

116 

AGNT40 KWNM 131233

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

833 AM EDT SAT AUG 13 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 COLD FRONT EXTNDG E

TO W ACROSS THE NT1 WTRS AND RUNNING ALONG THE NRN EDGE OF THE

GEORGES BANK ZONES. OTHERWISE...THE ANALYIS INDICATES HI PRES

RIDGING OVER THE NT2 WTRS WITH ANOTHER RIDGE BUILDING SE INTO THE

GULF OF MAINE. LATEST AVAILABLE ASCAT HI-RES AND ASCAT PASSES FROM

LAST NITE SHOW WINDS TO 20 KT OVER MOST OF THE NT1 AND NRN NT2

WTRS...EXCEPT FOR 20 TO 25 KT WINDS IN THE FAR SE NT1 AND FAR NE

NT2 WTRS. OTHERWISE...ASCAT IS SHOWING LIGHT WINDS OF 15 KT OR

LESS ACROSS THE OFSHR WTRS. LIGHTNING DENSITY PRODUCT DATA AT

1100Z SHOWS SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SRN NT1

AND NRN NT2 WTRS.



MAIN WEATHER FEATURES...THE WEAK COLD FRONT OVER THE NT1 AREA WILL

BECOME STATIONARY ACROSS THE GULF OF MAINE TODAY...THEN LIFT NE AS

A WARM FRONT TONITE INTO SUN AS IT PASSES N OF THE NT1 AREA. A

WEAK LOW WILL MOVE SE TONITE AND SUN...PASSING JUST N OF THE NT1

WTRS SUN EVENING...THEN ACCELERATE OFF TO THE E SUN NITE AND MON.

THE LOW WILL PULL A COLD FRONT SE OVER THE NT1 AND NRN NT2 WTRS

SUN NITE AND MON. ANOTHER RIDGE WILL BUILD OVER THE NT1 WTRS LATE

MON AND MON NITE...THEN MOVE E ACROSS THE NT1 AREA TUE INTO TUE

NITE. ANOTHER LOW WILL PASS E OVER THE NRN NT1 WTRS LATE WED AND

WED NITE.



MODELS...THE MED RNG MDLS ARE IN VERY GOOD AGREEMNT ACROSS THE

OFSHR WTRS THRU TUE NITE. THE CONSENSUS OF THE MDLS IS CONTINUING

TO SHOW THAT A LOW WILL PASS E OVER THE NT1 AREA LATER WED AND WED

NITE...BUT THE MED RNG MDLS ARE STILL NOT IN GOOD AGREEMNT

REGARDING THE STRENGTH AND TIMING OF THIS LOW. ECMWF WILL BE USED

TO POPULATE THE WIND GRIDS FOR THE ENTIRE FCST PERIOD...MAINLY

BECAUSE IT LOOKS LIKE THE BEST MEDIAN MDL SOLN. AM NOT PLANNING TO

MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.



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

WELL OVER THE OFSHR/COASTAL WTRS VERSUS THE 09Z RA1 SEA STATE

ANALYSIS. IN ORDER TO BE CONSISTENT WITH THE PREFERRED ECMWF...THE

ECMWF WAM WILL BE USED FOR THE WAVE HT GRIDS FOR THE ENTIRE FCST

PERIOD.



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION...



THE 00Z SFC ANALYSIS INDICATED A STATIONARY FRONT OVER THE GULF OF

MAINE...WITH HIGH PRES RIDGE COVERING THE REMAINDER OF AREA. AN

ASCAT PASS FROM LATE FRI EVENING INDICATED THE STRONGEST WINDS IN

THE 25 TO 30 KT RANGE JUST TO THE E OF THE GEORGES BACK OFFSHORE

WATERS. OVER THE OFFSHORE WATERS...WINDS WERE IN THE 10 TO 20 KT.

RANGE. SATELLITE IMAGERY AND LIGHTNING DATA INDICATE THE TSTMS

OVER THE GULF OF MAINE HAD WEAKENED CONSIDERABLY WITH NO STRIKES

NOTED AS OF 0515Z.



THE 00Z MODELS ARE IN VERY GOOD AGREEMENT DURING MOST OF THE FCST

PERIOD...HOWEVER THERE CONTINUE TO BE SOME SUBTLE TIMING

DIFFERENCES ON DAY 5. THE MODELS ARE ALL IN VERY GOOD AGREEMENT

INDICATING LOW PRES PASSING N OF THE GULF OF MAINE WATERS TONIGHT

AND SUN...THEN MOVING E OF THE OFFSHORE WATERS SUN NIGHT. THE MAIN

DIFFERENCES CONTINUE TO BE WED/WED NIGHT AS GFS REMAINS SLOWER

WITH LOW PASSING ACROSS NE U.S. COMPARED TO THE OTHER MODELS. THE

ECMWF CONTINUES TO LOOK LIKE A DECENT COMPROMISE...AND WILL LIKELY

NOT BE MAKING ANY DRASTIC CHANGES TO EXISTING GRIDS WHICH WAS

BASED ON 12Z ECMWF WINDS. 



.SEAS...THE 03Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS

CONTINUE TO MATCH UP WELL WITH THE MWW3/ECMWF WAM. SIMILAR TO

WINDS...DO NOT PLAN ON MAKING ANY MAJOR CHANGES TO SEAS PENDING

THE 00Z ECMWF.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER SCOVIL/KOSIER. OCEAN PREDICTION CENTER.

