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

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FXUS64 KEWX 050314
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
914 PM CST WED MAR 4 2015

.UPDATE...
OPTED TO MOVE UP THE START TIME OF THE WSW DUE TO REPORTS OF
FREEZING AND SUB FREEZING TEMPERATURES NOTED ON LCRA HYDROMET AS
WELL AS SITES ALONG THE CWA BORDER WITH SJT. RADAR TRENDS ARE
INDICATING PLENTY OF CONVECTIVE ENHANCEMENT WITH THE RAIN...EVEN
RESULTING IN THUNDER. WHILE HI-RES MODELS SHOW THIS CONVECTIVE
POTENTIAL DROPPING OFF AROUND 08-09Z...TEMPERATURES ARE ALREADY
VERY NEAR FREEZING ACROSS MUCH OF THE WARNING AREA AND AT OR BELOW
IN THE NORTHERN AREAS. IF ANY ICING IS ASSOCIATED WITH THIS
CONVECTIVE ACTIVITY...THEN IT WOULD ACCUMULATE RATHER QUICKLY AS
RAIN RATES ARE UP TO A QUARTER INCH PER HOUR WITH THE STRONGEST
ACTIVITY.

THE GOOD NEWS IS...INDICATIONS ARE THIS MORE ROBUST ACTIVITY
SHOULD STAY MORE OR LESS WITHIN THE WARNING AREA. TEMPERATURES IN
THE ADVISORY AREA ARE STILL IN THE 40S AS OF 03Z AND SOME UPPER
30S IN THE NORTHERNMOST PART OF IT. SO SHOULD HOLD OFF UNTIL
MIDNIGHT WITH THE BULK OF THE PRECIP NORTH.

OTHERWISE OVERALL IMPACTS ARE GENERALLY THE SAME EXPECTATIONS WITH
A TENTH OF AN INCH OF ICE ACCUMULATIONS GENERALLY THE CASE FOR THE
WARNING AREA AND UP TO A QUARTER INCH IN LOCALIZED AREAS WITH
HIGHER PRECIP RATES.

TB3

&&

.PREV DISCUSSION... /ISSUED 709 PM CST WED MAR 4 2015/

UPDATE...
MADE UPDATE TO WIND ADVISORY TO BEGIN AT 03Z RATHER THAN 06Z DUE
TO SUSTAINED WINDS BEING OBSERVED AT 23 KTS AND GUSTING TO OVER
30. ALSO EXTENDED THE ADVISORY TO ALL OF THE CWA MINUS
MAVERICK...ZAVALA...AND DIMMITT COUNTIES.

LOOKING TOWARDS TONIGHTS WINTER WEATHER...COLDER AIR IS MOVING IN
JUST A BIT MORE AGGRESSIVELY THAN PREVIOUSLY FORECAST. AS OF
7PM...MID 30S WERE ALREADY BEING OBSERVED IN WILLIAMSON AND BURNET
COUNTIES AND THE COLD AIR WAS BEGINNING TO ENTER
EDWARDS...KERR...GILLESPIE...AND LLANO AS WELL.

PRECIP IS DEVELOPING ALONG THE RIO GRANDE VALLEY AND ISOLATED
THUNDER HAS BEEN REPORTED WITH THIS ACTIVITY. KDRT SOUNDING
ANALYSIS SHOWS STRONG LAPSE RATES ABOVE THE TEMPERATURE INVERSION
SO STILL THINK CONVECTIVE ENHANCEMENT WILL BE AT PLAY FOR TONIGHT.
WILL LEAVE THE WARNING AS IS FOR NOW BUT IF TEMPS DROP FASTER...WE
MAY HAVE TO CONSIDER MOVING UP THE START TIME.

