Small Craft Advisory for Winds 2, NWS Brownsville, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1141 PM CST SAT JAN 7 2012

.DISCUSSION...SEE AVIATION SECTION BELOW FOR 06Z TAFS.

&&

.AVIATION...DENSE FOG HAS ALREADY COVERED KBRO AND IS EXPECTED TO
RAPIDLY DEVELOP MOST OF THE RIO GRANDE VALLEY BEFORE 8Z WITH THE
REST OF DEEP SOUTH TEXAS TO QUICKLY FOLLOW. VLIFR CONDITIONS TO
PERSIST THROUGH 14Z THEN SOUTHEAST WINDS TO INCREASE QUICKLY
DISSIPATING THE FOG. A SCT-BKN VFR DECK TO DEVELOP IN THE
AFTERNOON MOST LOCATIONS WITH WIND GUSTS APPROACHING 30 KNOTS.

&&

.PREV DISCUSSION... /ISSUED 945 PM CST SAT JAN 7 2012/

DISCUSSION...SEE SHORT TERM UPDATE FOR FOG POTENTIAL OVERNIGHT
AND EARLY SUNDAY.

SHORT TERM /TONIGHT THROUGH EARLY SUNDAY/...REALLY FENCE SITTING
FOR DENSE FOG ADVISORY THIS EVENING. ON THE ONE HAND...CALM WINDS
AND RAPIDLY FALLING TEMPERATURES ACROSS THE RANCHLANDS/UPPER
VALLEY WOULD SUGGEST SIX OR MORE HOURS OF 100 PERCENT HUMIDITY.
WITH SOUTH WINDS INCREASING OFF THE DECK BUT COLD DOME INHIBITING
ANY DOWNWARD MIXING IT WOULD SEEM LOGICAL FOR ANOTHER ROUND OF 1/4
MILE OR LOWER VISIBILITY THROUGH MID MORNING SUNDAY.
HOWEVER...STARTING DEW POINTS ARE 5 TO 10 DEGREES LOWER THAN THIS
TIME LAST NIGHT. AND...LOW LEVEL MOISTURE UP TO 850 MB IS STILL
VERY LOW DESPITE THE SOUTHERLY FLOW. FINALLY...WILL HIGH CLOUDS
BECOME MORE BROKEN PRIOR TO DAYBREAK? WITH ALL THIS
UNCERTAINTY...DECIDED TO HOIST SPS AND LEAVE FORECAST VISIBILITY
AT 1/2 MILE...JUST ABOVE CRITERIA.

CLOSER TO THE COAST...100 PERCENT RH IN REACH SHORTLY AND ALREADY
KBRO HAS DIPPED TO 6 SM...WITH VISUAL AND FEEL OF AIR HAVING THAT
POTENTIAL. IF TEMPERATURES CAN FALL INTO THE UPPER 50S IN THE
LOWER VALLEY DENSE FOG MAY WELL OCCUR HERE AS WELL. FOR NOW...HAVE
HELD AT 1 MILE VISIBILITY AND AREAS OF FOG...WITH SPS SECTION
COVERING THE POTENTIAL. PROBLEM HERE IS POSSIBILITY OF WARMER AIR
SLIPPING IN LATER TONIGHT WITH TEMPS/DEWPOINTS POSSIBLY RISING A
SMIDGE...ENOUGH TO ERODE SOME OF THE FOG.

EXPECT FOG TO CONTINUE THROUGH 9 AM WITH PATCHES REMAINING UP
NORTH AND WEST THROUGH 10 OR EVEN 11 AM BEFORE RAPIDLY SCOURING
UNDER INCREASINGLY GUSTY SOUTH WINDS.

/52-BSG/

PREV DISCUSSION... /ISSUED 606 PM CST SAT JAN 7 2012/

DISCUSSION...SEE AVIATION SECTION BELOW FOR 00Z TAF ANALYSIS.

AVIATION...ANOTHER DIFFICULT FORECAST THIS EVENING. LAST NIGHT
THIS TIME...MY 'GUT' WAS TELLING ME FOR POTENTIAL FOG EVENT AS
UPPER LOW HAD JUST CLEARED OUT AND CLEAR SKIES AND LACK OF DEEP
SOUTHERLY FLOW SET STAGE FOR EXCELLENT NEAR SURFACE RADIATIONAL
COOLING...AND SURE ENOUGH FOG THICKENED PARTICULARLY AT KMFE.

