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

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000
FXUS64 KEWX 311710
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1110 AM CST SAT JAN 31 2015

.AVIATION...
AT THIS HOUR AUS IS STILL MVFR WHILE SAT/SSF/DRT ARE A MIX OF
IFR/LIFR DUE TO PASSING RAIN SHOWERS. THE BULK OF THE RAIN HAS
MOVED OUT OF DRT BUT A FEW PASSING SHOWERS ARE STILL POSSIBLE
THROUGH 21Z. IFR CIGS SHOULD STICK AROUND AT DRT THROUGH THE
AFTERNOON BEFORE DROPPING TO LIFR WITH LOW VISBY TOMORROW MORNING
FOR A FEW HOURS. CONDITIONS AT DRT WILL IMPROVE MY 16Z SUNDAY.

THE TEXAS TECH WRF AND OTHER HIGH RESOLUTION MODELS HAVE A GOOD
HANDLE ON THE CLUSTER OF RAIN EXTENDING FROM KERRVILLE SOUTH TO
HONDO AND COTULLA. THE MODELS BRING THIS BATCH OF RAIN INTO SAN
ANTONIO BY 18Z/19Z AND INTO AUSTIN BY 21Z. THE TAFS REFLECT THIS
WITH CONDITIONS DROPPING TO LIFR CIGS DURING THE RAIN. RAIN ENDS
ALONG THE I-35 CORRIDOR BY 03Z WITH CIGS AND VISBY REMAINING A MIX
OF IFR/MVFR. WILL SEE FOG AND LOWER CIGS TOWARDS MORNING ALONG THE
I-35 CORRIDOR AS WELL...MAINLY AT THE SAN ANTONIO TERMINALS. FLIGHT
RULE CONDITIONS WILL BEGIN TO IMPROVE AT THE I-35 TERMINALS AROUND
NOON TOMORROW.

WINDS THROUGH MOST OF THE PERIOD WILL BE OUT OF THE SOUTHEAST
BETWEEN 6 AND 12 KNOTS. A COLD FRONT APPROACHES TOMORROW AND WILL
PASS THROUGH DRT BY 16Z SUNDAY. IT WILL MOVE THROUGH THE I-35
TERMINALS JUST BEYOND THIS TAF PERIOD.

TREADWAY

&&

.PREV DISCUSSION... /ISSUED 1028 AM CST SAT JAN 31 2015/

UPDATE...
A DEEPENING UPPER LEVEL STORM SYSTEM OVER BAJA CALIFORNIA IS
FORECAST TO PUSH SOUTHWARD THROUGH THE WEEKEND. MID TO UPPER
LEVEL SOUTHWEST FLOW WILL CONTINUE TO DRIVE EASTERN PACIFIC
MOISTURE ACROSS THE AREA. AT LOWER LEVELS...A LOW LEVEL JET OF 45
TO 50 MPH FROM THE SOUTHEAST IS INJECTING GULF MOISTURE ACROSS THE
AREA AND HELPING LIGHT TO MODERATE RAINS TO PERSIST ACROSS THE
WESTERN HALF OF SOUTH CENTRAL TEXAS. THE EASTERN HALF OF THE AREA
REMAINS RELATIVE DRY AS DEWPOINT SPREADS ARE 7 TO 8 DEGREES LOWER
THAN AIR TEMPS. HOWEVER...THE LOWER ATMOSPHERE HAS BEGUN TO
MOISTEN ALONG THE I-35 CORRIDOR AS LIGHT NEW RADAR ECHOES SHOWED
ON LAST RADAR VOLUME SCAN. EXPECT RAINS TO CONTINUE THROUGH LATE
THIS EVENING WITH EPISODES OF MODERATE RAINS AND EVEN ISOLATED
THUNDERSTORMS. RAINFALL AMOUNTS WILL GENERALLY RANGE FROM ONE
QUARTER TO ONE HALF AN INCH...WITH ISOLATED HIGHER TOTALS OF THREE
QUARTERS OF AN INCH TO ONE INCH.

PREV DISCUSSION... /ISSUED 520 AM CST SAT JAN 31 2015/

AVIATION DISCUSSION...FOR 12Z TAF PACKAGE...
RAIN ALREADY IMPACTING KDRT THIS MORNING WILL SLOWLY SPREAD
EASTWARD TO THE I35 CORRIDOR TERMINALS BY MID DAY. EXPECTING IFR
CIGS FOR ALL TERMINALS WHILE RAIN IS FALLING. THIS RAINFALL WILL
PUSH THROUGH AND CLEAR KAUS BY AROUND MIDNIGHT. MOIST SFC
CONDITIONS WILL LEAD TO FOG AND CONTINUED LOW CIGS UNTIL AT LEAST
MID MORNING TOMORROW. INCLUDED AN IMPROVEMENT TO MVFR FOR THE 30
HR TAF SITES TOMORROW MORNING. TAF AMENDMENTS WILL LIKELY BE
NEEDED THROUGHOUT THE PERIOD AS CONDITIONS WAVER. EXPECTING IFR
CONDITIONS TO PREVAIL FOR THE MAJORITY OF THE TAF PERIOD.

