

377 

AGNT40 KWNM 101213

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

813 AM EDT WED AUG 10 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 STATIONARY FRONT EXTNDG SE

TO NW ACROSS THE CENTRAL NT2 WTRS...BUT OTHERWISE INDICATES HI

PRES RIDGING OVER THE OFSHR WTRS. LATEST AVAILABLE ASCAT AND ASCAT

HI-RES PASSES FROM LAST NITE SHOW LIGHT WINDS OF 15 KT OR LESS

OVER THE OFSHR WTRS. LIGHTNING DENSITY PRODUCT DATA AT 1130Z SHOWS

A SMALL AREA OF ISOLATED SHOWERS AND TSTMS IN E TO SE FLOW OVER

THE FAR SRN PART OF THE NT2 AREA...BUT NOTHING ELSE OVER THE OFSHR

WTRS.



MAIN WEATHER FEATURES...A COLD FRONT WILL APPROACH THE NEW ENGLAND

REGION FROM THE NW TONITE THRU THU NITE...BECOME STATIONARY ACROSS

THE GULF OF MAINE FRI THRU SUN NITE. LOW PRES WILL PASS E ALONG

THE FRONT OVER THE GULF OF MAINE FRI NITE...THEN AGAIN SAT NITE.



MODELS...THE MED RNG MDLS ARE IN VERY GUD OVERALL AGREEMNT ACROSS

THE OFSHR WTRS FOR TODAY THRU FRI NITE...SO THE GFS 10M SOLN WILL

BE USED TO POPULATE THE WIND GRIDS FOR THIS TIMEFRAME. THE GFS

PUSHES THE FRONT S INTO THE SRN NT1 WTRS DURING THE SAT THRU SUN

NITE PERIOD...BUT THE OTHER MED RNG MDLS KEEP THE FRONT OVER THE

GULF OF MAINE...SO THE MORE REPRESENTATIVE ECMWF MDL WILL BE USED

FOR THE SAT THRU SUN NITE PERIOD. AM NOT PLANNING TO MAKE ANY

SIGNIF CHANGES TO THE CURRENT FCST PERIOD.



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

WELL OVER THE OFSHR WTRS. ALTHO THE MDLS ARE IN GUD AGREEMNT FOR

TODAY THRU FRI NITE...A 50/50 BLEND OF THE WNA WAVEWATCH III AND

ECMWF WAM WILL BE USED FOR THE WAVE HT GRIDS OVER THIS TIMEFRAME

TO SMOOTH OUT SOME MINOR DIFFERENCES BETWEEN THE MDLS. IN ORDER TO

BE CONSISTENT WITH THE PREFERRED ECMWF SOLN FOR SAT THRU SUN

NITE...WILL USE A 10/90 BLEND OF THE WNA WAVEWATCH/ECMWF WAM

DURING THIS PERIOD.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION...



SHORT TERM...1026 MB HIGH PRES IS MOVG SLOWLY SE FROM JUST S OF

GEORGES BANK EARLY THIS MORNING. A STATIONARY FRONT IS WEAKENING

OVER CENTRAL NT2 WTRS AND EXTENDING E-SE FROM NR VIRGINIA BEACH

PER THE 06Z PRELIM OPC-NCEP SFC ANALYSIS. THE FRONT IS FCST TO

DSIPT TODAY AS THE HIGH DRIFTS SE AWAY FROM THE WTRS. A WEAK COLD

FRONT IS FCST TO APPROACH THE NEW ENGLAND COAST LATER TONITE AND

THU AND STALL...AS A HIGH PRES RIDGE DOMINATES MOST OF THE CENTRAL

AND SRN NT2 WTRS. THE FRONT WILL LKLY REMAIN JUST N OF THE WTRS

INTO FRI AS LOW PRES SLIDES E FROM THE GRT LKS INTO NEW ENGLAND.

