000 AGXX40 KNHC 290734 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 334 AM EDT WED MAY 29 2013 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: HIGH CONFIDENCE IN THE PREVIOUS FORECAST BLENDED EQUALLY WITH THE 00Z GFS THROUGH WED THEN MEDIUM CONFIDENCE IN A BLEND OF THE GFS AND ECMWF WITH THE PREVIOUS FORECAST THU THROUGH SUN. MWW3 AND PREVIOUS FORECAST USED FOR WAVES...BUT ADJUSTED FOR THE WIND FORECAST. THE 00Z GFS APPEARS WELL INITIALIZED AND REASONABLE THROUGH WED. THE GFS DIVERGES WITH THE ECMWF OVER THE EASTERN GULF BY 00Z THU WHEN THE GFS DEVELOPS A STRONGER TROUGH E OF FLORIDA AND INCREASES THE PRESSURE GRADIENT ACROSS THE NORTHEAST GULF MORE THAN THE ECMWF...PRODUCING 25 KT WINDS THERE. NONE OF THE OTHER MODELS ARE THAT STRONG. THE GFS APPEARS TO HAVE GRID-SCALE FEEDBACK PROBLEMS IN THE ATLC THAT MAY BE INFLATING THE WIND FIELD ON THU. IN ADDITION...THE MODELS DIVERGE WITH THE REMNANTS OF EASTERN PACIFIC TROPICAL STORM BARBARA OVER THE SW GULF. THE 00Z GFS CARRIES A STRONGER TROUGH OVER THE SW GULF BY 00Z SAT AND DEVELOPS 25 KT WINDS ON ITS NE SIDE SAT NIGHT. THE ECMWF IS WEAKER AND CARRIES CONSIDERABLY BROADER TROUGHING THAT EATS INTO THE RIDGE OVER THE N GULF COASTAL PLAIN OVER THE WEEKEND. THE NAVGEM AND UKMET LIE BETWEEN THESE TWO SOLUTIONS. A BLEND OF THE 00Z GFS AND ECMWF SEEMS PERTINENT HERE. THE MWW3 WAS RELIED ON TO ADJUST WAVES WITH MANUAL EDITS MADE TO BE CONSISTENT WITH THE WIND FIELD. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: MEDIUM CONFIDENCE IN THE PREVIOUS OFFICIAL FORECAST BLENDED EQUALLY WITH THE 00Z GFS AND THE 00Z ECMWF THROUGH SUN. MWW3 AND PREVIOUS FORECAST USED AS A BASE FOR WAVE FORECAST...WITH ADJUSTMENTS MADE FOR THE BLENDED WIND FORECAST. WHILE THE 00Z GFS/MWW3 APPEARS SLIGHTLY STRONG WITH WINDS AND HIGH WITH SEAS IN THE CENTRAL CARIBBEAN THIS MORNING...THE 00Z ECMWF/EC WAVE IS TOO WEAK. A BLEND OF THEIR SOLUTIONS SEEMS BEST EARLY IN THE FORECAST PERIOD IN THE CARIBBEAN AS WELL AS LATER ON WHEN THE INFLUENCE OF EASTERN PACIFIC TROPICAL STORM BARBARA WILL DETERMINE THE WINDS OFF THE EAST COAST OF THE YUCATAN PENINSULA. THE GFS IS STRONGER/HIGHER WITH WINDS AND SEAS HERE THAN THE ECMWF. AGAIN...A BLEND SEEMS LIKE THE BEST BET. IN THE TROPICAL N ATLC...THE HIGHER RESOLUTION MWW3 WAS USED TO ADJUST THE FORECAST. