Freeze Warning 2, NWS Brownsville, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
224 PM CST THU DEC 3 2009

.DISCUSSION...AN INTERESTING WX SCENARIO CONTINUES TO SHAPE UP
FOR DEEP SOUTH TX DURING THE NEXT DAY TO DAY AND A HALF. TEMPS
HAVE REMAINED COOL TDA UNDERNEATH THICK OVERCAST SKIES AS
ANTICIPATED. THE CLD SHIELD WILL BE WITH US THROUGH AT LEAST THE
NEXT 24 HRS BEFORE WE BEGIN TO SEE INDICATIONS OF LOOSING IT.
UNFORTUNATELY THE LOSS OF THE CLD BLANKET WILL RESULT IN THE
COLDEST TEMEPRATURE READINGS OF THE SEASON SO FAR ACROSS DEEP
SOUTH TX. COLD POLAR HIGH PRESSURE WILL CONTINUE TO BUILD SWD INTO
SOUTH TX THE NEXT 24 HRS. THE SHALLOW COOL AIR AT THE SFC
COMBINING WITH SW FLOW ALOFT WILL SET UP AN OVERRUNNING SCENARIO
ACROSS THE AREA. PCPN CHC WILL INCREASING WITH TIME TNGT INTO FRI
MRNG. ANTICIPATED RAIN WITH DRIZZLE TO BE PRETTY MUCH THE NORM ON
FRI AS WINDS NORTHERLY WINDS INCREASE. MOST OF THE PCPN SHUD BE IN
THE LIQUID FORM...ALTHOUGH IT WOULD NOT BE TOTALLY OUT OF QUESTION
TO SEE SOME SNOWFLAKES MIXED IN ACROSS OUR NORTHERN ZONES TWD THE
AFTN AND EARLY EVE HRS. THE COMBINATION OF STEADY TEMPERATURES IN
THE 40S AND NW WINDS IN EXCESS OF 25 MPH WILL ALLOW FOR WIND CHILL
READINGS IN THE 30S. A VERY RAW AND UNCOMFORTABLE DAY TO BE
OUTDOORS TO SAY THE LEAST ACROSS DEEP SOUTH TX ON FRI.

THE UPPER LEVEL DISTURBANCE RESPONSIBLE FOR THE DAMP WX IS
ANTICIPATED TO PUSH THRU AND TO OUR EAST ON FRI NGHT. WINDS ALOFT
TURN TO THE NW AND ALLOW FOR DRIER AIR TO INVADE THE AREA. SKIES
WILL CLEAR FROM WEST TO EAST WITH TIME FRI NGT INTO EARLY SAT. THE
POLAR HIGH ADVECTING IN COOLER AIR THRU THE AFTN/EVE ON FRI AND
THEN CLEARING SKIES AND DRIER AIR LEADING TO RADIATIONAL COOLING
OVRNGT FRI NGT WILL ALLOW TEMPS TO QUICKLY FALL TO THEIR LOWEST
VALUES OF THE SEASON SO FAR. ALL INDICATIONS ARE THE TEMPERATURES
AT OR BELOW FREEZING WILL BE POSSIBLE FOR SOME LOCATIONS IN DEEP
SOUTH TX. IT APPEARS LOCATIONS NORTH OF A LINE FROM SOUTHERN
ZAPATA THRU NORTHERN STARR AND HIDALGO COUNTY EWD INTO WILLACY
COUNTY WILL STAND THE BEST CHC FOR FREEZING TEMPS. TEMPS BELOW 30
DEGREES WILL BE MORE LIKELY ACROSS OUR 4 NORTHERN TIER COUNTIES
IN OUR CWA AND HAVE ISSUED A FREEZE WATCH BEGINNING FRI EVE THRU
SAT MRNG. TEMPS WILL RECOVER ABOVE FREEZING BY MID MRNG SAT.
IMPROVING CONDITIONS WILL MORE SUNSHINE WILL BE POSSIBLE THRU THE
FIRST HALF OF THE WEEKEND AT TEMPS MODERATE BUT REMAIN BELOW
NORMAL FOR EARLY DEC.

&&

.AVIATION...FLIGHT CONDITIONS WILL BECOME MVFR THIS AFTERNOON AND
MVFR/IFR OVERNIGHT AND FRIDAY MORNING. DENSE/COOL AIR WILL BE WEDGED
INTO THE AREA AT THE SURFACE TONIGHT AND FRIDAY AS CYCLOGENESIS
OCCURS OVER THE GULF. WARM/MOIST AIR WILL RIDE OVER THE COOL AIR
TONIGHT LEADING TO THE DEVELOP OF DZ/-RA. CAN/T RULE OUT SOME CB AND
LIGHTNING AROUND DAYBREAK ON FRIDAY...ESPECIALLY ACROSS BRO AND
HRL...AS SOME ELEVATED INSTABILITY WILL EXIST BUT THUNDERSTORM
THREAT IS TOO LOW TO MENTION IN TAFS AT THIS TIME. WINDS WILL
STRENGTHEN AND BECOME GUSTY FROM THE NORTH LATE TONIGHT AND FRIDAY
BUT LLWS WILL LIKELY NOT BE OF CONCERN.

&&

.MARINE...CONDITIONS OVER THE COASTAL WATERS WILL BEGIN DETERIORATING
TONIGHT AS PRESSURE GRADIENT TIGHTENS AND WINDS COME UP TO SMALL CRAFT
ADVISORY CRITERIA SHORTLY AFTER MIDNIGHT. STRONG WINDS FRIDAY AFTERNOON
AND EVENING WILL LIKELY TOUCH GALE FORCE...35 TO 40 KNOTS AND HIGHER
GUSTS...ESPECIALLY IN THE 40 TO 60 NAUTICAL MILE OFFSHORE RANGE. SEAS
WILL RESPOND QUICKLY REACHING 12 TO 14 FEET OFFSHORE BY THE AFTERNOON.
VIGOROUS UPPER LEVEL SYSTEM WILL PRODUCE COLD RAIN OVER THE ENTIRE
MARINE AREA LATE TONIGHT AND THROUGH THE DAY FRIDAY CLEARING OUT BY
FRIDAY EVENING. SCA POSTED THIS AFTERNOON FOR THE POST MIDNIGHT AND
BEYOND TIME FRAME. WINDS AND SEAS WILL SUBSIDE DURING THE DAY ON FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  46  48  37  60 /  70  70  20  10
BROWNSVILLE          46  48  35  61 /  70  70  20  10
HARLINGEN            44  46  33  58 /  70  70  20  10
MCALLEN              44  46  33  57 /  70  70  20  10
RIO GRANDE CITY      42  44  33  56 /  60  50  20  10
SOUTH PADRE ISLAND   47  49  41  62 /  70  70  20  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR
     TXZ248>251.

GM...SMALL CRAFT ADVISORY FROM 4 AM FRIDAY TO 6 AM CST SATURDAY FOR
     GMZ130-132-135-150-155-170-175.

&&

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE

SYNOPTIC/GRIDS...VIPOND-57
MARINE/AVIATION...RYDELL-51
MESOSCALE...VEGA