

314 

AGNT40 KWNM 051219

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

819 AM EDT FRI AUG 5 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

ROUGHLY E TO W ACROSS THE SRN NT2 WTRS...WITH A WEAK LOW CENTERED

NEAR 35N70W ALONG THE ERN EDGE OF THE NT2 AREA. LATEST AVAIL 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

1100Z SHOWS ISOLATED SHOWERS OVER THE SRN NT2 WTRS.



MAIN WEATHER FEATURES...THE STATIONARY FRONT WILL WEAKEN

TODAY...THEN DISSIPATE TONITE. A COLD FRONT WILL APPROACH THE

COAST FROM THE NW TONITE AND SAT...MOVE OFFSHORE LATE SAT AND SAT

NITE...CONTINUE SE OVER THE OFSHR WTRS SUN AND SUN NITE...THEN

STALL AND WEAKEN ACROSS THE SRN NT2 WTRS MON INTO TUE.



MODELS...THE UKMET LOOKS SIGNIF TOO FAST WITH A NRN STREAM COLD

FRONT FOR TUE AND TUE NITE...BUT OTHERWISE THE MED RNG MDLS ARE IN

VRY GUD OVERALL AGREEMNT ACROSS THE OFSHR WTRS DURING THE FCST

PERIOD. GFS HAS BEEN SHOWING VRY GUD RUN TO RUN CONSISTENCY OVER

THE PAST COUPLE OF DAYS. THE GFS 10M SOLN LOOKS REPRESENTATIVE

ENUF TO BE USED FOR THE WIND GRIDS THRU THE ENTIRE FCST PERIOD. AM

NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE FCST TREND OR THE

GRIDS.



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

WELL OVER THE OFSHR WTRS. THESE MDLS ARE IN GUD OVERALL AGREEMNT

THRU TUE NITE...BUT WITH A FEW MINOR DIFFS NOTED OVER THE OFSHR

WTRS AT VARIOUS TIMES...SO WILL USE A 50/50 BLEND OF THE WNA

WAVEWATCH III/ECMWF WAM THRU THE FCST PERIOD TO SMOOTH OUT THESE

DIFFS.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION... 



AN 01Z METOP-A ASCAT OVERPASS RETURNED S 20 KT WINDS ACROSS THE 

WRN GULF OF MAINE. LAST EVENINGS PASSES MISSED AREAS IMMEDIATELY 

SURROUNDING SURFACE LOW NEAR THE ERN EXTENT OF NT2 WATERS WHERE 

THERE MAY ALSO HAVE BEEN WINDS TO 20 KT. ELSEWHERE ACROSS 

NT1/NT2 WATERS WINDS WERE 15 KT OR LESS. THE 00Z MODELS WERE ALL 

INITIALIZED ABOUT 5 KT LIGHTER WITH WINDS ACROSS THE GULF OF 

MAINE. OTHERWISE 00Z GUIDANCE IS IN EXCELLENT AGREEMENT ACROSS 

THE W ATLC FOR THE NEXT SEVERAL DAYS. AS THE SURFACE LOW 

MENTIONED ABOVE CONTINUES TO TRACK EASTWARD...THE STATIONARY 

FRONT EXTENDING SW FROM THE LOW ACROSS THE NT2 WATERS WILL BEGIN 

TO LIFT N AS A WEAK WARM FRONT TODAY BEFORE DISSIPATING TONIGHT. 

ALSO OVER THE NEXT 24 HOURS THE E TO W ORIENTED HIGH PRES RIDGE 

ACROSS THE NT1 WATERS WILL WEAKEN AND SHIFT E OF THE WATERS. 

THEN WITH THIS WEEKENDS COLD FRONT THE 00Z ECMWF/NAM ARE 

SLIGHTLY SLOWER THAN THE 00Z GFS/UKMET/CMC BUT MODELS ALL AGREE 

THAT WINDS SE OF THE FRONT SHOULD INCREASE TO 20 OR 25 KT MAINLY 

OVER WARMER GULF STREAM WATERS SAT THROUGH SUN. WITH THE 00Z GFS 

BEING VERY CONSISTENT WITH ITS PAST FEW RUNS...WILL NOT BE 

MAKING ANY CHANGES TO THE PREVIOUS OPC OFFICIAL GRIDS THROUGH 

THE WEEKEND.     

00Z GFS/ECMWF/UKMET THEN ALL INDICATE THAT THE WEAKENING COLD 

FRONT SHOULD STALL NEAR CAPE LOOKOUT BY EARLY MON. THE 

STATIONARY FRONT SHOULD PERSIST AT LEAST THROUGH TUE NIGHT AS 

HIGH PRES PASSES E ACROSS THE NT1 WATERS. AGAIN WITH THE GFS 

HAVING SUCH GOOD RUN TO RUN CONSISTENCY AND BEING WELL SUPPORTED 

BY 00Z ECMWF/UKMET SEE NO REASON TO MAKE ANY SIGNIFICANT CHANGES 

TO PREVIOUS OPC GRIDS. 



THE 00Z WAVEWATCH III AND TEH 00Z ECMWF WAM ARE BOTH WELL 

INITIALIZED WITH THE W ATLC WAVE HEIGHTS THIS MORNING. DUE TO 

SOME VERY MINOR NEAR TERM DIFFERENCES BETWEEN PREVIOUS GRIDS AND 

00Z WW3/ECMWF WAM PLAN TO BLEND IN 50 PERCENT OF 00Z ECMWF WAM 

INTO PREVIOUS WAVE HEIGHT GRIDS. 



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER SCOVIL/CLARK. OCEAN PREDICTION CENTER.

