Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 310431 CCA
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
1115 PM CDT THU OCT 30 2014

.UPDATE...
The cold front continues to make progress to the south this
evening and is located near an Ozona, to Eden, to Goldthwaite line
as of 1030 PM. Showers and a few thunderstorms developed over the
eastern Big Country earlier this evening and moved south across
Brownwood but continue to weaken as the boundary layer
destabilizes. Additional showers, and maybe a thunderstorm, will
be possible for the remainder of the night, but these chances will
generally be confined to the southeast quadrant of the CWA. PoPs
were left in the 20-30% range through sunrise, but most of this
activity will be out of here by 4 AM. Minor modifications were
made to hourly grids, namely slowing down the diurnal cooling
trend as the stronger cold advection is lagging the initial front
and north winds of 10-15 mph are keeping the boundary layer mixed.

Johnson

&&

.AVIATION...
/06Z TAFS/

VFR conditions will continue at all terminals through the next 24
hours. Post-frontal northerly winds will occasionally gust 15 to 20
knots at the northern terminals through the day.

&&

.PREV DISCUSSION... /ISSUED 605 PM CDT THU OCT 30 2014/

AVIATION...
/00Z TAFS/

A cold front will push south through West Central Texas tonight
with a slight chance of associated showers and thunderstorms.
Convective activity should be limited to the southern terminals...
have included VCTS at those terminals. After frontal passage VFR
ceilings over the southern terminals will degrade to MVFR after
midnight...lifting back to VFR by 12Z. Northerly winds after
frontal passage will gust to around 20 KTS at the northern
terminals.

PREV DISCUSSION... /ISSUED 337 PM CDT THU OCT 30 2014/

SHORT TERM...
(Tonight and Friday)

A cold front is currently approaching the northern Big Country,
and will move through much of West Central Texas this evening.
Ahead of the front, an increasingly unstable environment is
developing, along with 0-6 KM bulk shear values of 30 to 40 knots.
The front should provide enough lift to result in isolated to
scattered showers and thunderstorms late this afternoon into this
evening. The best chance will be across the eastern half of the
area, where the better moisture resides. A few storms could become
strong to marginally severe, with large hail being the main
concern.

Stratus may also develop behind the boundary, eventually moving
south of the area by early to mid morning. Drier, cooler air will
slowly filter into the area behind the front, with overnight lows
ranging from mid to upper 40s across the Big Country, to the lower
50s across the Interstate 10 corridor. Clouds will clear from
north to south Friday morning, giving way to mostly sunny skies.
High temperatures on Friday will be below seasonal normals. Cold
air advection is expected through the day, but abundant sunshine
should still allow temperatures to peak in the mid 60s north, to
near 70 across the Interstate 10 corridor.

LONG TERM...
(Friday night through Thursday)

An area of high pressure building over the area will usher in much
colder air across the area for the first part of the weekend,
with some patchy frost possible Friday night, as lows drop into
the mid to upper 30s in most areas. The cool air will linger over
the area for Saturday with highs generally in the mid 60s. As the
area of high pressure slides off to our east Sunday, a return flow
will develop as surface winds increase from the southeast.

Our attention then turns to an upper-level trough that will be
moving across the Intermountain West Sunday night and Monday and
a tropical system that is expected to be south of Baja California.
The GFS has trended towards the ECMWF in the overall pattern. As
the upper trough approaches the area, mid to upper-level moisture
from the tropical system will get absorbed by the trough. A cold
front will also approach the area Tuesday morning with abundant
moisture in place. This will allow showers and thunderstorms to
develop Monday evening and increase in coverage, especially during
the day Tuesday. There remains some model differences when the cold
front will clear our area, putting an end to the rain chances. The
GFS remains faster than the ECMWF, with the Canadian GEM model
supporting the slower ECMWF solution.

The forecast was trended towards the slower model solutions. Given
the better model agreement, POPs were increased for Monday evening
and Tuesday. It looks like this system will give West Central Texas
some much needed rainfall, with most areas receiving near 1 inch of
rainfall, with locally higher amounts possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  48  67  38  64  48 /   5   0   0   0   0
San Angelo  52  71  39  68  50 /  10   0   0   0   0
Junction  54  73  38  67  48 /  20   5   0   0   0

&&

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

&&

$$

15/25







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