Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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000
FXUS64 KEWX 070937
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
437 AM CDT THU MAY 7 2015

.SHORT TERM (TODAY THROUGH FRIDAY)...

GENERAL SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED TODAY WITH AN
UPTICK IN INTENSITY AND COVERAGE LIKELY FRIDAY AFTERNOON INTO EARLY
SATURDAY MORNING FOR PARTS OF THE RIO GRANDE PLAINS AND HILL
COUNTRY.

SOUTH-CENTRAL TEXAS REMAINS IN MOIST LOW-LVL SOUTHERLY FLOW
UNDERNEATH SW/W FLOW IN THE MID TO UPPER LEVELS WITH ONE SYSTEM
PULLING AWAY INTO THE CENTRAL PLAINS WITH ANOTHER SYSTEM DIVING
SOUTH ALONG THE CALIFORNIA COAST PER WATER VAPOR/RAP ANALYSIS. LOW
CLOUDS HAVE DEVELOPED THIS MORNING AND SOME PATCHY LIGHT DRIZZLE
COULD BE POSSIBLE THROUGH EARLY TO MID MORNING.

SLIGHTLY MORE COVERAGE OF SHOWERS AND A FEW THUNDERSTORMS TODAY
VS. YESTERDAY AS THE ONCE RELATIVE H85 THETA-E MINIMUM HAS NOW
BEEN REPLACED WITH A HIGHER MOISTURE CONTENT LAYER. YET...MOST HI-
RES MODELS AGREE THAT CAPPING OF -25 TO -50 J/KG SHOULD KEEP THE
CHANCE OF ROBUST STORMS AT BAY THROUGH THE MID TO LATE AFTERNOON.
SOUNDINGS ALSO SUGGEST CLOUDS WILL REMAIN INTACT THROUGH GOOD
PORTION OF EARLY TO MID AFTERNOON AND LIMIT FULL REALIZATION OF
SURFACE HEATING AND THUS INSTABILITY TO BE ABLE TO BREAK THE CAP.
00Z ARW/NMM ARE RUNNING QUITE HOT FOR CURRENT TRENDS AND HAVE
DISCOUNTED THEIR SOLUTIONS THROUGH THE DAY. SSEO AND NCAR
ENSEMBLES ADDITIONALLY SUGGEST THUNDERSTORMS SHOULD REMAIN BELOW
STRONG TO SEVERE LIMITS WITH THE ONLY OUTLIER BEING THE NAM. THE
NAM SHOWS MORE VIGOROUS DEVELOPMENT ACROSS THE EDWARDS PLATEAU
THIS AFTN AND NORTH IN PROXIMITY TO THE DRY LINE. THE NAM DID NOT
PERFORM WELL YESTERDAY WITH GFS AND HI-RES WINNING OUT. WILL
FOLLOW THIS GUIDANCE ENVELOPE AGAIN FOR TODAY WITH DECREASING
ACTIVITY THROUGH TONIGHT INTO EARLY FRIDAY MORNING.

BY FRIDAY AFTERNOON...THE LARGE DIGGING CLOSED LOW WILL BE OVER
SOUTHERN NEVADA WHILE FURTHER ENHANCING DIVERGENCE ALOFT OVER
TEXAS WITH H3 WINDS INCREASING TO 65-70 KT. GFS IS INDICATING
WEAKER CAPPING ALONG AND AHEAD OF A BULGING DRYLINE EXTENDING FROM
CHILDRESS TO ABILENE AND ARCING BACK TOWARDS DEL RIO. WITH
BACKED/CONVERGENT LOW-LVL FLOW INTO THE DRYLINE IN COMBINATION
WITH NEAR 3000 J/KG...VERTICAL TOTALS 28-32C..AND NEAR 50-55 0-6
KM DEEP LAYER SHEAR...A HEALTHY ENVIRONMENT WILL EXIST IN SUPPORT
OF STRONG AND SEVERE THUNDERSTORM DEVELOPMENT. THE BEST AREA
APPEARS TO ALONG AND WEST OF I-35...ESPECIALLY TOWARDS THE HILL
COUNTRY AND EDWARDS PLATEAU. LARGE HAIL AND DAMAGING WINDS WILL
BE THE INITIAL PRIMARY HAZARDS DURING THE MID AFTERNOON TO EARLY
EVENING HOURS. A TORNADO CAN NOT BE FULLY RULED OUT GIVEN NEAR 180
M2/S2 0-3KM SRH BUT LIKELIHOOD IS LOW WITH HIGHER CHANCES FARTHER
NORTH IN CENTRAL AND NORTH TEXAS. THESE STORMS COULD GROW UPSCALE
OR COMBINE WITH ADDITIONAL TSTROMS ALONG THE THE RIO GRANDE
PLAINS THROUGH THE OVERNIGHT HOURS INTO SATURDAY. IF THIS OCCURS
AND IN CONJUCTION WITH A MORE POTENT SHORTWAVE TROUGH THAT IS
ADVERTISED AT THAT TIME...HEAVY RAINFALL AND LOCALIZED FLASH
FLOODING COULD BECOME A CONCERN THROUGH SATURDAY MORNING. MORE ON
THIS IN THE LONG TERM SECTION.

&&

.LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...

