Small Craft Advisory 41, NWS Brownsville, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1235 AM CDT TUE MAY 28 2013

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

&&

.AVIATION...THE PRESSURE GRADIENT ALONG THE COAST AND THE GULF
WATERS WILL REMAIN TIGHT THROUGH THE NIGHT KEEPING MOST OF THE
RIO GRANDE VALLEY UNDER SOUTHEAST WINDS 10 TO 15 KNOTS. THE LOW
LEVEL CLOUDS AROUND 1000 FT WILL SPREAD ACROSS THE LOWER VALLEY
A FEW HOURS BEFORE SUNRISE AS THE SE FLOW INCREMENTS THE MOISTURE
IN THE AREA THROUGH THE NIGHT. EXPECT THIS CLOUD DECK TO QUICKLY
BREAK BY MID DAY BECOMING SCATTERED IN THE AFTERNOON. EXPECT GUSTY
WINDS IN THE AFTERNOON BETWEEN 25 TO 30 KNOTS AS THE LOW PRESSURE
OVER THE WESTERN PART OF THE STATE DEEPENS STRENGTHENING THE
GRADIENT FOR SOUTH TEXAS. THIS WINDY CONDITIONS WILL CONTINUE
THROUGH THE NIGHT WITH WINDS BETWEEN 15 TO 20 KNOTS LOWERING FOR
A FEW HOURS CLOSE TO MIDNIGHT.

&&

.PREV DISCUSSION... /ISSUED 614 PM CDT MON MAY 27 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...MARINE LAYER TO MOVE INLAND THIS EVENING WITH MVFR TO
IFR STRATUS FORMING BELOW THE SURFACE INVERSION AROUND 06Z. A FEW
STREAMER SHOWERS COULD ROLL NORTHWARD OFF THE GULF BETWEEN 09Z AND
15Z WITH COVERAGE NOT ENOUGH TO WARRANT ADDING TO TAFS. STRATUS
MIXES OUT BY TUESDAY AFTERNOON WITH VFR CONDITIONS PREVAILING.
PRESSURE GRADIENT STRENGTHENS TUESDAY WITH SOUTHEAST SURFACE WINDS
APPROACHING 30 KNOTS. LOW LEVEL JET STRENGTHENS FURTHER TUESDAY
NIGHT WITH WINDS INCREASING TO AROUND 40 KNOTS AT 2500-5000 FEET.

PREV DISCUSSION... /ISSUED 233 PM CDT MON MAY 27 2013/

SHORT TERM.../NOW THROUGH TUESDAY NIGHT/...BREEZY TO WINDY
CONDITIONS WILL CONTINUE THROUGH THE SHORT TERM PERIOD WITH
STRENGTHENING LOW PRESSURE TO OUR WEST UNDERNEATH DEEPENING MID
LEVEL TROUGH WHICH WILL MOVE ACROSS THE FOUR CORNERS BY TUESDAY
NIGHT. ONGOING SHOWERS...WHICH MOSTLY DEVELOPED OVER THE BAY OF
CAMPECHE THIS MORNING...WILL FIZZLE OUT THE NEXT FEW HOURS. PWAT
THIS MORNING FROM THE KBRO RAOB WAS 1.87 INCHES AND WILL DECREASE AS
MORE RIDGING AND DRY AIR SHIFTS OVER THE AREA. POSSIBILITY FOR
RAINSHOWERS TUESDAY MORNING WILL BE LESS AND WILL KEEP RAIN SILENT.
OTHERWISE...SKIES WILL BE MOSTLY CLOUDY OVERNIGHT BECOMING PARTLY
CLOUDY DURING THE DAY. LOWS WILL BE IN THE MIDDLE TO UPPER 70S WITH
HIGHS WILL BE IN THE UPPER 80S IN THE LOWER VALLEY TO THE MIDDLE 90S
IN THE UPPER VALLEY.

LONG TERM...WEDNESDAY THROUGH MONDAY...THE LONGER RANGE PERIOD
WILL BE DOMINATED BY A LARGE 500 MB TROUGH AXIS THAT WILL DIG EAST
ACROSS THE NORTH CENTRAL PORTION OF THE LOWER 48 STATES. THIS
TROUGH WILL SPIN OFF A CLOSED LOW OVER THE UPPER MIDWEST LATE WED
INTO THURS AND FRI. ANOTHER SHORT WAVE DIVING DOWN THE WEST SIDE
OF THE MID LEVEL LOW WILL OPEN IT UP AND WILL ALLOW THE FEATURE TO
MOVE FURTHER EAST AS AN OPEN TROUGH THIS WEEKEND. TO THE SOUTH OF
THIS FEATURE BROAD BUT SHALLOW RIDGING WILL REMAIN ANCHORED IN
PLACE OVER THE GULF COAST REGION INTO THE U.S./MEX BORDER AREA
THROUGH NEXT WEEKEND.

