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686
FXUS64 KSJT 251143 AAA
AFDSJT

Area Forecast Discussion...UPDATED
National Weather Service San Angelo TX
643 AM CDT Tue Jul 25 2017

.AVIATION...
/12Z TAFS/

Patchy low cloud development early this morning may briefly
affect our southern terminals. Around midday, a scattered
cumulus field should develop over much of our area. Winds
will be mainly from the south this morning and early afternoon,
backing to the southeast by late this afternoon and evening.
A few wind gusts 17-20 knots are possible late this morning and
during the afternoon. Late tonight and early Wednesday morning,
low cloud development/expansion is expected over a larger part
of our southern and southeastern counties, with KJCT the most
likely to have MVFR ceilings.

&&

.PREV DISCUSSION... /issued 338 AM CDT Tue Jul 25 2017/

SHORT TERM...
(Today and Tonight)

The upper high will build today and tonight over eastern New Mexico,
northwest Texas and Oklahoma. With building heights aloft and
increasing subsidence, rain chances across our area will be on a
diminishing trend. While the possibility of an isolated afternoon
shower or thunderstorm cannot be ruled out entirely for the
southeastern part of our area, the chance looks remote enough to not
mention in the forecast. High temperatures this afternoon will be in
the mid to upper 90s with a few locations near the 100 degree mark.
With somewhat humid conditions and dewpoints in the 60s, heat
indices will be in the 100-103 degree range at some locations this
afternoon. Warm and muggy conditions are expected tonight with lows
in the lower to mid 70s and dewpoints climbing into the upper 60s to
lower 70s overnight. Per the model boundary layer RH fields, low
cloud development is expected over the Hill country tonight after
Midnight, expanding northwest over the southeastern part of our area
by early Wednesday morning.

LONG TERM...
(Wednesday through Monday)

Upper level ridge continues to slowly shift west through the
period, but with fewer afternoon clouds and a little soil moisture
drying, afternoon temperatures should remain pretty close to
persistence through Friday. This means highs mainly in the mid
and upper 90s with a few locations making a run at the 100 degree
mark each day.

Pattern finally reaches the tipping point by late Friday into
Saturday, with the upper high shifting far enough west to allow
for better northwest and northerly flow, weakening the cap and
allowing for weak shortwaves to rotate around the high and into
the area. ECMWF remains farther west with the ridge as far as the
California and Nevada border by late in the weekend. GFS is not
quite as far west, and generates less convection across the area
for the weekend and into early next week. These large upper highs
tend to resist shifting quite that far quite so fast, so suspect
that a solution somewhere in the middle may be the best solution.
Will increase PoP`s for the weekend and into next week, but not
quite as widespread as the ECMWF would suggest at this point.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  98  75  99  74 /   5   0   5   5
San Angelo  99  74 100  74 /   5   0   5   5
Junction  96  73  96  73 /  10   5  10   5
Brownwood  96  73  98  74 /   5   5   5   5
Sweetwater  97  75  98  74 /   5   5   5   5
Ozona       95  73  94  73 /   5   5   5   5

&&

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

$$

Aviation and Short Term: 19
Long Term: 07