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

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000
FXUS64 KEWX 301809 AAA
AFDEWX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
109 PM CDT THU OCT 30 2014

.UPDATE...
PLEASE SEE THE 18Z AVIATION DISCUSSION BELOW.

&&

.AVIATION...
VFR CONDITIONS ARE CURRENTLY IN PLACE AND WE EXPECT THIS TO
CONTINUE THROUGH THIS EVENING. CLOUD COVER WILL BE ON THE INCREASE
AFTER MIDNIGHT AS A COLD FRONT APPROACHES FROM THE NORTH. WE/LL GO
WITH MVFR CLOUDS DEVELOPING AT MOST TERMINALS BETWEEN 06Z-08Z AS
THE LEADING EDGE OF THE COLD FRONT PROVIDES A SOURCE OF LIFT.
SHOWERS AND THUNDERSTORMS ARE ALSO EXPECTED OVERNIGHT AS THE COLD
FRONT MOVES THROUGH. WE/LL CONTINUE TO MENTION SHOWERS ALONG I-35
BETWEEN 08Z-12Z. FARTHER WEST...WE HAVE MENTIONED SHOWERS AT KDRT
BETWEEN 11Z-15Z. CAN/T RULE OUT ISOLATED THUNDERSTORMS AS WELL...
WITH THE WESTERN HILL COUNTRY AND RIO GRANDE PLAINS FAVORED.
CONDITIONS WILL IMPROVE FROM NORTH TO SOUTH TOMORROW AS GUSTY
NORTH WINDS AND DRIER AIR SPREAD ACROSS THE REGION. GUSTY NORTH
WINDS HAVE BEEN INCLUDED AT ALL TAF SITES TOMORROW.

&&

.PREV DISCUSSION... /ISSUED 1021 AM CDT THU OCT 30 2014/

UPDATE...FORECAST ON TRACK FOR TODAY AND TONIGHT WITH NO MAJOR
CHANGES IN THINKING AT THIS TIME. WE ARE STILL ANTICIPATING
SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THE COLD FRONT
ACROSS NORTH TEXAS LATE AFTERNOON AND EVENING...MOVING SOUTH INTO
THE NORTHERN CWA AROUND MIDNIGHT AND INTO CENTRAL AND SOUTHERN
AREAS OF THE CWA BETWEEN 3-6 AM FRI. DECENT POP CHANCES TONIGHT...
THAT MAY BE TRENDED FURTHER UPWARD IN THE AFTERNOON PACKAGE...
ESPECIALLY ALONG THE I-35 CORRIDOR AND WEST...IF 12Z RUNS CONTINUE
THEIR TRENDS. SPC HAS HIGHLIGHTED AREAS ROUGHLY ALONG AND NORTH OF
A ROCKSPRINGS TO SAN ANTONIO TO BASTROP LINE IN A MARGINAL RISK
FOR SEVERE STORMS...WITH MAIN THREAT BEING A STORM OR TWO THAT
COULD PRODUCE STRONG TO SEVERE STRAIGHT-LINE WINDS AND HAIL. THE
HWO AS BEEN UPDATED TO MENTION THIS.

PREV DISCUSSION... /ISSUED 353 AM CDT THU OCT 30 2014/

SHORT TERM (TODAY THROUGH FRIDAY)...
LIGHT EASTERLY WINDS CONTINUE ACROSS THE AREA AT THE PRESENT TIME
BUT WILL BECOME MORE SOUTHERLY TODAY AHEAD OF THE NEXT SYSTEM. AT
500 MB...THERE IS A BROAD TROUGH THAT COVERS THE EASTERN HALF OF
THE CONUS WHILE A WEAK BUT BROAD RIDGE COVERS THE WESTERN HALF OF
THE CONUS. A MUCH STRONGER LOW CENTER WILL MOVE INTO THE NORTHERN
CONUS LATE THIS AFTERNOON AND EVENING...WHICH WILL CAUSE THE UPPER
RIDGE ACROSS THE WESTERN CONUS TO QUICKLY BECOME MORE AMPLIFIED.
THIS PLACES THE CENTRAL PLAINS IN STRONG NORTH/NORTHWEST FLOW
ALOFT. THIS PATTERN WILL SEND A SURGE OF COLD AIR SOUTH INTO
SOUTH-CENTRAL TEXAS THIS EVENING AND OVERNIGHT INTO FRIDAY MORNING.