TB3

PREV DISCUSSION... /ISSUED 318 AM CST SAT JAN 31 2015/

SHORT TERM (TODAY THROUGH SUNDAY)...LARGE SCALE ASCENT INCREASING
ACROSS VAL VERDE COUNTY AT THE TIME OF THIS WRITING...WITH THE
APPROACH OF THE MID AND UPPER LEVEL SHORTWAVE. LOW LEVEL WARM AIR
ADVECTION WAS INCREASING AHEAD OF THE SYSTEM...WITH LOWERING
CLOUD DECK ACROSS THE WESTERN 3RD OF THE CWA AND PATCHY LIGHT
DRIZZLE DEVELOPING. THE LOW LEVEL MOISTENING WILL INCREASE THROUGH
THE MORNING FROM SW TO NE...WITH DEW POINTS MODIFYING BACK INTO
THE LOW TO MID 50 ACROSS MUCH OF THE CWA BY AFTERNOON.
AFOREMENTIONED LARGER SCALE FORCING COMBINED WITH LOW AND MID
LEVEL MOISTENING WILL RESULT IN RAIN DEVELOPING WEST TO EAST
THROUGH THE MORNING HOURS...WEST OF I-35. THE RAIN THEN EXPANDS
EAST OF I-35 DURING THE AFTERNOON. THE MAIN FORCING FROM THE
SHORTWAVE AND PRECIP WILL SKIRT THROUGH THE EAST AND NORTHEAST CWA
THIS EVENING...EXITING NORTHEAST AFTER MIDNIGHT. ISOLATED SHOWERS
CAN NOT BE RULED OUT WEST OF I-35 TONIGHT WITH EMBEDDED WEAKER
DISTURBANCES IN THE SOUTHWEST FLOW ALOFT. ISOLATED THUNDER IS ALSO
POSSIBLE TONIGHT INTO SUNDAY.

A PRE-FRONTAL TROUGH WILL MOVE INTO NORTHERN AND WESTERN AREAS OF
THE CWA MIDDAY SUNDAY...WITH THE ACTUAL COLD FRONT ARRIVING LATE
AFTERNOON ACROSS THE HILL COUNTRY AND AUSTIN AREA...AND THROUGH
SOUTHERN AREAS AND SAN ANTONIO SUNDAY EVENING. LOW AND MID LEVEL
FLOW TURNS WEST WITH THE PRE-FRONTAL TROUGH SUNDAY...RESULTING IN
DRYING AND THE BETTER MOISTURE POOL ACROSS THE EAST/SOUTHEAST CWA.

LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...COLD FRONT PUSHES
THROUGH SOUTHERN AREAS OF THE CWA SUNDAY EVENING. BREEZY
CONDITIONS LIKELY SUNDAY NIGHT...ESPECIALLY ALONG AND EAST OF THE
ESCARPMENT EDGE. DRYING IN THE LOW LEVELS TAKES PLACES MONDAY.
THE UPPER LEVEL LOW THAT WILL CUT OFF ACROSS BAJA CALIFORNIA BY
SUNDAY NIGHT IS FORECAST TO OPEN AND EJECT NORTHEAST ACROSS NORTH-
CENTRAL MEXICO TUESDAY AND SOUTH TEXAS WEDNESDAY. THE ECMWF AND
GFS HAVE TRENDED SLIGHTLY FURTHER NORTH WITH THE TRACK OF
THIS SYSTEM...WITH POTENTIALLY BETTER RAIN CHANCES NOW TUESDAY
INTO WEDNESDAY MORNING ACROSS THE EWX CWA. STILL ROOM FOR
SIGNIFICANT ERROR THIS FAR OUT...ESPECIALLY WITH SYSTEMS THIS FAR
SOUTH COMING OUT OF MEXICO...THEREFORE NO HIGHER THAN 20-40 POPS
AT THE MOMENT. ANOTHER COLD FRONT IS INDICATED BY THE GFS AND CMC
TO DROP SOUTH THROUGH THE AREA...BEHIND THE DEPARTING UPPER LEVEL
SYSTEM...WEDNESDAY NIGHT INTO THURSDAY. ECMWF IS MUCH WEAKER WITH
THE FRONT. HAVE SIDED TOWARDS SLIGHTLY STRONGER GFS SOLUTION.

JR

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              61  57  66  37  51 /  90  80  30  10  -
AUSTIN BERGSTROM INTL AIRPORT  63  56  66  37  50 /  90  70  30  10  -
NEW BRAUNFELS MUNI AIRPORT     64  57  68  39  52 /  80  70  30  10  -
BURNET MUNI AIRPORT            58  53  62  33  49 /  90  80  30  10  -
DEL RIO INTL AIRPORT           60  52  67  41  55 /  90  30  20  10  -
GEORGETOWN MUNI AIRPORT        59  55  63  34  49 /  90  80  40  10  -
HONDO MUNI AIRPORT             62  55  69  39  55 /  90  60  30  10  -
SAN MARCOS MUNI AIRPORT        63  56  67  38  51 /  90  70  30  10  -
LA GRANGE - FAYETTE REGIONAL   65  57  67  39  51 /  60  70  50  10  -
SAN ANTONIO INTL AIRPORT       63  56  68  39  53 /  90  70  30  10  -
STINSON MUNI AIRPORT           65  56  69  41  54 /  80  70  30  10  -

&&

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

$$

MESOSCALE/AVIATION...12
SYNOPTIC/GRIDS...17
PUBLIC SERVICE/DATA COLLECTION...30





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