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

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101
FXUS64 KEWX 180455
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1055 PM CST Tue Jan 17 2017

.AVIATION...
ISOLD-SCT SHRA/ISOLD TSRA will continue across South Central Texas
overnight into Wednesday, then slowly taper off from west to east
during the afternoon into Wednesday night, except for east of I-35.
Have kept mention of -RA at the I-35 TAF sites overnight into
Wednesday morning. IFR/LIFR CIGs will prevail with ocnl MVFR/IFR
VSBYs in SHRA/TSRA overnight into Wednesday. Out west, clouds will
lift and become VFR during the late morning into afternoon. Northerly
winds 4 to 10 KTS will slowly diminish on Wednesday.

&&

.PREV DISCUSSION... /ISSUED 957 PM CST Tue Jan 17 2017/

UPDATE...
Fast moving moderate to heavy showers and isolated thunderstorms are
expected to continue to affect areas along and east I-35 corridor
through the overnight hours. New rainfall accumulations could range
from one quarter to one inch. Some minor flooding can`t be ruled late
tonight into early Wednesday across local roads, underpasses and low
water crossings as groups of showers and thunderstorms move from the
coastal plains into the I-35 corridor. Also, Stronger storms are
capable to produce up to penny sized hail. A warm front along the
coastal plains is expected to push to the south overnight into
Wednesday as an upper level disturbance pushes across the Southern
Plains. This scenario will keep high chances for showers across the
eastern two-thirds of South Central Texas at least through mid day
on Wednesday. Clearing is expected from west to east Wednesday
afternoon into the evening as the upper level disturbance moves into
the Central Plains.

PREV DISCUSSION... /ISSUED 600 PM CST Tue Jan 17 2017/

AVIATION...
A mix of LIFR to MVFR CIGs will become LIFR/IFR this evening into
the overnight hours and continue on Wednesday across most areas,
except CIGs along the Rio Grande will rise to VFR on Wednesday.
IFR/MVFR VSBYs are expected in SHRA/ISOLD TSRA. Northerly winds of
5 to 10 KTs will prevail tonight through Wednesday, except speeds of
10 to 20 KTs will linger along parts of the I-35 corridor early this
evening.

PREV DISCUSSION... /ISSUED 329 PM CST Tue Jan 17 2017/

SHORT TERM (Tonight through Wednesday Night)...
The 14Z surface analysis showed a stationary front in place across
the coastal plains just north of Victoria. Surface pressure rises
behind this front have helped to nudge the boundary southward, with
the front now just south of Victoria to just north of Laredo. Cold
air advection in the low-levels with warm air advection just above
the frontal layer will keep rain chances high across all of south
central Texas tonight. With higher moisture levels aligned near the
coast, the coastal plains stand the best chance for increased rainfall
amounts overnight. Also, can`t completely rule out a strong storm or
two across the coastal plains in low CAPE, high shear environment.
Some of the hi-res models show potential for more robust convection
after midnight as a mid-level shortwave trough moves across the
region.

The synoptic pattern will largely remain unchanged on Wednesday,
although the models do show a decrease in lift across the Rio Grande
plains as an area of subsidence moves in from Mexico. This will
result in a dry forecast along the Rio Grande plains, with increasing
rain chances heading east into the I-35 and especially Highway 77
corridor.

LONG TERM (Thursday through Tuesday)...
On Thursday, southwesterly winds in the low-levels will result in
some drying from west to east across the region. We will keep a low
chance for rainfall across the coastal plains in the morning, but
then go with a dry forecast in the afternoon. A dry forecast is in
store on Friday with highs well into the 70s.

Attention will then turn to the upcoming weekend as an upper level
low moves across Texas. The main concerns with this low will be
very windy conditions along increasing fire weather concerns on
Sunday. The forecast models have trended slightly wetter across the
central and eastern portions of the region and we will include a low
chance for showers generally along and north of I-10. The models also
continue to show a pattern conducive for very windy conditions with
an impressive area of northwesterly 850mb winds in the 40-50kt range
during peak mixing. The surface pressure gradient remains stout and
as previously mentioned, we will likely need a Wind Advisory for all
areas. Also concerned that any of the stronger stronger showers may
produce enough rainfall to help drag some higher momentum air down to
the surface and produce very strong wind gusts. The weather pattern
should briefly turn a little quieter on Monday and Tuesday, with the
medium range models showing another upper trough moving in during the
middle of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              48  59  47  74  51 /  90  80  20  10   0
Austin Bergstrom Intl Airport  48  58  46  73  50 /  90  80  30  10   0
New Braunfels Muni Airport     49  59  48  74  51 /  90  70  30  10   0
Burnet Muni Airport            44  57  43  72  48 /  80  50  10  -    0
Del Rio Intl Airport           48  63  45  74  47 /  50  10   0   0   0
Georgetown Muni Airport        46  57  45  73  49 /  90  70  20  10   0
Hondo Muni Airport             50  63  47  75  48 /  80  50  20  10   0
San Marcos Muni Airport        49  59  48  73  51 /  90  80  30  10   0
La Grange - Fayette Regional   53  60  51  72  53 /  90  90  50  20   0
San Antonio Intl Airport       50  61  49  74  52 /  90  70  20  10   0
Stinson Muni Airport           52  62  49  73  51 /  90  70  20  10   0

&&

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

$$

Mesoscale/Aviation...04
Synoptic/Grids...17
Public Service/Data Collection...30



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