FXUS64 KCRP 040526 AAB
AFDCRP
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
1126 PM CST THU DEC 3 2009
.DISCUSSION...UPDATED FOR AVIATION DISCUSSION BELOW.
&&
.AVIATION...VFR CIGS WILL CONTINUE OVERNIGHT AS OVERRUNNING
GRADUALLY INCREASES AHEAD OF A DIGGING UPPER LEVEL LOW.
PRECIPITATION CHANCES WILL INCREASE ACROSS THE COASTAL PLAINS OF
SOUTH TEXAS AFTER 09Z AS ISENTROPIC ASCENT BECOMES AIDED BY
INCREASING DYNAMICS ALOFT. MVFR CIGS/LIQUID PRECIPITATION IS
ANTICIPATED AFTER 09Z THROUGH THE REST OF FRIDAY FOR THE SOUTHERN
TERMINAL AERODROMES (KLRD-KALI-KCRP). HOWEVER...FROZEN
PRECIPITATION MAY DEVELOP OVER KVCT AFTER 18Z AS A COLDER AIR
MASS BUILDS INTO SOUTHEAST TEXAS COOLING THE THERMAL PROFILE TO
ONE MORE CONDUCIVE FOR SLEET/SNOW. MVFR CIGS SHOULD ALSO DEVELOP
OVER KVCT AFTER 12Z. NORTHERLY SURFACE WINDS WILL GRADUALLY
INCREASE ACROSS SOUTH TEXAS THROUGH FRIDAY AFTERNOON AS A COASTAL
LOW DEEPENS OVER THE WESTERN GULF. A COLD/DRY/SUBSIDENT AIR MASS
WILL BUILD INTO THE REGION FRIDAY EVENING WITH WEAKENING WINDS
VFR CONDITIONS DEVELOPING AS A RESULT.
&&
.PREV DISCUSSION... /ISSUED 448 PM CST THU DEC 3 2009/
SHORT TERM (TONIGHT THROUGH FRIDAY)...A TRICKY WINTER WX FCST IS ON
TAP FOR FRI. BEGINNING WITH TONIGHT...HIGH PRESSURE WILL BE SURGING
INTO S TX WITH STRENGTHENING N WINDS USHERING IN A COLDER AIRMASS.
ISENTROPIC LIFT OVER THIS COLD HIGH PRESSURE WILL INCREASE OVERNIGHT
INTO FRI MORNING WITH A SLIGHT CHC ACROSS THE SRN CWA OVRNITE
BECOMING CATEGORICAL BY FRI MORNING ACROSS THE EASTERN HALF OF THE
CWA AND CHC TO LIKELY ACROSS THE W CWA. THE NAM IS SLIGHTLY WARMER
AND DRIER THAN THE GFS BUT THE GFS HAS BEEN CONSISTENT WITH PRECIP
IN THE FCST AND TEMPS DROPPING THRU THE AFTERNOON...THEREFORE HAVE
LEANED TOWARD THE GFS SOLN. A STRONG VORT MX WILL BE ROUNDING THE
BASE OF A POTENT LOW AND MOVG ACROSS S TX ON FRI. LARGE OMEGA/LIFT
WILL BE IN PLACE ALONG WITH THE LFQ OF A STRONG JET. WHAT WILL BE
LACKING WILL BE LOW LEVEL FORCING ALTHOUGH MID LEVEL FORCING IS
EVIDENT WITH SOME CONVERGENCE IN THE 750MB LEVEL...ALONG WITH
ISENTROPIC LIFT. GIVEN ALL OF THE AFOREMENTIONED
FEATURES...CONFIDENCE IS HIGH FOR RAIN. HOWEVER...SNOW WILL BE TOUGH
TO FCST DUE TO TIMING OF ARRIVAL OF THE COLDER AIRMASS AND TIMING OF
WHEN THE MOISTURE WILL EXIT THE AREA. THE GFS FCST SOUNDINGS ACROSS
THE NRN CWA...ESPECIALLY FOR THE NE CWA...SHOW A DECENT SNOW PROFILE
WITH MOIST LAYER WELL INTO THE -10 DEGREE C LEVELS WHICH IS NEEDED
FOR SNOW CATALYST. SLIGHTLY FARTHER S AND W...THE SOUNDINGS ARE
DRIER IN THE LEVELS AROUND -10 DEGREES...BUT DO SHOW MOISTURE IN THE
0 TO -4 DEGREES LEVELS WHICH MIGHT BE ENOUGH FOR A MIX OF SNOW AND
RAIN. AT THE SFC THE TEMPS ARE JUST ABV FREEZING BY AFTERNOON SO
SOME MELTING IS ALSO EXPECTED AND WITH GROUND TEMPS WELL ABV
FREEZING...AM NOT EXPECTING MUCH ACCUMULATION. THE BEST CHC OF ANY
ACCUM WOULD BE AROUND THE NE CWA WHERE THE DEEPER COLDER MOISTURE
IS EXPECTED BUT ACCUM ARE EXPECTED TO BE LESS THAN ONE INCH. ALSO
CAN NOT RULE OUT ISOL ELEVATED THUNDER GIVEN UPPER LEVEL DYNAMICS.
