

502 

AGNT40 KWNM 021235

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

835 AM EDT TUE AUG 2 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 NRN NT2 WTRS...WITH A COUPLE OF WEAK

LOWS ALONG THE FRONTAL BOUNDARY. THE SFC ANALYSIS ALSO SHOWS WEAK

HI PRES RIDGING OVER THE NT1 AND SRN NT2 WTRS. LATEST AVAIL ASCAT

HI-RES AND RAPIDSCAT PASSES FROM LAST NITE SHOW WINDS TO 25 KT IN

SW FLOW OVER THE NRN AND CENTRAL NT2 WTRS...WITH MAINLY 15 TO 20

KT WINDS ACROSS THE REMAINING OFSHR WTRS. LIGHTNING DENSITY

PRODUCT DATA AT 1100Z SHOWS SCATTERED SHOWERS AND TSTMS OVER THE

NRN NT2 WTRS E OF 1000 FATHOMS...WITH A LARGER AREA OF SCATTERED

SHOWERS AND TSTMS ACROSS THE CENTRAL AND SRN NT2 WTRS N OF CAPE

FEAR.



MAIN WEATHER FEATURES...LOW PRES WILL MOVE E ACROSS THE NRN NT2

WTRS TODAY...PASS E OF THE NT2 AREA THIS EVENING...THEN MOVE OFF

TO THE NE TONITE AND WED WHILE STRENGTHENING AND PULLING A COLD

FRONT S OVER THE CENTRAL NT2 WTRS. A WEAK LOW IS EXPCTD TO FORM

NEAR THE NORTH CAROLINA COAST BETWEEN CAPE HATTERAS AND CAPE FEAR

ON THU OR THU NITE...THEN PASS SLOWLY NE OVER THE NRN NT2 WTRS

FRI THRU SAT. ANOTHER COLD FRONT WILL APPROACH THE COAST LATE

SAT...THEN MOVE OFFSHORE SAT NITE.



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

OFSHR WTRS THRU THE FCST PERIOD...WITH THE ECMWF/GFS IN VRY GUD

AGREEMNT. THE GFS 10M SOLN IS REPRESENTATIVE ENUF TO BE USED FOR

THE WIND GRIDS THRU THE ENTIRE FCST PERIOD...EXCEPT WILL BE USING

A 50/50 BLEND OF THE GFS 10M/30M SOLNS OVER THE GULF STREAM DUE TO

STRONGER SW FLOW EXPECTED THERE DURING MUCH OF THE FCST PERIOD. AM

NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.



SEAS...WNA VERSION OF WAVEWATCH III AND ECMWF WAM BOTH INITIALIZED

WELL OVER THE OFSHR WTRS. THE WNA WW3 AND ECMWF WAM ARE IN GUD

OVERALL AGREEMNT THRU THE FCST PERIOD...WITH ONLY A FEW MINOR

DIFFERENCES NOTED...SO WILL USE A 50/50 BLEND OF THE MODELS OVER

THE ENTIRE FCST PERIOD TO SMOOTH OUT THE DIFFERENCES. 



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



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

PREVIOUS DISCUSSION...



THE LTST GOES IR IMGRY AND LGTNG DENSITY PROD INDC AREA OF TSTMS

ALONG A FRNTL BNDRY ACRS THE NRN NT2 WATERS...MAINLY IN THE

UNSTABLE ENVIRONMENT OVER THE GULF STREAM. THE 00Z GFS INDC THE

STATIC STABILITY WL RMN FAIRLY LOW AS THE WK CAA MOVES SLOWLY S

OVER THE GULF STREAM...EXPANDING THE CONVECTION ACRS THE C AND

SRN NT2 ZONES. AS A RESULT...PLANNING ON HAVING MENTION OF SHOWERS

AND TSTMS IN NT2 IN THE NEXT PKG.