AT FIRST...ONE WOULD THINK PERSISTENCE WOULD WORK FINE. ONLY
PATCHY HIGH CLOUDS...STILL FAIRLY LOW DEWPOINTS...AND PLENTY OF
DRY AIR ABOVE THE SURFACE TO GET INTO THE MIX AND HELP INCREASE
RADIATIONAL COOLING. NOT TO MENTION POSSIBILITY OF SHALLOW WIND
DIRECTION EDGING TOWARD A LAND BREEZE IF RADIATIONAL COOLING
BRINGS TEMPERATURES QUICKLY TOWARD 60 OR LOWER AT KHRL/KBRO LATER
THIS EVENING. SHOULD THIS OCCUR...THE FORECAST WOULD BE A SLAM
DUNK FOR GRADUAL MIST (BR) BEFORE MIDNIGHT AND FOG AFTER MIDNIGHT.

UNFORTUNATELY...THE NEXT 500 MB TROUGH IS QUICKLY MAKING ITS MOVE
INTO THE FOUR CORNERS OVERNIGHT AND WILL TURN THE MID LEVEL WINDS
FROM THE DRYING NORTHWEST TO A WEST-SOUTHWEST DIRECTION. THIS IN
TURN WILL HELP DEVELOP THE LEE SIDE OF THE SIERRA MADRE SURFACE
TROUGH...WHICH TYPICALLY INCREASES RETURN SOUTHERLY FLOW TO THE
SURFACE. SUCH FLOW INCREASES DEWPOINTS AND CAN INTERFERE WITH THE
RADIATIONAL COOLING/FOG MECHANISM. SUCH IS THE CASE IN THE LOWER
VALLEY WHERE THESE WINDS CAN MIX DOWN FASTER...INCLUDING ALL THREE
TERMINALS.

SO...ITS A RACE AGAINST TIME IN SOME WAYS TO SEE HOW THINGS SHAKE
OUT. LOOKING IN DETAIL: KMFE HAD VERY LIGHT WIND TODAY AND WITH
LOWER WET BULB TO START THE EVENING THINK THEY HAVE BEST CHANCE
FOR IFR PREVAILING CIG/VIS AND BR/FG. KHRL/KBRO HAVE BETTER
OPPORTUNITY TO SEE MODIFYING AIR MASS SOONER WHICH WOULD INCREASE
POSSIBILITY FOR JUST ENOUGH WIND TO KEEP DENSE FOG AT BAY. FOR
NOW...HAVE NUDGED KBRO FORECAST OUT OF LIFR (EVEN TEMPO GROUPS)
BUT LEFT KHRL IN WHICH OWES TO CLIMATOLOGY OF SUCH EVENTS.

ONE MORE THING TO WATCH LATER TONIGHT IS ANOTHER ROUND OF LOW
LEVEL WIND SHEAR. NAM MODEL SUGGESTS 35 KNOTS AT 1000 FEET ACROSS
AREAS WITH LIGHT TO CALM SURFACE WINDS BY DAYBREAK. THIS OCCURRED
EARLY THIS MORNING BUT WITH SOME UNCERTAINTY ON HOW MUCH COULD
START MIXING DOWN HAVE LEFT OUT FOR NOW AND DEFERRED TO LATER
FORECASTS FOR POSSIBLE ADDITION.

BY MID MORNING...THE FOG WILL QUICKLY BURN OFF AND BE REPLACED BY
THE ARRIVAL OF THE VALLEY WIND MACHINE AND ASSOCIATED
STRATOCUMULUS DECKS. HAVE CAPPED WINDS IN THE 20 TO 22 KNOTS RANGE
FOR THE BALANCE OF SUNDAY AFTERNOON.

