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

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FXUS64 KEWX 031729
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1229 PM CDT THU SEP 3 2015

.AVIATION...
VFR LEVEL CIGS WILL HANG ON FOR A FEW MORE HOURS IN AUSTIN AND SAN
ANTONIO. WINDS WILL PICK UP TO AROUND 10 KTS FROM THE SOUTHEAST AT
ALL TERMINALS THIS AFTERNOON. DEEP LAYER SOUTHEASTERLY FLOW WILL
CONTINUE THROUGH THE PERIOD AND MVFR CIGS WILL DEVELOP AGAIN
OVERNIGHT AT ALL TERMINALS. IMPROVEMENT TO VFR WILL COME LATE
MORNING FRIDAY.

&&

.PREV DISCUSSION... /ISSUED 1002 AM CDT THU SEP 3 2015/

UPDATE...NO SIGNIFICANT UPDATES THIS MORNING WITH TODAYS FORECAST
ON TRACK WEATHER AND TEMPERATURE WISE. ONE SMALL ADJUSTMENT MADE
WAS SLIGHTLY REDUCING THE 30% POP IN LAVACA AND FAYETTE COUNTIES
TO 20% AND SHIFTING THE 30% AREA INTO KARNES COUNTY THROUGH 1PM.
THIS SHIFTING WAS DUE TO ONGOING RADAR TRENDS. HOURLY DEWPOINTS
WERE ALSO INCREASED ACROSS EASTERN LOCATIONS TO BETTER MATCH
OBSERVATIONS. UPDATES ARE OUT AND MORE DETAILS CAN BE FOUND BELOW
IN THE UPDATED DISCUSSION.

DISCUSSION... SOME SHOWERS ARE ONGOING ALONG THE COAST AND EXTEND
INLAND INTO DEWITT AND KARNES COUNTY THIS MORNING. ADDITIONAL
ISOLATED TO SCATTERED SHOWERS WILL BE LIKELY THROUGH THE AFTERNOON
PRIMARILY EAST OF THE I-35/37 CORRIDOR WHERE THE SEA-BREEZE
ACTIVITY WILL BE MORE PRONOUNCED. WATER VAPOR AND MID TO UPPER
LEVEL RAP ANALYSIS DEPICTS A CLOSED CUT-OFF LOW OVER THE GULF OF
MEXICO SE OF THE TEXAS COAST. THIS FEATURE MAY BE JUST DISTANT
ENOUGH NOT TO HAVE TO MUCH BEARING ON OUR WEATHER TODAY OTHER THAN
DEEPER LEVEL STEERING FLOW FROM THE EAST. THIS FLOW MAY HELP SOME
SEA-BREEZE ACTIVITY PUSH FROM THE EAST TO WEST TOWARDS THE 35
CORRIDOR THIS AFTERNOON AND EARLY EVENING. HOWEVER...OVERALL
CHANCES REMAIN LOW WITH 20-30%. LOW 800-500MB LAPSE RATES AND A
WARM NOSE NEAR 500MB WILL HAMPER DEEPER DEVELOPMENT OF THE
CONVECTION AND THUNDERSTORMS MAY BE HARD TO COME BY IN THIS
ENVIRONMENT. AN UPDATE DURING THE AFTN MAY REMOVE THE CURRENT
THUNDER WORDING AND BE REPLACED WITH GENERAL SHOWERS INSTEAD.

PREV DISCUSSION... /ISSUED 650 AM CDT THU SEP 3 2015/

AVIATION...
STRATUS CLOUDS CONTINUE TO DEVELOP THIS MORNING...WITH MVFR CIGS
ALREADY IN PLACE ACROSS MOST AREAS. STILL THINK THERE IS SOME
OPPORTUNITY FOR IFR CIGS FOR THE NEXT FEW HOURS AND WILL MENTION
TEMPO GROUPS ALONG THE I-35 CORRIDOR THROUGH 15Z. IMPROVING
CONDITIONS ARE IN STORE AFTER 16Z-17Z WITH VFR CONDITIONS
RETURNING TO ALL TERMINALS. ISOLATED CONVECTION IS STILL POSSIBLE
TODAY...BUT GIVEN LACK OF COVERAGE...WILL NOT MENTION IN THE
FORECAST AT THIS TIME. LOW CLOUDS WILL DEVELOP AFTER LATE TONIGHT
INTO FRIDAY MORNING...WITH MVFR CIGS EXPECTED AFTER 04/08Z. WINDS
WILL GENERALLY REMAIN FROM THE EAST AND SOUTHEAST AT OR BELOW
10KTS THROUGH THE PERIOD.

