Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 252023

323 PM CDT Sat Apr 25 2015

(Tonight and Sunday)

Dry air will reside over the forecast area tonight with clear
skies and morning lows in the mid to upper 50s.

An upper trough digging south over the northern and central
Rockies  will close off over the Four Corners area by mid-day
tomorrow as a north-south oriented dryline tightens over the
central CWA. Low-level gulf moisture will spread initially over
the southeastern CWA tomorrow morning ahead of the dryline with
the gulf moisture advancing over the eastern half of the CWA
through the afternoon hours. Given strong afternoon heating with
highs in the upper 80s, and an eroding cap, should begin see
isolated to widely scattered thunderstorm development by mid to
late afternoon. SPC has the area east of a line from Haskell to
Abilene to Junction in a slight risk for primarily large hail
tomorrow afternoon through tomorrow evening. As the upper low
continues to move east over northern New Mexico through the
afternoon hours, the dryline and associated thunderstorm activity
will push further east over our eastern tier of counties by early


(Sunday night through Saturday)

The dryline will be located along the eastern fringe of the CWA
(roughly east of a Throckmorton-Junction line) by Sunday evening.
Any storms that develop along the southern flank of the dryline
are expected to quickly move downshear into central TX. Farther
north, storms could persist a bit longer into the evening as
surface winds back in response to an approaching backdoor surface
boundary. How far south this boundary moves through midday Monday
is still up in the air. The NAM pushes this boundary south to the
Colorado River, while the GFS keeps southerly flow in place south
of I-20.

This boundary will likely be the focus for convective development
on Monday. If the NAM verifies, we`re looking at ample
instability along and northeast of the quasi-stationary surface
boundary. Given the instability and shear, a few severe storms
could not be ruled out. If the GFS solution should prove more
correct, then much of the area will be well into the dry air,
limiting the potential for thunderstorms. As it stands, the
current forecast will be a compromise between these two solutions,
with the main precipitation chances being across the Big Country
and Heartland. Temperatures on Monday are forecast to range from
the mid 70s in the northeast to the low/mid 80s across the Concho
Valley and I-10 corridor.

A cold front will move south across the area on Monday night,
maintaining the potential for showers and thunderstorms. Again,
the most likely areas to see precipitation will be the area from
Abilene to Brownwood. Scattered rain showers may linger into the
day Tuesday owing to weak isentropic ascent over the frontal zone,
but cooler and drier air is anticipated in the wake of this front.
The combination of cold advection and widespread cloud cover
should keep highs in the 60s on Tuesday with overnight lows in the
40s areawide by Wednesday morning.

Generally quiet weather is anticipated for the remainder of the
work week as a mid-level ridge builds over the Rockies,
eventually overspreading the Plains. The medium range models are
in fair agreement with the synoptic pattern. The departing
shortwave trough is progged to hang up over the southeast CONUS,
with the trough axis extending to the west into the Lone Star
State. However, this is not expected to result in rain chances or
have much affect on temperatures. Expect afternoon temperatures
back in the 80s in most areas by Friday, with overnight lows
returning to the mid/upper 50s.



Abilene  58  86  57  79  48 /   5  20  30  30  50
San Angelo  56  88  56  84  52 /   5  10  20  10  20
Junction  59  89  55  85  53 /   5  20  20  10  10





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