BEGINNING LAST NIGHT...MODELS HAVE BEEN TRENDING WETTER WITH THIS
FROPA. FORECAST SOUNDINGS SHOW A DECENT MOIST LAYER BETWEEN THE
SURFACE AND 700 MB. UPPER DYNAMICS ARE MOSTLY LACKING WHICH WOULD
NORMALLY LIMIT WIDESPREAD RAIN CHANCES. THE FOCUS FOR LIFT THEN
SHIFTS TO ANY MESOSCALE FEATURES THAT MAY BE PRESENT WHICH COULD
LOCALLY ENHANCE LIFT. 850 CHARTS FROM ALL MODELS SHOW A THETA-E
RIDGE AT 850 MB JUST AHEAD OF THE 850 MB FRONT. THE 850 FRONT IS
STACKED NEARLY VERTICAL OVER THE SURFACE FRONT AND ANY LIFT
ASSOCIATED WITH THE THETA-E RIDGE WOULD BE JUXTAPOSED WITH LOCALLY
ENHANCED LIFT ASSOCIATED WITH THE SURFACE FRONTAL CONVERGENCE. THE
MOISTURE AVAILABLE IS SUFFICIENT FOR CONVECTION TO DEVELOP WITH
THE LIFT AS THE FRONT MOVES THROUGH THE CWA TONIGHT. INSTABILITY
IS ENOUGH TO WARRANT THE MENTION OF THUNDER...BUT SEVERE STORMS
ARE NOT EXPECTED. THE 00Z NAM IS SHOWING SOME HEAVY RAINFALL
TONIGHT...BUT THERE APPEARS TO BE SOME CONVECTIVE FEEDBACK AT 500
MB IN THE VORTICITY FIELDS. SOMETIMES...CONVECTIVE FEEDBACK
ALTHOUGH WRONG...CAN BE A HINT AT SOMETHING....BUT OVERALL
MOISTURE LEVELS IN THE ATMOSPHERE SHOULD NOT SUPPORT WIDESPREAD
HEAVY RAIN. ISOLATED LOCATIONS COULD RECEIVE ABOUT AN INCH OF
RAIN. WENT WITH 30/40 POPS ACROSS MUCH OF THE AREA...BUT THESE
MAY NEED TO BE RAISED FURTHER ON THE DAY SHIFT IF CONFIDENCE
CONTINUES TO INCREASE.

ALL PRECIP SHOULD BE SOUTH OF THE FORECAST AREA SHORTLY AFTER
DAYBREAK FRIDAY. THE REST OF HALLOWEEN IS EXPECTED TO HAVE CLEARING
SKIES...BREEZY NORTHERLY WINDS...AND TEMPERATURES STRUGGLING TO
REACH THE MIDDLE 70S FOR MOST LOCATIONS. YOU MADE NEED TO A JACKET
OR BLANKET FOR THE TRICK OR TREATERS AS TEMPERATURES AROUND SUNSET
WILL BE DROPPING INTO THE LOWER 60S AND EVEN THE 50S BY 9 PM.

LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...
SOUTHERLY WINDS WILL RETURN ON SATURDAY AFTER LOWS REACH THE 40S
FOR MUCH OF THE AREA...WITH SOME 30S POSSIBLE IN THE HILL COUNTY.
INCREASING MOISTURE AND WARMER TEMPERATURES ARE EXPECTED BY
SUNDAY/MONDAY AHEAD OF THE NEXT STORM SYSTEM. OTHERWISE...THE
WEEKEND LOOKS GREAT FOR ANY OUTDOOR ACTIVITIES. THE GFS IS SHOWING
WARM AIR ADVECTION SHOWER AND THUNDERSTORM ACTIVITY ON MONDAY. THE
GFS NORMALLY TENDS TO OVERDO THESE SORT OF THINGS...BUT WITH
SURFACE DEWPOINTS QUICKLY REACHING THE 60S...CANT RULE OUT
ANYTHING. WILL CONTINUE WITH THE 20 POPS FOR MONDAY.

