Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 270510
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1110 PM CST FRI DEC 26 2014

.AVIATION...
/06Z TAFS/

Deteriorating flight conditions will develop overnight, with
ceilings dropping to 2500 feet at all terminals by sunrise. By mid
afternoon, KABI and KSJT`s ceilings will climb above 3000 feet.
Farther southeast, ceilings won`t improve to shortly before sunset
at KBBD and KJCT. Gusty northeast winds near 20 kts may also develop
across the southern terminals. May see some light sprinkles for the
KABI area...but not significant enough to reduce visibilities.

&&

.PREV DISCUSSION... /ISSUED 517 PM CST FRI DEC 26 2014/

AVIATION...
/0Z TAFS/
Strong cold front is showing up on radar From just north of
Abilene to near Sterling City. Expect wind shift to occur a bit
sooner than previous forecast...so have adjusted based on latest
radar. Front should be through the forecast area by 10Z with
north winds of 10 to 20 kt. Will also see some mid level clouds
develop overnight...but should be vfr through the period. May see
some virga or very light precipitation for the KABI area by
sunrise...but confidence is low that it will cause any visibility
restrictions. Dry air near the surface should evaporate most
precip trying to fall.

PREV DISCUSSION... /ISSUED 349 PM CST Fri Dec 26 2014/

SHORT TERM...
(Tonight and Saturday)

Upper trough axis early this afternoon lies along the spine of
the Rockies with an associated cold front moving through the
Panhandle. The cold front should be through most of the Big
Country by late this evening and through the remainder of the
forecast area by daybreak tomorrow. Soundings do not favor snow
and suggest only rain, albeit light, with the best chance over our
southeastern counties Saturday afternoon. Morning lows tomorrow
will depend on the speed of the cold front with temperatures
ranging from the mid 30s over the Big Country to the lower 40s
over the Interstate 10 corridor. Saturday will be mostly cloudy
behind the cold front with north winds 10 to 15 mph. Afternoon
highs will be around 25 degrees cooler than today with highs
ranging from around 40 in the Big Country to the upper 40s along
the Interstate 10 corridor.

15

LONG TERM...
(Saturday night through next Friday)

Only minor changes made to the forecast overall, with the most
active weather still expected next week as an arctic airmass moves
into the area.

Saturday night, the base of a trough will move through our
southwestern counties, bringing a slight chance of precipitation
with it. Have gone ahead and added a mention of a rain/snow mix to
the forecast for Crockett and Irion Counties for this system as it
is expected to be a compact, but potent wave. This will result in
cooling through lift, and enhance chances for at least a mix of
some snow and/or sleet in the precipitation as it moves through.

We still expect to see a short warming trend Sunday and Monday
with dry weather, as flow aloft becomes zonal.

The arctic cold front is still due into the area Monday night
into Tuesday morning. Have reduced PoPs Tuesday as the only
available lift will be in the form of isentropic flow over the top
of the cold airmass at the surface, mainly resulting in low clouds
more than actual precip. Any precipitation that does fall will be
very light. Temperatures Tuesday will struggle to get out of the
30s, and may remain below freezing north of I-20.

On Wednesday, northeasterly flow will continue at the surface
with westerly flow becoming more southwesterly aloft. This will be
due to the next shortwave dropping south into southern California
and western Arizona and deepening. Wednesday into Thursday, as
this low approaches, weak embedded shortwaves will move across the
area, resulting in slight chance of light precipitation until
Thursday and Thursday night when the main low begins to lift
east/northeast, bringing better lift into the area. For Wednesday,
soundings indicate a rain/sleet/freezing rain type of precipitation
forecast, with moisture available above 500mb, but then a fairly
deep dry layer until you work done to below 800mb where the
atmosphere again saturates. By Wednesday night into Thursday
morning, the column looks to be become saturated throughout,
arguing for the potential for snow to be introduced, but there
will also be a persistent warm tongue around 800mb that argues for
keeping a mention of sleet in the forecast as well. As the system
exits, Thursday night into Friday, we will keep at least a slight
chance of precipitation, and temperatures will finally begin to
warm across the area, so will bring liquid precipitation
progressively farther north Thursday night and Friday.

20

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  69  35  41  26  53 /   5  20  20  10   5
San Angelo  71  37  47  28  55 /   5  10  10  10   5
Junction  71  43  49  31  57 /   5  10  20  10   5

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

08/21/60






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