OTRW...THE 0240Z ASCAT WIND RETRIEVALS AND CRNT SFC RPRTS INDC UP

TO 25 KT IN NT2 IN SW FLOW...S OF THE AFOREMENTIONED FRONTAL

BNDRY. THE 00Z GFS 10M WINDS ARE INIT A LTL LOW S OF THE FRONTAL

BNDRY WHEN COMPARED WITH THE CRNT DATA...AND THE 30M GFS WINDS ARE

A LTL STG. THE 00Z ECMWF/UKMET ARW BOTH WKR...THO THE 00Z GEM

WINDS SEEM TO BE INIT OK. AS A RESULT...PLANNING ON STARTING OFF

WITH A BLEND OF THE 00Z GFS 10M/30M WINDS...WHICH SEEMS TO REFLECT

CRNT CONDITIONS FAIRLY WELL. 



THE GOES WV IMGRY INDC A WK SHORTWAVE TROF CRNTLY OVR THE NEW YORK

STATE...AND HEADING QUICKLY FOR THE OFSHR WTRS. THE 00Z MODELS

ALL INDC IT WL MOV OFSHR TDA AND DVLP WAVE ALONG THE FRONT CRNTLY

OVR NT2...THEN MOVE QUICLY E OF THE AREA. THE GFS AGREES FAIRLY

WELL WITH THE REST OF THE 00Z GUID...AND INDC IT WL DVLP AT LEAST

GALE FORCE WINDS E OF THE AREA BTWN 36 AND 60 HRS. THE GFS ALSO

INDC IT WL PULL THE FRONT THROUGH THE NT2 WATERS...MAINTAINING

MDTLY STG SW FLOW AHD OF IT. THE GFS 30M WINDS INDC 30 KT BY

THIS AFTN...WHICH SEEMS A LTL STG AT THIS PT...ESP WITH THE REST

OF THE 00Z MODELS IN 20 TO 25 KT RNG. THE 10M WINDS ALSO SEEM A

LTL WK...SO PLANNING CONTG THE 10M30M BLEND OF THE GFS OVR THE

GULF STREAM TO REFLECT THE SLIGHTLY HIGHER WINDS XPCTD. THE GFS IS

ALSO IN DECENT AGRMT WITH THE TMG OF THE FRONT WITH THE REST OF

THE 00Z MODELS...SO CONFDC IS FAIRLY HIGH WITH IT IN THE SHORT

TERM.



THE BIGGEST FCST PROBLEM IS IN THE EXTENDED PD...WITH A LOW THAT

DVLPS ALONG THE FRONT AS IT HANGS UP OVR SRN NT2 THU NGT INTO FRI.

THE GFS HAS BEEN THE WEAKEST SOLN WITH THE LOW...AND HAS

STRENGTHENED ONLY SLIGHTLY WITH THE 00Z RUN. THE 12Z ECMWF HAD

BEEN A STG OUTLIER...BUT THE 00Z RUN TRENDED WKR AND IS NOW FAIRLY

CLOSE TO THE 00Z GFS SOLN. THE 00Z UKMET/GEM ARE SLIGHTLY

STGR...AND A LTL FASTER. THE PREV FCST FAVORED THE GFS SOLN...AND

ATTM PREFERRING IT AS IT HAS BEEN CONSISTENT...AND IS NOW

SUPPORTED BY THE 00Z ECMWF SOLN. 



SEAS...THE 00Z WAVEWATCH III AND ECMWF WAM HV BOTH INITIALIZED

THE CURRENT SEAS THRUT THE WTRS VERY WELL...WITH SEAS ONLY UP TO

ABT 6 FT IN THE OFSHR WTRS...THO LOW A GALE FORCE LOW S OF

NEWFOUNDLAND AS A 03Z ALTIMETER PASS INDC 12 FT...OR 3 FT HIGHER

THAN THE GUID. THE 00Z WAVE MDLS AGREE FAIRLY WELL THRUT THE FCST

PD...AS THE ASSOC WX MDLS AGREE FAIRLY WELL. AS A

RESULT...PLANNING ON USING A 50/50 BLEND OF THE TWO...AS A

COMPROMISE TO THE MINOR DIFFS BTWN THE 2 SOLNS.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER SCOVIL/KELLS. OCEAN PREDICTION CENTER.

