

423 

AGNT40 KWNM 130105

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

905 PM 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.



NO CHANGES ARE PLANNED FOR THE EVENING UPDATE. SATELLITE IMAGERY

AND LIGHTNING DATA INDICATE A FEW STRIKES OVER FAR W GULF OF MAINE

WATERS AND NW PORTION OF GEORGES BANK ZONE...OTHERWISE REMAINDER

OF OFFSHORE ZONES FREE OF CONVECTION THIS EVENING. THE 18Z GFS WAS

SIMILAR TO THE PREVIOUS 12Z RUN...AND IS STILL A SLIGHT STRONGER 

OUTLIER SUN/SUN NIGHT...AND DO NOT PLAN ON ANY CHANGES TO EXISTING

WIND GRIDS WHICH WERE POPULATED WITH 12Z ECMWF. THE 00Z SEA STATE

ANALYSIS INDICATED THAT OBSERVED SEAS MATCHED UP WELL WITH THE

MWW3/ECMWF WAM FCST VALUES. 



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

PREVIOUS DISCUSSION...



SUMMARY...12Z 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 THIS MORNING SHOW AN AREA OF 20 TO 25 WINDS IN SW FLOW OVER

ZONES 900 AND 905 AROUND GEORGES BANK...WITH WINDS TO 20 KT IN

ZONE 805...AND LIGHT WINDS OF 15 KT OR LESS INDICATED ACROSS THE

REMAINER OF THE OFSHR WTRS. LIGHTNING DENSITY PRODUCT DATA AT

1840Z SHOWS A SMALL AREA OF SCATTERED SHOWERS OVER ZONE 920 IN THE

NRN NT2 WTRS...WITH NO OTHER ACTIVITY IN THE REST OF THE OFSHR

WTRS.



MAIN WEATHER FEATURES...A WEAK STATIONARY FRONT WILL PERSIST

ACROSS THE GULF OF MAINE THIS EVENING 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 SUN NITE INTO 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

NE OVER THE NT1 WTRS AS A WARM FRONT LATER TUE INTO WED. YET

ANOTHER LOW IS EXPECTED TO MOVE E ACROSS THE GULF OF MAINE LATE

WED AND WED NITE.



MODELS...THE 12Z GFS IS STRONGER THAN THE OTHER MED RNG MDLS WITH

THE LOW PASSING E OVER THE GULF OF MAINE SUN NITE INTO MON NITE

AND WITH ITS ASSOCD SW FLOW. THE CONSENSUS OF THE 12Z MED RNG MDLS

INDICATES THAT A LOW WILL MOVE E OR NE ACROSS THE NRN NT1 WTRS

WED AND WED NITE...BUT THE MDLS ARE NOT IN GUD AGREEMNT WITH THE

TIMING AND STRENGTH OF THE LOW. THE 12Z 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.



SEAS...BOTH THE 12Z WNA WAVEWATCH III MDL AND THE 12Z ECMWF WAM

INITIALIZED WELL OVER THE OFSHR WTRS...AND ARE IN GOOD AGREEMNT

THROUGH TUE NITE. SINCE THE 12Z ECMWF IS THE PREFERRED MDL SOLN

THRU WED NITE...IN ORDER TO BE CONSISTENT THE 12Z ECMWF WAM WILL

BE USED FOR THE WAVE HT GRIDS THRU THE ENTIRE FCST PERIOD.



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





.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KOSIER/SCOVIL. OCEAN PREDICTION CENTER.

