

713 

AGNT40 KWNM 020113

MIMATN



MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

913 PM EDT MON AUG 1 2016



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

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



GOES IR IMGRY AND LGTNG DENSITY PROD INDC AREA OF TSTMS ALONG

FRNTL BNDRY ACRS THE NT2 WATERS...MAINLY IN THE UNSTABLE

ENVIRONMENT OVER THE GULF STREAM. THE 18Z GFS INDC THE STATIC

STABILITY WL CONT TO DCRS AS THE WK CAA MOVES FURTHER S OVER THE

GULF STREAM...AND THE CONVECTION WL EXPAND ACRS C AND SRN NT2

ZONES. THE PREV FCST HAD SHOWERS AND TSTMS ACRS THE S PORTION...SO

PLANNING ON MAINTAINING THEM IN THE UPDATE PKG.



THE 18Z GFS HAS NOT CHANGED MUCH FM THE 12Z RUN...AND INDC A WK

SHORTWAVE TROF CRNTLY OVR THE WRN GREAT LAKES WL MOVE SE INTO THE

AREA...AND DVLP THE FRONTAL WAVE CRNTLY ALONG THE COAST...WHILE

MOVING E OF THE AREA. THE GFS AGREES SOMEWHAT WELL WITH THE REST

OF THE 12Z GUID. THE MODELS ALL INDC GALES WL DVLP NR THE LOW

CENTER E OF THE AREA...AND THE PREV FCST KEPT WINDS BLO GL FORCE

BY WED. THIS STILL LOOKS RSNBL...SO NOT PLANNING ON DIVERTING FM

PREV LINE OF THINKING.



THE BIGGEST FCST PROBLEM CONT IN THE EXTENDED PD...WITH A FRONTAL

WAVE ACRS THE NT2 WATERS. THE 12Z/18Z GFS INDC A VRY WK FRONTAL

WAVE...AND ON THE OTHER END OF THE SPECTRUM THE 12Z ECMWF DVLPS A

STG LOW. THE 12Z GEM/UKMET ARE SOMEWHERE IN THE MIDDLE...THO BOTH

ARE FAIRLY WK. THE PREV FCST FAVORED THE WKR SOLNS...NR THE 12Z

GFS. THIS LINES UP WITH THE WPC MED RANGE GUID...SO PLANNING ON

STAYING NR GFS FOR THE UPDATE PKG.



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

PREVIOUS DISCUSSION...



OVER THE SHORT TERM...THE NEW 12Z MDLS PRESENT NO MAJOR CHNGS FM

THEIR PREV RESPECTIVE RUNS. THE MDLS OVERALL REMAIN IN GOOD AGRMT

THAT THE STNRY FRONT NOW ACRS THE NRN NT2 WTRS WL REMAIN IN PLACE

TONITE INTO TUE WHL SVRL WEAK LOWS TRACK E ALONG THE FRONT. BY

LATE TUE/TUE NITE THE MDLS SHARE SMLR TIMING FOR THE FRONT TO PUSH

S AS A COLD FRONT INTO THE CNTRL NT2 WTRS AS A STRONGER SFC LOW ON

THE FRONT CROSSES THE OUTERMOST NRN NT2 WTRS. THEN WED/WED NITE

WITH SLIGHT POSITION DIFFERENCES...THE 12Z MDLS FCST THE FRONT TO

BCM QSTNRY W-E IN THE VCNTY OF 34N WITH PRHPS A WEAK FRONTAL WAVE

(PER THE 12Z GFS/ECMWF) MOVING OFF THE SE COAST WED NITE BUT WITH

ASCD GRADIENTS RMNG WEAK WITH LITE WINDS. SO WITH THE DIFFERENCES

IN THE 12Z MDLS FCST BL WINDS RMNG MINIMAL...SMLR TO THE PREV FCST

PACKAGE...PLAN ON POPULATING OUR FCST WIND GRIDS WITH THE

REPRESENTATIVE 12Z GFS 10M BL WINDS FOR TONITE THRU WED NITE WHICH

WL RESULT IN MINIMAL CHNGS TO THE PREV OFSHR FCSTS.



IN THE LONG RANGE...THE 12Z MDLS AGREE THAT THE FRONT WL REMAIN

QSTNRY ACRS THE SRN NT2 WTRS THU THRU FRI...THEN DSIPT FRI NITE

WITH SVRL WEAK ASCD SFC LOWS TRACKING E ALONG THE FRONT BUT WITH

WEAK ASCD GRADIENTS PERSISTING WITH LITE WINDS. BASED ON THE WEAK

UPR LEVEL SUPPORT FCSTD...WULD FAVOR THE WEAKER FRONTAL WAVES FCST

BY THE 12Z GFS VS THE STRONGER 12Z GEM/UKMET/ECMWF. THEREFORE WL

CONT TO POPULATE WITH THE 12Z GFS 10M BL WINDS ON THU THRU FRI.

FURTHER N BY LATE FRI THRU SAT THE 12Z GLOBAL TO VARYING DEGREES

CONT TO FCST A GRADLY STRENGTHENING SLY GRADIENT TO DVLP ACRS THE

NRN WTRS AS THE NEXT COLD FRONT APRCHS FM THE NW...THEN MOVES

OFSHR SAT NITE. FOR THE TIMING OF THIS FRONT WULD FAVOR THE SMLR

12Z GFS/ECMWF/GEFS MEAN SOLUTIONS...WHICH ON SAT NITE BCM LESS

PROGRESSIVE THAN THE 12Z GEM/UKMET AND IN BETTER AGRMT WITH THE

LATEST WPC MEDIUM RANGE GUIDANCE. BUT FOR THE FCST GRADIENTS ASCD

WITH THIS FRONT...WL FAVOR THE MR CONSISTENT 12Z GFS. SO WL CONT

TO POPULATE OUR FCST WIND GRIDS WITH THE 12Z GFS 10M BL WINDS FOR

FRI NITE THRU SAT NITE.



SEAS...OVERALL THE 12Z WAVEWATCH III AND 12Z ECMWF WAM HV BOTH

INITIALIZED THE CURRENT SEAS THRUT THE WTRS VERY WELL. WITH THIS

IN MIND AND SINCE THEIR ASCD 12Z GFS/ECMWF SOLUTIONS BEING

SMLR...AND WITH THEIR FCST DIFFERENCES GNRLY RMNG IN THE 1-2 FT

RANGE...WL POPULATE OUR FCST WAVE GRIDS WITH A 50/50 BLEND OF THE

12Z WAVEWATCH III AND 12Z ECMWF WAM MDLS TONITE THRU WED NITE.

THEN SINCE THE 12Z GFS WL BCM FAVORED...WL TRANSITION TO

POPULATING WITH ALL 12Z WAVEWATCH III FCST SEAS ON THU THRU SAT

NITE.



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



.WARNINGS...PRELIMINARY.



.NT1 NEW ENGLAND WATERS...

     NONE.



.NT2 MID ATLC WATERS...

     NONE.



$$



.FORECASTER KELLS/VUKITS. OCEAN PREDICTION CENTER.