PREV DISCUSSION... /ISSUED 419 AM CDT THU SEP 3 2015/

SHORT TERM (TODAY THROUGH FRIDAY)...
WV IMAGERY AND UPPER AIR ANALYSES SHOW THAT THE WEAK SHEAR AXIS
AND ASSOCIATED TROUGH THAT STRETCHES FROM THE LOWER MISSISSIPPI
RIVER VALLEY TO THE SE TX AND LA GULF COAST CONTINUES TO WEAKEN.
ISOLATED SHOWERS AND THUNDERSTORMS ARE FORMING OVER THE GULF AND
MOVING ONSHORE...BUT THE COVERAGE IS LOWER THAN THE LAST FEW
NIGHTS. MOST OF THESE SHOWERS WILL DISSIPATE...BUT A ROGUE
SHOWER OR TWO MAY MOVE INTO OUR SE COUNTIES TOWARDS DAYBREAK. LOW
STRATUS HAS BEEN SLOWER TO DEVELOP TONIGHT THAN THE PREVIOUS FEW
EVENINGS...BUT STILL EXPECT THEM TO MOVE IN WITHIN THE NEXT FEW
HOURS AND PERSIST FOR A FEW HOURS AFTER SUNRISE TODAY AND FRIDAY.

MODELS ARE CONSISTENT IN BUILDING AND INTENSIFYING THE UPPER
LEVEL RIDGE OVER THE SOUTHERN PLAINS TODAY AND FRIDAY AS AN
INVERTED TROUGH BREAKS OFF FROM THE PROGRESSIVE TROUGH AND
RETROGRADES UNDER THE RIDGE AS IT WEAKENS. THIS WILL HELP CAUSE A
0.2-0.3 INCH SURGE IN PWAT VALUES AND SLIGHTLY DEEPER CONVERGENCE
WITH THE SEA BREEZE THAN OCCURRED ON WEDNESDAY...ALLOWING FOR
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS IN THE COASTAL
PLAINS THAT WILL DISSIPATE AS THEY MOVE INTO THE I-35 CORRIDOR.
MODELS HAVE GENERALLY BACKED OFF FROM SHOWERS MOVING INTO THE HILL
COUNTRY EXCEPT FOR THE ECMWF AND A FEW HI-RES MODELS FOR FRIDAY.

LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...
THE UPPER LEVEL RIDGE WILL CONTINUE TO INTENSIFY THROUGH THE
WEEKEND AS THE RETROGRADING SHEAR AXIS DISSIPATES. THIS WILL LEAD
TO HOT AND GENERALLY DRY DAYS ASIDE FROM ISOLATED AFTERNOON
SHOWERS AND THUNDERSTORMS IN THE COASTAL PLAINS ON SATURDAY. HEAT
INDEX VALUES WILL RISE INTO THE 100-105 RANGE EVERYWHERE EXCEPT
THE COUNTRY FOR ALL OF LABOR DAY WEEKEND...WITH HIGH TEMPS IN THE
MID-TO-UPPER 90S EXCEPT FOR A FEW SPOTS IN THE RIO GRANDE PLAINS
THAT REACH THE CENTURY MARK. THE RIDGE GRADUALLY BEGINS TO WEAKEN
AND SLIDE TO THE WEST BY WEDNESDAY...WHICH MAY ALLOW A WEAK FRONT
TO MOVE INTO THE REGION LATE THURSDAY INTO FRIDAY JUST PAST THE
FORECAST PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              73  95  75  97  76 /  20  20  10  10  -
AUSTIN BERGSTROM INTL AIRPORT  72  94  73  96  73 /  20  20  10  10  -
NEW BRAUNFELS MUNI AIRPORT     73  96  74  97  75 /  20  20  10  10  -
BURNET MUNI AIRPORT            73  94  73  95  74 /  10  10  10  10  -
DEL RIO INTL AIRPORT           75  97  76  98  77 /  10  10  10  10  -
GEORGETOWN MUNI AIRPORT        73  94  75  95  75 /  10  10  10  10  -
HONDO MUNI AIRPORT             73  96  74  97  73 /  10  10  10  10  -
SAN MARCOS MUNI AIRPORT        73  94  75  96  74 /  20  20  10  10  -
LA GRANGE - FAYETTE REGIONAL   73  94  75  95  76 /  30  20  10  20  10
SAN ANTONIO INTL AIRPORT       74  95  76  96  76 /  20  10  10  10  -
STINSON MUNI AIRPORT           74  96  76  97  75 /  20  10  10  10  -

&&

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

$$

MESOSCALE/AVIATION...05
SYNOPTIC/GRIDS...ALLEN
PUBLIC SERVICE/DATA COLLECTION...30



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