TB3

PREV DISCUSSION... /ISSUED 604 PM CST WED MAR 4 2015/

AVIATION...
/00Z TAFS/
A COLD FRONT IS QUICKLY PUSHING ACROSS THE AREA AND MOVING OVER
KSAT AT THIS MOMENT (O0Z THURS). THE FRONT WILL CONTINUE TO PUSH
TO THE SOUTH AND EXIT SOUTH CENTRAL TEXAS BY 8 PM THIS EVENING.
AN ARCTIC AIRMASS WILL PUSH ACROSS ALL OF SOUTH CENTRAL TEXAS
TONIGHT THROUGH THURSDAY WITH NORTH WINDS PREVAILING AROUND 20
KNOTS AND GUSTING 30 TO 40 KNOTS TONIGHT INTO THURSDAY MORNING.
LIGHT RAIN OR DRIZZLE IS EXPECTED TONIGHT CONTINUING THROUGH MID-
DAY THURSDAY. HOWEVER...NEAR FREEZING TEMPERATURES ARE EXPECTED
AROUND THE 10Z/14Z WINDOW ACROSS KAUS AND HAVE A TEMPO GROUP
SHOWING -FZRA. WINDS WILL DECREASE IN THE AFTERNOON BUT REMAIN IN
THE 12 TO 18 KNOTS RANGE AND VFR CONDITIONS ARE EXPECTED TO RETURN
ACROSS THE I-35 SITES AROUND 22Z THURS.

PREV DISCUSSION... /ISSUED 253 PM CST WED MAR 4 2015/

SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...
OBSERVATIONS OVER NORTH TEXAS AND RECENT MODELS ARE TRENDING
TOWARD THE MOST SIGNIFICANT WINTER WEATHER EVENT OF THE SEASON FOR
OUR AREA TONIGHT AND THURSDAY MORNING. A STRONG COLD FRONT IS JUST
NORTH OF OUR CWA AND WILL BE MOVING THROUGH THE ENTIRETY OF THE
AREA LATE THIS AFTERNOON NORTH...MID-EVENING CENTRAL...AND LATE
EVENING SOUTH. MODEL SOUNDINGS INDICATE A MOIST ADIABATIC
LAYER ABOVE THE NEAR SURFACE COLD DOME...SO THE FRONT...APPROACH
OF A SHORTWAVE TROUGH...AND ENTRANCE REGION TO A JET STREAK WILL
PROVIDE THE MOISTURE...INSTABILITY...AND LIFT FOR SHOWERS AND
ISOLATED THUNDERSTORMS ALONG AND WITHIN 50-100 MILES BEHIND THE
FRONT. ARCTIC AIR BEHIND THE FRONT WILL CAUSE TEMPERATURES
TO DROP 20-25 DEGREES WITHIN THE FIRST HOUR OR TWO. THE PRESSURE
GRADIENT LAGS A BIT...WITH STRONG AND GUSTY WINDS STARTING ABOUT
TWO HOURS AFTER FROPA. A WIND ADVISORY IS IN EFFECT FROM MIDNIGHT
UNTIL NOON THURSDAY TO ACCOUNT FOR THE STRONG AND GUSTY WINDS.

THE COLD DOME WILL CONTINUE TO DEEPEN OVERNIGHT...AND WE EXPECT A
MIX OF FREEZING RAIN AND SLEET TO DEVELOP AROUND MIDNIGHT IN THE
HILL COUNTRY...THEN SPREAD SOUTH AND EAST TO A GIDDINGS...SAN
ANTONIO...DEL RIO LINE BY 4-6 AM THURSDAY. TEMPERATURES WILL BE
COLD ENOUGH FOR THE FREEZING RAIN AND SLEET TO PERSIST UNTIL LATE
MORNING THURSDAY. THE PRECIPITATION SHOULD RAPIDLY END ACROSS THE
WESTERN HALF OF THE AREA AROUND NOON...AND TEMPERATURES
SIMULTANEOUSLY WARM TO ABOVE FREEZING. THE AMOUNT OF ICING COULD
BE OVER 1/10 INCH IN THE HILL COUNTRY AND METRO AUSTIN
(WILLIAMSON...TRAVIS...AND HAYS COUNTIES)...WHICH IS WHERE THE
WINTER STORM WARNING IS IN EFFECT. FOR THE COUNTIES ALONG THE
BALCONES ESCARPMENT AND THE ADJACENT PLAINS TO THE EAST...ICING
SHOULD BE BELOW 1/10 INCH...THUS LIMITING THE IMPACT TO MAINLY
BRIDGES AND OTHER ELEVATED ROADS. A WINTER WEATHER ADVISORY IS IN
EFFECT FOR THIS AREA. THE NORTHERN METRO OF SAN ANTONIO IS IN THE
WINTER WEATHER ADVISORY...MAINLY LOCATIONS OUTSIDE OF LOOP 1604 IN
THE NORTHERN AND WESTERN PORTIONS OF THE COUNTY.

