Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 211700

1100 AM CST SUN DEC 21 2014

/18Z TAFS/

Stratus is resulting in MVFR ceilings at all sites late this
morning. Clouds are expected to slowly clear from west to east, with
most sites becoming VFR by 20z. Southwest winds of 10 to 16 knots,
with higher gusts, are expected today. Stratus is once again
forecast to develop after midnight, affecting mainly KSOA, KBBD and
KJCT. More uncertainty remains at the other two sites, so VFR
ceilings were continued at this time.


.PREV DISCUSSION... /ISSUED 553 AM CST Sun Dec 21 2014/

/12Z TAFS/

Main impacts today are IFR to MVFR Cigs and gusty south to
southwest winds this afternoon of 15 to 20KTS. Patchy MVFR Fog will
impact some terminals, too. KSOA had IFR CIG with MVFR VIS at 12Z
while the remaining sites had MVFR CIGs. Expect mostly MVFR at
most TAF sites except KSOA. However, IFR Cigs could develop
temporarily between 12Z and 13Z across remaining TAF sites. VFR
Cigs are expected to develop after 19z at most TAF sites by 19Z as
drier air filters into the area from the west.


PREV DISCUSSION... /ISSUED 343 AM CST Sun Dec 21 2014/

(Today and Tonight)

Patchy fog was observed in Ozona at 09Z/3AM while low clouds
continue to overspread the region.  A surface trough of low
pressure, located across far West Texas, was providing low level
warm air advection, gusty south winds and isentropic lift, causing
low clouds to develop early this morning.  This surface trough
developed in response to a broad upper level trough located across
the Plains.

Latest models forecast the surface pressure gradient to tighten
through today and result in gusty south winds of 20 to 25 mph this
afternoon. Patchy fog will burn off by mid morning. Clouds will
be slow to clear from west to east through this afternoon,
resulting in mild temperatures across the west and slightly cooler
high temperatures across the Northwest Hill Country.

The models differ with the timing of the 850 MB trough passage
through West Central Texas tonight.  A slower passage could maintain
the low clouds in the area while a faster passage would decrease the
low clouds.  The NAM is slower compared to the faster ECMWF and GFS
models.  For now, went with a faster passage and decided not to
include fog for tonight.  However, fog and low clouds could form
across the eastern half of West Central Texas early Monday morning
if winds go light and the 850 MB trough holds off.

(Monday through Saturday)

Mild temperatures and dry weather are expected through Monday night.

On Tuesday a vigorous upper level trough swings in from the west
across the forecast area. This trough will cause rising air,
increasing cloud cover and a chance for light scattered rain
showers mostly north and west of a line from southern Shackelford
County to northwest Coke County. Rain chances of 30 to 40 percent
will be highest across north and northwest most counties. South of
a Brownwood to San Angelo to Ozona line rain chances will be
mostly less than 20 percent. The remainder of the forecast period
is expected to be dry. The NAM model keeps the area dry with only
clouds moving through with the upper level trough but all other
models are in agreement with the current forecast.

Thursday, Christmas Day, will be dry and very mild with morning
lows in the upper 30`s and afternoon highs in the 60`s.

A dry cold front will move south through the area on Friday,
December 26 and temperatures will drop significantly. As a
result, high temperatures on Saturday, December 27 will reach only
into the upper 40`s to near 50 with morning lows near or just
below freezing.


Abilene  60  45  72  42  53 /   0   5   5  20  10
San Angelo  64  44  76  42  56 /   0   5   5  20  10
Junction  59  43  74  42  58 /   5   5   5  10  10




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