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000
FXUS64 KEWX 101446
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
846 AM CST WED FEB 10 2010

.UPDATE...
GIVEN CURRENT RADAR RETURNS AND QUICK GLANCE AT 12Z MODEL DATA...
HAVE LOWERED POPS FOR THIS MORNING TO 20 PERCENT OR LESS AND
MENTION ONLY LIGHT OR VERY LIGHT PRECIPITATION. ALSO LOWERED POPS
FOR THE AFTERNOON BY 10 PERCENT AND USE LIGHT RAIN INSTEAD OF
RAIN. 12Z DRT SOUNDING HAS FREEZING LAYER AROUND 4-7K FEET WHICH
WOULD SUPPORT SOME LIGHT SLEET.

&&

.PREV DISCUSSION... /ISSUED 523 AM CST WED FEB 10 2010/

DISCUSSION...
SEE AVIATION FOR THE 12Z TAF DISCUSSION.

AVIATION...
VFR CONDITIONS WILL PREVAIL THIS MORNING AS MID AND HIGH LEVEL CLOUDINESS
STREAMS ACROSS SOUTH CENTRAL TEXAS IN ADVANCE OF AN UPPER LEVEL STORM
SYSTEM CURRENTLY LOCATED OVER SOUTHERN CALIFORNIA. LIGHT RAIN WILL DEVELOP
THIS AFTERNOON LOWERING VSBYS TO MVFR AFTER 06Z. CONDITIONS WILL CONTINUE
DETERIORATE TO IFR AFTER 10Z THURSDAY. SFC WINDS TODAY AT THE I-35
TERMINALS WILL BE NORTHEAST TO EAST AT 10 KTS OR LESS...KDRT WILL BE
SOUTHEAST AT AROUND 10 KTS.

PREV DISCUSSION... /ISSUED 503 AM CST WED FEB 10 2010/

DISCUSSION...
MODELS STILL HAVING SOME DIFFICULTY ON THERMAL PROFILE OF THE
AIRMASS WHICH WOULD DETERMINE PRECIPITATION TYPE AND SPEED OF
UPPER LOW WHICH WOULD DETERMINE DURATION OF PRECIPITATION. THERE
ARE NO SIGNIFICANT CHANGES TO THE PREVIOUS SOUTH CENTRAL TEXAS
FORECASTS AS MODEL AVERAGE SHOWS NO TRENDS. THE UPPER LOW SEEN
OVER SOUTHERN CALIFORNIA WILL TRACK EAST ALONG THE UNITED STATES
AND MEXICO BORDER REGION TODAY INTO THURSDAY AND THEN MOVE ACROSS
TEXAS THURSDAY NIGHT INTO EARLY FRIDAY. ISENTROPIC LIFT INCREASES
TODAY LEADING TO THE DEVELOPMENT OF LIGHT PRECIPITATION ALONG THE
RIO GRANDE THIS MORNING SPREADING TO REMAINDER OF SOUTH CENTRAL
TEXAS THIS AFTERNOON AND EVENING. ON THURSDAY, THE STRONGEST LIFT,
UPPER DIFFLUENCE, AND MOISTURE COINCIDE RESULTING IN THE HEAVIEST
PRECIPITATION OF THE EVENT. THE UPPER LOW MOVES OFF TO THE EAST
BY FRIDAY WITH PRECIPITATION ENDING FROM WEST TO EAST THURSDAY
NIGHT. AS FOR PRECIPITATION TYPE, FORECAST SOUNDINGS STILL SHOW
THE POTENTIAL FOR SOME SLEET AND SNOW, ESPECIALLY AT THE ONSET OF
THE EVENT DUE TO EVAPORATIVE COOLING WET BULB EFFECTS AND THE
ENDING OF THE EVENT DUE TO COOLING OF THE AIRMASS COLUMN. EXPECT
MOSTLY A COLD RAIN, HOWEVER WILL MAINTAIN MENTION OF LIGHT SNOW
OR LIGHT SLEET MAINLY ACROSS THE HILL COUNTRY TO ESCARPMENT AREAS.
DUE TO WARM GROUND AND AIR TEMPERATURES ABOVE FREEZING, LITTLE OR
NO SNOW AND ICE ACCUMULATIONS ARE EXPECTED, HOWEVER EXPOSED
SURFACES MAY BECOME SLICK AND HAZARDOUS. OVER WEEKEND AND INTO
MUCH OF NEXT WEEK, THE MODELS INDICATE UPPER TROUGHINESS OVER THE
CENTRAL TO EASTERN STATES. ANOTHER COLD FRONT MOVES THROUGH ON
SUNDAY, HOWEVER MOISTURE RETURN IS LIMITED AND HAVE GONE WITH 10
POPS. ZONAL FLOW ALOFT DEVELOPS TOWARD THE MIDDLE OF NEXT WEEK
RESULTING IN AN INCREASE IN CLOUDINESS. WILL GO SLIGHTLY BELOW
GUIDANCE HIGHS TODAY DUE TO CLOUDS AND RAIN, OTHERWISE WILL BE
NEAR GUIDANCE TEMPERATURES. HPC QPF SEEMS REASONABLE AND WILL
FOLLOW, EXCEPT WILL GO A LITTLE HIGHER TODAY AND THURSDAY NIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              45  35  41  35  55 /  40 100 100  70  -
AUSTIN BERGSTROM INTL AIRPORT  45  36  42  34  56 /  40 100 100  70  -
NEW BRAUNFELS MUNI AIRPORT     44  33  41  36  56 /  50 100 100  70  -
BURNET MUNI AIRPORT            43  33  37  32  51 /  40 100 100  70  -
DEL RIO INTL AIRPORT           44  38  44  36  67 /  50  70  60  20   0
GEORGETOWN MUNI AIRPORT        45  34  39  34  52 /  30 100 100  70  10
HONDO MUNI AIRPORT             44  37  44  34  60 /  70 100 100  60  -
SAN MARCOS MUNI AIRPORT        44  36  42  36  56 /  40 100 100  70  -
LA GRANGE - FAYETTE REGIONAL   46  37  43  38  52 /  30  80 100  80  10
SAN ANTONIO INTL AIRPORT       45  36  43  36  59 /  60 100 100  60  -
STINSON MUNI AIRPORT           45  37  43  35  60 /  60 100 100  70  -

&&

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

$$

99/01