Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 201145
AFDSJT

Area Forecast Discussion
National Weather Service San Angelo TX
645 AM CDT Fri Oct 20 2017

.AVIATION...
/12Z TAFS/

MVFR ceilings will affect the terminals this morning, with
ceilings lifting to VFR this afternoon. Widely scattered showers
and isolated thunderstorms will be possible across the area
through early afternoon but due to sporadic coverage will keep
precipitation out of the forecast at this time and monitor
trends. Expect VFR conditions this evening, with MVFR ceilings
returning to the southern terminals towards the end of the
forecast period.

&&

.PREV DISCUSSION... /issued 419 AM CDT Fri Oct 20 2017/

SHORT TERM...
(Today and Tonight)

An weakening upper level shortwave will move across the area today,
bringing a few showers and thunderstorms to West Central Texas
through this afternoon. Early this morning, scattered showers and
isolated thunderstorms are approaching far western counties ahead of
the aforementioned shortwave. Latest Hi-Res models weaken this
activity as it moves east across West Central Texas later today.
Given the model trends, will maintain slight POPs areawide today,
with precipitation ending by mid to late afternoon across eastern
sections. Cloud cover will be quite extensive this morning, with a
combination of mid/high clouds advancing east across the area and
some low clouds affecting areas generally south of interstate 20
this morning. Cloud cover will limit insolation today, resulting in
pleasant afternoon highs near 80 degrees. It will be breezy again
today, with south winds 10 to 20 mph.

Dry and warm conditions will prevail overnight, with low clouds
developing over southern sections towards daybreak. Lows will be
mainly in the mid 60s.

LONG TERM...
(Saturday and Sunday)

The models are in fairly good agreement in bringing an open upper
trough east into western parts of the Plains states Saturday
afternoon, and across the Plains and western half of Texas Saturday
night. A closed low is progged to develop withing the southern
part of this trough over the ArkLaTex vicinity by Sunday night.
Cold front with this system will push south across the Texas
Panhandle Saturday afternoon and early evening, and across west
central Texas between approximately 11 PM Saturday and 7 AM Sunday.

With upper support, lift along the cold frontal boundary and a
moist, unstable airmass in place, our area will have increased
chances for showers and thunderstorms mainly on Saturday night. A
few thunderstorms will be possible ahead of the approaching front
across our far northern counties late Saturday afternoon and
evening. Thunderstorms should develop south along the cold front
as it advances south across our area Saturday night. With a
favorable combination of instability and vertical shear, the Day
2 Convective Outlook from the Storm Prediction Center has Slight
Risk for severe storms across a few of our northeastern counties,
with Marginal Risk encompassing roughly the northeastern half of
our area. Large hail and damaging winds will be the primary severe
weather threats Saturday late afternoon and evening, with strong
and possibly damaging wind gusts becoming the main threat Saturday
night. The highest PoPs Saturday night are across approximately
the eastern third of our area, with lower rain chances farther
west where the coverage is expected to be lower. We have a
lingering slight chance PoP across our far southeastern counties
early Sunday morning.

Gusty north winds will follow the cold frontal passage Saturday
night, with breezy conditions continuing through about midday
Sunday. After warm and humid conditions on Saturday, cooler and much
drier conditions are expected on Sunday. North winds will decrease
in the afternoon and diminish in the evening. Good radiational
cooling is expected Sunday night with clear skies, dry air and light
winds as surface high pressure shifts southeast across our area.

(Monday through Thursday)

Dry conditions are indicated for our area Monday through Thursday of
next week, with mostly clear skies expected. Temperatures are
expected to rebound on Monday after a cool start to the day. A
cold frontal passage is progged late Monday night, associated with
an upper trough deepening over the Midwest. After a cooler day
Tuesday, good radiational cooling is indicated Tuesday night when
surface high pressure is forecast to move southeast across our
area. A warming trend follows Wednesday and Thursday, with the
arrival of another cold front possible by Thursday night. The 00Z
GFS shows a favorable pattern for compressional heating effects
across parts of our area ahead of the front Thursday afternoon.
This would result in well-above normal high temperatures Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  80  66  86  54 /  30  10  20  50
San Angelo  81  65  87  55 /  30  10  10  40
Junction  81  65  85  58 /  20  10  10  60
Brownwood  80  66  85  56 /  20  10  20  70
Sweetwater  80  65  85  53 /  30   5  10  30
Ozona       78  64  84  56 /  30  10   5  40

&&

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

$$

99/99/24



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