Marine Interpretation Message
Issued by NWS

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000
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.

-----------------------------------------------------------------
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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