/52-BSG/

PREV DISCUSSION... /ISSUED 158 PM CST SAT JAN 7 2012/

SHORT TERM... /TONIGHT THROUGH SUNDAY NIGHT/...MAIN CONCERN TONIGHT
WILL BE FOG DEVELOPING ACROSS THE RIO GRANDE VALLEY. QUESTION IS
WHETHER WINDS TONIGHT WILL BE STRONG ENOUGH TO KEEP DENSE FOG FROM
DEVELOPING. BELIEVE WINDS WILL BE LIGHT ENOUGH WITH THE CLEAR SKIES
TO ALLOW FOG TO DEVELOP BUT ENOUGH MIXING TO KEEP VISIBILITIES ABOVE
A QUARTER OF A MILE. SURFACE LOW PRESSURE ACROSS SOUTHWEST TEXAS AND
NORTHEAST MEXICO WILL ALLOW THE PRESSURE GRADIENT TO INCREASE ACROSS
THE LOWER TEXAS COAST SUNDAY. BREEZY CONDITIONS WILL LIKELY DEVELOP
SUN AFTERNOON AFTER THE FOG BURNS OFF AND LIFTS WITH DIURNAL
HEATING. LOW TO MID LEVEL MOISTURE IS EXPECTED TO INCREASE ACROSS
NORTH AND CENTRAL TX SUN NIGHT AS LOW PRESSURE CONTINUES TO DEEPEN
ACROSS THE UPPER PORTIONS OF THE RIO GRANDE VALLEY ALLOWING
CONVECTION TO DEVELOP NORTH OF THE CWA AS LAPSE RATES BEGIN TO
STEEPEN ALOFT AS A 500MB LOW/TROUGH MOVES INTO WEST TX/NORTHERN
MEXICO. WILL CONTINUE TO MENTION RAIN CHANCES DEVELOPING LATE SUN
NIGHT ACROSS THE AREA AS MOISTURE AND INSTABILITY INCREASE ACROSS
THE RIO GRANDE PLAINS.

LONG TERM.../MONDAY THROUGH FRIDAY...TWO BIG UPPER LEVEL STORM
SYSTEMS WILL MOVE ACROSS TEXAS AND IMPACT THE RGV OVER THE NEXT
WEEK. THE FIRST SYSTEM WILL BRING A CHANCE OF SHOWERS SUNDAY NIGHT
AND PERHAPS A THUNDERSTORM OR TWO MONDAY...BEFORE THE SYSTEMS
EXITS THE AREA MONDAY NIGHT. AN ASSOCIATED COLD FRONT WILL MOVE
THROUGH THE RGV AND DEEP SOUTH TEXAS DURING THE DAY MONDAY BRING
COOLER TEMPERATURES FOR TUESDAY. THE FRONT MAY PROVIDE ENOUGH
DYNAMICS OR LIFT TO GENERATE THUNDER MONDAY. RAPID CLEARING MONDAY
NIGHT WILL MAKE FOR A SUNNY TUESDAY AND WEDNESDAY. BREEZY
CONDITIONS SUNDAY AS SOUTHEAST WINDS FEED THE APPROACHING STORM
SYSTEM WITH BREEZY NORTHWEST WINDS ON MONDAY IN THE WAKE OF THE
COLD FRONT. WINDS WILL DIMINISH MONDAY NIGHT WITH IDEAL WEATHER
CONDITIONS TUE THROUGH WED...ALTHOUGH TEMPS WILL BE A BIT COOL ON
TUE. TEMPS MAY REBOUND TO A BIT ABOVE SEASONAL NORMALS ON
WED...AND MAYBE NEARING 80 DEGREES IN A FEW LOCATIONS ACROSS THE
MID VALLEY. ADJUSTED TEMPS UP A BIT ON MONDAY DUE TO THE EXPECTED
LATER ARRIVAL OF THE COLD FRONT...BUT ADJUSTED TEMPS DOWNWARD ON
TUESDAY. LOOKS LIKE A CALM BUT COOL DAY AS WE WILL BE INFLUENCED
BY THE CIRCULATION OF THE LARGE COLD CORE UPPER LOW OVER CENTRAL
TEXAS.

THE NEXT AND POTENTIALLY MORE IMPACTFUL SYSTEM WILL BEGIN TO
IMPACT THE AREA THU AS CLOUDS INCREASE AND A SLIGHT CHANCE OF
SHOWERS DEVELOPS THU AFTERNOON. A STRONG COLD FRONT IS ANTICIPATED
TO MOVE THROUGH THE AREA LATE THU NIGHT OR EARLY FRIDAY AS RAIN
CHANCES INCREASE. THE UPPER LEVEL SYSTEM APPEARS TO BE A SLOW
MOVER SO CLEARING WILL BE SLOW TO OCCUR. IN FACT...THE CHANCE FOR
SHOWERS WILL LIKELY LINGER INTO SATURDAY. HAVE ADJUSTED TEMPS DOWN
A BIT FRIDAY AND FRIDAY NIGHT TO BE MORE IN LINE WITH THE GFS 12Z
RUN...BUT EVEN COOLER CONDITIONS ARE POSSIBLE. DUE TO EXPECTED
CLOUD COVER...FREEZING TEMPS NOT ANTICIPATED AT THIS TIME...BUT
OVERNIGHT LOWS FALLING INTO THE MID TO UPPER 30S ACROSS THE BRUSH
COUNTRY AND WESTERN ZONES MAY WELL OCCUR NEVERTHELESS.

