000
FXUS64 KBRO 191146
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
646 AM CDT SUN MAY 19 2013

.DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

&&

.AVIATION...EXPECTING MVFR CONDITIONS TO IMPROVE TO VFR IN THE NEXT
FEW HOURS. GUSTY SOUTHEAST WINDS WILL INCREASE IN ABOUT THE SAME
TIME FRAME WITH GUSTS OF 24 TO 28KTS EXPECTED. VFR CONDITIONS
EXPECTED THROUGH EARLY EVENING BUT A BKN TO OVC CLOUD DECK AT AROUND
1800 TO 2200 FT IS EXPECTED TO DEVELOP FAIRLY QUICKLY IN THE EVENING
HOURS AND PERSIST THROUGH THE OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 348 AM CDT SUN MAY 19 2013/

SHORT TERM /NOW THROUGH MONDAY/...
WE ARE JUST WEST OF AN UPPER TROUGH AXIS PUSHING INTO THE WESTERN
GULF OF MEXICO. A STRONG UPPER TROUGH IS PUSHING INTO THE PANHANDLES
REGION WHILE BECOMING NEGATIVELY TILTED. A WEST SOUTHWESTERLY
SUBTROPICAL JET IS ORIENTED OVER THE SIERRA MADRES INTO THE WESTERN
GULF OF MEXICO. THIS RESULTS IN MODERATE SURFACE RIDGING OVER THE
GULF...AND A DEEPENING CYCLONE OVER THE PLAINS STATES AND WEAK LEE
TROUGHING TO OUR WEST.

TODAY...A SENSIBLE WEATHER REPEAT OF SATURDAY IS BASICALLY EXPECTED.
THE WIND DIRECTION MAY BE ABOUT 10 TO 20 DEGREES WEST OF WHAT WE SAW
ON SATURDAY WHICH MAY WARM THINGS UP SLIGHTLY MORE...BUT OVERALL NOT
A SUBSTANTIAL CHANGE. CLOUD COVER EARLY SHOULD GIVE WAY TO MOSTLY
SUNNY SKIES BY LATE AFTERNOON. HIGHS WILL BE IN THE LOWER 90S
EAST...LOW 100S WEST. WIND SPEEDS SOUTH BE ABOUT 20 TO 25 MPH WITH
GUSTS IN THE 35 MPH RANGE AT PEAK. CURRENT AND PROJECTED GRADIENT
AND MAV/MET GUIDANCE SUGGEST CONDITIONS BELOW WIND ADVISORY LEVEL
FOR TODAY. DRIER AIR AT 850MB AND VICINITY SHOULD MIX DOWN WELL
ENOUGH TO KEEP OUR HEAT INDEX AT ABOUT 100 TO 103 EVEN IN THE
WARMEST SPOTS. AGRICULTURAL FIRES FROM THE YUCATAN WILL KEEP HAZE IN
THE AIR THROUGH THE DAY.

TONIGHT...HUMIDITY WILL INCREASE QUICKLY OVERNIGHT WITH LOW CLOUDS
RETURNING. A STEADY SOUTH BREEZE WILL ALSO KEEP UP OVERNIGHT.
TEMPERATURES SHOULD BE HELD UP BY HIGH DEWPOINT AND CLOUD COVER AS
WELL AS PERSISTENT WIND WITH LOWS IN THE MID TO UPPER 70S.

MONDAY...WE WILL BE IN BETWEEN SYSTEMS ON MONDAY WITH THE LOW LEVEL
PRESSURE GRADIENT RELAXED A BIT. ABOUT A 3 TO 4 MPH DECREASE IN WIND
SPEED WHICH WILL STILL BE BREEZY BY ANY ACCOUNT. THE DRIER NEAR SFC
AIR WILL STILL BE IN PLACE CLEARING SKIES QUICKLY IN THE MORNING
THROUGH THE AFTERNOON AND KEEPING PM HUMIDITY SOMEWHAT IN CHECK.
TEMPERATURES LOOK PRETTY SIMILAR NEAR 90 ALONG 77 AND NEAR 100 IN
ZAPATA COUNTY.