PRECIP IS EXPECTED TO RAPIDLY DIMINISH AND EXIT TO THE E AND NE
THROUGH LATE FRI AFTERNOON/EVENING. HOWEVER...ANY WET SURFACES THAT
DO NOT HAVE TIME TO DRY BEFORE THE ONSET OF FREEZING
TEMPS...ESPECIALLY OVERNIGHT WHEN A HARD FREEZE IS EXPECTED...MAY
PRODUCE HAZARDOUS TRAVEL CONDITIONS. THIS WOULD MAINLY BE A PROBLEM
FOR BRIDGES AND OVERPASSES.
ANOTHER CONCERN WILL BE THE POTENTIAL FOR MINOR TIDAL OVERFLOW DUE
TO A STRENGTHENING NE FLOW OVER THE GULF WATERS. HOWEVER...BY THE
TIME IT IS HIGH TIDE...THE WINDS WILL BECOME N WHICH SHOULD
INHIBIT TIDAL OVERFLOW. WILL CONTINUE TO MONITOR WINDS FOR A NE
DIRECTION LASTING LONGER THAN ANTICIPATED.
MARINE...SCA CONDITIONS WILL DEVELOP TONIGHT AS A STRONG HIGH
PRESSURE SYSTEM BUILDS ACROSS THE REGION. WINDS WILL CONTINUE TO
STRENGTHEN ON FRI WITH WINDS AROUND 30 KNOTS ACROSS THE COASTAL
WATERS AND GUSTS IN EXCESS OF GALE FORCE ACROSS THE OFFSHORE WATERS.
VERY COLD AND RAINY CONDITIONS CAN BE EXPECTED THROUGH MUCH OF THE
DAY FRIDAY THEN TAPERING OFF IN THE EVENING.
LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)...GFS/ECMWF AND NAM ARE
ALL SHOWING ANY REMAINING PRECIP OFFSHORE BY 00Z SAT W/ CLOUDS
CLEARING RAPIDLY FROM NW TO SE AS THE UPR TROUGH MVS EAST OF THE
AREA. THE COLD HIGH CENTER WILL SETTLE DIRECTLY OVER THE REGION BY
12Z SAT AND THIS WILL LEAD TO A VERY COLD MORNING W/ LOTS OF MID 20S
INLAND AND THE FREEZE LINE VERY CLOSE TO THE COAST IF NOT RIGHT UP
TO THE BAYS IN SOME SPOTS. HAVE ISSUED A FREEZE WATCH TO INCREASE
EARLY AWARENESS OF THIS MAJOR FREEZE EVENT AND THIS WILL ALMOST
CERTAINLY BE UPGRADED TO A WARNING ON FRI.
MODELS SHOW A COASTAL TROUGH DEVELOPING ON SAT W/ OVERRUNNING
MOISTURE AND PRECIP SAT NIGHT INTO SUN AS AN UPPER DISTURBANCE MOVES
ACROSS THE REGION. THE COASTAL TROUGH MOVES OFFSHORE BUT IS FORECAST
TO RE-DEVELOP EARLY NEXT WITH W/ LOW PRECIP CHCS CONTINUING AS
ADDITIONAL WEAK DISTURBANCES MOVE ACROSS THE REGION. THE TIMING OF
ALL THIS IS HIGHLY UNCERTAIN AND CLOUDS AND PRECIP WILL PLAY A HUGE
ROLE IN TEMPS SUN AND MON AND THIS IS PROVIDING LOW CONFIDENCE IN
BOTH THE POP AND TEMP FORECAST...NOT TO MENTION WINDS DURING THIS
PERIOD. MODELS DO AGREE ANOTHER STRONG FRONT WILL MOVE ACROSS THE
REGION AROUND WEDNESDAY W/ TEMPS COOLING ONCE AGAIN AFTER A BRIEF
WARMUP AND HIGHS POSSIBLY BACK INTO THE 70S TUE AHEAD OF THIS FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 40 41 29 53 42 / 50 80 10 0 20
VICTORIA 38 39 25 52 36 / 20 80 10 0 20
LAREDO 39 41 30 59 41 / 30 40 0 0 10
ALICE 38 39 26 55 40 / 50 80 10 0 20
ROCKPORT 40 41 31 53 44 / 40 80 10 0 20
COTULLA 39 40 23 55 38 / 20 40 0 0 10
KINGSVILLE 39 40 27 54 42 / 50 80 10 0 20
NAVY CORPUS 43 44 33 53 47 / 50 80 10 0 20
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR
THE FOLLOWING ZONES: ARANSAS...BEE...CALHOUN...DUVAL...
GOLIAD...JIM WELLS...KLEBERG...LA SALLE...LIVE OAK...
MCMULLEN...NUECES...REFUGIO...SAN PATRICIO...VICTORIA...
WEBB.
WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST FRIDAY FOR THE
FOLLOWING ZONES: BEE...CALHOUN...GOLIAD...LIVE OAK...
REFUGIO...VICTORIA.
GM...SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS OUT
20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT ARANSAS
FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL FROM 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM CST FRIDAY FOR THE FOLLOWING
ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS...
BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O'CONNOR.
&&
$$
TM/95...AVIATION
