000
FXUS64 KEWX 211405
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
905 AM CDT TUE MAY 21 2013

.UPDATE...
QUICK UPDATE TO ADD MORNING SHOWERS IN THE NORTHEAST. A SMALL AREA
OF SHOWERS IS MOVING THROUGH THE AREA AND WE HAD POPS IN THE
REGION...BUT NO MENTION OF WEATHER BEFORE NOON.

&&

.PREV DISCUSSION... /ISSUED 632 AM CDT TUE MAY 21 2013/

DISCUSSION...
SEE AVIATION FOR THE 12Z TAF DISCUSSION.

AVIATION...
MAIN FORECAST CHALLENGE FOR THIS ISSUANCE IS THE TIMING OF CONVECTION
AT THE TAF SITES. TSTM IMPACTS AT THE TAF SITES WILL BE BASED ON A
BLEND OF THE 00Z HI-RES ARW AND NMM ALONG WITH THE 00Z 3KM TTU WRF.
ALL OF THE I-35 TERMINALS ARE ALSO IN THE SPC SLIGHT RISK AREA FOR
THIS AFTERNOON AND EVENING. ATTM WILL GO WITH A TEMPO GROUP AT KAUS
WITH PROB30 GROUPS AT KSAT AND KSSF. WILL NOT MENTION TSTMS IN THE
KDRT TAF DUE TO LOW CONFIDENCE OF OCCURRENCE. MVFR CIGS THIS MORNING
WILL IMPROVE TO VFR BY 17Z WITH TSTMS MOST LIKELY ON THE INCREASE
AFTER 22Z. TIMING OF THE RETURN OF MVFR CIGS LATE TONIGHT INTO
WEDNESDAY MORNING WILL BE DIRECTLY DEPENDENT OF THE STRENGTH OF
THE CONVECTIVE OUTFLOW BOUNDARIES. ATTM WILL DELAY RETURN OF MVFR
CIGS BY A COUPLE OF HOURS COMPARED TO PERSISTENCE.

PREV DISCUSSION... /ISSUED 316 AM CDT TUE MAY 21 2013/

SHORT TERM (TODAY THROUGH WEDNESDAY)...
DEEP VORTEX OVER THE PACIFIC NORTHWEST WILL DIG SOUTHWARD AND EJECT
THE DOWNSTREAM TROUGH PUSHING OVER NORTHWEST TEXAS TODAY. EXTREMELY
UNSTABLE AIR-MASS IN PLACE OVER SOUTH CENTRAL TEXAS WITH WIDESPREAD
3000-4000 J/KG MLCAPES EXPECTED THIS AFTERNOON INTO TONIGHT. THE
UPPER TROUGH WILL PUSH INTO CENTRAL TEXAS THIS AFTERNOON WITH AN
ATTENDANT COLD FRONT SLIDING INTO FAR WESTERN PORTIONS BY EARLY
AFTERNOON AND SLOWLY INTO THE HILL COUNTRY BY EARLY EVENING.
INITIALLY...A STRONG CAP MAY INHIBIT STORMS FROM FORMING ALONG THE
FRONT OVER FAR WESTERN PORTIONS THIS AFTERNOON HOWEVER AS THE UPPER
TROUGH DIGS A LITTLE FURTHER SOUTH ACROSS THE HILL COUNTRY AND
NORTHEAST CORRIDOR TOWARDS EVENING...STORMS WILL BE EXPECTED TO
BACK-BUILD ACROSS CENTRAL TEXAS INTO OUR AREA. AN INCREASING LOW
LEVEL JET OVER THE EASTERN HALF OF THE REGION IMPINGING THE FRONT
WILL ONLY WORSEN THE SEVERITY. THE MAIN THREATS WILL BE FROM LARGE
HAIL (AND IN SOME CASES VERY LARGE HAIL) AND DAMAGING THUNDERSTORM
WINDS FROM LATE AFTERNOON TO THE EARLY MORNING HOURS WEDNESDAY.

THE MAIN THREAT AREA PER SPC WILL BE GENERALLY ACROSS THE EASTERN
HALF OF THE REGION...BUT OUR ANALYSIS WOULD GIVE HEIGHTENED
CONCERN FROM THE EASTERN HILL COUNTRY THROUGH THE NORTHEAST
CORRIDOR...INCLUDING THE CITIES OF BURNET...GEORGETOWN...AUSTIN
AND GIDDINGS. THIS IS BECAUSE OF THE UPPER LEVEL CAP...WHICH
ACCORDING TO SOUNDING PROGS THIS EVENING...WILL HAVE SUFFICIENTLY
ERODED BY THE SLIGHT DIG OF THE UPPER TROUGH BY THE TIME OF
FRONTAL PASSAGE. WITH THE EXTREME AMOUNT OF INSTABILITY PRESENT...
ISOLATED TORNADOES CANNOT BE RULED OUT FROM DEVELOPING SUPER-CELLS
ACROSS THE EASTERN HILL COUNTRY THROUGH THE NORTHEAST CORRIDOR
LATE THIS AFTERNOON THROUGH THIS EVENING. RAINFALL OF 1 TO 3
INCHES IS POSSIBLE AS WELL ACROSS EASTERN PORTIONS OF SOUTH
CENTRAL TEXAS THIS EVENING WHERE THE LOW LEVEL JET MEETS THE
FRONT.

