Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 292344

Area Forecast Discussion
National Weather Service SAN ANGELO TX
644 PM CDT SUN MAY 29 2016

/00Z TAFS/

Have VCTS at KABI beginning 2Z as an outflow boundary with
associated thunderstorms in NW Texas move southeast. Expected
storm development in the Permian Basin/TransPecos is delayed due
to thick mid/upper cloud cover. Due to uncertainty, kept mention
of thunder out of the rest of terminals. MVFR ceiling otherwise
return overnight and towards daybreak. MVFR ceiling should rise to
MVFR at KABI and KSJT around noon, but persist into mid afternoon
for areas farther south.


.PREV DISCUSSION... /issued 338 PM CDT SUN MAY 29 2016/

(Tonight and Monday)

This is basically your run of the mill Memorial Day forecast for
West Central TX. A shortwave trough is approaching West TX this
afternoon and its effects are readily apparent on the latest water
vapor loop. Large scale forcing for ascent will help erode what cap
remains, allowing the strong instability to be a factor. The latest
mesoanalysis indicates MLCAPE on the order of 2000-3000 J/kg across
much of the CWA, but effective bulk shear is only 25-35 kts. This is
sufficient to support organized convection, but shear is expected to
increase over the next several hours as the low-level jet kicks in.
There will be a non-zero tornado threat, but the primary hazards at
this time appear to be large hail and damaging winds, similar to
what was experienced yesterday.

The favored area for convective initiation will be over the far
western reaches of the CWA. However, storms will move east with time
and are expected to grown upscale into an MCS this evening. As this
MCS moves into the southern portion of the CWA, it is expected to
slow, turning into more of a heavy rainfall event. Precipitable
water values on the order of 1.5" and very slow moving convection
will result in locally heavy rainfall. Around 1" of rain is expected
on average across the northwest Hill Country, but localized amounts
of 3 inches are possible in some areas. The 1 hr flash flood
guidance for the area from Junction to Mason is less than 2 inches.
Thus a Flash Flood Watch has been issued through 10 AM Monday. This
covers areas along/south of a Sonora-Menard-Mason line.

Convection should continue to weaken/dissipate during the morning
hours on Monday with the loss of the low-level jet. This should
result in generally dry weather for much of the day tomorrow.
However, the air mass will be largely unchanged, with diurnal
convection once again in the forecast. The greatest chance for
showers and thunderstorms on Monday will be during the evening
hours, but low-end chance PoPs were retained to account for possible
earlier initiation along residual outflow boundaries. Temperatures
tomorrow are forecast to warm into the mid 80s.


(Monday night through Sunday)

..Showers and thunderstorms, some severe, will continue
through the middle of the week...

An upper level low will be centered across Arizona late Monday,
putting West Central Texas in southwest flow aloft, with
intermittent disturbances tracking across the region. One of these
disturbances is forecast to move across the area late Monday. This
combined with daytime heating should allow for the development of
showers and thunderstorms across West Texas, near the dryline, which
will move across much of West Central Texas during the evening
hours. Similar to what is expected today, a very unstable atmosphere
is forecast, along with 0-6 KM Bulk Shear values of 30 to 40 knots.
Strong to severe thunderstorms will be possible, with the main
hazards being large hail, damaging winds, and a possible tornado.
Overnight lows will mainly be in the mid to upper 60s.

The aforementioned upper level low will slowly approach West Central
Texas through the middle of the week. Rain chances will increase
Tuesday into Wednesday as the low gets closer and upper level lift
increases. In addition, a cold front will move through the area on
Wednesday, which may serve as a focus for additional shower and
thunderstorm development.

In addition to the severe weather threat through the next few days,
locally heavy rainfall will be possible. This may result in flash
flooding and a Flash Flood Watch for portions of the area may
eventually be needed. Rainfall totals of 1 to 3 inches can be
expected, with isolated amounts above 4 inches possible.

High temperatures Monday and Tuesday will generally be in the mid
80s, with overnight lows in the 60s. Extensive cloud
cover/precipitation will result in highs on Wednesday in the low
80s. Cooler temperatures are expected behind the front on Thursday,
with highs mainly in the mid to upper 70s and overnight lows in
upper 50s to lower 60s.



Abilene  65  84  66  84 /  70  30  40  50
San Angelo  65  87  67  86 /  60  30  50  50
Junction  68  86  68  84 /  60  30  40  50


.SJT Watches/Warnings/Advisories...
Flash Flood Watch through Monday morning for Kimble-Mason-Menard-



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