THE UPPER MIDWEST TROUGH AXIS DOES DIG PRETTY FAR SOUTH ON WED AND
WED NIGHT AND SOME FAIRLY DECENT MOISTURE VALUES POOL OVER CENTRAL
TX. THIS IN COMBINATION WITH DAYTIME HEATING MAY FIRE OFF SOME
ISOLD CONV MAINLY OVER THE WESTERN COUNTIES EARLY IN THE EXTENDED
RANGE PERIOD. HOWEVER...AM NOT CONFIDENT ENOUGH TO RAISE POPS UP
TO 20 PERCENT FOR MIDWEEK. AFTER MIDWEEK MOISTURE LEVELS DECREASE
AND SUBSIDENT FLOW INCREASES WHICH WILL TEND TO LIMIT THE CONV
POTENTIAL. ACCORDINGLY...WILL MAINTAIN SILENT 10% POPS THROUGH DAY
7.

THE GFS/ECWMF AND CMC MODELS ARE IN DECENT AGREEMENT IN THE
HANDLING OF THE SYNOPTIC SYSTEMS THROUGH DAY 7. THE GFS AND ECMWF
TEMPS ARE ALSO IN FAIRLY CLOSE AGREEMENT THROUGH NEXT MONDAY. THE
ECMWF HAS A LITTLE WARMER BIAS VERSUS THE GFS. RUN TO RUN
CONSISTENCY WITH THE GFS MEX MOS NUMBERS IS PRETTY DECENT. SO WENT
WITH BLEND OF THE TWO MODELS FOR TEMPS THROUGH DAY 7.

LOOKING TOWARDS THE TROPICS...NHC IS MONITORING AN AREA OF LOW
PRESSURE LOCATED ABOUT 200 MILES SOUTH-SOUTHWEST OF THE GULF OF
TEHUANTEPEC. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR
ADDITIONAL DEVELOPMENT...AND A TROPICAL DEPRESSION COULD FORM
DURING THE NEXT DAY OR SO IN THE GULF OF TEHUANTEPEC. BOTH THE
GFS AND ECMWF TEND TO BRING THIS FEATURE GRADUALLY NORTHWARDS
AFFECTING SOUTHERN MEXICO AND CENTRAL AMERICA AS THE WEEKEND
APPROACHES. PLEASE REFER TO THE LATEST TROPICAL WEATHER OUTLOOKS
AND STATEMENTS FROM THE NATIONAL HURRICANE CENTER CONCERNING THE
PROGRESS OF THIS SYSTEM.

OVERALL CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS ABOVE
AVERAGE TODAY.

MARINE....NOW THROUGH TUESDAY NIGHT...PREDOMINATELY
SOUTHEASTERLY ONSHORE FLOW THROUGH THE PERIOD. SCA FOR THE LAGUNA
MADRE IS ON TRACK AND WILL EXPIRE AT 7 PM TODAY. SCEC CONDITIONS
WILL CONTINUE ACROSS THE COASTAL WATERS THROUGH TONIGHT. SCA
POSSIBLE TUESDAY AND TUESDAY NIGHT ACROSS ALL LOWER TEXAS COASTAL
WATERS AS THE PRESSURE GRADIENT STRENGTHENS FURTHER. SEAS WILL
RESPOND BY BUILDING TO 5 TO 7 FEET.

WEDNESDAY THROUGH SATURDAY...THE COMBINATION OF THE SURFACE RIDGING
TO OUR EAST AND THE STRONG SURFACE LOW PRESSURE SYSTEM MOVING OVER
THE NORTHER PORTION OF THE COUNTRY WILL LIKELY MAINTAIN A FAIRLY STRONG
PGF OVER THE LOWER TX COASTLINE WED AND THUR. THIS WILL KEEP THE BAY
AND GULF CONDITIONS PRETTY CLOSE TO SCEC/SCA CRIT AROUND MIDWEEK.
AS THE UPPER MIDWEST SYSTEM MOVES FURTHER EAST THE PGF OVER THE
REGION WILL START TO RELAX SOMEWHAT FOR FRI AND SAT REDUCING THE
RISK OF SCA CONDITIONS.

&&

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

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

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