Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 271811
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1210 PM CST SAT DEC 27 2014

.UPDATE...
Updated to remove winter weather advisory for Haskell and
Throckmorton counties and lower highs for today to current
observations.

&&

.DISCUSSION...
Models end most precipitation this afternoon, although some of
the short range models still keep some light precipitation in the
eastern Big Country. Will continue a slight chance of a mixture
of light snow and rain in eastern and northern Big Country this
afternoon, and remove rain chances elsewhere. Temperatures
otherwise will be remaining steady or slowly fall a couple degrees
this afternoon under strong cold advection.

&&

.PREV DISCUSSION... /ISSUED 1136 AM CST SAT DEC 27 2014/

AVIATION...
/18Z TAFS/

Expect VFR conditions to return later this afternoon. An upper-
level system will continue to slowly move east this afternoon. As
it does, it will pull low ceilings and weather with it. Look for
weather to end and ceilings to gradually rise to VFR ranges from
now through 00Z this evening. For the remainder of the forecast
period, plan for VFR conditions and light winds to dominate.

PREV DISCUSSION... /ISSUED 725 AM CST Sat Dec 27 2014/

UPDATE...

Quick update to account for current radar and weather trends.

Calls to Haskell and Throckmorton counties show mostly snow
falling across those areas as of 7 AM...with sleet falling at
Sweetwater and a rain/sleet mixture at Abilene. Back edge of the
precip area has reached Sweetwater as well, so it`s a bit of a race
to see how quickly areas can switch over to sleet/snow before the
precip diminishes. Have updated forecasts to go just snow for
Haskell and Throckmorton and added a little snow accumulation,
although we are still talking only a quarter inch or so.

PREV DISCUSSION... /ISSUED 536 AM CST SAT DEC 27 2014/

AVIATION...
/12Z TAFS/

High end MVFR/low end VFR ceilings in the 2500-3500 feet range will
persist across West Central Texas terminals through the morning
hours and into the afternoon. Patchy light rain will continue as
well, mainly near Abilene, although any drops in visibilities will
be brief. AS the rain ends from the west, ceilings will climb this
afternoon and evening well into VFR range, as north winds gust to
over 20 kts at times.

PREV DISCUSSION... /ISSUED 330 AM CST Sat Dec 27 2014/

SHORT TERM...
(Today and Tonight)

Messy forecast for today, although not as messy as what is possible
next week.

Large area of precipitation extends from the Permian Basin north and
northeast across the Texas South Plains and clips the western
portion of West Central Texas near Sweetwater early this morning.
Across the South Plains, this precipitation is in the form of a
decent little snow band. Farther south and east, its still rain and
with dry lower levels, a lot of this rain is not reaching the
ground. However, as this rain continues to saturate the lower
levels, some is finally starting to reach the surface.

What form is will take is another question. Evaporative cooling will
allow temperatures to fall during the morning hours, especially in
that sunrise to mid morning time frame. Model soundings suggest that
aloft, snow crystals will be made, and its a matter of will they
melt as they drop towards the ground. For the most part, should be a
cold rain with enough of a warm layer at the surface to cause
melting. For areas towards Roby and Rotan, there is a decent chance
that some snow will mix in at times with the rain, with lesser
chances towards Sweetwater and Abilene. Still, given the chances,
opted to include a mention of rain or snow in the forecast for much
of the Big Country west of an Abilene to Throckmorton line.

All the precip this morning is in advance of an Upper Level low over
Arizona. This low will weaken as it pushes southeast towards the Big
Bend tonight. Still, might be just enough lift with the system for a
little wintry precipitation across the Edwards Plateau as the system
moves across. Previous forecast had this well covered and made few
adjustments tonight.

Finally, temperatures. Readings will continue to fall tonight and
probably through a big part of the morning hours before leveling
off. Highs for the day for areas from San Angelo to Brownwood
southward towards I-10 will likely occur at sunrise, with afternoon
readings much cooler. Tonight, models had forecast lows down in the
mid 20s for much of the area, but models also suggest a fairly
extensive mid level cloud deck. Boosted clouds tonight and went a
little above guidance lows with this in mind.

LONG TERM...
(Sunday through Friday)

An upper trough axis will pass through the forecast area during
the day on Sunday with afternoon temperatures warming into the
lower 50s as surface winds begin to back to the southwest. Will
see some good warming on Monday in advance of an Arctic cold front
that will push through the area late Monday. After Monday morning
lows in the lower 30s, afternoon highs on Monday will warm into
the lower 60s south on Interstate 20 and into the 50s over the Big
Country. Postfrontal temperatures Tuesday morning will be in the
mid to upper 20s over the Big Country and around 30 over the
remainder of the CWA. Afternoon highs on Tuesday will range from
the mid 30s in the Big Country to the lower and mid 40s elsewhere.
Not expecting any precipitation during the day on Tuesday. Will
however continue to carry a slight chance of a mix of
precipitation Tuesday night with a slight chance on snow over the
western Big Country Tuesday evening and over the remainder of the
Big Country and the northern Concho Valley overnight Tuesday. The
remainder of the area will see a slight chance of a wintry mix of
freezing drizzle...freezing rain and sleet.

Winds aloft over the forecast area will back to the southwest
ahead of closed upper low over southern California on Wednesday.
After a brief respite from precipitation on Wednesday, the chance
of precipitation will increase Wednesday night as the upper
Pacific low moves eastward. Periodic disturbances in the southwest
flow aloft will move over the forecast area. Forecast soundings
indicate a saturated column, giving the CWA its best chance of
precipitation. There will be a chance of a wintry mix over the
entire area Wednesday night ranging from light snow over the
western Big Country to freezing rain over the remainder of the area.

Thursday will warm into the upper 30a and lower 40s with a slight
chance of light rain over the area and some freezing precipitation
over the northern CWA Thursday night. There is a slight chance of
rain on Friday as the upper low moves over New Mexico.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  35  27  52  35  58 /  10  10   5   0   0
San Angelo  42  29  54  34  63 /  10  10   5   0   0
Junction  45  31  55  30  64 /  10  10   5   0   0

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon CST today FOR THE FOLLOWING
ZONES: Haskell...Throckmorton.

&&

$$

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