Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 182057
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
357 PM CDT Thu Sep 18 2014

.SHORT TERM...

(Tonight and Friday)

Showers and thunderstorms have developed and increased in coverage
across our northern, central and eastern counties this afternoon. An
unstable and very moist airmass is in place, and a weak surface
convergence boundary has developed from south of Sterling City to
southern San Saba County. Additional development to the south is
expected through this evening. Carrying the highest PoPs prior to 7
PM this evening. With much of this convection diurnally driven, the
coverage should decrease during the night. With precipitable water
values between 1.8 and 2.05 inches, along with slow movement of the
showers and storms, locally heavy rainfall is likely with a
possibility for flooding. Considered issuing a Flash Flood Watch,
but holding off at this time for a couple of reasons. The convection
so far today has shown enough movement to not persist for too long
in any one area. The new development to the south is occurring into
areas where little rainfall has occurred recently. We will closely
monitor the situation, however.

The very moist airmass remains in place on Friday. The remnants of
Odile are forecast to track from eastern Mexico into the Texas
Panhandle. Have chance PoPs across our area, with slightly higher
PoPs across our northern and northwestern counties. Expect to have
an increase in coverage during the afternoon, with diabatic heating
and destabilization of the airmass. Lows tonight will be in the
upper 60s to lower 70s, with highs on Friday in the range of 83-87
degrees.

.LONG TERM...
(Friday night through Monday)

The potential for rain will continue through Monday, with the
potential for locally heavy rainfall continuing through at least
Saturday. With remnants of Hurricane Odile supplying mid- and upper-
level moisture, the potential for locally heavy rainfall, and
possible flash flooding, will continue through at least Saturday.
The NAM and GFS present nearly saturated sounding profiles, with
precipitable water amounts mainly between 1.75 and 2 inches,
through Saturday night. Also, cross sections of NAM and GFS Omega
fields, along several tracks across West Central Texas, indicate
deep assent from Friday night through Saturday night. Although, the
GFS Omega fields are more promising for rainfall than the NAM
fields. Nevertheless, the NAM does show good assent Saturday into
Saturday night. As for numerical PoP guidance from these two
models, their numbers are very close for Saturday and Saturday
night, which is the last period for the NAM based numerical
guidance. The only negative indicator for widespread heavy
rainfall this model run is the spotty QPF fields the models
present. This QPF spottiness diminishes confidence for widespread
heavy rainfall and its associated flash-flood potential. The best
rain chances continue along and north of Interstate 20 through
Saturday night, with deeper moisture and better upper dynamics.
On Sunday, a weak cold front moves into West Central Texas from
the north. This boundary will enhance rain chances for Sunday,
especially if it stalls somewhere over West Central Texas. Then,
rain chances diminish into Monday, as an upper ridge builds over
the Rockies and drier air moves into Texas.

(Monday night through Thursday)

A dry forecast dominates the remainder of the long term, with
afternoon highs near seasonal normals.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  70  84  70  86  69 /  40  40  40  40  40
San Angelo  70  85  71  88  70 /  50  30  30  30  30
Junction  72  87  72  86  70 /  50  30  30  30  30

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

Short Term: 19
long Term:  23





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