Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 050025
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
825 PM EDT SAT JUL 4 2015

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

UPDATE...NCEP 18Z SFC ANALYSIS SHOWS A WARM FNT EXTDNG NE TO SW
ACROSS THE NRN NT2 WTRS...WITH A LOW PRES CNTR ALG THE FNTL BNDRY
NEAR ZONE 915. A HI PRES RDG EXTNDS E TO W ACROSS BERMUDA AND
TOWARDS THE NT2 AREA. THE WARM FNT AND THE RDG ARE INTERACTING TO
PRODUCE SW FLOW ACROSS THE NT2 WTRS THIS EVNG. LATEST ASCAT PASSES
AT ARND 14Z TODAY WERE SHOWING SW WINDS TO 25 KT IN THE GULF
STREAM OFF THE NORTH CAROLINA COAST. LIGHTNING DENSITY PRODUCT
DATA AT 23Z INDICATES BANDS OF SCT SHOWERS/TSTMS ACROSS THE NRN
AND CNTRL NT2 WTRS IN THE SW FLOW.

MODELS...ASIDE FROM THE NAM/GEM MDLS WHICH HAVE GALES FOR THIS
EVNG AND TONITE...THE MED RNG MDLS ARE SHOWING MAX WINDS OF ONLY
25 TO 30 KT...SO AM NOT PLANNING TO INTRODUCE ANY GALE WRNGS ATTM.
THE MED RNG MDLS ARE IN GUD OVERALL AGREEMNT ACROSS THE OFSHR WTRS
DURG THE FCST PRD...EXCEPT THERE ARE SOME TIMING DIFFS WITH A WEAK
COLD FNT MOVG SE OVER THE NT1 AREA WED NITE THRU THU NITE. ALSO
THE MDLS SEEM TO BE AGREED THAT THERE WILL BE A WEAK LOW OR LOWS
TRACKING NE ALG THE FRONT...BUT THERE ARE TIMING DIFFS WITH THE
LOW AS WELL. THE LAST FEW RUNS OF THE GFS HV SHOWN VRY GUD
CONSISTENCY...AND THE REPRESENTATIVE GFS 30M SOLN WILL BE USED FOR
THE WIND GRIDS. AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE
CURRENT FCST TREND.

SEAS...WNA VERSION OF THE WAVEWATCH III MDL WILL BE USED TO
POPULATE THE SEA HT GRIDS THRU THE ENTIRE FCST PRD...SINCE THE GFS
MDL IS BEING FAVORED AND THE WAVEWATCH MDL HAS VRY GUD SUPPORT
FROM THE ECMWF WAM.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

THE LTST GOES WV IMGRY INDC A TROF OVR THE GRT LAKES...MOVG E TWD
THE NEW ENGLAND COAST. THE MODIS RGB IMGRY INDC SHRTWV ENERGY ON
SE SIDE OF THE TROF...APRCHG THE MID ATLC AND NEW ENGLAND COAST N
OF THE VA CAPES. THE IR/VIS IMGRY INDC A FRNTL BNDRY ACRS
NT2...WITH A LOW OVR NRN NT2. THE 15Z ASCAT AND EARLIER 12Z RSCAT
WND RTRVLS INDC WNDS IN THE 25 TO 30 KT RNG IN THE UNSTABLE ENVRMT
OVR THE GLF STRM...AHD OF THE FRNT. CRNT SFC RPRTS OVR THE OFSHR
WTRS INDC WINDS UP TO 30 KT AS WELL OVR THE OFSHR WTRS...AND THE
12Z GFS/ECMWF/UKMET ALL INDC 30 KT AT 18Z. THE 12Z NAM/GEM LOOK A
LTL TOO...WITH GALES OVR NT2. THE MDLS ALL AGREE WELL ON THE TMG
OF THE SHRTWV MOVG THRU THE W ATLC TNGT...AND DVLPG THE SFC LOW
THRU THE AREA WHILE MOVG TO THE NE WHILE PULLING THE ASSOC SFC
BNDRY WITH IT. THE GFS INDC FAIRLY STG FRCG NR THE FRNT...AND INDC
GALES WL DVLP WITH THIS SYS...E OF THE OFSHR WTRS. ATTM CONFDC IS
NOT HIGH ENUF TO INTRDUCE GALES IN THE OFSHR WTRS...SO WL START
OFF AT 30 KT WITH THIS SYS. ALSO...THE LGTNG DENSITY PROD INDC A
FEW SHOWERS AND TSTMS ALNG THE BNDRY...SO PLANNING ON KEEPING PREV
MENTION IN THE NEXT PKG.

OTRW...THE 12Z MDLS RMN IN RSNBLY GUD AGRMT IN THE SHORT
TERM...AND ALL INDC A RDG BLDS OVR THE AREA TUE AFTER THE UPR TROF
MOVES E OF THE RGN. THE BIGGEST FCST PRBLM CONT ON WED...WITH THE
12Z GFS RMNG ABT 6 HOURS FASTER WITH THE PRGRSN OF THE NEXT FRNTL
SYS THRU THE W ATLC. THE 12Z ECMWF/UKMET/GEM ARE ALL SLOWER...AND
AGREE FAIRLY WELL WITH EACH....SO ATTM FAVORING THE TMG OF THE
NON NCEP MDLS. WL STICK WITH 12Z GFS FOR GRIDS...BUT WL USE A TIME
SHIFT TO MATCH TMG OF GENL MDL CONSENSUS.

 SEAS...THE 12Z NWW3 AND ECWMF WAM ARE INIT OK IN THE W
ATLC...THO SLGTLY LOW INVOF OF THE LOW OVR NT2. THE MDLS AGREE
FAIRLY WELL THRUT THE PD...THO AFOREMENTIONED TMG DIFFS ON WED
CAUSE DIFFS IN WV HGTS BTWN THE TWO SOLNS. AS A RESULT...PLANNING
ON USING A TIME SHIFT TO MATCH WV GUID...SMLR TO WHAT WL BE USED
FOR WX GUID.

.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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