000 FXUS64 KEWX 050523 AAC AFDEWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 1123 PM CST THU DEC 4 2008 .AVIATION... NO CHANGES TO PREVIOUS FORECAST THINKING...VFR CONDITIONS FORECAST TO PERSIST FOR THE NEXT 24H WITH A LIGHT ENE LOW LEVEL FLOW. && .PREV DISCUSSION... /ISSUED 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. && $$ 06/11/05