MARINE...TONIGHT THROUGH SUNDAY NIGHT...SEAS WERE NEAR 4 FEET
WITH SOUTH WINDS NEAR 14 KNOTS AT BUOY020 EARLY THIS AFTERNOON.
MODERATE SOUTH WINDS WILL PREVAIL ACROSS THE COASTAL WATERS
TONIGHT BEFORE INCREASING SLIGHTLY SUNDAY AS THE PRESSURE GRADIENT
INCREASES SLIGHTLY ACROSS THE LOWER TEXAS COAST SUN AFTERNOON.
MODERATE TO STRONG SOUTH TO SOUTHEAST WINDS WILL PREVAIL ACROSS
THE WESTERN GULF OF MEXICO SUNDAY THROUGH SUN NIGHT AS A RESULT.

MONDAY THROUGH WEDNESDAY...SMALL CRAFT CONDITIONS LIKELY MONDAY AS
BREEZY CONDITIONS AND ROUGH SEAS ARE EXPECTED MONDAY DUE A STRONG
COLD FRONT MOVING THROUGH THE AREA. SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS ARE EXPECTED MONDAY WITH RAPID CLEARING MONDAY
NIGHT. WINDS AND SEAS WILL DIMINISH MONDAY NIGHT WITH IDEAL MARINE
CONDITIONS ANTICIPATED FOR TUE AND WED.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

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

59/66

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1045 AM CST SAT JAN 7 2012

TXZ248>257-081045-
ZAPATA-JIM HOGG-BROOKS-KENEDY-STARR-HIDALGO-INLAND WILLACY-
INLAND CAMERON-COASTAL WILLACY-COASTAL CAMERON-
1045 AM CST SAT JAN 7 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR DEEP SOUTH TEXAS.

.DAY ONE...REST OF TODAY AND TONIGHT.

DENSE FOG MAY REDEVELOP ACROSS ALL AREAS OF DEEP SOUTH TEXAS AFTER
MIDNIGHT TONIGHT INTO SUNDAY MORNING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

A MODERATE RISK OF RIP CURRENTS IS EXPECTED SUNDAY BECOMING HIGH
FOR MONDAY AND TUESDAY.

THUNDERSTORMS ON MONDAY MAY PRODUCE OCCASIONAL CLOUD TO GROUND
LIGHTNING STRIKES AND GUSTY WINDS TO 35 MPH.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

GMZ130-132-135-150-155-170-175-081045-
LAGUNA MADRE FROM THE PORT OF BROWNSVILLE TO THE ARROYO COLORADO-
LAGUNA MADRE FROM THE ARROYO COLORADO TO 5 NM NORTH OF PORT
MANSFIELD TX-
LAGUNA MADRE FROM 5 NM NORTH OF PORT MANSFIELD TO BAFFIN BAY TX-
COASTAL WATERS FROM PORT MANSFIELD TO THE RIO GRANDE OUT 20 NM-
COASTAL WATERS FROM BAFFIN BAY TO PORT MANSFIELD OUT 20 NM-
WATERS FROM PORT MANSFIELD TO THE RIO GRANDE EXTENDING FROM 20 TO
60 NM-
WATERS FROM BAFFIN BAY TO PORT MANSFIELD EXTENDING FROM 20 TO
60 NM-
1045 AM CST SAT JAN 7 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE GULF OF MEXICO AND THE
LAGUNA MADRE.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

SMALL CRAFT ADVISORIES ARE POSSIBLE AS EARLY SUNDAY AFTERNOON FOR
THE LAGUNA MADRE AND THE OFFSHORE WATERS. SMALL CRAFT ADVISORIES
ARE LIKELY ACROSS THE OFFSHORE WATERS SUNDAY NIGHT THROUGH
TUESDAY. THE LAGUNA MADRE WILL SEE SMALL CRAFT ADVISORY CONDITIONS
MONDAY AFTERNOON AS COLD FRONT SWEEPS EAST THROUGH THE REGION.
SOME GALE FORCE GUSTS ARE POSSIBLE MONDAY AFTERNOON OR EVENING
ACROSS THE OFFSHORE WATERS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

GB/MC