LONG TERM (FRIDAY THROUGH WEDNESDAY)...
THERE WILL BE LINGERING COLD FRIDAY MORNING...WITH A HARD FREEZE
LIKELY IN MANY LOCATIONS. A SLOW WARMING TREND BEGINS FRIDAY
AFTERNOON AS THE SURFACE AIRMASS MODIFIES AND MOVES EAST.
HOWEVER...MODERATE AMPLITUDE FLOW WILL BRING A SERIES OF
DISTURBANCES ACROSS THE REGION LATE IN THE WEEKEND AND NEXT WEEK.
AT THIS TIME IT APPEARS POPS WILL BE LOW AND MAINLY AS
SHOWERS WITH LOW QPF.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              32  40  27  48  33 / 100  30  10  10  10
AUSTIN BERGSTROM INTL AIRPORT  33  40  26  47  31 / 100  30  10  10  10
NEW BRAUNFELS MUNI AIRPORT     33  42  28  49  34 / 100  30  10  10  10
BURNET MUNI AIRPORT            28  37  24  45  30 / 100  30  10  10  10
DEL RIO INTL AIRPORT           37  44  30  49  36 /  90  30   0   0  10
GEORGETOWN MUNI AIRPORT        30  38  24  46  30 / 100  30  10  10  10
HONDO MUNI AIRPORT             35  44  27  50  35 / 100  30  10  10  10
SAN MARCOS MUNI AIRPORT        33  41  26  48  32 / 100  30  10  10  10
LA GRANGE - FAYETTE REGIONAL   34  42  29  49  35 / 100  30  10  10  10
SAN ANTONIO INTL AIRPORT       35  42  28  49  35 / 100  30  10  10  10
STINSON MUNI AIRPORT           36  44  29  50  36 /  90  30  10  10  10

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL NOON CST THURSDAY FOR THE FOLLOWING COUNTIES:
ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL...
COMAL...DE WITT...EDWARDS...FAYETTE...FRIO...GILLESPIE...GONZALES...
GUADALUPE...HAYS...KARNES...KENDALL...KERR...KINNEY...LAVACA...
LEE...LLANO...MEDINA...REAL...TRAVIS...UVALDE...VAL VERDE...
WILLIAMSON...WILSON.

WINTER STORM WARNING UNTIL NOON CST THURSDAY FOR THE FOLLOWING
COUNTIES: BANDERA...BLANCO...BURNET...EDWARDS...GILLESPIE...HAYS...
KENDALL...KERR...LLANO...REAL...TRAVIS...VAL VERDE...WILLIAMSON.

WINTER WEATHER ADVISORY UNTIL NOON CST THURSDAY FOR THE FOLLOWING
COUNTIES: BASTROP...BEXAR...CALDWELL...COMAL...GUADALUPE...KINNEY...
LEE...MEDINA...UVALDE.

&&

$$

MESOSCALE/AVIATION...17
SYNOPTIC/GRIDS...03
PUBLIC SERVICE/DATA COLLECTION...00


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