AGNT40 KWNM 091749
MIMATN
MARINE WEATHER DISCUSSION 
NWS OCEAN PREDICTION CENTER WASHINGTON DC
150 PM EDT SAT 9 MAY 2009 
.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT 
.WEATHER FOR NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N. 
OVER THE SHORT TERM...THE NEW 12Z MDLS PRESENT NO DRAMATIC CHNGS 
FM THEIR PREV RESPECTIVE RUNS. THE 12Z NAM/GFS/GEM/UKMET AND THE 
OLD 00Z ECMWF ALL FCST RSNBLY SMLR TRACKS FOR A DVLPG SFC LOW 
PASSING JUST N OF THE NT1 WTRS LATE TONITE/EARLY SUN...WHILE 
PULLING A TRAILING COLD FRONT OFSHR. THE 12Z NAM/GEM THO LOOK 
SLIGHTLY TOO FAST. WITH THE 12Z GEFS ENSEMBLE MEMBERS PROVIDING 
SPRT...PLAN ON FAVORING THE 12Z GFS FCST TRACK FOR THIS SFC LOW. 
IN RGRDS TO THE ASCD FCST GRADIENTS INVOF THIS LOW AND ASCD 
FRONT...PLAN ON USING A BLEND OF THE 12Z NAM/GFS/UKMET FCST BL 
WINDS. PER THIS BLENDED SOLUTION...PLAN ON CONTG WITH THE PREVLY 
FCST TIMING AND AREAL COVERAGE FOR ASCD MARGINAL GALES. THE ONLY 
SIG CHNG IS WL NOW LKLY END THE GALES THRUT THE NT1 WTRS BY LATE 
SUN VS THE PREVLY FCSTD EARLY SUN NITE. ELSWHR NO SIG SHORT TERM 
CHNGS ARE PLANNED TO THE PREV OFSHR FCSTS. 
IN THE LONG RANGE...THE LATEST MDLS CONT TO DIFFER SIGLY ON BOTH 
THEIR FCST TIMING AND STRENGTH OF ANY FRONTAL WAVES RACING ACRS 
THE SRN MOST NT2 WTRS MON INTO TUE. VS ITS PREV RESPECTIVE 
RUNS...THE 12Z GFS NOW FCSTS A SIGLY DEEPER SFC LOW WITH ASCD 
GALE FORCE BL WINDS CROSSING THE SRN NT2 WTRS LATE MON. LOOKING 
AT THE MDL/S 1000 MB VORTICITY AND PRECIP FCST FIELDS...BLV THE 
MDL IS LKLY SUFFERING FM GRIDSCALE CONVECTIVE FEEDBACK AND AS A 
RSLT IS FCSTG TOO STRONG A LOW. THE 12Z NAM/GEM/UKMET ALL FCST  
WEAKER SFC LOWS MOVG MR SLOWLY ACRS THE SRN NT2 WTRS LATE MON 
INTO EARLY TUE. THE 00Z ECMWF FCSTD EVEN WEAKER SFC LOW(S?). FOR 
NOW AS A COMPROMISE PLAN ON FAVORING A BLENDED 12Z GEM/UKMET AND 
00Z ECMWF SOLUTION FOR THESE FRONTAL LOW(S?) AND SMLR TO THE 
PREV NT2 FCST WL FCST MAX ASCD WINDS UP TO 20 OR 25 KT. THEN BY 
LATE THU VS ITS PREV 06Z RUN...THE 12Z GFS IS NOW SMWHT SLOWER 
WITH A WEAK COLD FRONT APRCHG THE E COAST WHICH BRINGS IT INTO 
BETTER AGRMT WITH THE OTHER 12Z GLOBAL MDLS AND THE 00Z ECMWF. 
UNLESS THE 12Z ECMWF COMES IN LATER RADICALLY DIFFERENT...WL 
GNRLY ACPT THE 12Z GFS SOLUTION FOR THIS FRONT AND WL FCST 
PREFRONTAL SLY WINDS INCRSG UP TO 20 KT OR AT MOST 25 KT ACRS 
THE OFSHR WTRS N OF HAT CNYN LATE THU.
OVERALL THE 12Z WAVEWATCH III FCST SEAS LOOK REPRESENTATIVE AND 
WL NOT BE DEVIATED FM SIGLY.
.WARNINGS/FORECAST CONFIDENCE...WARNINGS ARE PRELIMINARY AND ARE 
SUBJECT TO CHANGE. ANY CHANGES WILL BE COORDINATED THROUGH AWIPS 
12 PLANET CHAT OR BY TELEPHONE. 
.NT1 NEW ENGLAND WATERS... 
.GULF OF MAINE...GALE SUN...MOD CONFDC. 
.GEORGES BANK...GALE SUN...MOD CONFDC. 
.S OF NEW ENGLAND...GALE TONITE INTO SUN...MOD CONFDC. 
.NT2 MID ATLC WATERS... 
.HUDSON TO BALT CNYN...NONE. 
.BALT CNYN TO HAGUE LINE...GALE TONITE INTO SUN NITE...MOD 
CONFDC. 
.BALT CNYN TO HATTERAS CNYN...GALE TONITE...MOD CONFDC. 
.HATTERAS CNYN TO CAPE FEAR...NONE. 
.CAPE FEAR TO 31N...NONE. 
.FORECASTER VUKITS. OCEAN FORECAST BRANCH.