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AGXX40 KNHC 270752
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
352 AM EDT WED AUG 27 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.


...GULF OF MEXICO...

MODEL PREFERENCE: LATEST GFS/ECMWF BLENDED WITH PREVIOUS OFFICIAL. NWPS/MWW3 BLEND USED FOR WAVE PARAMETERS. MEDIUM CONFIDENCE.

THE PRESSURE GRADIENT ACROSS THE NW GULF REMAINS TIGHT THIS MORNING BETWEEN THE LINGERING REMAINS OF THE FRONTAL BOUNDARY THAT PLOWED THROUGH THE NE HALF OF THE GULF OVER THE LAST TWO DAYS AND HIGH PRES TO THE N. THE ASCAT PASSES FROM 0250 UTC AND 0338 UTC SHOWED 25 KT WINDS IN THE NW HALF OF ZONE GMZ013. SHIP C6KJ5 REPORTED 11 FT SEAS AT 00Z IN THIS AREA. NONE OF THE MODELS ARE STRONG ENOUGH INITIALLY. ADJUSTMENTS WERE MADE TO THE GRIDS TO ACCOUNT FOR THE STRONGER OBSERVATIONS. OTHERWISE...THE ONLY OTHER SIGNIFICANT CHANCE OF EXCEEDING ADVISORY CRITERIA COMES EARLY SAT MORNING OFF THE W COAST OF THE YUCATAN PENINSULA AS A TROPICAL WAVE APPROACHING THE AREA ENHANCES THE NORMAL NOCTURNAL TROUGH THAT PUSHES OFF THE PENINSULA IN THE OVERNIGHT HOURS. THE GEFS SHOWS A 10-20 PERCENT CHANCE OF WINDS MEETING ADVISORY CRITERIA BOTH EARLY SAT MORNING AND EARLY SUN MORNING...WITH PROBABILITIES INCREASING SUN NIGHT IN THE WAKE OF THE TROPICAL WAVE TO AROUND 30 PERCENT. THE ECMWF IS FASTER CARRYING THE WAVE THROUGH THE SOUTHERN GULF AND DOES NOT DEVELOP A LOW PRES SYSTEM HERE THE WAY THE 00Z GFS DOES JUST BEYOND THE 5 DAY PERIOD. CONFIDENCE IS LOW IN THE DETAILS HERE THIS FAR OUT...SO A BLEND OF THE GFS AND ECMWF WILL BE USED TO ADJUST THE GRIDS. A BLEND OF THE MWW3 AND NWPS WAS USED TO ADJUST THE WAVE...WITH MANUAL EDITS MADE TO MATCH THE PREFERRED WINDS.




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

MODEL PREFERENCE: LATEST GFS/ECMWF BLENDED WITH PREVIOUS OFFICIAL. NWPS BLENDED WITH OFFICIAL FOR WAVE PARAMETERS. MEDIUM- LOW CONFIDENCE.

THE NORMALLY STRONG TRADE WINDS IN THE CENTRAL CARIBBEAN HAVE DIMINISHED SINCE THE SUBTROPICAL RIDGE TO THE N HAS RETREATED E DUE TO CRISTOBAL. THE RIDGE IS TRYING TO REBUILD S OF CRISTOBAL...WITH THE 0248 UTC ASCAT-B PASS SHOWING 20-25 KT WINDS IN THE GULF OF GUACANAYABO WHICH HAVE DIMINISHED SOME SINCE THE 0156 UTC ASCAT-A PASS. THESE WINDS SHOULD RAPIDLY DIMINISH AS CRISTOBAL CONTINUES TO PULL N...CARRYING THE TROUGHING EXTENDING TO ITS SE...CURRENTLY ACROSS WESTERN CUBA...ALONG WITH IT. NONE OF THE MODELS PICKED UP ON THIS AREA OF WINDS OVER ADVISORY CRITERIA. OTHERWISE...THE LARGEST MODEL DIFFERENCES COME WITH THE FORECAST OVER THE TROPICAL N ATLC AND EASTERN CARIBBEAN WED NIGHT THROUGH SAT. THE GFS DEVELOPS A SMALL CLOSED LOW LEVEL CIRCULATION THAT IT CARRIES THROUGH MARTINIQUE AND DOMINICA FRI. THE NAVGEM IS THE CLOSEST MODEL TO THE GFS...WITH THE OTHERS CONSIDERABLY WEAKER AND FOCUSING MORE ENERGY WITH THE TROPICAL WAVES TO THE E AND W. CONFIDENCE IN THE GFS DIPS HERE. A BLEND OF THE GFS AND ECMWF WILL BE USED TO ADJUST THE GRIDS TO ACCOUNT FOR UNCERTAINTY HERE AND IN THE WIND OVER THE CENTRAL CARIBBEAN WHICH IS DEPENDENT ON THE TIMING OF THE WAVES PASSING THROUGH THE REGION. THIS ALSO HELPS TEMPER THE WIDESPREAD 20-25 KT WINDS THE GFS PUTS IN THE NW CARIBBEAN SAT AS THE TROPICAL WAVE CURRENTLY NEAR 54W MOVES THROUGH THE REGION. THE OTHER MODELS DO NOT SUPPORT WINDS AS STRONG. THE NWPS WAS MAINLY RELIED ON HERE TO ADJUST THE WAVES.




