

037 

AGNT40 KWNM 200059

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

859 PM EDT FRI AUG 19 2016



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

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



GOES IR IMGRY INDC A FRONTAL BNDRY OVR C NT2...AND THE LGTNG

DENSITY PROD INDC SHOWERS AND TSTMS ALONG THE FRONT. THE PREV FCST

HAD MENTION IN THE LAST FCST...SO ATTM PLANNING ON MAINTAINING IT

IN THE UPDATE PKG. THE 18Z/12Z GFS/NAM AND 12Z ECMWF/UKMET/GEM ALL

AGREE WITH KEEPING A WK FRNTL BNDRY IN C NT2 INTO SUN...WHICH SHUD

ACT AS A FOCUS FOR CONVECTION IN THE MRNGLLY UNSTABLE ENVIRONMENT

NEAR THE GULF STREAM. THE 21Z SREF MDL INDC CONVECTIVE ACTIVITY IS

LIKELY ALONG THE FRONT...SO PLANNING ON HAVING SHOWERS AND TSTMS

THRU AT LEAST THE FIRST 4 PERIODS IN NT2. IN ADDITION...THE

EARLIER ASCAT WINDS FM 15Z INDC 20 KT AHEAD OF THE FRONT.

HOWEVER...THE PASS IS FAIRLY OLD...AND CRNT SFC RPRTS INDC NO MORE

THAN 15 KT AHD OF THE FRONT. THE PREV FCST STARTED OUT WITH 15

KT...WHICH SEEMS ABT RIGHT...AND IS IN LINE WITH THE 12Z/18Z MDL

GUID...SO WL KEEP AT THE INTNSTY FOR THE UPDATE PKG. THE MDLS ALL

INDC THAT THE FRONT WL RETURN N SUN INTO SUN NGT...AND AGREE WELL

ON THE TMG AND INTNSTY. THE PREV FCST FAVORED THE 12Z GFS FOR

THUIS FEATURE...SO PLANNING ON CONTG ALONG THOSE LINES IN THE

UPDATE PKG.



OTRW...THE MDLS ALL INDC ANOTHER FRONT WL MOV INTO THE W ATLC SUN

NGT INTO MON. EARLIER RUNS OF THE ECWMF HAD WINDS UP TO 25 KT IN

THE S FLOW OVR NT1 AHD OF THE FRONT...AND THE GFS HAD BEEN

CONSISTENT WITH 20 KT. THE ECWMF HAS TRENDED WKR...AND NOW AGREES

WELL WITH THE GFS INTNSTY OF THE WINDS OVR THE GULF OF MAINE. THE

MDLS ALL AGREE VRY WELL NOW ON THE TMG OF THE FRONT...AND WITH THE

INTNSTY OF THE WINDS IN THE CAA....WITH MAINLY 20 KT MAX. THE PREV

FCST STAYED NR THE 12Z GFS FOR THE PREV FCST...AND WITH THE REST

OF THE 12Z MDLS AND 18Z GFS AGREEING WITH THE PREV FCST...NOT

PLANNING ON MKG ANY SIG CHANGES IN THE UPDATE PKG.



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

PREVIOUS DISCUSSION...



SUMMARY...12Z NCEP SFC ANALYSIS SHOWS A WEAK LOW CENTERED JUST E

OF THE NRN NT2 WTRS...WITH AN ASSOCD TROF EXTNDG SW FROM THE LOW

ACROSS THE CENTRAL NT2 WTRS TO THE CAPE HATTERAS AREA. THE SFC

ANALYSIS ALSO INDICATES A COLD FRONT MOVING S OVER THE GEORGES

BANK ZONES. LATEST AVAILABLE ASCAT AND ASCAT HI-RES PASSES FROM

THIS MORNING SHOW AREAS OF WINDS TO 20 KT IN SW FLOW OVER THE

CENTRAL AND SRN NT2 WTRS...BUT OTHERWISE INDICATE LIGHT WINDS OF

15 KT OR LESS. LIGHTNING DENSITY PRODUCT DATA AT 1840Z SHOWS

AREAS OF ISOLATED SHOWERS AND TSTMS OVER THE NRN AND CENTRAL NT2

WTRS...AND SCATTERED SHOWERS AND TSTMS ACROSS THE INNER ZONES OF

THE SRN NT2 WTRS.



MAIN WEATHER FEATURES...THE COLD FRONT WILL MOVE SE OVER THE NRN

AND CENTRAL NT2 WTRS TONITE...STALL ACROSS THE CENTRAL NT2 WTRS

SAT...THEN LIFT N AS A WARM FRONT SAT NITE THRU SUN NITE. ANOTHER

COLD FRONT WILL APPROACH THE COAST FROM THE NW SUN...MOVE OFSHR

SUN NITE...SWEEP SE OVER THE OFSHR WTRS MON INTO MON NITE....THEN

STALL NE TO SW ACROSS THE WTRS N AND W OF BERMUDA TUE INTO WED

NITE.



MODELS...THE 12Z MED RNG MDLS ARE IN VERY GUD OVERALL AGREEMNT

ACROSS THE OFSHR WTRS DURING THE FCST PERIOD. THE 12Z GFS 10M

SOLN LOOKS REPRESENTATIVE ENUF TO BE USED FOR WIND GRIDS THRU THE

ENTIRE FCST PERIOD. AM NOT PLANNING TO MAKE ANY SIGNIFICANT

CHANGES TO THE CURRENT FCST TREND.



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

INITIALIZED WELL OVER THE OFSHR WTRS...AND THESE MDLS ARE IN GUD

AGREEMNT THRU THE FCST PERIOD WITH ONLY RELATIVELY MINOR

DIFFERENCES NOTED AT VARIOUS TIMES. WILL USE A 50/50 BLEND OF THE

12Z WNA WAVEWATCH III/ECMWF WAM THRU THE ENTIRE FCST PERIOD TO

SMOOTH OUT THE DIFFERENCES.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KELLS/SCOVIL. OCEAN PREDICTION CENTER.

