HAMweather.com Area Forecast Discussion for County Warning Area BRO

Thu, 16 Feb 2012 11:41:00 GMT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
541 AM CST THU FEB 16 2012

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

.AVIATION...CONDITIONS HAVE DETERIORATED RECENTLY SURROUNDING THE
DEVELOPMENT AND PASSAGE OF CONVECTION THROUGH DEEP SOUTH TEXAS AND
THE RIO GRANDE VALLEY. LIFR CONDITIONS REMAIN AT BOTH THE BRO AND
HRL AERODROMES. CONDITIONS SHOULD GRADUALLY IMPROVE THIS MORNING
AND ESPECIALLY THIS AFTERNOON AS A COLD FRONT BECOMES STATIONARY
IN OUR REGION...CAUSING BACKING WINDS WITH RISING CLOUD DECKS AND
THE OPPORTUNITY FOR PRECIPITATION. FLYING CONDITIONS WILL BEGIN TO
DEGRADE TONIGHT. 

.PREV DISCUSSION... /ISSUED 351 AM CST THU FEB 16 2012/ 

SHORT TERM /TODAY THROUGH FRIDAY/...KBRO DOPPLER RADAR CURRENTLY 
SHOWS WIDESPREAD SHOWERS WITH EMBEDDED ISOLATED THUNDERSTORMS OVER 
THE NEIGHBORING STATES OF NUEVO LEON AND TAMAULIPAS IN 
MEXICO...WITH THIS ACTIVITY BEGINNING TO MOVE ACROSS THE RIO
GRANDE RIVER INTO DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY. THIS
ACTIVITY IS ASSOCIATED WITH AN OVERHEAD SOUTHWEST-TO-NORTHEAST
MID-LEVEL FLOW COURTESY OF A CUTOFF 500 MB LOW PRESSURE AREA OVER
THE CALIFORNIA AND BAJA CALIFORNIA BOUNDARY...WITH A WEAK COLD
FRONT STRETCHING ALONG A BEAUMONT-PALACIOS-ZAPATA LINE. MAV MODEL
GUIDANCE SUGGESTS SCATTERED PRECIPITATION FOR TODAY...WHILE THE
MET IS MORE ROBUST WITH LIKELY POPS. GIVEN THE PATTERN MENTIONED
ABOVE...AND THE FACT THAT INHERITED FORECAST WAS ALREADY IN THE
LIKELY REALM REGARDING RAINFALL...HAVE KEPT THIS TREND FOR TODAY.
GIVEN THE CLOUDS AND THE EXPECTED RAINFALL...BLENDED MET AND MAV
TEMPERATURES FOR TODAY AS WELL. PRECIPITATION SHOULD CONTINUE IN
THE LIKELY REGION TONIGHT PER MET GUIDANCE...A SLOW PROGRESSION OF
THE 500 MB LOW ROUGHLY DOWN THE NORTHERN HALF OF THE GULF OF
CALIFORNIA...AND THE TRANSITION OF THE WEAK COLD FRONT TO A
STATIONARY ONE WITHIN THE BRO CWFA. FRIDAY... STORM PREDICTION
CENTER MENTIONS IN DAY 2 CONVECTIVE OUTLOOK THAT ATMOSPHERIC
CONDITIONS "COULD YIELD AN ENVIRONMENT CONDUCIVE TO A FEW STORMS
CAPABLE OF PRODUCING AT LEAST MARGINALLY SEVERE HAIL" FOR SOUTH
TEXAS INTO THE TEXAS COASTAL AREAS. HAVE NOT INCLUDED THE MENTION
OF STRONG OR SEVERE THUNDERSTORMS FOR FRIDAY IN THE FORECAST AT
THIS TIME...BUT WILL ALLOW SUCCESSIVE SHIFTS TO CAREFULLY MONITOR
THIS DEVELOPING SITUATION. REGARDLESS...PRECIPITATION APPEARS
LIKELY AGAIN TOMORROW AS THE 500 MB LOW BEGINS TO FILL AS IT
ADVANCES INTO THE TEXAS BIG BEND AREA.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...MODELS IN FAIRLY
GOOD AGREEMENT WITH 500MB TROUGH ACROSS NORTHERN MEXICO FRIDAY
MOVING EAST AND NORTHEAST SATURDAY AND A FRONTAL SYSTEM DEVELOPING
ACROSS NORTHEAST MEXICO AND MOVING NORTHEAST INTO SOUTHERN
LOUISIANA. SHOWERS AND THUNDERSTORMS WILL LIKELY DEVELOP ALONG AND
AHEAD OF THE UPPER TROUGH ACROSS THE RIO GRANDE PLAINS FRI NIGHT
THROUGH EARLY SATURDAY MORNING BEFORE DRIER AIR PUNCHES INTO THE
AREA FROM THE WEST. SUBSIDENCE WILL PREVAIL ACROSS THE RIO GRANDE
VALLEY THROUGH THE WEEKEND BEFORE AN ONSHORE FLOW RETURNS LATE
SUNDAY INTO MONDAY AS THE SURFACE RIDGE ACROSS THE CENTRAL U.S.
MOVES EASTWARD. MAY SEE SOME ISOLATED STREAMER SHOWERS MONDAY AND
TUESDAY BEFORE THE NEXT 500MB TROUGH BRINGS ANOTHER PACIFIC
FRONTAL SYSTEM THROUGH SOUTH TX BY THE END OF THE FORECAST PERIOD.
WILL NOT INCREASE POPS MUCH TUESDAY AND WEDNESDAY AS THERE IS SOME
UNCERTAINTY WITH THE TIMING OF THE NEXT SYSTEM AS ADVERTISED BY
THE DIFFERENCES BETWEEN THE ECMWF AND THE GFS THROUGH THE EXTENDED. 

