FXUS64 KEWX 050247
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
847 PM CST THU DEC 4 2008

.UPDATE...
RERAN THE ZONES FOR THE ADDITION OF A FREEZE WARNING FOR MAVERICK
COUNTY. DEWPOINTS HAVE FALLEN TO THE TEENS ACROSS THE HILL COUNTRY
AND ESCARPMENT REGIONS. COMPARING TONIGHT'S TEMPS/DEWPOINTS WITH
THE NIGHT OF NOV 15TH (WHEN FREEZING TEMPS WERE REACHED ALL AREAS
EXCEPT MAVERICK COUNTY) SHOWS THE RATE OF COOLING IS FASTER THAN
THE 15TH DESPITE THE INFLUX OF CIRRUS CLOUDS. SO HAVE GONE AHEAD
AND ISSUED A FREEZE WARNING FOR MAVERICK COUNTY TONIGHT.
OTHERWISE, SOME MINOR ADJUSTMENTS TO THE SKY GRIDS. UPDATES ARE
AVAILABLE.

&&

.PREV DISCUSSION... /ISSUED 533 PM CST THU DEC 4 2008/

AVIATION...
VFR CONDITIONS TO PERSIST THROUGH THE TAF PERIOD WITH A LIGHT ENE
LOW LEVEL FLOW.

PREV DISCUSSION... /ISSUED 352 PM CST THU DEC 4 2008/

DISCUSSION...
COLD ADVECTION CONTINUES ACROSS SOUTH CENTRAL TEXAS AS A SURFACE
HIGH BUILDS INTO THE AREA THIS AFTERNOON. THIS HIGH SETTLES OVER
THE AREA BY FRIDAY, THEN SLOWLY DRIFTS EAST ON SATURDAY. A WEAK
UPPER LEVEL TROUGH WILL MOVE ACROSS THE AREA ON FRIDAY, THIS WILL
BRING A QUICK INCREASE IN MID AND UPPER LEVEL CLOUDS LATE TONIGHT
THEN A QUICK DECREASE FRIDAY EVENING. OTHERWISE, LIGHT WINDS, LOW
DEWPOINTS, AND MOSTLY CLEAR SKIES WILL LEAD TO NEARLY EFFICIENT
RADIATIONAL COOLING. LOWS NEAR OR BELOW FREEZING ARE EXPECTED OVER
MUCH OF THE AREA TONIGHT AND AGAIN FRIDAY NIGHT. THE CLOUDINESS ON
FRIDAY WILL KEEP HIGHS WELL BELOW AVERAGE IN THE UPPER 40S TO MID
50S. A SOUTHWESTERLY FLOW ON SATURDAY WILL BRING HIGHS CLOSER TO
AVERAGE. A WARMING AND MOISTENING TREND DEVELOPS BY SUNDAY AS
SURFACE PRESSURES FALL IN THE PLAINS AND THE SURFACE HIGH MOVES
OFF TO THE EAST ALLOWING FOR A SOUTHERLY FLOW AHEAD OF AN UPPER
TROUGH OVER BAJA CALIFORNIA. THIS TROUGH MOVES ACROSS TEXAS ON
MONDAY. STRONG LIFT AND ADEQUATE MOISTURE WITH PWS OF 1 TO 1.3
INCHES ARE INDICATED LATE SUNDAY NIGHT INTO MONDAY. MEX POPS SEEM
HIGH WITH SPEED OF SYSTEM AND LACK OF SURFACE FOCUS AND WILL ONLY
GO WITH SLIGHT CHANCE POPS. A COLD FRONT WILL MOVE ACROSS THE AREA
ON TUESDAY. MODELS CONTINUE THEIR LACK OF CONSISTENCY/CONSENSUS ON
THE PASSAGE OF THE NEXT UPPER TROUGH. THE GFS BRINGS IT ACROSS
TEXAS TUESDAY, THE CANADIAN WEDNESDAY, AND THE ECMWF, NOGAPS, AND
UKMET WEDNESDAY NIGHT. SYSTEMS SEEM MORE PROGRESSIVE LATELY AND
WILL LEAN TOWARD THE FASTER MODELS AND CONTINUE SLIGHT CHANCE POPS
ONLY INTO TUESDAY. COLDER AND DRIER FOLLOWS WEDNESDAY AND THURSDAY.
HAVE GENERALLY GONE WITH MEX TEMPERATURES THIS FORECAST, EXCEPT
FAVORED THE COLDER MET LOWS TONIGHT AND FRIDAY NIGHT DUE LOWER
DEWPOINTS AND LIGHT WINDS.

FIRE WEATHER...
DRY CONDITIONS WILL PREVAIL WITH RELATIVE HUMIDITIES NEAR OR BELOW
20 PERCENT AT TIMES DURING THE AFTERNOON THROUGH SATURDAY, HOWEVER
EXPECT WINDS LESS THAN 10 MPH. RELATIVE HUMIDITIES RECOVER SUNDAY
INTO MONDAY. THEY WILL FALL AGAIN MIDDLE OF NEXT WEEK AFTER THE
FRONTAL PASSAGE WITH GUSTY WINDS. THIS WILL HAVE TO MONITORED FOR
CRITICAL FIRE WEATHER AS SOME PARTS OF SOUTH CENTRAL TEXAS ARE NOW
IN AN EXCEPTIONAL DROUGHT, THE MOST SEVERE CATEGORY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 32 52 32 69 42 / 0 - 0 0 0
AUSTIN BERGSTROM INTL AIRPORT 26 51 26 67 36 / 0 - 0 0 0
DEL RIO INTL AIRPORT 33 55 32 69 43 / 0 - 0 0 0
SAN ANTONIO INTL AIRPORT 30 53 30 69 42 / 0 - 0 0 0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING FROM 5 AM TO 8 AM CST FRIDAY FOR THE FOLLOWING
COUNTIES: MAVERICK.

&&

$$

06/11


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