

743 

AGNT40 KWNM 030140

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

940 PM 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.



THE GOES IR IMGRY INDC DVLPG LOW PRES JUST E OF THE NE NT2

WATERS...WITH A FRONTAL BNDRY EXTENDING TO THE SW INTO THE CENTRAL

NT2 WATERS...THEN INLAND JUST N OF CAPE HATTERAS. CRNT SFC RPRTS

INDC WINDS UP TO 15 KT OR SO OVR NT2 IN THE SW FLOW AHD OF THE

FRONT...AND THE LGTNG DENSITY PROD INDC TSTMS IN THE UNSTABLE

ENVIRONMENT AHEAD OF IT...WITH THE FRONT ACTING AS A FOCUS FOR THE

CONVECTION. THE PREV FCST HAD TSTMS IN THE LAST FCST...SO

PLANNING ON KEEPING THEM IN THE UPDATE PKG. AS FAR AS THE WINDS

ARE CONCERNED...ASCAT FM 15Z IN C NT2 IN THE SW FLOW...THO THE

STGST GRAD HAS MOVED E OF THE AREA...WITH THE STGST SW

FLOW...WHICH IS SHOWN THROUGH THE CRNT SFC RPRTS. THE 18Z GFS

CONCURS...AND INDC THE STGST WINDS NR 65W. THE PREV FCST STARTED

OFF WITH ROUGHLY 20 KT IN THE OFSHR WTRS...WHICH AGREES WITH THE

BULK OF THE 12Z/18Z GUID...SO PLANNING ON STAYING AT THE INTNSTY

FOR EARLY TNGT.



THE MDLS GENLY AGREE IN THE SHORT TERM WITH TAKING THE

AFOREMENTIONED FRONTAL BNDRY S...AND STALLING IT ACRS THE C AND

SRN NT2 WTRS WED INTO WED NGT. THE BIGGEST FCST PROBLEM IS ON THE

DVLPMT OF A LOW NR CAPE HTRS ALONG THE FRONT. THE GFS/ECMWF/UKMET HAVE

BEEN INDCG WK DVLPMT...AND THE GEM HAS BEEN A BIT STGR WITH THE

LOW. THE ECMWF/UKMET DIFFER ON THE TRACK...AND TAKE THE WK FEATURE

FURTHER E...WHILE THE GFS IS SLOWER AND TAKES IT TO THE NE. THE

LOW DVLPS AS THE RESULT OF A WK H5 VORT MOVG ACRS THE FRONT...AS

INDC BY THE MDLS. AS EXPECTED...THE GEM IS A BIT STGR WITH THE MID

LEVEL FEATURE...AND IS THE OUTLIER SOLN. THE PREV FCST FAVORED

THE GFS SOLN...WHICH IS SOMEWHAT SPRTD BY THE 12Z ECMWF/UKMET...SO

PLANNING ON STAYING WITH IT SINCE THE 18Z GFS HAS NOT CHANGED

MUCH.



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

PREVIOUS DISCUSSION...



SUMMARY...12Z 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 THIS MORNING SHOW WINDS OF 25 TO

30 KT IN SW FLOW OVER THE CENTRAL NT2 WTRS...WITH 20 TO 25 KT

WINDS ACROSS THE OUTER ZONES OF THE NT2 WTRS BETWEEN 37N AND 32N.

LIGHTNING DENSITY PRODUCT DATA AT 1840Z SHOWS SCATTERED SHOWERS

AND TSTMS OVER THE CENTRAL NT2 WTRS...WITH ISOLATED SHOWERS AND

TSTMS ACROSS THE NRN NT2 WTRS E OF 1000 FATHOMS AND IN THE FAR SRN

NT2 WTRS E OF 77W.



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

WTRS THIS AFTERNOON...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 NE OVER THE NRN NT2 WTRS FRI

THRU SAT. ANOTHER COLD FRONT WILL APPROACH THE COAST SAT...MOVE

OFFSHORE LATE SAT INTO SAT NITE...THEN SWEEP SE OVER THE OFSHR

WTRS SUN AND SUN NITE.



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

OFSHR WTRS THRU THE FCST PERIOD...EXCEPT THE GEM/UKMET ARE A BIT

FASTER WITH THE COLD FRONT ON SUN AND SUN NITE. THE 12Z ECMWF/GFS

ARE IN VRY GUD AGREEMNT...THE GFS HAS CONTINUED TO SHOW VRY GUD

RUN TO RUN CONTINUITY AND HAS STRONG SUPPORT FROM THE LATEST WPC

MED RNG FCSTR GUIDANCE...SO 12Z GFS SOLN IS REPRESENTATIVE ENUF

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

USING THE 12Z GFS 30M SOLN OVER THE NT2 WTRS WHERE STRONGER SW

FLOW IS EXPECTED FOR MOST OF THE FCST PERIOD...BUT OTHERWISE OVER

THE NT1 AREA THE 12Z GFS 10M SOLN WILL BE USED GIVEN THE STABILITY

CONSIDERATIONS. 



SEAS...WNA VERSION OF THE 12Z WAVEWATCH III AND 12Z ECMWF WAM

BOTH INITIALIZED WELL OVER THE OFSHR WTRS. THE 12Z WNA WW3 AND 12Z 

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 THESE

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.

