Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 030209
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
1009 PM EDT THU JUL 2 2015

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

00Z NCEP SFC ANAL HAS A FNTL BNDRY ACRS THE SE NT1 WTRS TO NE NC
CONTAINING A FNTL WAVE OFF VA CAPES. A WEAKER FNTL BNDRY IS STNRY
ALONG OUTER NT2 WTRS AND APPRS MARKED BY SCT TSTMS. LTG DENSITY
PROD SHOWS CONVECTION MOST PREVALENT AND HEAVIER WITH FIRST BNDRY
OVR CAROLINAS AND WITH BOTH BNDRIES INVOF GLF STRM. ARE CARRYING
WX IN FORM OF SCT SHWRS AND TSTMS NRN AND CENTRAL NT2 WTRS AND
MAINLY SHWRS SRN NT1 WHERE LTG DENSITY SHOWS LTL ACTVTY.

LATEST MDLS APP WELL INITIALIZED AND PICK UP ON WEAK WAVE OFF
DELMARVA MOVG NE AND OFFSHORE...SLIDING NE NR 1000 FM AND A
SOMEWHAT STRONGER FNTL WAVE EXPECTED SAT ALSO IN MDLS. BIGGEST
THREAT FOR GALES IS WITH SECOND WAVE ON S SIDE WHERE 12Z
ECMWF/UKMET SHOW SOME 30 KT 10M WNDS DURING ITS PASSAGE BUT THE
USUALLY MORE ROBUST CNDN IS NOT THAT IMPRESSIVE AND GFS PEAKS AT
30 KT BUT FOR ITS HIGHER 30M WNDS WHICH APPR BEST REPRESENTATIVE
ALG/S OF GLF STRM. WITH NEW GFS RUN SHOWING LTLCHG AND WITH GOOD
OVERALL MDL AGRMT SEE NO NEED TO REPOPULATE WND GRIDS.

 SEAS...THE 18Z WNA WW3 AND 12Z ECMWF WAM BOTH INDICATE SEAS TO 10
FT OUTER NT2 WTRS ASCD WITH FIRST WAVE WITH SOME DIFFERENCES DVLPG
SAT WITH STRONGER FNTL WAVE WITH DIFFERENCES MAINLY OVR NT2 WTRS.
WITH 18Z GFS SHOWING LTLCHG IN SFC FCST THE CURRENTLY USED MDL
BLEND LOOKS RSNBL.
-----------------------------------------------------------------
PREVIOUS DISCUSSION...

THE CRNT GOES WV IMGRY INDC AN UPR RDG NR 50W AND AN UPR LOW OVR
SE CANADA WITH A TROF EXTENDING TO S OVR THE NT1 WTRS. THE IR/VIS
IMGRY INDC A FRNTL BNDRY ACRS NT2...AND THE LGTNG DENSITY PROD
SHOWS CNVCTN ALNG THE BNDRY MAINLY OVR THE GULF STRM. THE ASCAT
FM 1340Z SHOWS THE LESS STABLE ENVMT OVR THE GLF STRM...WITH WIND
RTRVLS SHOWING GALES E OF THE OFSHR WTRS IN SW FLOW OVR IT...AND
A MARKED DCRS IN WND INTNSTY TO THE N OF IT. THE RSCAT PASS RM 12Z
MISSED THE HIGHEST AREAS OF WINDS...BUT DETECTED 30 KT ALNG THE
EDGES OF THE PASS. CRNT SFC RPRTS INDC WND TO 25 KT...BUT NONE ARE
NR THE HIGHEST WINDS INDCD BY ASCAT. THE 12Z GFS WNDS ARE INIT OK
WHEN COMPARED WITH THE CRNT DATA...BUT THE 12Z ECMWF/UKMET ARE
INIT A LTL LOW. THE 12Z GEM AND NAM ARE INIT OK OVR THE GLF
STRM...BUT THE NORMAL BIAS OF TOO HIGH WNDS N OF THE GLF STRM
APPEAR IN THE INITIALIZATION. WITH THE GFS INITIALIZED ABT THE
BEST...WL STAY CLOSE TO IT IN THE SHORT TERM.ALSO...WL MAINTAIN
MENTION OF TSTMS IN THE NEXT PKG WITH LGTNG DENSITY PROD INDCG
THEM.

THE 12Z MDLS AGREE FAIRLY WELL THRUT MOST OF THE FCST PD...AND
SLOWLY WKN THE UPR RDG NR 50W INTO MON...AS SEVL WK H5 VORT MAXES
MORE ENE THRU THE W ATLC. AT THE SFC...THE AFOREMENTIONED SFC FRNT
WL STALL OVR THE W ATLC...AS A CPL OF WK LOWS MOV E ALNG THE BNDRY
ASSOC WITH THE WK SRTWV ENERGY THAT MOVES THRU THE AREA. THE 12Z MDLS
DISAGREE SLGTLY ON THE TMG AND TRACK OF THE WAVES...BUT AGREE ON
THE OVERALL LOC AND INTSTY OF THE FRNT. THE 12Z GFS HAS BEEN A
BIT STGR WITH THE WNDS IN THE SW FLOW OF THE FRNT THAN THE
ECWMF/UKMET...BUT WKR THAN THE NAM/GEM...WHICH SHOW GALES IN SW
FLOW...N OF THE GLF STRM...AND SEEMS OVERDONE. ATTM FAVORING THE
GFS SOLNS...AS IT IS A DECENT CMPRMS BTWN THE WKR AND STGR SOLNS.
PLANNING ON USING THE 30M WNDS OVR THE GLF STRM...WHICH BRINGS THE
WNDS UP TO 30 KT ON A FEW OCCASIONS. WL ALSO USE THE 10M WNDS N OF
THE GLF STRM...WHICH SEEMS RSNBL ESP IN LIGHT OF THE CRNT
SCENARIO.

IN THE EXTENDED...THE 12Z MDLS ALL INDC THE UPR RDG WL WKN BY
MON...AS THE TROF SWINGS THRU THE W ATLC. THE 12Z GFS/GEM INDC A
WAVE WL MOVE ALONG THE PREV FRTNL BNDRY...AND AGREE FAIRLY WELL
ON THE TMG AND TRACK. THE 12Z ECMWF/UKMET KEEP THE LOW FURTHER
W...AND MAINTAIN THE RDG OVR THE OFSHR WTRS. ATTM UNCERTAINTY IS
HIGH ON THE TRACK...SO PLANNING ON STAYING WITH THE GFS...AS IT
HAS BEEN CONSISTENT.

.SEAS...THE 12Z NWW3 AND ECMWF WAM INDC SEAS UP TO ABT 10 FT OVR
THE OFSHR WTRS...AND AGREE SOMEWHAT WELL THRUT A MAJORITY OF THE
PD. PLANNING ON USING A 50/50 BLEND...AS A CMPRMS TO THE MINOR
DIFFS BTWN THE TWO SOLNS.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER BANCROFT/KELLS. OCEAN PREDICTION CENTER.


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