Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 290439

1139 PM CDT Sat Mar 28 2015

/06Z TAFS/

VFR conditions will continue across the terminals the next 24
hours. Expect an increase in south and southwest winds again on
Sunday. A weak cold front will move across the northern terminals
early Sunday evening, shifting winds to the north in its wake.


.PREV DISCUSSION... /ISSUED 625 PM CDT Sat Mar 28 2015/

/00Z TAFS/

VFR conditions will continue across the terminals the next 24
hours. South to southwest winds will diminish this evening but
increase again on Sunday. A cold front will approach the KABI
terminal towards the end of the forecast period, with winds
shifting to the north after 23Z.

PREV DISCUSSION... /ISSUED 328 PM CDT Sat Mar 28 2015/

(Tonight and Sunday)

Temperatures across west central Texas have warmed into the lower
to middle 80s at mid-afternoon. Shortwave upper ridge over the
Desert Southwest will shift east into Texas on Sunday. With south-
southwest low-level flow, our above normal temperatures will
continue, and to a greater extent on Sunday. Wind speeds will
decrease this evening, but should have some increase overnight in
the favored areas near/downstream of the higher terrain with low-
level jet developing. Overnight low temperatures are expected to
range from around 50 along the I-10 corridor, to the upper
50s/near 60 degrees in our northern counties.

With an upper trough moving southeast across the upper Midwest on
Sunday, trailing portion of associated cold front will move south
into our far north and northwest counties by early Sunday evening.
Strong 850mb thermal ridging pattern is indicated just ahead of
this front with compressional warming effects. With this pattern
and sunny skies, temperatures are expected to soar into the lower
90s for highs across much of the Big Country and Concho Valley
areas (including Abilene, Sweetwater, Ballinger and San Angelo),
with mid-90s possible at a few locations. Having mentioned this,
the record highs for Sunday (96 degrees at Abilene and 97 at San
Angelo) look safe and are expected to hold. South-southwest winds
will continue ahead of the front. Winds will shift to the north
with the frontal passage late in the day across the far
north/northwest part of our area (Haskell, Throckmorton, Fisher
and Jones Counties).


(Sunday night through next Saturday)

An upper level trough is currently in place over the eastern U.
S. with a ridge breaking down over the western states, and Texas
under northwest flow. There is a compact upper level low west of
the southern California coast.

As the upper level low out over the Pacific approaches the area
Monday night into Tuesday, rain chances will come into the picture.
Both the GFS and ECMWF weaken the low, flattening it into an open
wave. However, the GFS suppresses the best lift to our south, and
the ECMWF is more amplified with the system as a whole. Thus, the
ECMWF leads to more synoptic lift, and better rain chances/higher
rainfall amounts for our area than does the GFS. Trends remained
generally similar to previous models runs, bringing in rain
chances Monday night into Tuesday, so no significant changes were
made to the forecast, keep at least slight chances in from Monday
night through Tuesday night.

The GFS develops a large trough across the western U. S. at the
end of the week with southwest flow over Texas. A shortwave will
move across the central plains region Thursday night into Friday,
sending a cold front into Texas. The GFS develops precipitation
Saturday into Saturday night across the area associated with
shortwave impulses embedded in the southwest flow, and the cold
front entering the area. While this can`t be ruled out, timing
these shortwaves and cold fronts 6 to 7 days in advance is very
tricky, so have not gone higher than slight chance PoPs at the end
of the forecast. Temperatures behind the cold front Saturday look
to be significantly cooler, with highs only in the upper 60s to
around 70 degrees.

In between these two potential rain chances, zonal flow and a
strengthening low level thermal ridge will lead to warming
temperatures through the middle of the work week. Medium range MOS
guidance from the GFS warms San Angelo into the upper 90s, and
Abilene into the mid to upper 90s on Wednesday and Thursday. And
although we should bounce back quickly from the cold front that
moves through the area Sunday night/Monday morning, we are not
expecting mid to upper 90s by the second half of the week, and
have tempered highs significantly from the very warm MEX numbers.



Abilene  59  92  53  77  59 /   0   0   0  10  20
San Angelo  56  94  53  80  60 /   0   0   0   5  20
Junction  52  87  54  80  60 /   0   0   0  10  20




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