

783 

AGNT40 KWNM 121225

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

825 AM EDT FRI AUG 12 2016



.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT

.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.



UPDATE...06Z NCEP SFC ANALYSIS SHOWS A WEAK LOW PRES TROF OVER THE

GULF OF MAINE...BUT OTHERWISE HIGH PRES RIDGING OVER THE REST OF

THE OFSHR WTRS. LATEST AVAILABLE ASCAT HI-RES AND ASCAT PASSES

FROM LAST NITE SHOW AN AREA OF WINDS TO 20 KT IN SW FLOW OVER

ZONES 900 AND 905 AROUND GEORGES BANK...WITH LIGHT WINDS OF 15 KT

OR LESS INDICATED ACROSS THE REMAINER OF THE OFSHR WTRS. LIGHTNING

DENSITY PRODUCT DATA AT 1100Z SHOWS A SMALL AREA OF SCATTERED

SHOWERS OVER THE GEORGES BANK ZONES 805 AND 900...WITH NO OTHER

ACTIVITY IN THE REST OF THE OFSHR WTRS.



MAIN WEATHER FEATURES...A WEAK SUMMERTIME PATTERN WILL PREVAIL

ACROSS THE OFSHR WTRS THRU THE ENTIRE FCST PERIOD...WITH MAX WINDS

OF 20 OR 25 KT. A WEAK STATIONARY FRONT WILL PERSIST ACROSS THE

GULF OF MAINE TODAY THRU SAT NITE. A COUPLE OF WEAK LOWS WILL

PASS E ALONG THE FRONT OVER THE GULF OF MAINE TONITE THRU SAT NITE.

THE FRONT WILL LIFT N AS A WARM FRONT SUN. ANOTHER LOW WILL PASS E

OVER THE GULF OF MAINE MON AND MON NITE...PULLING A COLD FRONT SE

OVER THE NT1 AND NRN NT2 WTRS. THE COLD FRONT WILL STALL OVER THE

NRN NT2 WTRS EARLY TUE...THEN LIFT N INTO THE NT1 AREA AS A WARM

FRONT LATER TUE AND TUE NITE.



MODELS...THE GFS IS STRONGER THAN THE OTHER MED RNG MDLS WITH THE

LOW PASSING E OVER THE GULF OF MAINE ON MON AND MON NITE AND WITH 

ITS ASSOCD SW FLOW...AND IS MORE SOUTHWARD WITH THE WARM FRONT

FOR TUE AND TUE NITE. THE ECWMF LOOKS LIKE THE MOST REPRESENTATIVE

MDL SOLN...AND HAS VERY GUD SUPPORT FROM THE LATEST WPC MED RNG

FCSTR GUIDANCE...SO IT WILL BE USED TO POPULATE THE WIND GRIDS FOR

THE ENTIRE FCST PERIOD. AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES

TO THE CURRENT FCST TREND.



SEAS...BOTH THE WNA WAVEWATCH III AND THE ECMWF WAM INITIALIZED

WELL OVER THE OFFSHORE/COASTAL WATERS...AND ARE IN REASONABLY GOOD

AGREEMNT THROUGH SUN. FOR THE WAVE HT GRIDS WILL BE USING A 50/50

BLEND OF THE WNA WAVEWATCH III/ECMWF WAM THROUGH SUN...THEN GOING

WITH ALL ECMWF WAM FOR SUN NITE THRU TUE NITE.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION... 



0100Z AND 0145Z ASCAT OVERPASSES ACROSS OFFSHORE WATERS E OF 70W 

RETURNED ONLY A FEW LIMITED AREAS OF 20 KT WINDS. ONE WAS JUST E 

OF CAPE COD AND A SECOND WAS LOCATED SE OF GEORGES BANK 

COINCIDENT WITH A LARGE MEANDER OF THE GULF STREAM IN THAT 

VICINITY. THE 00Z GFS/UKMET AND 12Z/11 ECMWF ARE ALL WELL 

INITIALIZED WITH WINDS ACROSS THIS AREA. THE SUBSEQUENT 0240Z 

OVER PASS ALSO SHOWED SOME 20 KT WINDS ALONG THE SRN NJ COAST. 

THE 12Z/11 ECMWF AND 03Z HRRR APPEAR TO HAVE BETTER HANDLE ON 

THESE WINDS THAN THE WEAKER 00Z GFS/UKMET. THE 00Z MODELS ARE IN 

AGREEMENT THAT MID/UPPER FLOW ACROSS THE ERN SEABOARD AND W ATLC 

WILL REMAIN MOSTLY WEAK AND ZONAL FOR THE NEXT SEVERAL DAYS AS A 

WEAK UPPER RIDGE PERSISTS OFF THE COAST. THE SW 15 TO 20 KT 

WINDS SHOULD GENERALLY PERSIST ACROSS THE SRN NT1 AND NRN NT2 

ZONES THROUGH THE WEEKEND WITH SURFACE HIGH PRES IN PLACE OFF 

THE MID ATLC COAST AND A SLOW MOVING COLD FRONT DROPPING S 

THROUGH NEW ENGLAND TODAY...AND STALLING ACROSS THE GULF OF 

MAINE TONIGHT WITH SEVERAL WEAK LOWS THEN MOVING E ALONG THE 

FRONT TONIGHT THROUGH SUN NIGHT. 00Z MODELS IN AGREEMENT THAT 

STATIONARY FRONT SHOULD BRIEFLY LIFT BACK N INTO COASTAL MAINE 

LATE SAT NIGHT AND SUN. MODEL WINDS ARE IN PRETTY GOOD AGREEMENT 

THROUGH THE NEXT 60 HOURS BUT DUE TO ITS SLIGHTLY BETTER 

INITIALIZATION AM FAVORING THE 00Z ECMWF WINDS THROUGH SUN.  



LATER IN THE WEEKEND THROUGH EARLY NEXT WEEK GFS IS SOMEWHAT OF 

AN OUTLIER WITH A STRONGER LOW MOVING OFF THE NEW ENGLAND COAST 

AND STRONGER ASSOCIATED SW WINDS LATE SUN AND SUN NIGHT. THEN AS 

THIS LOW PULLS THE FRONT S INTO THE NRN NT2 WATERS MON NIGHT THE 

GFS APPEARS TOO AGRESSIVE IN MOVING THE FRONT FURTHER S THAN THE 

ECMWF/UKMET/CMC CONSENSUS. OPC PREFERENCE CONTINUES WITH THE 

ECMWF THROUGH EARLY NEXT WEEK WITH THE GENERAL IDEA THAT FRONT 

SHOULD STALL FURTHER N AND THEN BEGIN TO LIFT N AS A WARM FRONT 

TUE/TUE NIGHT PER ECMWF/UKMET.  



SEAS...BOTH THE 00Z WNA WAVEWATCH III MDL AND THE 00Z ECMWF WAM 

INITIALIZED WELL OVER THE OFFSHORE/COASTAL WATERS...AND ARE IN 

REASONABLY GOOD AGREEMNT THROUGH SUN. FOR WAVE HEIGHT GRIDS WILL 

BE USING A 50/50 BLEND OF THE 00Z WW3 AND 00Z ECMWF WAM THROUGH 

SUN...THEN TRANSITIONING TO THE 00Z ECMWF WAM SUN NIGHT THROUGH 

TUE NIGHT. 



.EXTRATROPICAL STORM SURGE GUIDANCE...N/A. 



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER SCOVIL/CLARK. OCEAN PREDICTION CENTER.

