Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 310446

1146 PM CDT WED JUL 30 2014

/06Z TAFS/

The initial wind shift associated with this evening`s convection
has moved south to near a KSJT to KBWD line. However, the stronger
front is located over the Big Country near I-20. As this boundary
moves south, light and variable winds will shift to the north at
10-15 kts, occasionally gusting over 20 kts. Scattered showers,
and a few thunderstorms, were affecting the Concho Valley south
toward I-10 but aviation impacts are expected to be minimal. The
biggest forecast concern in the next 12 hours is the potential for
MVFR ceilings behind the cold front later tonight. Ceilings around
2000 ft were included at KSJT and KABI for a few hours, with
ceilings improving to 4-6 kft by midday. Diurnal convection will
be possible in the vicinity of the cold front Thursday afternoon,
but this boundary will likely stall south of I-10, keeping the
threat for convection at the forecast terminals on the low side.




/00Z TAFS/

Most of the area remains dry as of 23z, but there are a few cells
developing in the vicinity of a cold front north of I-20. As this
front moves slowly south this evening, convection is expected to
move across the Big Country, potentially affecting the KSWW and
KABI terminals after 01z. This front is expected to reach KSJT
after 06z but the potential for convection is less clear.
Thunderstorms (vicinity) were added for a few hours at KABI but
were left out at the other terminals at this time.

An expansive low cloud deck exists across the TX Panhandle east
into OK. These clouds are expected to move south in the wake of
this front, bringing MVFR ceilings to KABI and KSJT for a few
hours. However, this is certainly not a climatologically favored
occurrence so confidence is not all that high. The front is
expected to slow/stall near or just south of I-10 on Thursday
afternoon, providing a focus for diurnal showers and
thunderstorms. A VCSH remark was included for KSOA and KJCT during
this time.



(Tonight and Thursday)

Models continue to advertise a faster frontal passage, and this
looks reasonable based on current surface observations. Most of
the short range models indicate scattered showers and
thunderstorms will develop in the next few hours, mainly north
of Interstate 20, spreading south as we head through the evening.
Given the faster frontal passage advertised by the models,
precipitation chances were expanded south. Overall, the coverage
of the showers/thunderstorms looks spotty at best.

The front will clear the I-10 corridor Thursday morning, stalling
just south of the area by afternoon. Moisture will be slow to
scour out across the southern half of the area, with precipitable
water values remaining above 1.5 inches south of a Sterling City
to Brownwood line. Given the proximity of the front, and favorable
upslope flow following the cold frontal passage, precipitation
chances were increased near Interstate 10. With cold advection and
increased cloud cover behind the front, highs were lowered a few
degrees, ranging from the mid 80s across northern areas, to near
90 degrees farther south.


/Thursday Night through Saturday/
There will be a slight chance of rain across the southern 1/3 of
the area late this week into the first part of the weekend. The
combination of weak ascent and some instability will lead to
isolated showers and thunderstorms mainly during the afternoon and
evening. Also, cooler temperatures are expected behind the cold
front with highs in the mid 80s to lower 90s. Lows will be in the
mid 60s to lower 70s.

/Saturday Night through Wednesday/
Looks like a dry forecast with temperatures warming back to
around seasonable levels. Weak upper level north to northwest flow
will prevail through the early part of the next week, then a
high pressure ridge builds across the area. As a result, not much
instability or upper level forcing to work with. Highs will be in
the lower to mid 90s with lows in the upper 60s to lower 70s.


Abilene  68  85  65  87  67 /  20  20  10  10  10
San Angelo  71  90  67  90  68 /  20  20  20  10  10
Junction  73  92  71  92  70 /  10  30  20  10  20




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