MARINE...
TODAY THROUGH FRIDAY...BUOY 42020 REPORTED EAST-NORTHEAST WINDS
AROUND 3.9 KNOTS WITH SEAS SLIGHTLY UNDER 4 FEET WITH A PERIOD OF
7 SECONDS AT 03 CST/09 UTC. A DENSE FOG ADVISORY WILL REMAIN IN
EFFECT THROUGH MID-MORNING TODAY FOR THE LOWER TEXAS COASTAL
WATERS DUE TO LIGHT WINDS AND A MOIST ATMOSPHERE INTERACTING WITH
COOLER SEAWATER. THE DENSE FOG ADVISORY MAY NEED TO BE EXTENDED
THROUGH MUCH OF TODAY WITH LITTLE CHANGE IN CONDITIONS EXPECTED.
OTHERWISE... LIGHT TO MODERATE WINDS AND LOW TO MODERATE SEAS ARE
ANTICIPATED FOR TODAY THROUGH TOMORROW AS A COLD FRONT TRANSITIONS
TO A STATIONARY FRONT OVER DEEP SOUTH TEXAS AND THE RIO GRANDE
VALLEY. SMALL CRAFT EXERCISE CAUTION MAY BE NEEDED FOR PORTIONS OF
THE LOWER TEXAS COASTAL WATERS THROUGH THE NEXT 36 HOURS.

FRIDAY NIGHT THROUGH MONDAY...LIGHT SOUTHEAST WINDS FRIDAY WILL
SHIFT TO THE NORTHWEST FRI NIGHT AND INCREASE RAPIDLY IN THE WAKE
OF A COLD FRONT. STRONG NORTHWEST WINDS WITH GUSTS TO NEAR GALE
FORCE WILL LIKELY DEVELOP ACROSS THE COASTAL WATERS LATE FRIDAY
INTO EARLY SATURDAY AS A RESULT. A GALE WATCH MAY BE NEEDED EARLY SAT
MORNING AS A RESULT. IF NOT...SMALL CRAFT ADVISORIES WILL BE
NEEDED LATE FRI NIGHT THROUGH SATURDAY. WINDS WILL BEGIN TO
DIMINISH SATURDAY AS THE PRESSURE GRADIENT ACROSS THE WESTERN GULF
QUICKLY WEAKENS AFTER TIGHTENING RAPIDLY LATE FRI NIGHT/EARLY SAT
MORNING. STRONG NORTHWEST WINDS SATURDAY SHOULD VEER TO THE
NORTHEAST AND BECOME LIGHT SUNDAY AS THE PRESSURE GRADIENT
CONTINUES TO WEAKEN AND SURFACE HIGH PRESSURE SETTLES ACROSS THE
WESTERN GULF. WINDS ARE PROGGED TO VEER TO THE SOUTHEAST MONDAY
AND INCREASE AS LOW PRESSURE DEVELOPS ON THE LEE SIDE OF THE
ROCKIES AND HIGH PRESSURE ACROSS THE EASTERN U.S. INCREASES THE
PRESSURE GRADIENT ACROSS THE LOWER TX COAST.

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR GMZ130-132-
     135-150-155-170-175.