FXUS64 KEWX 241235
AFDEWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
635 AM CST THU DEC 24 2009
.UPDATE...
UPDATED FORECAST TO RELECT DEPARTED BAND OF RAIN. A FEW WRAP-
AROUND SPRINKLES ARE MOVING FROM WEST CENTRAL TX TOWARD THE HILL
COUNTRY...BUT THE DRY WESTERLY WINDS SHOULD EVAPORATE MOST OF THIS
MOISTURE. THE CLOUDS WRAPPING AROUND APPEARS TO BE HOLDING STEADY
OVER WEST TX SO THIS COULD FURTHER IMPACT TEMPS OVER AREAS WEST OF
I-35. HIGH TEMPS WERE ADJUSTED DOWN ANOTHER DEGREE OR TWO OVER
THESE AREAS...AND SOME MORE CLOUDINESS WAS ADDED TO MAINLY THE
HILL COUNTRY.
&&
.PREV DISCUSSION... /ISSUED 553 AM CST THU DEC 24 2009/
AVIATION...
AN UPPER LOW WILL MOVE ACROSS TEXAS TODAY. A STRATOCUMULUS DECK
WITH MVFR CIGS WILL MOVE EAST ACROSS CENTRAL TEXAS AND MAY REACH
AS FAR SOUTH AS A KDRT TO KSAT TO K3T5 LINE DURING THE DAYLIGHT
HOURS TODAY. THERE MAY EVEN BE -SHRA IN THE DECK. OTHERWISE, VFR
SKIES WITH FEW CLOUDS WILL PREVAIL. THE UPPER LOW AND A SURFACE
HIGH BUILDING INTO THE AREA WILL BRING NWLY WINDS 20 TO 30 KTS
WITH GUSTS TO 35 KTS TODAY. WINDS WILL DECOUPLE THIS EVENING AND
DECREASE TO 5 TO 10 KTS OVERNIGHT INTO FRIDAY CHRISTMAS DAY.
PREV DISCUSSION... /ISSUED 442 AM CST THU DEC 24 2009/
DISCUSSION...
UPPER LOW CONTINUES TO TREND DEEPER AND SLOWER AS IT MOVES ACROSS
TEXAS EARLY TODAY. THIS HAS RESULTED IN MODEL DATA BECOMING
PROGRESSIVELY MORE PESSIMISTIC ON THE STRONG WINDS FORECAST. THUS
THE WIND ADVY WAS EXPANDED TO ALL AREAS AND SHIFTED A BIT EARLIER
TO ACCOUNT FOR WESTERN COUNTIES WHERE THE HIGHER TERRAIN ENHANCES
EARLIER MIXING. THE WINDS COULD STILL BE STRONG INTO THE EVENING
HOURS WITH GUSTS TO 30 MPH STILL POSSIBLE. THE SLOWER AND DEEPER
TRACK HAS HELPED MINIMIZE ANY FIRE WEATHER CONCERNS AS A COLDER
ADVECTION PATTERN WILL HOLD MAX TEMPS SEVERAL DEGREES COOLER THAN
WAS EXPECTED IN YESTERDAYS FORECAST. THE COLD ADVECTION WILL GET
ASSISTANCE FROM SIGNIFICANT SNOWFALL AMOUNTS EXPECTED EARLY TODAY
ALONG THE I-20 CORRIDOR OF WEST CENTRAL TX. A FREEZE IS LIKELY
FOR NEARLY ALL OF SOUTH CENTRAL TX AND A HARD FREEZE IS PROBABLE
FOR MOST OF THE HILL COUNTRY AND ADJACENT LOW SPOTS ALONG THE
BALCONES ESCARPMENT. OVERNIGHT FREEZES ARE ALSO ANTICIPATED FOR
THE WEEKEND.
MODELS ARE SHOWING BETTER CONSISTENCY ON THE DEEPENING UPPER LOW
ONCE IT MERGES WITH ANOTHER PIECE OF ENERGY DIVING OUT OF CANADA.
THIS LARGE WINTER STORM WILL LIKELY CONTINUE PUSHING COLD AIR
SOUTH INTO TX OVER THE WEEKEND. HOWEVER...SUNSHINE AND DAYTIME
MIXING OF SW LOW LEVEL WINDS ALONG THE RIO GRANDE ON CHRISTMAS DAY
AND SATURDAY COULD ALLOW WESTERN COUNTIES TO REACH 60 DEGREES. A
ZONAL FLOW PATTERN ALOFT WILL GRADUALLY INCREASE HIGH LEVEL CLOUDS
OVER THE WEEKEND AND EVENTUALLY PRODUCE A MOSTLY CLOUDY TO CLOUDY
SKY ON MONDAY. AS THE COLD AIR CONTINUES TO FUNNEL SOUTHWARD...AN
DISTURBANCE MOVING IN THE ZONAL PATTERN ALOFT COULD PRODUCE A
WINTER WEATHER EVENT OVER THE AREA TUESDAY. IF THE SCENARIO PLAYED
OUT AS DEPICTED BY THE 00Z MODEL CONSENSUS THE PRECIP TYPE WOULD
BE A MIX OF RAIN AND SLEET...POSSIBLY SOME BRIEF FREEZING RAIN.
THE SCENARIO IS NOT IN HIGH CONFIDENCE THIS FAR OUT...ONLY A BRIEF
MENTION PROVIDED IN THE HWO FOR NOW.
LATER IN THE WEEK...THE 00Z GFS ADVERTISED ANOTHER WINTER STORM
FOR NEW YEARS EVE. THIS SCENARIO WAS DISCOUNTED FOR NOW AS IT
DEVIATED QUITE A BIT FROM ENSEMBLES AND THE ECMWF. THE 06Z GFS HAS
COME INTO BETTER ALIGNMENT WITH THE OTHER RUNS...POINTING TOWARD
COOL AND DRY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 49 34 55 31 56 / - - - - -
AUSTIN BERGSTROM INTL AIRPORT 51 28 56 22 55 / - - - - -
NEW BRAUNFELS MUNI AIRPORT 54 31 56 28 56 / - - - - -
BURNET MUNI AIRPORT 45 26 50 24 50 / 10 - - - -
DEL RIO INTL AIRPORT 58 33 57 31 60 / 0 0 0 - -
GEORGETOWN MUNI AIRPORT 46 29 52 25 53 / 10 - - - -
HONDO MUNI AIRPORT 56 27 55 25 57 / 0 0 - - -
SAN MARCOS MUNI AIRPORT 53 31 55 25 56 / - - - - -
LA GRANGE - FAYETTE REGIONAL 53 32 52 31 54 / 10 - - 10 -
SAN ANTONIO INTL AIRPORT 56 31 56 29 57 / 0 0 - - -
STINSON MUNI AIRPORT 56 30 57 28 58 / 0 0 - - -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING
COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...
CALDWELL...COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...
GILLESPIE...GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...
KINNEY...LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...
UVALDE...VAL VERDE...WILLIAMSON...WILSON...ZAVALA.
&&
$$
18/04