THE FOCUS OF THE REST OF THE FORECAST THEN SHIFTS TO THE STRONG
UPPER TROUGH OR LOW CENTER EXPECTED TO BE OVER THE WESTERN CONUS
ON MONDAY AND ITS EVENTUAL TRACK INTO TEXAS. MODELS HAD BEEN
HAVING A HARD TIME AGREEING ON WHETHER THE PATTERN WOULD BE
PROGRESSIVE AS THE GFS HAS BEEN SHOWING OR THE LOW WOULD CUT OFF
AND SLOW AS THE ECMWF HAS SHOWN. THESE TWO MODELS CONTINUE TO HAVE
THE SAME DISAGREEMENT....BUT IT SEEMS THE ECMWF IS SLOWLY COMING
INTO LINE WITH THE GFS. THE ECMWF NOW HAS A FRONT MOVING THROUGH
THE ENTIRE CWA...ALTHOUGH 12 HOURS SLOWER THAN THE GFS. THIS IS A
SIGN THAT THE PARENT UPPER TROUGH IS GOING TO REMAIN STRONG AND
PROGRESSIVE TO OUR NORTH. THE GFS CONTINUES TO SHOW THE SOUTHERN
END OF THE LONGWAVE TROUGH OPEN AND PROGRESSIVE BEFORE BECOMING
CLOSED OVER TEXAS WEDNESDAY. THE ECMWF CONTINUES TO CUT THE LOW
OFF EARLY IN THE WEEK AND THEN MOVE IT OVER TEXAS THURSDAY/FRIDAY.
HOWEVER...THE GFS SOLUTION REMAINS PREFERRED AS THERE IS
CONSIDERABLE AGREEMENT BETWEEN IT AND THE CANADIAN AND THE NORTH
AMERICAN ENSEMBLE FORECAST SYSTEM. UPPED POPS ON TUESDAY TO 50/60
PERCENT FOR MUCH OF THE CWA...WITH 50S CONTINUING TUESDAY
NIGHT....AND 30S/40S FOR WEDNESDAY. THE GFS AND CANADIAN CONTINUE
TO SHOW A VERY FAVORABLE PATTERN FOR RAINFALL EXCEEDING 1-2 INCHES
ACROSS MUCH OF THE CWA. THIS WILL BE IN PART TO PACIFIC MOISTURE
FROM A REMNANT TROPICAL SYSTEM MEETING THE FRONT AND STRONG UPPER
LOW AT THE SAME TIME. IT IS STILL TOO EARLY TO GET INTO THE
SPECIFICS OF MESOSCALE FEATURES ALONG THE BOUNDARY...BUT
CONFIDENCE IS INCREASING THAT MOST OF SOUTH CENTRAL TEXAS WILL
RECEIVE MUCH NEEDED RAINFALL. STAY TUNED.

HAMPSHIRE

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              61  76  46  67  46 /  40  -    0   0  -
AUSTIN BERGSTROM INTL AIRPORT  57  76  41  67  44 /  40  10   0   0  -
NEW BRAUNFELS MUNI AIRPORT     62  76  46  69  45 /  40  10   0   0  -
BURNET MUNI AIRPORT            57  73  42  64  44 /  40  -    0   0  -
DEL RIO INTL AIRPORT           64  75  51  71  56 /  30  10  -    0  -
GEORGETOWN MUNI AIRPORT        57  73  42  65  43 /  40  -    0   0  -
HONDO MUNI AIRPORT             60  77  42  71  47 /  40  10   0  -   10
SAN MARCOS MUNI AIRPORT        60  76  44  68  43 /  40  10   0   0  -
LA GRANGE - FAYETTE REGIONAL   59  76  45  67  45 /  40  10   0   0  -
SAN ANTONIO INTL AIRPORT       64  77  49  69  50 /  40  10   0  -   -
STINSON MUNI AIRPORT           63  79  49  70  48 /  40  10   0  -   -

&&

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

$$

MESOSCALE/AVIATION...24
SYNOPTIC/GRIDS...76
PUBLIC SERVICE/DATA COLLECTION...32






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