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556
FXUS64 KSJT 220843
AFDSJT

Area Forecast Discussion
National Weather Service San Angelo TX
343 AM CDT Sun Sep 22 2024

...New SHORT TERM...

.SHORT TERM...
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(Today and tonight)
Issued at 342 AM CDT Sun Sep 22 2024

...Thunderstorms expected this afternoon through tonight...

Currently, an upper level low is located over CO, with southwest
flow over west central Texas. This low is expected to open into a
wave while slowly moving east into the central and southern plains
by Monday morning. This will maintain southwesterly flow over our
area. At the surface, a cold front is expected to move south into
our CWA by this afternoon, making its way through the rest of the
area by late tonight. Scattered to widespread thunderstorms are
expected to develop along and ahead of the cold front this
afternoon, and continue through most of the overnight hours.

With temperatures warming well into the 80s to lower 90s this
afternoon, combined with plentiful low level moisture
(precipitable water values near 2 inches), low levels will
destabilize ahead of the front. Mixed layer CAPE values are
forecast to be in the 500 to 1500 J/kg range during peak heating
hours. Deep layer shear values of 40 to 50 knots over the area,
combined with the instability will allow some of the storms to
become strong, with a few storms possibly severe. The main concern
with the storms will be wind gusts over 60 mph, but hail up to
the size of quarters will also be possible. After sunset,
instability will wane, and although storms may continue, the
concern for severe weather will diminish. The other concern will
be heavy rain and localized flooding with precipitable water
values near 2 inches.

Storms are expected to develop first over the Big Country along
the front, then spread southward over the rest of the area during
the afternoon and overnight hours as the front moves south.
Overall coverage should diminish late tonight, but isolated to
scattered activity will still be possible after midnight, mainly
south of Interstate 20.
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&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 153 PM CDT Sat Sep 21 2024

...Rain chances and cool temperatures to continue through
Wednesday. Drier with a slow warming trend expected Thursday into
the weekend...

An upper low over Colorado is expected to open into a trough as
it moves into the Central Great Plains late Sunday into Monday.
This will put our area in the troughing regime with an upper high
generally located to our southeast along the Texas Gulf Coast. At
the surface, a cold front will be pushing into our area with
showers and storms ongoing by 00Z Monday. The front will progress
through most of the area by 12Z Monday. There is expected to be a
lull in activity for much of day on Monday as the front slowly
retreats back to the north and zonal flow aloft prevails. Isolated
to scattered chances for precipitation remains as an embedded
shortwave impulse aloft cannot be ruled out. Convective activity
begins to ramp back up Tuesday as a weak secondary trough is
expected to develop just to our north and west with the frontal
boundary still in our general area. Moisture will still be
abundant with above normal pWats across the area in the 1.4+ inch
range. This activity will not be as focused along the front (as
compared to Sunday) and is expected to be more scattered in nature
leading to widespread chance PoPs through early Wednesday. As the
surface forcing begins to weaken across our area with the front
pushing south, activity will become more nebulous and should
eventually come to an end by late Wednesday. Temperatures during
this timeframe will be well below normal for this time of year
with highs Monday and Wednesday being the coolest in the mid 70s
to low 80s. Highs Tuesday will be a bit warmer with the front
drifting back north in the low to mid 80s. Overnight lows will be
cool in the upper 50s to mid 60s.

Uncertainty in the upper pattern begins to take shape later in
the week. Mid range models tend to agree that an upper low will
drop out of the Upper Plains and Midwest by late Wednesday into
Thursday and should stall out. Where exactly the low stalls out
remains a point of contention. The general consensus though is
that much drier air will filter in behind the cold front Wednesday
and that West Central Texas will be on the backside of this upper
low in an area of greater subsidence. Most ensemble members of
both the GFS and ECMWF keep our area free of precipitation from
Thursday through next weekend. We will see a gradual warming
trend, largely due to the 850 mb thermal ridge slowly working its
way back into our area as we will still be seeing a dry northerly
wind at the surface. Highs will be in the low to mid 80s with
overnight lows getting slightly cooler in the mid 50s to low 60s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1242 AM CDT Sun Sep 22 2024

MVFR ceilings are expected to move into all sites except KABI by
12Z Sunday morning. These low clouds are expected to scatter out
or rise to VFR heights by 17Z. Later in the day, a cold front will
move into the area, with TSRA expected to develop along the front.
KABI will be first impacted between 18Z and 21Z, with KSJT next
between 21Z and 00Z late tomorrow afternoon. KBBD, KSOA, and KJCT
should not see storms hit until after 00Z. If storms move in
faster than currently expected, these times will have to be
adjusted by future forecasts.

&&

.PRELIMINARY POINT TEMPS/POPS...
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Abilene     91  59  75  62 /  60  80  30  20
San Angelo  93  62  76  63 /  50  80  40  20
Junction    92  66  82  65 /  10  40  40  10
Brownwood   91  64  78  64 /  30  60  40  20
Sweetwater  88  59  75  63 /  80  70  20  20
Ozona       89  63  77  64 /  30  70  40  20
Brady       91  64  78  64 /  20  50  40  20
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&&

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

$$

SHORT TERM...20
LONG TERM....50
AVIATION...20