Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 280440

1140 PM CDT Wed May 27 2015

/06Z TAFS/

MVFR stratus in the Hill Country was moving toward KJCT and will
eventually spread north across the terminal tonight. Stratus
should lift to VFR 17-18Z. Isolated to scattered showers and
thunderstorms possible tonight and Thursday. High resolution
models put the best chance of rain tonight at KSOA and KSJT, so a
VCSH for those terminals. Have VCTS beginning 00Z-03Z Friday as a
upper shortwave approaches, and a band of showers and strong
thunderstorms moves east across the terminals, temporarily
affecting airport operations.


.PREV DISCUSSION... /ISSUED 630 PM CDT Wed May 27 2015/

/00Z TAFS/

Thunderstorm outflow boundaries will pass through KABI and KSJT
just before 00Z. This should produce wind gusts to 30 KTS at KSJT
and 25 KTS at KABI. Isolated thunderstorm possible along/behind
the outflow boundary at KSJT and KABI, but potential is low, so
have VCTS mentioned until 2Z. MVFR stratus otherwise returns after
midnight from south to south, persisting until early afternoon across
all terminals.

PREV DISCUSSION... /ISSUED 332 PM CDT Wed May 27 2015/

(Tonight and Thursday)

Temperatures have warmed into the mid/upper 80s this afternoon, with
dewpoints holding steady in the upper 60s across most of West
Central TX. With steep mid-level lapse rates in place, MLCAPE values
are in the neighborhood of 3000 J/kg. Numerous residual outflow
boundaries from the convection yesterday and early this morning
exist across the region, but we`ve only seen convection develop
across the northwest Hill County near Mason, and in the Big Country
east of Albany. Additional storms are expected to develop over the
next few hours, but will likely remain somewhat loosely organized
due to relatively weak vertical wind shear. Mesoanalysis suggests
effective bulk shear values of 30-35 kts, which would favor strong
multicells and possibly a few weak supercells. An isolated severe
weather threat will exist through the evening, with the potential
for large hail and damaging winds.

Given the weak forcing for ascent and the only modest vertical
shear, this activity is not expected to persist as long as last
night`s convection. Most of these storms should dissipate by 10 PM,
resulting in relatively quiet conditions during the early morning
hours. Low clouds are expected to develop again tonight, with low
temperatures Thursday morning in the upper 60s. Low clouds will
gradually improve by late morning, with temperatures forecast to
warm into the low/mid 80s. A weak cap is forecast to develop on
Thursday, keeping convection in check through the afternoon hours. A
few storms may be able to develop via diabatic heating, but most
areas will remain dry through 7 PM.


(Thursday night through Wednesday)

An active weather pattern continues through this weekend. Models
continue to indicate an upper level trough, currently moving ashore
the coast of California, approaching far West Texas Thursday
evening. As this feature approaches, large scale lift will
overspread West/West Central Texas, with showers and thunderstorms
initially developing across West Texas during the late afternoon
hours, the spreading east across West Central Texas during the
overnight hours. A few strong to severe thunderstorms will be
possible, especially during the early evening hours, with 0-6 KM
bulk shear values in the 25 to 40 knot range, MU CAPE values of
1500-3000 J/KG range, and steep mid level lapse rates. Heavy
rainfall still looks to be the main concern during the overnight
hours as precipitable water values increase to 1.3 to 1.6 inches. At
this time, we expect fairly widespread rainfall amounts of one half
to one and a half inches, with isolated higher amounts. We have
opted to hold off on the issuance of a Flash Flood Watch, given the
uncertainty in just how much rainfall will be received. If higher
rainfall amounts become more imminent, future shifts may need to
eventually issue a watch. Rain chances will decrease from west to
east Friday, with most convection east of the area by Friday

The next chance of showers and thunderstorms will be Friday night
and Saturday as a weak front moves into the area. This front will
serve as focus for showers and thunderstorms, first across the Big
Country Friday night, then across much of the rest of the area
Saturday. Again, the main threat with these storms will be locally
heavy rainfall, although a few strong to severe thunderstorms will
be possible. Rain chance will slowly decrease from north to south
Saturday night, with a few showers or thunderstorms possibly
lingering across mainly the southern counties Sunday morning.
Abundant cloud cover should keep high temperatures Friday through
Sunday generally in the 80s, with overnight lows in the 60s.

Weak upper level ridging will build into the area for much of next
week, resulting in drier/warmer conditions. Although isolated to
scattered afternoon showers and thunderstorms cannot be ruled out,
rain chances look low, so the forecast was kept dry for now.



Abilene  68  84  67  84  66 /  40  30  70  40  50
San Angelo  69  85  68  87  68 /  30  30  70  30  30
Junction  69  86  69  85  68 /  30  30  70  50  30




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