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AGXX40 KNHC 011755
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
155 PM EDT FRI AUG 1 2014

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS.

2 PM MODEL UPDATE... NO SIGNIFICANT CHANGES TO THE FORECASTS IN THE GULF OF MEXICO AND THE CARIBBEAN. CONDITIONS IN THE GULF WILL STRUGGLE TO SEE WINDS OVER 15 KT OR SEAS OVER 4 FT THROUGH WED. THE CARIBBEAN FORECAST IS MORE DEPENDENT ON THE TRACK OF T.S. BERTHA AND ITS IMPACT ON THE SUBTROPICAL RIDGE DRIVING THE WINDS IN THE CENTRAL CARIBBEAN. THE 12Z GFS SOLUTION IS VERY CLOSE TO THE OFFICIAL FORECAST THROUGH MON...THEN THE GFS TAKES BERTHA ON A MORE SHARP RIGHT TURN...ALLOWING IT TO MOVE EASTWARD MORE RAPIDLY THAN THE OFFICIAL FORECAST ONCE THE STORM MOVES N OF 27N. IN CONTRAST...THE 12Z UKMET IS SLIGHTLY MORE TO THE LEFT AT THAT TIME AS IS THE MUCH WEAKER 00Z ECMWF. THE GFS IS THE MODEL CLOSEST TO THE OFFICIAL TRACK/INTENSITY OVERALL...SO IT WAS USED TO ADJUST THE GRIDS. THIS SHOULD ACCOMMODATE ANY CHANGES IN THE SUBTROPICAL RIDGE AND RESULTING WINDS IN THE CENTRAL CARIBBEAN.


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PREVIOUS DISCUSSION...


...GULF OF MEXICO...

MODEL PREFERENCE: GFS

WEAK FRONTAL BOUNDARY ACROSS THE SE GULF CONTINUES TO MEANDER FROM NEAR NAPLES TO 24N89W. RECENT ASCAT PASS DEPICTS SHEARLINE LIKE PROPERTIES...YIELDING SUFFICIENT LLVL CONVERGENCE FOR ISOLATED TO WIDELY SCT TSTMS ACROSS MOISTURE FIELD. BOUNDARY EXPECTED TO DRIFT SE AND WEAKEN FURTHER NEXT 24 HOURS BEFORE REMNANTS DRIFT BACK TOWARD THE NW SAT-SUN. WEAK HIGH TO PREVAIL N OF BOUNDARY AND YIELD WEAK WIND FLOW. WEAK FRONT MOVING INTO TEXAS COASTAL PLAINS EXPECTED TO MOVE SLOWLY SE AND INTO COASTAL WATERS TONIGHT BEFORE DISSIPATING SAT EVE-NIGHT ACROSS OFFSHORE COASTAL WATERS. MODELS SUGGEST WINDS TO REMAIN LIGHT TO MODERATE THROUGH EARLY NEXT WEEK WITH BES CHANCES FOR 15-20 KT WINDS OCCURRING WITH TYPICAL YUCATAN EVENING THERMAL TROUGH AND POSSIBLY ALONG UPPER MEXICAN COAST WITH AFTERNOON SEABREEZE SAT. NO SIG CHANGES FROM RECENT GUIDANCE.


...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...

MODEL PREFERENCE: GFS-UKMET CONSENSUS

11 PM PACKAGE WAS UPDATED TO REFLECT UPDATED NHC FORECAST FOR NOW T.S. BERTHA. GOES-R PROVING GROUND AIRMASS IMAGERY SUGGESTS BERTHA ENTERING MORE UNSTABLE MIDDLE TO UPPER LEVEL CONDITIONS RESIDING ACROSS THE E CARIB AND ADJACENT ATLC OF 58W...AND THIS MAY ALLOW FOR SAL TO GRADUALLY FILTER OUT NEXT 24-36 HRS. CNVTN INCREASING ACROSS E/SE SEMICIRCLE AND WAS MAIN REASONING FOR TC CLASSIFICATION...SINCE LLVL STRUCTURE AND GALE FORCE WINDS SHOWN TO EXIST EARLIER THU. MODELS REMAIN IN GOOD GENERAL AGREEMENT WITH 06Z RUNS HAVING SHIFTED EVER SO SLIGHTLY TO THE RIGHT AFTER 48 HOURS WITH GFS NOT ON LEFT HAND SIDE OF ENVELOPE. UNFORTUNATELY... UKMET IS NOT AVAILABLE FOR GFE USAGE AND AM FORCED TO MANUFACTURE WIND AND WAVE HEIGHT FIELDS FROM GFS. GLOBAL MODELS UNABLE TO RESOLVE SMALL WIND FIELD OF THIS SYSTEM...AND UPCOMING FORECASTS WILL CONTINUE TO ATTEMPT TO SHRINK 20-33 WIND FIELD DURING NEXT 48 HOURS. BASED ON CURRENT NHC FORECAST...BERTHA TO MOVE ACROSS PORTIONS OF DOMINICA AND MARTINIQUE THEN ACROSS NE CARIB AND MONA ISLAND AND THROUGH EXTREME NE PART OF DOM REP. ISLANDS AND BATHYMETRY WILL DISRUPT WAVE FIELD AND REGROWTH OF HIGH SEAS WILL NEED TO OCCUR INSIDE CARIB. OTHERWISE...NO SIG CHANGES TO PREVIOUS FORECAST...WITH GFS SHOWING STRONG TRADES PULSING TO 25 KT EACH NIGHT ACROSS CARIB JET REGION...WHICH SHIFTS EWD TO 70-73W SAT AND SUN AS BERTHA PASSES TO N...THEN RIDGING OCCURS BEHIND BERTHA AND AHEAD OF NEXT TROPICAL WAVE SUN NIGHT FOR RETURN TO NOCTURNAL MAX OF 30 KT OFF COLOMBIA. BROAD FETCH OF FRESH E-NE WINDS WITH AND BEHIND THIS NEXT TROPICAL WAVE TO BRING 7-9 FT SEAS INTO N HALF OF TROPICAL N ATLC WATERS SUN THROUGH TUE.