LONG TERM...MONDAY NIGHT THROUGH SATURDAY...INITIALLY A LARGE
CLOSED 500 MB LOW WILL BE LOCATED OVER THE CENTRAL PORTION OF THE
COUNTRY WITH A FAIRLY STRONG SHORT WAVE TROUGH DIGGING AROUND THE
BOTTOM OF THE CLOSED LOW. THIS SHORT WAVE WILL MOVE OVER THE SOUTH
CENTRAL PLAINS STATES ON TUES AND WILL EXIT THE REGION ON WED.
ENOUGH MOISTURE AND INSTABILITY MAY POOL OVER CENTRAL AND
SOUTHERN TX AHEAD OF THIS FEATURE FOR SOME ISOLD CONV TO FIRE OFF
TUES AND WED WITH ADDITIONAL ASSISTANCE FROM DIURNAL AND
OROGRAPHIC EFFECTS OVER SOUTHERN TX AND NORTHEAST MEXICO. AFTER
THIS FEATURE EXITS THE REGION MID LEVEL RIDGING WILL REBUILD OVER
THE SOUTH CENTRAL PLAINS STATES DURING THE LATTER HALF OF THE WEEK
THROUGH SATURDAY WHICH WILL INCREASE THE STABILITY OF THE ATMS AND
DECREASE OVERALL MOISTURE LEVELS.

LONGER RANGE MODEL GUIDANCE FROM THE GFS/ECMWF AND CMC ALL POINT
TOWARDS PRETTY GOOD AGREEMENT IN THE HANDLING FO THE OVERALL
SYNOPTIC PATTERN. GOOD RUN TO RUN AGREEMENT SHOWS UP WITH THE LAST
SEVERAL MEX MOS CYCLES. THE ECMWF TEMPS AND POPS ARE ALSO TURNING
UP PRETTY CLOSE TO THE GFS NUMBERS. SO WILL STICK WITH A BLEND OF
THE GFS AND ECMWF NUMBERS DUE TO THE GOOD AGREEMENT.

OVERALL CONFIDENCE WITH THE LONGER TERM WORDING IS ABOVE AVERAGE
THIS MORNING.

MARINE...
NOW THROUGH MONDAY...A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE
LAGUNA MADRE FROM MID MORNING THROUGH THIS AFTERNOON FOR WINDS
AROUND 20 KNOTS...ESPECIALLY ON THE WESTERN HALF OF THE BAY. WINDS
WILL BE LIGHTER DURING THE DAY ON THE OPEN GULF WATERS. ANOTHER
NIGHT OF EXERCISE CAUTION LEVEL WINDS IS EXPECTED ON SUNDAY NIGHT ON
THE GULF WATERS BEFORE SOMEWHAT MORE FAVORABLE MARINE CONDITIONS
DEVELOP ON MONDAY. SEAS WILL BE MODERATE THROUGH MONDAY.

MONDAY NIGHT THROUGH THURSDAY...THE PGF WILL LIKELY REMAIN PRETTY
STRONG OVER THE LOWER TX BAY AND GULF WATERS FOR MONDAY AND
TUESDAY AS THE SURFACE LOW PRESSURE SYSTEM OVER THE CENTRAL STATES
WILL NOT MAKE MUCH PROGRESS TO THE EAST. THE PGF WILL LIKELY RELAX
A LITTLE BIT ON WED AND THURS AS THE 500 MB LOW AND ASSOCIATED
SURFACE LOW SHIFTS EASTWARDS. ACCORDINGLY THERE WILL BE THE
POTENTIAL FOR SCEC/SCA CONDITIONS THROUGH MIDWEEK WITH A LOWER
PROBABILITY DURING THE LATTER HALF OF THE WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  92  77  86  78 /   0   0   0   0
BROWNSVILLE          93  77  90  78 /   0   0   0   0
HARLINGEN            94  77  92  77 /   0   0   0   0
MCALLEN              95  77  95  77 /   0   0   0   0
RIO GRANDE CITY      97  77  96  77 /   0   0   0   0
SOUTH PADRE ISLAND   83  76  81  75 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FOR WINDS FROM 10 AM THIS MORNING TO 7 PM
     CDT THIS EVENING FOR GMZ130-132-135.

&&

$$

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

59...AVIATION/SHORT TERM