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

MODEL PREFERENCE: LATEST GFS/ECMWF BLENDED WITH PREVIOUS OFFICIAL. MWW3/NWPS USED FOR WAVE OVER W HALF AND MWW3/ECMWF USED FOR WAVE PARAMETERS. MEDIUM CONFIDENCE.

CRISTOBAL IS ACCELERATING...MOVING OUT OF THE FORECAST AREA LATER TODAY. THE ECMWF IS SLIGHTLY FASTER THAN THE GFS WITH THE TRACK...BUT THE OFFICIAL NHC FORECAST IS BETWEEN THE GFS AND ECMWF SOLUTIONS. NEITHER OF THOSE MODELS ARE PICKING UP ON THE FRESH TO STRONG SOUTHERLY FLOW BETWEEN THE TROUGH EXTENDS SW FROM CRISTOBAL INTO CENTRAL CUBA AND THE RIDGE TRYING TO EXPAND S OF CRISTOBAL. THE WINDS HERE HAVE DIMINISHED SOME BETWEEN THE 0156 UTC ASCAT-A AND THE 0248 UTC ASCAT-B PASS. THESE WINDS SHOULD RAPIDLY DIMINISH AS CRISTOBAL CONTINUES TO PULL N...CARRYING THE TROUGHING EXTENDING TO ITS SE...CURRENTLY ACROSS WESTERN CUBA...ALONG WITH IT. THE GFS SHOWS AN AREA OF 20 KT WINDS IN THE SOUTHERN BAHAMAS. IT IS THE STRONGEST OF THE MODELS...BUT NOT STRONG ENOUGH COMPARED TO THE 25 KT OBSERVATIONS IN THE MORE RECENT ASCAT PASS. MANUAL ADJUSTMENTS WILL BE MADE TO ACCOUNT FOR THESE CONDITIONS. THE NEXT FEATURE OF NOTE IN THE REGION WILL BE THE NORTHERN EDGE OF THE TROPICAL WAVE CURRENTLY ALONG 54W. THE GFS IS SLOWER WITH THE WAVE THAN THE ECMWF AND SUPPORTS A LARGER AREA OF FRESH TRADES. THE NAVGEM IS STRONGER AND FASTER HERE WHILE THE UKMET AND ECMWF AREA WEAKER AND FASTER. THE GFS HAS BEEN BACKING OFF ON THE TROUGHING ASSOCIATED WITH THIS WAVE...BUT AFRAID TO GO AWAY FROM IT TOTALLY AS ITS STRONGER WINDS OVER AREAS OF LOCALIZED ENHANCEMENT...LIKE IN THE APPROACHES TO THE WINDWARD PASSAGE...GENERALLY PAN OUT. WITH WINDS EXPECTED TO REMAIN BELOW ADVISORY CRITERIA HERE...IMPACTS ARE LOW. OVERALL...A BLEND OF THE GFS AND ECMWF HELPS MITIGATE SOME OF THE UNCERTAINTY. THIS WILL BE USED TO ADJUST THE GRIDS WITH THE NWPS...MWW3 AND EC WAVE ALL RELIED ON FOR WAVES. THE NWPS WAS FAVORED FOR ITS BATHYMETRY NEAR THE BAHAMAS AND THE EC WAVE USED OVER THE OPEN WATERS OF THE ATLC.



$$


.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... NONE.


.SW N ATLANTIC INCLUDING THE BAHAMAS...
.AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W... HURRICANE WARNING TODAY. TROPICAL STORM WARNING TODAY.
.AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W... TROPICAL STORM WARNING TODAY.

$$

*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. NATIONAL HURRICANE CENTER.

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