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

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000
FXUS64 KEWX 160446
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1146 PM CDT MON SEP 15 2014

.AVIATION... /06Z TAF UPDATE/
AFTER A REVIEW OF THE 00Z MODEL RUNS THE MVFR CIGS ARE LESS LIKELY
TO ARRIVE IN TIME FOR THE THE 00Z TAF PROJECTIONS. UPDATES WERE
ALREADY MADE TO SHOW A SLOWER ONSET OF MVFR CIGS. THE WIND FIELDS
OVERNIGHT ARE LIGHTER THAN PROJECTED WHICH MEANS A FEW AREAS COULD
SEE IFR CIGS AND PERHAPS A DIP IN VSBY BELOW 6 NM. A SURFACE LOW
MOVING INTO DEEP S TX SHOULD HAVE LESS INFLUENCE ON WINDS BY LATE
MORNING...AND THE MVFR CIGS FROM SELY WINDS SHOULD BE MORE
CONSISTENT ON HEIGHT. HOWEVER...HIGH PWAT VALUES COULD ADD TO
BUOYANCY AND MAKE CIG COVERAGE LESS CONSISTENT. LATER IN THE
DAY...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED
WITH TROPICAL MOISTURE FILLING INTO THE AREA AT SEVERAL LEVELS
FROM BOTH THE GULF AND THE PACIFIC DUE TO TROPICAL STORM ODILE.

&&

.PREV DISCUSSION... /ISSUED 946 PM CDT MON SEP 15 2014/

UPDATE...
OVERALL...SHORT-TERM FORECAST IS ON TRACK WITH ONLY MINOR
ADJUSTMENTS MADE TO THE OVERNIGHT SKY AND WEATHER GRIDS.
LATEST NAM12...SREF AND RUC13 SOLUTIONS SHOW AN AREA OF ISOLATED
SHOWERS OVERNIGHT ACROSS THE I-35 CORRIDOR...ESPECIALLY OVER
PARTS OF COMAL...HAYS AND TRAVIS COUNTIES. THEREFORE...INCREASED
POP ACROSS THAT AREA TO A 20%. STILL LOOKS GOOD FOR RAIN CHANCES
LATE TUESDAY INTO WEDNESDAY AND THURSDAY AS TROPICAL AIRMASS
ARRIVES FROM THE SOUTH AT LOWER LEVELS AND FROM THE NORTHWEST AT
MID TO UPPER LEVEL.

PREV DISCUSSION... /ISSUED 657 PM CDT MON SEP 15 2014/

AVIATION...
HIGH PRESSURE SHOULD HOLD BACK CLOUD COVER TO VFR THROUGH AT LEAST
07Z DESPITE A GOOD AMOUNT OF AVAILABLE MOISTURE AND SELY LOW LEVEL
WINDS. SOME ISOLATED SEA-BREEZE CONVECTION FORMING OVER THE
COASTAL BEND IS SUGGESTED TO SHIFT FOCUS TO THE I-35 TAF SITES BY
THE FINER RES MODEL DATA TOWARD MIDNIGHT...BUT WITH SLOW STORM
MOTIONS NOTED...WILL LEAVE THIS FEATURE OUT OF THE TAFS FOR NOW.
ABUNDANCE OF HIGH CLOUDS COULD DELAY THE MVFR CIG DEVELOPMENT LATE
TONIGHT AND WILL LOOK AT A POSSIBLE UPDATE FOR THIS SHIFT AS 00Z
MODEL DATA ARRIVES. LATE IN THE PERIOD...A WEAK SURFACE LOW MOVES
ONSHORE INTO DEEP S TX AND NW FLOW DEVELOPS ALOFT...LEAVING MORE
FAVORABLE CONDITIONS FOR CONVECTION IN THE AFTERNOON AND EARLY
EVENING.