OVERALL...THE 00Z GLBL MDLS REMAIN IN VRY GOOD AGREEMENT THRU MOST

OF FRI. WE WILL STAY CLOSE TO THE 00Z GFS 10M WINDS THRU FRI AND

REDUCE WINDS BY ABOUT 5 PERCENT OR SO N OF THE GULF STREAM OR OVR

NT1 AND NRN NT2 WTRS WHICH WILL MAINTAIN BETTER CONTINUITY AND

BRING THE OFF WTRS INTO BETTER AGREEMENT WITH THE ADJACENT COASTAL

WTRS FCSTS FOR TODAY INTO FRI. THE LATEST SATELLITE...RADAR...AND

LIGHTNING DENSITY DATA INDICATES A FEW SCTD TSTMS MAINLY OFF THE

SE U.S. COAST MOVG NW. THIS ACTIVITY IS MAINLY ASSOC WITH WEAK LOW

PRES OVR THE GULF STATES AND FAR NE GULF OF MEXICO. AS THIS LOW

TRACKS W AWAY FROM THE WTRS THE SHWR AND TSTM ACTIVITY WILL LKLY

DIMINISH LTR TODAY INTO THU. ADTL SHWRS AND TSTMS MAY OCCUR NR THE

WEAKENING STNRY FRONT TODAY...AND AHEAD OF THE COLD FRONT OVR NRN

NT2 AND NT1 WTRS BY THU AND THU NITE INTO FRI. LOCALLY GUSTY WINDS

AND ROUGH SEAS ARE PSBL IN OR NR ANY OF THE HEAVIER SHWRS OR

TSTMS.



LONG TERM...THE 00Z GLBL MDLS ARE IN PRETTY GOOD AGREEMENT LATE

FRI THRU SUN NITE OVR THE WTRS. FROM AROUND 00Z SAT THRU SUN NITE

WE WILL TRANSITION THE OPC FCST MORE TOWARD THE 00Z ECMWF

SOLUTION AS IT HAS DECENT SUPPORT FROM THE 00Z UKMET AND KEEPS A

COLD FRONT A LITTLE FURTHER N OVR NT1 WTRS VERSES THE 00Z GFS

WHICH BRINGS THE FRONT A LITTLE FURTHER S. OVERALL...THERE WILL

NOT BE MAJOR CHANGES FOR THE EARLY AM PACKAGE FROM THE PREV OPC

FCST. WE WILL REDUCE WINDS SLIGHTLY (LESS THAN 5 PERCENT) OVR NT1

AND NRN NT2 WTRS TO MAINTAIN FCST CONTINUITY...AND TO MAINTAIN

SLIGHTLY LOWER WINDS OVR THE COOLER SHELF SSTS AS WAS NOTED IN

THE PREV FEW OPC FCSTS. NO HEADLINES ARE LKLY THRU SUN NITE OVR

THE WTRS...WITH FCST CONFDC LVLS REMAINING NR TO ABV AVERAGE.



SEAS...BOTH THE 00Z WAVE WATCH III AND 00Z ECMWF WAM MDLS APPEAR

TO HAVE INITIALIZED WELL OVR THE WTRS PER THE LATEST OBS AND

ALTIMETER PASSES. FOR TODAY THRU FRI WE WILL USE A 50-50 BLEND OF

THESE TWO WV MDLS IN ORDER TO LIMIT MINOR DIFFERENCES NOTED IN

THEIR OUTPUT...AND USE A 10-90 WW3-WAM MIX FOR FRI NITE INTO SUN

NITE TO MAINTAIN CONTINUITY FROM THE PREV FCSTS...AND TO FIT

NEARBY COASTAL WTRS AND TAFB FCSTS RATHER WELL...WITH A FEW MINOR

MANUAL ADJUSTMENTS. OVERALL...THERE WILL NOT BE MAJOR CHANGES IN

THE WV HEIGHTS FCST FOR THE EARLY AM PACKAGE.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER SCOVIL/MILLS. OCEAN PREDICTION CENTER.

