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

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FXUS64 KEWX 250005
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
705 PM CDT Mon Apr 24 2017

.AVIATION.../00Z TAFS/
VFR conditions are expected to continue at all sites until MVFR
ceilings develop at the I-35 sites around 11Z as southerly 10 knot
winds bring Gulf moisture back into the region. Some models are
indicating that ceilings may lower to IFR at SAT/SSF, but given that
this is the first day of moisture return we have stuck with higher
ceilings for now. Ceilings should lift to VFR by 17Z at all sites
with southerly winds gusting to 20-25 knots tomorrow at AUS.



&&

.PREV DISCUSSION... /ISSUED 256 PM CDT Mon Apr 24 2017/

SHORT TERM (Tonight through Tuesday Night)...
A compact mid level impulse crossing the Mexican mountains will
generate isolated showers and thunderstorms there this afternoon.
Only the HRRR shows any of this moving across the Rio Grande into our
area this evening. Also, previous runs of TTU-WRF showed some moving
into our far western counties. Have a 5 POP for Maverick and Dimmit
Counties where steering flow would take them.

As an upper level trough moves across the Rockies and out into the
High Plains, a surface low drifts to the northeast across the
Southern Plains. South to southwest lower level flow will result.
This increases moisture for stratus formation later tonight into
Tuesday morning, then it mixes out by midday. The main impact of
this will be a rapid strong warmup as 850 MB temperatures warm to
21C-27C and 925 MB to 27C-33C on Tuesday. High temperatures Tuesday
will be about 10 degrees above normal, with some approaching 100
along the Rio Grande. A dryline moves into western areas late Tuesday
night. There may deep enough moisture below a strong cap for patchy
drizzle along and east of Highway 281 by Wednesday morning. Have
silent 10 POPs for this.

LONG TERM (Wednesday through Monday)...
The upper level trough moves out across the Plains on Wednesday with
the dryline moving across the remainder of our area by midday. In
spite of a right entrance region of an upper level jet passing
overhead, moisture will be confined to below a strong cap with only
patchy drizzle for only silent 10 POPs east of I-35. Should moisture
become deeper and linger longer, then isolated showers and perhaps a
thunderstorm are possible along the Highway 77 corridor around
midday. Downslope flow will keep temperatures above normal Wednesday.
Strong mixing and a tight pressure gradient will result in breezy
conditions. Some guidance shows speeds near advisory levels. Low
humidities combined with the winds mentioned above will create
elevated to near critical fire weather conditions with best chances
for these conditions west of San Antonio along and southwest of the
Escarpment to the Rio Grande. A cold front moves across our area late
in the afternoon into evening after peak heating. No rain is
expected with the front as moisture will have been scoured out by the
dryline. Cool surface high pressure settles into our area Wednesday
night for a return to below normal low temperatures. Cool down will
be short lived as south to southwest lower level flow quickly returns
on Thursday with high temperatures back above normal. The surface
high moves off to the east as surface pressures lower in the Plains
as an upper level trough takes shape over the western states. Another
strong warming trend is expected for late week into next weekend as
850MB and 925MB temperatures rise again. There are good chances for
100 degree high temperatures along parts of the Rio Grande on Friday
and Saturday as 925MB temperatures near 35C.

The western states upper level trough moves across the Plains next
weekend with a dryline/pre-frontal trough and a cold front moving
across South Central Texas. Timing and consistency issues have been
noted in the models and run to run. The 12Z runs show slightly better
agreement and for now, have gone with a Saturday night frontal
passage and a Sunday upper trough passage. Expect isolated showers
and thunderstorms on Saturday to become more numerous Saturday night
and then end on Sunday. There is a potential of strong to severe
storms as forecast soundings indicate high CAPE and shear.
Temperatures fall below normal in the wake of the front and remain
below normal into next Monday due to cool surface high pressure.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              63  89  72  89  55 /   0  -   10  10  -
Austin Bergstrom Intl Airport  61  88  72  88  52 /   0  -   10  10  -
New Braunfels Muni Airport     61  88  71  90  53 /   0  -   10  10  -
Burnet Muni Airport            60  89  68  84  51 /   0   0  10  -   -
Del Rio Intl Airport           62  97  67  91  58 /   0   0   0   0   0
Georgetown Muni Airport        63  88  71  86  52 /   0  -   10  10  -
Hondo Muni Airport             60  92  66  91  53 /   0   0   0  -    0
San Marcos Muni Airport        61  88  71  89  53 /   0  -   10  10  -
La Grange - Fayette Regional   61  87  72  89  54 /   0  -   10  10  -
San Antonio Intl Airport       63  89  72  90  55 /   0  -   10  -    0
Stinson Muni Airport           62  90  71  91  56 /   0  -   -   -    0

&&

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

$$

Mesoscale/Aviation...LH
Synoptic/Grids...05
Public Service/Data Collection...Treadway



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