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Area forecast discussion
National Weather Service San Angelo Texas
358 am CDT Fri Apr 20 2018

Short term...
(today and tonight)

This morning, mid and high level clouds are spreading over the
region from the southwest, with east to southeasterly surface winds
of 5-10 mph and temperatures in the 50s. Water vapor satellite shows
a low pressure system over southern Utah moving east, while a weak
ridge remains over Texas. This system will continue to move east
today, with the trough axis reaching a position over southeast
Colorado/OK and Texas panhandles by late tonight. As the trough moves
east today, the dry-line (currently stretching south to north from
El Paso through central new mexico) will move east to a position
just west of our forecast area by late tonight, and a surface low
will develop behind the dry-line and strengthen, resulting in a
tighter pressure gradient and strengthening southeast winds. These
blustery southeast winds (generally 15-20 mph with gusts to 30 mph)
are expected to develop around mid-morning and be strongest over
western portions of Concho Valley and the northern Edwards Plateau,
which is where a Wind Advisory has been issued. Some showers and
isolated thunderstorms will get generated along and east of the dry-
line, but models indicate that most of this activity will be west of
our region and any measurable rain in our forecast area will be
spotty at best this afternoon. Thus we have just a mention of slight
chance for showers/thunderstorms for this afternoon. With mostly
cloudy skies expected today, highs are expected to get only into the
low to mid 70s.

Shower/thunderstorm coverage should increase tonight as a jet streak
rotates around the trough and into our region, providing additional
lift, and increasing and deepening moisture moves in as well. Models
are in good agreement with the Big Country getting the most rainfall
(around 0.20-0.40 inches overnight tonight), with lesser amounts
south of that area. The high moisture content in the atmosphere
tonight will result in warmer overnight lows tonight in the mid to
upper 50s.



Long term...
(saturday through thursday)

Showers with isolated thunderstorms continue into Saturday. The
center of the upper trough, however, will be passing through
midday, with increasing subsidence over west central Texas. Drier
southwest winds will also moving in from the west, as a surface
low moves through. An afternoon cold front in the Big Country will
keep a few showers going, mainly north of the I-20 corridor. Storm Prediction Center
has a marginal risk of severe thunderstorms, in eastern sections
including Brown and San Saba counties, but the potential looks
limited with GFS most unstable CAPES of 1000 j/kg or less. Cold
front will push through the rest of west central Texas Saturday
evening, with cooler temperatures Sunday.

The next chance of shower and thunderstorms comes Tuesday night.
Northwest flow aloft, combined with a cold front, could produce a
mesoscale convective system. Widespread severe weather may be lacking, however, as
instabilities will not be strong. Cooler on Wednesday, with a few
lingering showers. Another northwest flow event is possible
Thursday night, but confidence isn't high 7 days out.


Preliminary point temps/pops...
Abilene 70 56 75 46 / 20 70 40 10
San Angelo 74 58 81 48 / 20 60 20 5
Junction 74 60 83 50 / 20 50 30 10
Brownwood 71 57 79 47 / 20 50 40 10
Sweetwater 70 57 74 44 / 20 70 30 5
Ozona 72 58 82 47 / 20 50 20 5


Sjt watches/warnings/advisories...
Wind Advisory from 1 PM this afternoon to 9 PM CDT this evening
for Crockett-Irion-Sterling.

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