THE UNSETTLED AND ACTIVE WEATHER PATTERN WILL CONTINUE OVER THE
WEEKEND AND INTO EARLY NEXT WEEK WITH MULTIPLE ROUNDS OF SHOWERS
AND STORMS WITH SOME POSSIBILITIES OF HEAVY RAIN AND STRONG TO
SEVERE STORMS.

GFS AND SOME OF THE LONG TERM HI-RES GUIDANCE HAS BEEN HINTING AT
A STRONGER WAVE EJECTING AHEAD OF THE PARENT LOW FRIDAY NIGHT INTO
SATURDAY MORNING ACROSS SOUTH-CENTRAL TEXAS. MASS FIELD SIGNALS
CERTAINLY INDICATE A DEVELOPING OR MERGING COMPLEX OVERNIGHT INTO
SATURDAY MORNING. THE REGION WILL UNDER THE LEFT EXIT REGION OF
A LOCALIZED UPPER H3 JET WHILE H85 NOCTURNAL JET INCREASES TO
NEAR 40 KT. DEEPEST MOISTURE LOOKS TO BE OVER THE RIO GRANDE
PLAINS PER THETA-E FIELDS AND WITH PWATS RANGING FROM
1.5-1.8...HEAVY RAIN COULD BE QUITE LIKELY. THE ONE DRAWBACK IS
THAT THE EC DOES NOT SHOW LARGE RAIN AMOUNTS DURING THIS TIME BUT
DOES SHOW THE IMPULSE SIMILAR TO THE GFS ALONG WITH SIMILAR
MOISTURE DEPTH AND LOW-LVL JET. TRENDS WILL NEED TO BE MONITORED
CLOSELY IF A FLASH FLOOD WATCH COULD BE NEEDED DURING THIS TIME
FRAME. AM NOT FULLY SOLD ON THE GFS SOLUTION BUT WILL WEIGHT IT
MORE HEAVILY THEN THE EC.

THE MAIN CLOSED LOW AND NEGATIVELY TILTED TROUGH AXIS WILL PIVOT
THROUGH THE REGION SATURDAY AFTERNOON. CONVECTIVE EVOLUTION
SATURDAY AFTERNOON WILL DEPEND ON HOW QUICKLY THE SATURDAY MORNING
COMPLEX (IF IT OCCURS) SHIFTS EAST OF THE REGION. IF EARLY
ENOUGH...SOME ADDITIONAL SHOWER AND TSTORM ACTIVITY COULD OCCUR
THAT AFTERNOON ALONG THE DRYLINE. AN INCREASE IN MORE ACTIVITY
APPEARS LIKELY SUNDAY AFTERNOON AS A DEEPER SPOKE OF ENERGY SHIFTS
ACROSS THE STATE AND THE DRYLINE IS SITUATED OVER THE HILL
COUNTRY.

BY EARLY NEXT WEEK...A STRONGER SURFACE HIGH ACROSS THE COLORADO
FRONT-RANGE WILL HELP SEND A WEAK BOUNDARY/FRONT TOWARDS THE
REGION. MODELS HAVE HAD A DIFFICULT TIME PLACING THIS BOUNDARY AND
CONFIDENCE IS LOW THAT IT WILL MAKE IT THROUGH THE REGION.
UNFORTUNATELY...IT MAY LIKELY SERVE AS A FOCUS FOR ADDITIONAL
RAINFALL ACROSS PORTIONS OF THE REGION...NAMELY THE SOUTH AND
SOUTHEAST. WHILE GOOD FOR THE LONG TERM DROUGHT...THIS PATTERN
MAY SET UP AN ELEVATED RISK FOR HIGH CREEKS AND RIVERS ALONG WITH
FLASH FLOODING CONCERNS. BOTH GFS AND EC BOTH SUGGEST EVEN HIGHER
RAINFALL ACCUMULATION TOTALS THROUGH THE END OF NEXT WEEK VS.
EARLIER RUNS. THE ONCE ADVERTISED DRIER TREND IS SLOWLY
WANING WITH MODELS SIGNALING MORE SW FLOW AND SOUTHERN JET STREAM
ENHANCEMENT FOR INCREASED RAIN CHANCES. /ALLEN/

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              84  72  84  72  86 /  30  20  40  30  50
AUSTIN BERGSTROM INTL AIRPORT  84  72  85  72  86 /  30  20  40  30  50
NEW BRAUNFELS MUNI AIRPORT     83  71  84  71  85 /  30  20  30  30  40
BURNET MUNI AIRPORT            80  70  82  70  83 /  30  20  40  30  50
DEL RIO INTL AIRPORT           89  72  89  71  90 /  20  20  30  40  20
GEORGETOWN MUNI AIRPORT        82  71  83  71  85 /  30  20  40  30  50
HONDO MUNI AIRPORT             84  71  85  71  87 /  30  20  30  40  40
SAN MARCOS MUNI AIRPORT        83  72  84  72  85 /  30  20  30  30  40
LA GRANGE - FAYETTE REGIONAL   83  73  85  74  86 /  20  20  30  30  30
SAN ANTONIO INTL AIRPORT       84  72  85  71  86 /  30  20  30  30  40
STINSON MUNI AIRPORT           83  73  85  72  86 /  30  20  30  40  40

&&

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

$$

MESOSCALE/AVIATION...29
SYNOPTIC/GRIDS...15


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