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FXUS64 KEWX 230455
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1055 PM CST Tue Jan 22 2019

.UPDATE...
Please see the 06Z aviation forecast discussion below.

&&

.AVIATION...
Scattered showers and even a few thunderstorms are currently moving
into the I-35 corridor late this evening. We will mention MVFR vsbys
with showers at SAT and SSF through 06Z, with similar activity
expected through 07Z at AUS. Cloud to ground lightning strikes have
been isolated and for now we will continue to monitor before adding
to the AUS forecast. Otherwise, gusty northwest winds will continue
behind the cold front through most of the morning hours with
sustainedwinds near 20kt and gusts to 30kt. Wind gusts should tend
to east around 18Z, but sustained speeds will be close to 15kt. Winds
should finally ease around 24/00Z as the pressure gradient relaxes.
At DRT, gusty northwest winds will continue through mid-morning, the
begin a slow decreasing trend through the remainder of the daytime
hours.

&&

.PREV DISCUSSION... /ISSUED 944 PM CST Tue Jan 22 2019/

UPDATE...
The front has accelerated through the Hill Country and is now south
of an Austin to New Braunfels to Del Rio line. Strong pressure rises
and deepening frontal inversion is producing wind gusts between
25 and 35 mph behind the front. A few locations could see sustained
winds over 25 mph, Wind Advisory criteria, but overall should not be
widespread enough for an advisory. Nevertheless have increased winds
behind the front from previous package.

Strong ascent is resulting in rapid expansion over precipitation over
the last hour and has necessitated an increase in PoPs. Steep
650-500mb lapse rates also promoting deeper convective element and
have now seen a few lightning strikes along with a report of small
hail across the southern Hill Country. We have included a mention of
isolated thunder in the forecast. Can't completely rule out some
sleet pellets across the far northern CWA, given the potential for
significant wet-bulb cooling beneath 700mb on forecast soundings.

PREV DISCUSSION... /ISSUED 746 PM CST Tue Jan 22 2019/

UPDATE...
Minor update to extend 20 PoPs west to the Rio Grande. Isolated,
elevated showers have developed across western portions of the CWA
near the Rio Grande and precipitation was reaching the ground per
DRT ASOS. Minor adjustments also made to hourly T/Td trends based on
current observations. The cold front is currently located near a
line just north of Lampasas to south of Rocksprings.

PREV DISCUSSION... /ISSUED 605 PM CST Tue Jan 22 2019/

UPDATE...
Please see the 00Z aviation forecast discussion below.

AVIATION...
A strong cold front will bring gusty northwest to north winds to the
region between 01-02Z at DRT and between 03-04Z along I-35. Expect
sustained winds around 15kt with gusts to around 25kt following the
frontal passage. Some light showers may also develop as the front
moves through, but only light rain with no restriction to visibility
is expected at this time. Gusty conditions will persist into the early
afternoon along I-35, with gusts at DRT expected to decrease by late
morning. Sustained wind speeds will still be above 12kt at all sites
through tomorrow afternoon. We should see light winds develop around
24/00Z.

PREV DISCUSSION... /ISSUED 242 PM CST Tue Jan 22 2019/

SHORT TERM (Tonight through Wednesday Night)...
Mostly cloudy skies persists across the region as mid and upper level
lift increases as a strong upper trough approaches the area from the
west. At the surface, temperatures currently range from the upper
50s in the Hill Country to lower 70s in the southeastern CWA. A pre-
frontal trough axis is moving through the Hill Country which has led
to slightly cooler temperatures this afternoon. The main cold front
is located along a line from near Midland to Wichita Falls. Current
radar imagery shows some elevated light returns as a result of the
mid-level lift across our eastern areas, but little to nothing of
this is reaching the ground as a dry layer remains below 700 mb. Some
of the high-res model guidance continues to develop some light
showers that would reach the ground later this afternoon for areas
east of the pre-frontal trough.

The cold front is expected to reach the northern areas around 8 PM
and will then move south through the entire CWA around 2 AM. There
could be a weak line of showers along the front as it makes it to the
eastern counties where better low-level moisture should be located.
Rain chances will actually be best for areas mainly along and east of
the I35 corridor post-frontal as the main trough axis brings upper
support to the area. This will help increase lift and develop
scattered showers for these areas mainly between 9 PM and 3 AM.
Rainfall will move out of the area by the mid morning hours
Wednesday.

There has been some talk around for possible sleet mixing
in with the rain, but at the present time, forecast soundings appear
much too warm for this to occur. Even if it were to happen, surface
temperatures will be near 38-40 after midnight and any frozen pellets
would immediately melt upon reaching the surface.

In addition to the rain chances, winds tonight behind the front will
be around 15-25 mph with higher gusts. There could be a site or two
that briefly flirt with wind advisory criteria, but this should not
be long enough to warrant any advisories behind this cold front. Lows
tonight will bottom out in the middle 30s to lower 40s. Clearing
skies can be expected tomorrow with afternoon highs reaching the
50s. Clear skies, light winds, and dry air should allow for lows
tomorrow night to reach the freezing mark for portions of the Hill
Country and I35 corridors with temperatures just a few degrees warmer
for the rest of the forecast area.

LONG TERM (Thursday through Tuesday)...
Dry weather will continue for the beginning of the long-term forecast
with cool weather continuing through Friday. Yesterday, there was
some disagreement between the GFS and ECMWF on a front and subsequent
rain chances for the area on Saturday. The operational GFS yesterday
was the warmest and driest in the extended vs its ensemble members,
but today the operation run has come into agreement with the wetter
and cooler members and the ECMWF. A strong upper low should drop
southeast into the area on Saturday with a cold front and most likely
a good chance of rain for much of the area. Increased PoPs for the
area with 50 percent now forecasted for most locations except the
western areas. This front will keep temperatures cool through Monday,
but a stronger front is progged by both the GFS and ECMWF to come
through on Tuesday. At this time both models agree that this front
will be dry, but it could possibly bring a freeze to much of the area
Tuesday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 36 53 35 62 37 / 90 - 0 0 0
Austin Bergstrom Intl Airport 37 53 31 62 34 / 90 10 0 0 0
New Braunfels Muni Airport 38 55 32 62 35 / 90 - 0 0 0
Burnet Muni Airport 33 52 32 60 34 / 40 0 0 0 0
Del Rio Intl Airport 41 59 36 66 37 / 20 0 0 0 0
Georgetown Muni Airport 34 51 32 60 34 / 90 0 0 0 0
Hondo Muni Airport 40 59 32 66 36 / 60 0 0 0 0
San Marcos Muni Airport 38 53 32 61 36 / 90 10 0 0 0
La Grange - Fayette Regional 39 51 33 60 36 / 90 20 0 0 0
San Antonio Intl Airport 40 56 35 63 38 / 90 0 0 0 0
Stinson Muni Airport 41 56 34 64 38 / 90 - 0 0 0

&&

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

$$

Aviation...Platt
Short-Term/Long-Term...Runyen
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