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: MEDIUM CONFIDENCE IN THE PREVIOUS OFFICIAL FORECAST BLENDED WITH THE 00Z GFS THROUGH WED. THEN LOW CONFIDENCE IN THE OFFICIAL FORECAST BLENDED WITH THE 00Z ECMWF THU THROUGH SUN. THE MWW3 WAS BLENDED WITH THE PREVIOUS FORECAST TODAY THROUGH SUN...WITH MANUAL EDITS MADE FOR THE BLENDED WIND FORECAST. SEVERAL SHIP REPORTS SHOW 8-9 FT SEAS NORTH OF PUERTO RICO AND HISPANIOLA AS WELL AS JUST E OF THE BAHAMAS. THESE SEAS ARE CLOSER TO THE MWW3 THAN THE EC WAVE MODEL...BUT STILL HIGHER THAN THE MWW3. ADJUSTMENTS WILL BE MADE TO THE FORECAST TO ACCOUNT FOR THESE INITIAL DIFFERENCES. AGAIN...THE STRONGER 00Z GFS FORECAST HAS THE BEST HANDLE ON THE 20-25 KT SHIP REPORTS IN THE BAHAMAS THIS MORNING. WITH HIGH PRESSURE BUILDING TO THE NORTHEAST...THE STRONGER GFS CONTINUES TO LOOK REASONABLE THROUGH WED. ON THU...THE GFS DEVELOPS GRID-SCALE FEEDBACK ALONG THE SURFACE TROUGH EXPECTED TO BE NEAR THE E COAST OF FLORIDA. FROM 00Z THU TO 00Z SAT...THE GFS GENERATES COPIOUS AMOUNTS OF PRECIPITATION OVER THE BAHAMAS. LESS THAN HALF OF THIS PRECIPITATION CAN BE ACCOUNTED FOR BY CONVECTIVE PROCESSES. AS A RESULT OF THE FEEDBACK...THE GFS BUILDS 30 KT WINDS OVER THE NORTHERN BAHAMAS BY 18Z THU AND RAPIDLY WEAKENS WINDS ALONG THE SOUTHERN PORTION OF ITS AMPLIFYING SURFACE TROUGH. NONE OF THE OTHER MODELS ARE THIS AGGRESSIVE. THE GFS GOES ON TO HAVE SIMILAR FEEDBACK ISSUES WITH A SECOND SURFACE TROUGH DEVELOPING E OF THE TURKS AND CAICOS LATE SUN. DESPITE THE FEEDBACK...HESITANT TO COMPLETELY DISREGARD THE GFS BECAUSE ITS STRONGER SOLUTIONS HAVE BEEN CLOSER TO OBSERVATIONS THE LAST FEW RUNS. THE CURRENT OFFICIAL FORECAST HAS THE 00Z GFS WITHIN ITS BLEND OF MODEL SOLUTIONS. FOR THE UPDATE...WILL BLEND THE ECMWF WITH THE OFFICIAL FORECAST FOR WINDS. A BLEND OF THE 12Z EC WAVE AND MWW3 WAS USED FOR THE PREVIOUS OFFICIAL FORECAST. GIVEN THE POOR INITIAL PERFORMANCE OF THE LOWER RESOLUTION EC WAVE...WILL MAKE ADJUSTMENTS TOWARD HIGHER SEAS USING THE MWW3 WITH MANUAL EDITS TO SYNCH WITH THE WIND FORECAST. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... GMZ011...NONE. GMZ013...NONE. GMZ015...NONE. GMZ017...NONE. GMZ019...NONE. GMZ021...NONE. GMZ023...NONE. GMZ025...NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... AMZ011...NONE. AMZ013...NONE. AMZ015...NONE. AMZ017...NONE. AMZ019...NONE. AMZ021...NONE. AMZ023...NONE. AMZ025...NONE. AMZ027...NONE. AMZ029...NONE. AMZ031...NONE. AMZ033...NONE. AMZ035...NONE. AMZ037...NONE. AMZ039...NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... AMZ111...NONE. AMZ113...NONE. AMZ115...NONE. AMZ117...NONE. AMZ119...NONE. AMZ121...NONE. AMZ123...NONE. AMZ125...NONE. AMZ127...NONE. *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANES.GOV/MARINE $$ .FORECASTER SCHAUER. NATIONAL HURRICANE CENTER.