...SW N ATLANTIC INCLUDING THE BAHAMAS...

MODEL PREFERENCE: GFS-UKMET CONSENSUS

TSTMS CONTINUE TO FIRE ACROSS NW PORTIONS IN SLY FLOW TO E OF OLD BO0UNDARY THAT HAS DRIFTED NW AND INLAND PAST 24 HOURS...AND EXPECTED TO REMAIN ACTIVE ACROSS THIS AREA NEXT 24 HOURS AS MID LEVEL CONVERGENCE MAINTAINS MOIST ENVIRONMENT. SIMILAR EFFECTS OCCURRING ACROSS SE WATERS AS LARGE TUTT LOW N OF PUERTO RICO AND HISPANIOLA EXTENDS INTO MID LEVELS AND AIDING IN MAINTAINING LOW- MID LVL MOISTURE CONVERGENCE E OF 71W AND TRIGGERING BROAD AREA OF MOD TO STRONG CNVTN. ACTIVITY TO GRADUALLY DIMINISH NEXT 36-48 HOURS AND LOW WEAKENS AND RETROGRADES WWD...AND BECOME PLAYER IN FUTURE OF BERTHA AS IT DROPS SW AHEAD. SLY INDUCED SHEAR COULD PLAY ROLE IN INTENSITY OVER THE WEEKEND AND BEYOND. OTHERWISE...WEAKENED ATLC RIDGE CONTINUES FROM NW ATLC SW TO NEAR NW BAHAMAS...BUT BLOCKED SOMEWHAT BUT PAIR OF LLVL TROUGHS E OF BAHAMAS. FRESH TO STRONG E TO SE WINDS WILL SHIFT FROM OFFSHORE WATERS OF PUERTO RICO SAT...NW AND ACROSS SE PORTIONS WITH AND SLIGHTLY AHEAD OF BERTHA...AFFECTING BAHAMAS AND WATERS TO ADJACENT E. RECURVATURE EXPECTED WITH BERTHA AFTER LIFTING N OF NW BAHAMAS AND WILL LEAVE S TO SW FLOW THROUGH BAHAMAS AND ACROSS BANKS...WITH RIDGING BUILDING ACROSS NE CARIB BEHIND BERTHA AND OVER TROPICAL WAVE ENTERING E CARIB SUN-MON ESTABLISHING STRONG TRADES ACROSS SE PORTIONS AND INTO SE BAHAMAS AND APPROACH TO WINDWARD PASSAGE. AGAIN...UKMET NOT AVAILABLE FOR GFE USE AND DOING OUR BEST TO CREATE ACCURATE GRIDS FROM GFS-ECMWF BLENDING.

$$


.WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE:


.GULF OF MEXICO... NONE.


.CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...
.AMZ023...CARIBBEAN N OF 15N BETWEEN 64W AND 72W... TROPICAL STORM WARNING SAT.
.AMZ025...OFFSHORE WATERS LEEWARD ISLANDS... TROPICAL STORM WARNING TONIGHT.
.AMZ027...TROPICAL N ATLANTIC FROM 15N TO 19N BETWEEN 55W AND 60W... TROPICAL STORM WARNING TODAY.
.AMZ035...OFFSHORE WATERS WINDWARD ISLANDS INCLUDING TRINIDAD AND TOBAGO... TROPICAL STORM WARNING TONIGHT.
.AMZ037...TROPICAL N ATLANTIC FROM 07N TO 15N BETWEEN 55W AND 65W... TROPICAL STORM WARNING TODAY.


.SW N ATLANTIC INCLUDING THE BAHAMAS...
.AMZ119...ATLANTIC FROM 22N TO 27N E OF BAHAMAS TO 70W... TROPICAL STORM WARNING SUN.
.AMZ123...ATLANTIC S OF 22N W OF 70W INCLUDING APPROACHES TO THE WINDWARD PASSAGE... TROPICAL STORM WARNING SUN.
.AMZ125...ATLANTIC S OF 22N BETWEEN 65W AND 70W INCLUDING PUERTO RICO TRENCH... TROPICAL STORM WARNING SAT NIGHT INTO SUN.

$$

*FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF

NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP

FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANE WARNINGS.GOV/MARINE

$$


.FORECASTER SCHAUER/STRIPLING. NATIONAL HURRICANE CENTER.

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