TODAY THOUGH...MORNING CLOUDS WILL DECREASE TO PARTLY CLOUDY THIS
AFTERNOON WITH A SLIGHT CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS
HILL COUNTRY TO THE NORTHEAST CORRIDOR IN A CAPPED ATMOSPHERE. HIGHS
TODAY RANGING FROM THE UPPER 80S HILLS TO THE UPPER 90S RIO GRANDE
PLAINS. TONIGHT...AS MENTIONED EARLIER...SEVERE STORMS WILL
BACK-BUILD OR DEVELOP ACROSS THE HILL COUNTRY AND SPREAD
SOUTHEASTWARD OVER THE REMAINDER OF SOUTH CENTRAL TEXAS LATE THIS
AFTERNOON AND DURING THE EVENING...EXITING THE AREA DURING THE EARLY
MORNING HOURS. LOWS TONIGHT LOW TO MID 60S HILLS TO MID 70S SOUTHERN
AND EASTERN PORTIONS. ON WEDNESDAY WEST NORTHWEST FLOW ALOFT WILL
BRING IN DRIER AIR WHILE A SUBTROPICAL RIDGE BEGINS DEVELOPING
NORTH OVER THE AREA. DECREASING CLOUDINESS BECOMING PARTLY CLOUDY
WEDNESDAY AFTERNOON WITH HIGHS NEAR 90 OR LOW 90S OVER MUCH OF THE
REGION EXCEPT MID TO UPPER 90S OVER SOUTH CENTRAL PORTIONS AND THE
RIO GRANDE PLAINS.

LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...
THE SUBTROPICAL RIDGE WILL CONTINUE BUILDING ACROSS SOUTH AND
CENTRAL TEXAS WEDNESDAY NIGHT AND THURSDAY BUT WITH A CONTINUED
SOUTHEAST FLOW OFF THE GULF...MORNING CLOUDS ARE EXPECTED BECOMING
PARTLY CLOUDY BY THURSDAY AFTERNOON. THIS WILL LIKELY REMAIN THE
OVERALL WEATHER PATTERN FRIDAY THROUGH THE EARLY PART OF NEXT WEEK
AS THE SUBTROPICAL RIDGE REMAINS DOMINANT. AS THE RIDGE BUILDS
ALOFT...WEAKER SOUTHEAST WINDS MAY ALLOW FOR TEMPERATURES TO COOL
MORE OVERNIGHT (TO NEAR SEASONAL) WHILE HIGHS WILL REMAIN A FEW
DEGREES ABOVE NORMAL EACH DAY FRIDAY THROUGH MONDAY. A FEW WEAK
WAVES ON THE BACKSIDE OF THE RIDGE MAY HELP DEVELOP BURRO MOUNTAIN
DEVELOPMENT OVER NORTHERN MEXICO FRIDAY THROUGH SUNDAY BUT
UNCERTAINTIES WHETHER OR NOT THEY WILL REACH OUR AREA WILL RESULT
IN SILENT 10 POPS EACH DAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              92  70  92  71  94 /  20  40  -   -   -
AUSTIN BERGSTROM INTL AIRPORT  91  69  91  69  92 /  20  40  -   -   -
NEW BRAUNFELS MUNI AIRPORT     92  70  92  69  93 /  10  40  -   -   -
BURNET MUNI AIRPORT            88  66  90  68  91 /  20  30   0  -   -
DEL RIO INTL AIRPORT           99  72  98  75  98 /  10  20  -   -   -
GEORGETOWN MUNI AIRPORT        88  68  88  69  91 /  20  40  -   -   -
HONDO MUNI AIRPORT             95  70  95  71  96 /  10  30  -   -   -
SAN MARCOS MUNI AIRPORT        90  71  90  70  91 /  20  40  -   -   -
LA GRANGE - FAYETTE REGIONAL   91  75  92  73  92 /  10  40  10  -   -
SAN ANTONIO INTL AIRPORT       92  71  93  72  93 /  10  30  -   -   -
STINSON MUNI AIRPORT           92  71  92  71  93 /  10  30  -   -   -

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

MESOSCALE/AVIATION...24
SYNOPTIC/GRIDS...05
PUBLIC SERVICE/DATA COLLECTION...31