000
FXUS64 KSJT 130902
AFDSJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
402 AM CDT THU JUN 13 2013

.SHORT TERM...
A FEW THUNDERSTORMS MADE IT TO THE SOUTHERN CWA BORDER YESTERDAY
EVENING NEAR JUNCTION BEFORE DISSIPATING. HOWEVER...SIMILAR ACTIVITY
IS EXPECTED TO DEVELOP FARTHER NORTH TODAY...PRESENTING A CHANCE FOR
PRECIPITATION FOR THE SOUTHWEST HALF OF THE FORECAST AREA. THE UPPER
LEVEL CYCLONE WE HAVE BEEN WATCHING FOR A FEW DAYS REMAINS NEARLY
STATIONARY NEAR EXTREME SOUTHERN CHIHUAHUA WITH A WEAKER...MORE
SUBTLE MID LEVEL WAVE ALONG THE RIO GRANDE TO THE EAST OF THE BIG
BEND. THE ASCENT ASSOCIATED WITH THESE WAVES CONTINUES TO OFFSET THE
STRONG SUBSIDENCE ATTENDANT WITH THE SUBTROPICAL RIDGE FOUND TO THE
NORTH. GULF MOISTURE CONTINUES TO INCREASE AS NOTED BY GPS PWAT
MEASUREMENTS...WHICH INDICATE CURRENT PWAT VALUES NEAR 1.4 INCHES.
SHORT RANGE GUIDANCE SUGGESTS THAT PWATS WILL CLIMB TO JUST AROUND
1.5 INCHES IN THE NEXT 12-24 HOURS WHICH IS IN THE UPPER QUARTILE OF
CLIMATOLOGY BASED ON SURROUNDING RAOB SITES.

POINT SOUNDINGS INDICATE UNCAPPED THERMAL PROFILES BY MIDDAY WITH
MLCAPE VALUES OF 1000-2000 J/KG THIS AFTERNOON. THIS WILL BE
SUPPORTIVE OF MODEST UPDRAFTS AND THE INCLUSION OF THUNDER.
HOWEVER...CONVECTION SHOULD REMAIN LARGELY UNORGANIZED GIVEN THE
WEAK WIND SHEAR AND SLIGHT BACKING OF WINDS IN THE LOWEST 4 KM. IN
ADDITION...THE MELTING LEVEL IS PROGGED TO RESIDE ABOVE 14 KFT.
THESE FACTORS WILL KEEP THE SEVERE THREAT QUITE LOW. HOWEVER...WE
ARE STILL LOOKING AT CLOUD BASES AROUND 5-7 KFT THIS AFTERNOON SO
THE ISOLATED GUSTY WIND THREAT CANNOT BE IGNORED COMPLETELY. ANY
STORMS THAT DEVELOP ARE EXPECTED TO PERSIST INTO THE EVENING HOURS...
EVENTUALLY WEAKENING WITH THE LOSS OF DAYTIME HEATING.

THE LOW CLOUDS THAT HAVE DEVELOPED THIS MORNING WILL LIFT AND
SCATTER OUT BY MID/LATE MORNING...REPLACED BY A SURFACE BASED CU
FIELD. EXPECT MAX TEMPS TODAY RANGING FROM THE LOWER 90S ALONG THE
I-10 CORRIDOR TO THE MID 90S ACROSS THE CONCHO VALLEY AND BIG
COUNTRY. TONIGHT...LOW TEMPERATURES WILL BE IN THE NEIGHBORHOOD OF
70 DEGREES. WINDS WILL PREVAIL FROM THE SOUTH AND SOUTHEAST AT 10-15
MPH...DECREASING AFTER SUNSET.

JOHNSON

.LONG TERM...
FRIDAY AND SATURDAY...THE MEDIUM RANGE MODELS HAVE BEEN
ADVERTISING A WEAKNESS IN THE RIDGE FOR THE FIRST PART OF THE
WEEKEND. THE UPPER LEVEL HIGH WILL BE PUSHED EAST INTO THE LOWER
MISSISSIPPI VALLEY AND REPLACED BY A TROF/LOW OVER WESTERN TEXAS.
SOME GOOD NEWS...A DECENT CHANCE OF RAIN ACROSS MUCH OF WEST
CENTRAL TEXAS. THE INGREDIENTS FOR RAINFALL ARE A SLOW MOVING
UPPER LEVEL SYSTEM AND TROPICAL AIRMASS POINT SOUNDINGS/PWAT
VALUES AROUND 1.5 INCHES/ ACROSS THE WESTERN HALF OF THE CWFA
FRIDAY AND SATURDAY. THE WPC 5 DAY RAINFALL GRIDS HAVE THE
HIGHEST AMOUNTS OVER THE WESTERN HALF OF THE AREA/0.50 TO 1 INCH/.
WILL GO WITH CHC POPS ACROSS THE WESTERN 2/3 OF THE AREA AND SLGT
CHC POPS ACROSS THE EASTERN 1/3 DURING THIS EVENT. THE BEST
COVERAGE COVERAGE OF SHOWERS AND STORMS WILL BE ACROSS THE WESTERN
BIG COUNTRY...CONCHO VALLEY AND NORTHERN EDWARDS PLATEAU. THE RAIN
AND CLOUD COVER WILL KEEP TEMPERATURES DOWN WITH HIGHS MAINLY IN
THE 80S FRIDAY...SLIGHTLY WARMER ON SATURDAY.

SUNDAY THROUGH THURSDAY...THE UPPER LEVEL RIDGE WILL BUILD BACK OVER
THE SOUTHERN PLAINS NEXT WEEK...RESULTING IN A DRY FORECAST.
HOWEVER...50H HEIGHTS WILL ONLY BE IN THE LOWER 590S. THIS WILL
HELP KEEP HIGHS BELOW TRIPLE DIGITS. HIGHS WILL MAINLY BE IN THE
90S. LOWS WILL BE 70 TO 75.

21

&&

.PRELIMINARY POINT TEMPS/POPS...
ABILENE  95  72  90  71  90 /   5   5  10  20  30
SAN ANGELO  94  72  89  72  92 /  20  20  30  40  30
JUNCTION  91  71  86  71  92 /  30  30  30  40  20

&&

.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$