Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 271112
AFDSJT

Area Forecast Discussion
National Weather Service San Angelo TX
612 AM CDT Sat May 27 2017

.AVIATION...
/12Z TAFS/

MVFR cigs have developed across all of the West Central Texas
terminals except KABI this morning. Expect these to continue
through around mid morning, and then lift and dissipate. VFR
conditions will then prevail through the evening hours. A few
isolated storms are possible late this afternoon and early this
evening and then again overnight, but given the uncertainty in
timing and location will not mention at this time. Southwest to
south winds will continue, ahead of a cold front that will reach
KABI after midnight and then the remainder of the terminals Sunday
morning.

&&

.PREV DISCUSSION... /issued 413 AM CDT Sat May 27 2017/

SHORT TERM...
(Today and Tonight)

Low level moisture continues to surge north and west into West
Central Texas early this morning, with surface dewpoints in the low
70s across the Northwest Hill Country and even higher values
stretching from the Rio Grande east into Central Texas. All models
have a dryline developing across the Permian Basin this morning and
moving east into West Central Texas late this morning and into the
afternoon. Dryline movement is largely a matter of moisture mixing
and how each model handles this determines how far east the dryline
will move. The HRRR is the farthest west, stretching from roughly
Abilene to San Angelo to Ozona. In contrast, the TTU WRF pushed the
dryline most of the way through the area. The NAM12 has a decent
compromise between the two and will be used as a rough idea for
dewpoints and winds for this afternoon.

Hot once more behind the dryline, with afternoon temperatures
climbing to near or above the 100 degree mark. Most of the models
are dry for this afternoon, with fairly weak convergence along the
dryline and a strong cap. The HRRR is the exception, developing
fairly strong convergence along the dryline by mid to late
afternoon. Suspect the cap really will hold, but if convection can
go, CAPE is extreme and storms could quickly become strong to
severe. With that in mind, worth keeping a mention of isolated
storms in the forecast just in case.

Cold front moves into West Central Texas tonight, mainly between
midnight and sunrise. Dryline will retreat back west so moisture
will not be a problem, but strong cap will be. Better convergence
along the front however and will continue the forecast of slight
chance PoP`s in the forecast.

LONG TERM...
(Sunday through Friday)

Cold front will move through the rest of West Central Texas
Sunday morning. There will still be strong instability however,
particularly along and south of a Big Lake to San Angelo to
Brownwood line...where GFS MUCAPES range from 2000 to 4400 J/KG
Sunday afternoon and evening. The highest CAPES are along I-10.
Day 2 SPC severe weather outlook has this area in slight risk,
with the marginal risk extending north to Sweetwater...Abilene and
Albany. Large hail and damaging winds will be the main threat.

With drier air behind front, the best chance of storms Monday
into Tuesday night will be south of the Big Country. For Wednesday
into Friday, moisture and instability will return to all of West
Central Texas as surface high pressure moves farther east. The Big
Country may be favored for storms the second half of the week, as
an upper trough moves through Colorado and New Mexico.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene 100  66  82  61 /  10  20  20  30
San Angelo 102  70  84  64 /  10  20  40  50
Junction  93  75  86  66 /  10  20  50  60
Brownwood  95  71  83  62 /  10  20  30  40
Sweetwater 101  65  80  61 /   5  20  20  20
Ozona      100  72  84  64 /  10  20  50  60

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

07



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