Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 300006
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
806 PM EDT MON JUN 29 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

UPDATE...

SUMMARY...NO ASCAT COVERAGE FOR THE CSTL/OFSHR WTRS SINCE ARND
1440Z THIS MRNG. 18Z NCEP SFC ANALYSIS SHOWS A WKNG FNTL BNDRY
EXTNDG NE TO SW ACROSS THE NRN/CNTRL NT2 WTRS...WITH HI PRES RDG S
AND SE OF THE FNT...AND A LOW PRES TROF EXTNDG ROUGHLY N TO S
ACROSS THE NEW ENG STATES.

MODELS...12Z/18Z GFS 30M SOLNS ALG WITH 12Z GEM SUGGEST MARG GALES
ARE PSBL OVER THE NE PART OF THE NT2 AREA FOR TUE NITE...WHILE 12Z
GFS 10M SOLN AND 12Z ECMWF/UKMET DO NOT HAVE ANY GALES OVER THE
OFSHR WTRS DURG THE FCST PRD. OTHW...THE MED RNG MDLS ARE IN GUD
AGREEMNT WITH THE OVERALL FLOW PATTERN THRU SAT NITE. THE MOST
REPRESENTATIVE SOLN ATTM SEEMS LIKE A BLEND OF THE 12Z GFS 30M/10M
SOLNS FOR THE WIND GRIDS. AM NOT PLANNING TO MAKE ANY SIGNIF
CHANGES TO THE CURRENT FCST TREND FOR NOW.

SEAS...WNA VERSION OF THE WAVEWATCH III MDL AND ECMWF WAM BOTH
INITIALIZED WELL ACROSS THE OFSHR WTRS. THERE ARE SOME MINOR DIFFS
BTWN THESE TWO MDLS FOR TUE AND TUE NITE...SO A 50/50 BLEND OF THE
WNA WW3/ECMWF WAM WILL BE USED TO POPULATE THE SEA HT GRIDS THRU
THE ENTIRE FCST PRD.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

THE LTST GOES WV IMGRY INDC A MID-LVL TROF OVR THE ERN CONUS
EXTENDING INTO THE WRN ATLC...AND A RDG OVR THE W ATLC CTRD NR
60W. THE ASSOC VIS IMGRY INDC A LOW PRES SYSMOVG INTO THE GULF OF
ST LAWRENCE...WITH A WKNG FRNTL BNDRY EXTENDING SW INTO NT2. THE
1440 UTC ASCAT WND RETRIEVALS INDCD A FEW GALES IN THE GULF OF ST
LAWRENCE...AND RECENT SFC RPRTS CONCUR. HOWEVER...THE ASCAT INDC
WNDS TO 30 KT ELSEWHERE NR THE FRNT...AND 12Z GFS WNDS ARE INIT OK
WHEN COMPARED WITH THE DATA. IN CONTRAST...THE 12Z ECMWF/UKMET
ARE INIT LOW...AND THE 12Z NAM/GEM ARE A LTL TOO HIGH...SO CRNT
DATA SPRTS GFS INITIALIZATION. HOWEVER...THE 12Z MDLS ALL INDC THE
SYS WL MOVE OFF TO THE NE TNGT...WHILE SLOWLY WKNG. WL FAVOR 12Z
GFS WITH THIS SYS...AS IT SEEMS TO HAVE A GOOD HANDLE ON IT. ALSO...CRNT
LGTNG DENSITY PROD INDC AN AREA OF TSTMS ACRS SRN NT2...SO WL
CONT MENTION IN NEXT PKG.

OTRW...12Z MDLS CONT TO AGREE WELL THRUT THE FCST PD ON OVERALL
PTTN...THOWITH SOME SLGT DIFFS...STARTING TMW. THE 12Z GFS INDC A
WK H5 VORT WL GENERATE A SFC LOW ALNG THE AFOREMENTIONED SFC
FRNT...STALLED OVR NT2. THE GFS INDC AN AREA OF GALES NR THE LOW
CTR...THO SEEMS SLGTLY OVRDONE WITH THE WK FRCG...ESP TAKING THE
INTNSTY ON THE VORT INTO CONSIDERATION. ALSO...12Z MDL SPRT FOR
GALES IS VRY WK AT BEST...AS THE 12Z NAM/GEM HAVE TRENDED
WKR...AND THE 12Z ECMWF/UKMET ONLY SHOWING ABT 25 KT AT BEST. AS A
RESULT...CONFDC IS LOW WITH GALES...SO WL CONT TO STAY BLO WRNG
CRITERIA IN THE FCST...AND KEEP WNDS AT 25 TO 30 KT RANGE FOR THE
HIGHEST CONDITIONS...MAINLY IN THE FRNTL FRCG IN THE LESS STABLE
ENVRMT OVR THE GLF STRM.

IN THE EXTENDED...THE 12Z GFS MAINTAINS THE MID LVL PTTN THRUT THE
PD...THO LESS AMPLIFIED LATE IN THE PD. THE MDLS ALL INDC A FEW
WK FRNTL LOWS WL MOVE ALNG THE BNDRY...AND THERE ARE A FEW TMG AND
INTSTY DIFFS WITH THEM ASSOC WITH THE WK H5 ENERGY. THE GFS HAD
BEEN INDCG GALES WITH THE THE LOW ON THU INTO FRI...BUT HAS SINCE
BACKED OFF IN THE 12Z RUN. THIS SEEMS MORE RSNBL...AS THE UPR
ENERGY WOULD NOT SUGGEST GALES. THE REST OF THE 12Z MDLS...EXCEPT
FOR THE GEM...CONCUR WITH WKR SOLN...SO CONFDC WITH GALES IN THU
IS LOW ATTM. OTRW THE LOC OF THE FRNTL BNDRY IS SOMEWHAT
CONSISTENT BTWN SOLNS...AND WITH THE TG SOMEWHAT SIMLR BTWN THE
GFS/ECWMF...WL STAY WITH THE 12Z GFS FOR THE RMNDR OF THE PD.

.SEAS...THE 12Z WAVEWATCH III AND 12Z ECMWF WAM MDLS HV BOTH
INITIALIZED THE CURRENT SEAS RSNBL WELL...THO SLGTLY UNDERDONE S
OF NOVA SCOTIA...SO WL BOOST SEAS INTIIALLY. OTRW...THE NWW3 LOOKS
SLIGHTLY OVERDONE TUE IN CONJUNCTIONO WITH THE GFS GALES...AND THE
ECWMF LOOKS A LTL BETTER...SO WL USE 50/50 CMPRMS. OTRW THE MDLS
AGREE FAIRLY WELL...SO WL USE A 50/50 CMPRMS THRUT THE FCST TO
CMPRMS MINOR DIFFS BTWN 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.


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