Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 242323
AFDSJT

Area Forecast Discussion
National Weather Service San Angelo TX
623 PM CDT Tue Apr 24 2018

.AVIATION...
/00Z TAFS/

Scattered showers and thunderstorms will move east across the Big
Country this evening. Going with a TEMPO group for TSRA at the
KABI terminal from 01-04Z. The storms will move east of our area
by 06Z. These storms are initially expected to affect areas mainly
north of KSJT/KSOA/KBBD/KJCT for the evening/overnight hours. The
cold front will move south through the entire area by 18Z
tomorrow, bringing a chance of showers and thunderstorms with it
as it moves south. So, will include a mention of SHRA or TS
tomorrow morning for southern TAF locations as the front moves
through, and MVFR ceilings developing at the terminals. Also,
possible IFR ceilings at times tomorrow, but will let later shifts
refine ceiling heights.  21

&&

.PREV DISCUSSION... /issued 243 PM CDT Tue Apr 24 2018/

LONG TERM...
(Tonight and Wednesday)

Currently, temperatures have warmed into the mid 80s to lower 90s
across the region under mainly sunny skies. A cold front was
moving south through the Panhandle region towards Lubbock, with an
upper level shortwave moving into the western part of the state at
the same time. The front, combined with increasing moisture, very
warm temperatures, the approaching shortwave, and a pseudo-triple
point to the west of our CWA will likely result in showers and
thunderstorms developing to the west of our area this afternoon.
Visible satellite imagery/radar data at 215PM does indicate storms
trying to get going. These storms are expected to develop, then
move east into our Big Country area during the evening hours.
Most of the storms are expected to remain below severe levels,
but, there is a Marginal Risk for severe thunderstorms for the
Big Country with these thunderstorms, mainly for gusty winds to
near 60 mph, and hail up to the size of quarters, so some of these
storms will be strong.

As the cold front spreads south overnight, and through the rest of
the area tomorrow, additional shower/thunderstorm chances will
also spread south across the area. We will continue to have the
chance for isolated thunderstorms mixing in with these showers
tomorrow, but we`re not expecting any strong/severe storms
tomorrow. The other notable difference for tomorrow will be much
cooler temperatures behind the front as it moves through. The
colder air will be in the Concho Valley by 10 AM, and moving
through the I-10 corridor by Noon or 1 PM. Temperatures behind the
front will be in the low to mid 50s most of the day due to the
cold air advection, combined with cloud cover and rain-cooled air.
Temperatures will warm into the 60s and 70s along the I-10
corridor and Northwest Hill Country before the front moves
through, dropping temperatures down into the upper 50s during the
afternoon.

20

LONG TERM...
(Wednesday Night through next Tuesday)

Rain chances will shut off from north to south across our area
Wednesday night, as drier air moves in. Expect clearing skies from
the north during the night as well. Temperatures will be chilly
Wednesday night, with overnight lows expected to be in the 40-45
degree range. Cannot rule out the possibility of upper 30s lows in a
few low-lying areas. Patchy fog will also be a possibility with low
dewpoint depressions, recent rainfall and light winds overnight, but
confidence is too limited to include in the forecast at this time.

Thursday looks to be a pleasant weather day across our area with
mostly sunny skies and winds remaining light. Highs on Thursday are
expected to be mostly in the upper 70s, with lower 80s in some of
our central and southern counties.

Another cold front is progged to move south across our area Thursday
night, but the models have trended dry with this frontal passage.
With rather limited low-level moisture return indicated, have
removed rain chances for all except our far southern counties.
Another pleasant day for Friday expected with mostly sunny skies and
highs in the lower to mid 70s, with a surface ridge of high pressure
shifting southeast across the southern Plains.

The pattern looks quiet for our area for the weekend, with surface
ridge shifting east of our area and southeast to south winds
developing. Breezy conditions for Sunday are indicated with lee
surface trough development to our west and increased pressure
gradient.

Our area may have increasing chances for showers and thunderstorms
early next week, but model uncertainties remain. The 12Z GFS has an
upper trough deepening over the western CONUS on Monday, gradually
progressing east across the Rockies by Tuesday night. With this
setup, the GFS also has a dryline approaching our western counties
on Tuesday afternoon. The 12Z ECMWF is considerably slower to deepen
the western U.S. system and has a closed low along the southern
California coast on Tuesday. Given these model differences, keeping
PoPs low for Monday and Tuesday.

19

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  53  56  43  78 /  60  50  10   5
San Angelo  60  63  42  81 /  10  50  10   5
Junction  58  74  44  81 /   5  60  20   5
Brownwood  57  62  41  78 /  30  60  20   5
Sweetwater  48  54  46  77 /  60  50  10   5
Ozona       63  65  41  79 /  10  60  20   5

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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