PREV DISCUSSION... /ISSUED 305 PM CDT MON SEP 15 2014/

SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)...
ISOLATED SHOWERS CONTINUE OVER THE HILL COUNTRY AND EDWARDS
PLATEAU...BUT AMOUNTS ARE NEGLIGIBLE AND THE SHOWERS SHOULD MOVE
OFF TO THE NORTHEAST AND OUT OF OUR AREA BY 00Z. THE PRIMARY SHORT
RANGE ISSUE IS THE INCREASE IN MOIST AIR...AT LOW AND MID-LEVELS
FROM THE GULF...AND AT MID- AND UPPER LEVELS FROM PACIFIC HURRICANE
ODILE. WE EXPECT SPRINKLES TONIGHT AS THE MOIST GULF AIR (PW OVER
2 INCHES) UNDERGOES GENTLE LIFT DUE TO TERRAIN. WITHOUT A SIGNIFICANT
LOW LEVEL SOURCE OF LIFT OTHER THAN A WEAK SEA-BREEZE...WE EXPECT
SCATTERED POPS AND MODEST QPF TUESDAY AND TUESDAY NIGHT. TEMPS WILL
REMAIN SLIGHTLY BELOW NORMAL WITH EXTENSIVE CLOUDCOVER AND SCATTERED
STORMS.

LONG TERM (WEDNESDAY THROUGH MONDAY)...
HIGHER POPS AND QPF ARE FORECAST FOR WEDNESDAY AND THURSDAY AS
ODILE BECOMES EXTRATROPICAL AND IS SHEARED/ABSORBED BY A SHORTWAVE
TROUGH MOVING THROUGH THE SOUTHWESTERN STATES. PW SHOULD BE AT OR
ABOVE TWO STANDARD DEVIATIONS ABOVE NORMAL FOR SEPTEMBER...SO WHEN
COMBINED WITH GENERAL LIFT AHEAD OF THE TROUGH AXIS...WILL BRING
MORE SUBSTANTIAL CONVECTION. HOWEVER...WITHOUT A SOURCE OF LOW-
LEVEL LIFT AND FOCUS...WE STILL EXPECT QPF TO ONLY BE IN THE 1/4
OT 1/2 INCH RANGE AT MANY SITES FOR WEDNESDAY THROUGH FRIDAY.

THE SOUTHWESTERN STATES TROUGH IS SLOW TO MOVE OVER THE WEEKEND...
AND MAY BE BOLSTERED BY ANOTHER EASTERN PACIFIC TROPICAL CYCLONE
BY SUNDAY/MONDAY. WE DECIDED TO MAINTAIN POPS EACH DAY...BUT LESS
COVERAGE AND WITH LOW QPF DUE TO A LACK OF LOW-LEVEL FOCUS.
HOWEVER...LESSER CLOUDCOVER AND CONVECTION SHOULD ALLOW
TEMPERATURES TO REBOUND TO NEAR NORMAL. LONGER RANGE MODELS
INDICATE A COLD FRONT PASSAGE JUST BEYOND THIS FORECAST (MIDDLE OF
NEXT WEEK)...WHICH SHOULD LEAD TO CONTINUED LOW TO MODERATE POPS
AND NEAR TO SLIGHTLY BELOW NORMAL TEMPS.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              72  90  74  91  74 /  20  30  30  30  50
AUSTIN BERGSTROM INTL AIRPORT  69  90  72  90  71 /  20  30  30  30  50
NEW BRAUNFELS MUNI AIRPORT     71  91  73  92  72 /  20  30  30  30  40
BURNET MUNI AIRPORT            71  88  72  90  72 /  10  30  30  40  50
DEL RIO INTL AIRPORT           72  88  75  89  75 /  10  20  30  30  30
GEORGETOWN MUNI AIRPORT        72  88  74  89  73 /  10  30  30  30  50
HONDO MUNI AIRPORT             71  91  73  91  72 /  10  30  30  40  30
SAN MARCOS MUNI AIRPORT        71  90  73  90  73 /  20  30  30  30  40
LA GRANGE - FAYETTE REGIONAL   73  90  74  90  73 /  10  40  30  30  40
SAN ANTONIO INTL AIRPORT       73  91  76  91  75 /  10  30  30  30  40
STINSON MUNI AIRPORT           73  91  75  92  75 /  10  30  30  30  40

&&

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

$$

MESOSCALE/AVIATION...18
SYNOPTIC/GRIDS...17





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