Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 231142

Area Forecast Discussion
National Weather Service San Angelo TX
642 AM CDT Thu Mar 23 2017

/12Z TAFS/

Look for very challenging flight weather for most of the next 24
hours. First, returning stratus will create MVFR ceilings, across
much of West Central Texas this morning, mainly south of Interstate
20. Conditions should improve to VFR by 18Z. Then, an approaching
cold front will produce very strong winds across all of West
Central Texas today. By 18Z, expect winds from the south around
30 knots, with possible gusts around 40 knots. Winds will continue
at these higher speeds until around midnight tonight, when they
will begin to diminish slightly. Finally, watch for thunderstorms
from 00Z to 12Z. Some thunderstorms may be severe.


.PREV DISCUSSION... /issued 531 AM CDT Thu Mar 23 2017/

(Today and Tonight)

..Hazardous Winds...

Although unseasonably warm temperatures will continue for another 24
hours, the main short-term forecast highlight is hazardous winds
this afternoon and evening. An approaching cold front will produce a
strong surface pressure gradient, across West Central Texas for much
of the next 12 to 18 hours. Winds from the south today will likely
range from around 20 to 30 mph, with possible gusts in the 40 to 45
mph range. Thus, a Wind Advisory is in effect today from 1 PM CDT
this afternoon until 1 AM CDT tomorrow morning. Wind speeds in this
range will create hazardous driving conditions, especially for high-
profile vehicles. Also, expect hazardous boating conditions on area
lakes, especially for smaller watercraft. Winds should begin to
diminish after midnight tonight. As a cold front, and its associated
upper disturbance moves closer to West Central Texas tonight,
showers and thunderstorms may develop along and near a surface
dryline as it moves from west to east across West Central Texas.
Showers and thunderstorms will likely form a squall line as they
move across West Central Texas. A few thunderstorms may produce
large hail and damaging winds.

(Friday through Wednesday)

A progressive and active weather pattern is in store late this week
through at least the middle of next week.

On Friday, an upper low will track slowly east along the KS/OK
border, with the upper trough axis shifting east across our area.
Ongoing showers and thunderstorms are expected across the area
southeast of a Brownwood to Junction line early Friday morning, just
ahead of a dryline. This convective activity will exit that area
during the morning, while clearing occurs from the west.

Attention turns to fire weather and wind concerns on Friday. The
The Fire Weather part of our discussion (below) addresses the
fire weather concern. Given the setup with the increased surface
pressure and low-to-mid level height gradients, gusty southwest
to west winds will develop by mid-morning across our area and
continue through late afternoon. Wind speeds could be borderline
near Wind Advisory criteria Friday afternoon across the area north
of a Mertzon to San Angelo to Baird line. High temperatures Friday
afternoon are expected to be in the upper 70s to lower 80s.

Winds will become north-northwest with a weak cold frontal passage
across our northern counties late Friday afternoon and early
evening, and across the rest of our area early Friday night. With
clear skies, dry air and diminishing winds overnight, temperatures
should drop into the mid to upper 40s for overnight lows Friday
night. Saturday looks dry and pleasant with surface high pressure
moving southeast across our area. Temperatures will rebound into
the upper 70s to lower 80s for highs on Saturday.

An upstream shortwave trough is progged to move east from the
southern Rockies into the Southern Plains on Sunday. A dryline is
expected to advance east across much of our area to near a Brownwood-
Junction line by late afternoon. The dryline could begin to make a
partial retreat Sunday evening before being overtaken by a weak cold
front overnight. With limited moisture return indicated, carrying
low PoPs in the vicinity of the anticipated position of the dryline.
Elevated fire weather conditions are anticipated behind the dryline
on Sunday afternoon with increased and gusty southwest winds, dry
air and well-above normal temperatures.

After a warm day Sunday with highs in the mid to upper 80s,
temperatures will be 5-10 degrees cooler for highs Monday across the
northern part of our area, and slightly cooler across the
southern part.

The 00Z GFS and ECMWF have overall agreement with the next upstream
system progged to affect our area in the Tuesday-Thursday time frame
next week, but still have notable differences in the timing and
track of the system. Both models have an upper trough diving
southeast into the western CONUS on Monday, with closed low
development and position of the upper low over northern Arizona by
early Tuesday morning. The ECMWF is faster and farther north with
the track of the upper low and trough, taking it across the Texas
Panhandle on Wednesday evening. The GFS takes the low to near El
Paso Wednesday night, then lifts it northeast across west central
Texas on Thursday. Both models show increased moisture and lift with
increased chances for convection across our area. Given the model
differences and uncertainty on days 6-7, we are being conservative
with rain chances at this time, and are carrying slight chance
PoPs on Tuesday, and chance PoPs Wednesday and Wednesday night.



..Fire Weather Watch...

Another cold front will move, from west to east across West Central
Texas, tomorrow and bring much drier air, at the surface. This drier
air will combine with gusty surface winds, from the west and
northwest, to create critical fire weather conditions across
portions of West Central Texas tomorrow afternoon. A Fire Weather
Watch is currently in effect for those counties along and north of
Interstate 20, from tomorrow morning through tomorrow evening.


Abilene  82  58  79  48 /   5  50   5   0
San Angelo  83  57  82  48 /   5  40  10   0
Junction  80  59  82  47 /   5  40  20   0
Brownwood  82  59  80  49 /   5  40  20   0
Sweetwater  82  54  78  48 /   5  50   5   0
Ozona       79  56  79  47 /  10  40   5   0


Fire Weather Watch from Friday morning through Friday evening
for Callahan-Fisher-Haskell-Jones-Nolan-Shackelford-Taylor-

Wind Advisory from 1 PM this afternoon to 1 AM CDT Friday for
Jones-Kimble-Mason-McCulloch-Menard-Nolan-Runnels-San Saba-


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