knots and will become
 north at 15kt behind the front with gusts to 25kt. A cold front will
 move through with winds becoming north from 08Z through 10-11Z.

-SHRA will linger through the day Wednesday with little to no
 recovery out of IFR to low-end MVFR during the afternoon with north
 winds continuing.

&&

.PREV DISCUSSION... /ISSUED 312 PM CST Tue Feb 20 2018/

SHORT TERM (Tonight through Wednesday Night)...
Showers and isolated thunderstorms have pushed to the eastern half of
the area at the present time with more robust activity currently
located in North Texas. The best low-level jet dynamics are pointing
to this same area and this will likely keep the bulk of the activity
in those places for several more hours. The attention will then turn
to the southwest as another impulse of energy within the subtropical
jet moves into the area. High-res models continue to show this area
of shower and thunderstorms moving northeast into the area this
evening. At the same time a strong arctic cold front will also be
pushing south and this will bring additional activity into our
northern counties in the evening hours as well. Showers and
thunderstorms will likely continue through most of the night and
into Wednesday before downsloping behind the front moves into the
region lessening the coverage. The threat of heavy rainfall will
likely diminish after the FROPA as well as the access to rich
boundary layer fuel is cut off. With today`s precipitation not
included, additional rainfall amounts through tomorrow will average
1-2 inches for areas north of I-10 with slightly higher amounts for
the Austin area and points to the north. There will be lesser amounts
to the southwest of the I-10 corridor. There could be some isolated
spots reaching 3-4 inches in the higher rainfall areas. Although we
can`t rule out any small hail with some of the stronger updrafts,
widespread severe weather is not anticipated from the activity.

The expected cold front is much stronger than what most guidance was
able to pick up on and this is not out of the norm for these shallow
arctic airmasses. Earlier this afternoon, the temperature in Wichita
Falls fell from 71 to 36 in an hour. The front is expected to reach
the northern counties before midnight and will move through the
remainder of the area by the mid-morning hours. There were some
thoughts that the front might stall in our area, but with the dense
cold air behind it, that does not seem at all possible and most
guidance members show the front now making it to the coast. Low
temperatures tonight and highs tomorrow will be dependent on where
the front is in the morning. Lows will likely reach the 40s behind
the front and will be in the 60s ahead of it. Highs tomorrow will
likely also be around the morning hours with temperatures likely
falling through the afternoon or holding steady. Precip chances will
lessen a bit for Wednesday night with low temperatures in the upper
30s to lower 40s expected.

LONG TERM (Thursday through Tuesday)...
Shower and thunderstorm chances will continue to be high Thursday as
the upper trough remains to the west and southerly flow increases at
850 owing to decent warm-air advection. Highs will likely remain in
the 50s under the cloud cover and remnant effects of the cold air.
The surface front will move back north as a warm front Thursday night
with the higher PoPs across the northern counties on the northern
nose of the front. The next frontal system arrives Saturday bringing
continued 30 to 60 PoPs to the region. Lower rain chances will
continue Sunday through Tuesday mainly across the eastern CWA. High
temperatures in the extended will be in the 60s/70s with lows in the
50s/60s.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              48  50  41  53  51 / 100 100  50  60  60
Austin Bergstrom Intl Airport  48  51  42  53  52 / 100 100  50  60  60
New Braunfels Muni Airport     54  57  43  54  53 / 100 100  50  60  50
Burnet Muni Airport            41  45  36  49  49 /  90  90  30  70  60
Del Rio Intl Airport           57  62  43  59  54 /  60  60  30  40  40
Georgetown Muni Airport        45  47  39  50  50 / 100 100  40  60  60
Hondo Muni Airport             58  62  44  53  53 /  80  80  30  60  50
San Marcos Muni Airport        51  54  42  54  53 / 100 100  50  60  50
La Grange - Fayette Regional   58  60  43  57  57 /  80  90  70  60  40
San Antonio Intl Airport       56  60  44  54  54 / 100 100  40  60  50
Stinson Muni Airport           59  62  45  55  55 / 100 100  40  60  40

&&

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

$$

Mesoscale/Aviation...Allen
Synoptic/Grids...05
Public Service/Data Collection...YB



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