Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 291131
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
631 AM CDT Fri May 29 2015

.AVIATION...
/12Z TAFS/
Showers and thunderstorms have moved east of the area this
morning, leaving behind high clouds clearing from west to east.
Behind these high clouds, we do expect to see at least a brief
period of MVFR conditions from low CIGS across most sites. Have at
least a TEMPO for these conditions in at each site this morning.
Can see low clouds beginning to move northeast toward KSOA behind
the high cloud shield, which lends some confidence to the low
cloud trend expected. Expect these low clouds to lift to VFR by
late morning or early afternoon. Overnight, another round of
thunderstorms is expected to move through the area, but this is
expected to be much later, after 06Z tonight. 20

&&

.PREV DISCUSSION... /ISSUED 418 AM CDT Fri May 29 2015/

SHORT TERM...
(Today and Tonight)

Expecting another round of thunderstorms late tonight into
Saturday morning.

Light to moderate rain has largely moved east and out of our area
early this morning. Upstream of our area in Wyoming, the next
shortwave trough is moving southeast toward our area. At the
surface, a cold front stretching roughly from northern Minnesota
southwest into northeastern CO. Both of these features will
advance to the south/southeast today toward west Texas. Ahead of
the cold front, lee troughing will allow south/southeast winds to
develop at surface in our area. This will help the low levels
quickly recover from last night`s convective overturning. Expect
dewpoint values to climb back into the mid to upper 60s later
today, and temperatures to warm back into the 80s, depending on
how much clearing we see later today. Models show ML CAPE values
greater than 2000 J/kg by late afternoon in our area, and
remaining greater than 1500 J/kg during the overnight hours ahead
of the cold front as it moves southward.

The combination of the approaching cold front, good instability,
and the upper level shortwave bringing in synoptic lift is
expected to result in scattered thunderstorms developing to our
north this evening, then moving south and growing upscale into an
MCS/broken line of thunderstorms late Friday night as they move
toward west central Texas. Expect this line to move into our area
after 10 PM tonight, and be aided by cold pool development and
interaction with a strengthening LLJ. Although the storms will
have good instability to work with producing strong updrafts,
0-6km shear values will be marginal, resulting in a relative lack
of organization, so severe concerns will be limited to isolated
damaging wind gusts and marginal hail hazards.

In addition, with the widespread rainfall received today, most
areas received 1"+ totals, with isolated amounts of greater than
3" in our eastern counties. This will bring a threat of flash
flooding as these storms move through. PWAT values are expected to
climb back up to 1.5" ahead of these storms tonight, so any quick
rainfall amounts of 1 to 2 inches could lead to flash flooding,
especially in urban areas. So, will have a Flash Flood Watch again
in effect for the entire area from tonight after 10 PM through
Saturday midday.

Have raised PoPs for tonight into Saturday morning to account for
these thunderstorms. Will hold on to some chance PoPs this morning for
eastern areas as light rain exits the area.

LONG TERM...
(Saturday and Saturday Night)

The combination of an upper level shortwave trough and abundant
moisture(PW values of 1.5 to 1.75 inches) will result in showers
and thunderstorms across West Central Texas Saturday. There will
probably be an MCS in progress across the southern part of the
area Saturday morning. Heavy rainfall amounts of 1 to 2 inches are
possible along and south of a San Angelo to Brownwood line after
12Z. A Flash Flood Watch is effect through midday Saturday.
However, rainfall amounts will be tapering off across the Big
Country. Will keep the chance Pops going across the southeast half
of the area Saturday night, mainly during the evening hours.

(Sunday through Friday)

Looks like mainly a dry forecast through next week. An upper level
ridge will build across Texas, building a mid level cap and drying
things out. Pleasant temperatures are expected Sunday with highs
in the upper 70s to lower 80s. Warmer conditions are expected the
rest of the week with highs in the mid to upper 80s and lows in the
60s.

&&

.PRELIMINARY POINT TEMPS/POPS...
Abilene  84  65  79  60  79 /  20  70  60  20  10
San Angelo  88  67  80  62  82 /  20  60  60  30  20
Junction  87  69  82  63  81 /  20  40  60  40  30

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH from this evening through Saturday afternoon
FOR THE FOLLOWING ZONES: Brown...Callahan...Coke...Coleman...
Concho...Crockett...Fisher...Haskell...Irion...Jones...Kimble...
Mason...McCulloch...Menard...Nolan...Runnels...San Saba...
Schleicher...Shackelford...Sterling...Sutton...Taylor...
Throckmorton...Tom Green.

&&

$$





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