Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 210052
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
852 PM EDT SAT SEP 20 2014

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

A LOW PRES CENTER OVER THE FAR SRN NT2 WTRS HAS MAX ASCD WINDS
PRIMARILY IN THE 20-30 KT RANGE S OF HAT CNYN. MAX ASCD SEAS ARE
IN THE 8-12 FT RANGE...HIGHEST IN THE COUNTERFLOW AGAINST THE GULF
STREAM W OF THE LOW...WHICH ARE RUNNING SVRL FT HIGHER THAN FCST
BY THE 18Z WAVEWATCH III AND 12Z ECMWF WAM MDLS.

OVER THE SHORT TERM...THE LATEST MDLS GNRLY AGREE THAT THE SFC LOW
WL TRACK SLOWLY NE OFF THE SE COAST TONITE...RACE NE INTO THE SE
NT1 WTRS BY LATE SUN...THEN CONT OFF TO THE NE SUN NITE WHL
PULLING A TRAILING COLD FRONT SE OF THE OFSHR WTRS BY EARLY MON.
WITH THE 12Z GEM/UKMET FCSTG THE STRONGEST LOW AND THE 12Z ECMWF
THE WEAKEST...THE 12Z/18Z GFS SOLUTION LOOKS LIKE A RSNBL
COMPROMISE SOLUTION FOR NOW. THEREFORE WL CONT TO USE THE PREVLY
POPULATED 12Z GFS 10M WINDS FOR THIS SYSTEM WITH SM FURTHER MINOR EDITS
MADE IN DEFERENCE TO THE 12Z ECMWF. SO WL BE MAKING SM MINOR CHNGS
TO THE PREVLY FCSTD GALE WRNGS FOR OUTER WTRS IN THE SLY GRADIENT
E OF THIS SYSTEM AND ITS FRONT.

IN THE LONG RANGE...THE LATEST GLOBAL MDLS GNRLY AGREE THAT STRONG
HIGH PRES WL BUILD IN FM THE W AND NW TUE/TUE NITE...MOVE INTO THE
NT1 WTRS WED/WED NITE...THEN MAINTAIN A RIDGE ACRS THE NT1 WTRS
THU/THU NITE CAUSING A MOD STRONG (PRIMARILY IN THE 15-25 KT
RANGE) ENELY GRADIENT TO ITS S ACRS THE NT2 WTRS. BLV THE 12Z
ECMWF IS FCSTG A SLIGHTLY TOO WEAK GRADIENT WHL THE 12Z GEM IS TOO
STRONG. THEREFORE PREFER A LONG RANGE SOLUTION CLOSEST TO THE
12Z/18Z GFS AND 12Z UKMET FOR THIS GRADIENT. SO FOR NOW WL CONT TO
USE THE PREVLY POPULATED 12Z GFS 10M BL WINDS FOR THE LONG RANGE
THRU THU NITE WITH SM MINOR TWEAKS.


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

SUMMARY...LIGHTNING DATA PRODUCT SHOWS AREAS OF ISOLD/SCTRD SHWRS
AND TSTMS OVER THE NT2 ZONES THIS AFTN. LATEST HI-RES ASCAT PASS
AT 1425Z THIS MRNG SHOWED A SWATH OF 25 TO 30 KT WINDS OVER THE
ERN PART OF THE NRN/CNTRL NT2 OFSHR WTRS...AND A SECOND SWATH OF
25 TO 30 KT WINDS OVER THE SRN NT2 OFSHR WTRS. A STG HI PRES RDG
WILL MOVE E ACROSS THE OFSHR WTRS THIS EVNG...THEN SHIFT E OF THE
AREA TONIGHT INTO SUN. A DVLPG LOW WILL FORM OFF THE SE CST EARLY
TONITE...PASS NE OVER THE NT2 AREA SUN...THEN MOVE OFF TO THE NE
SUN NITE INTO MON. THE LOW WILL PULL A COLD FRONT E ACROSS THE ERN
NT2 WTRS SUN INTO MON. ANOTHER COLD FRONT WILL APPROACH FROM THE
NW LATE SUN INTO SUN NIGHT...THEN MOVE SE ACROSS THE AREA MON INTO
MON NITE. ANOTHER STG RDG WILL BUILD IN FROM THE W AND NW TUE THRU
WED NITE...THEN MAINTAIN A RDG OVER THE OFSHR WTRS THU AND THU
NITE.

MODELS...12Z UKMET LOOKS MUCH TOO STG/DEEP WITH THE LOW MOVG NE
OVER THE OFSHR WTRS SUN INTO MON...AND ALSO DVLPS AN ANOMALOUS LOW
IN THE WTRS NEAR CAPE HATTERAS THU AND THU NITE. 12Z GEM DVLPS
ANOTHER ANOMALOUS LOW JUST E OF THE NT2 AREA TUE NITE...THEN
DRIVES THE LOW NWD ALG 70W WHILE DEEPENING IT. SO THE 12Z GEM AND
UKMET ARE NOT PREFERRED MDL SOLNS. OTHW...THE 12Z MED RNG MDLS
ARE IN GUD AGREEMNT THRU THE FCST PRD. WILL USE THE REPRESENTATIVE
12Z GFS 10M FOR THE WIND GRIDS.

.SEAS...BASED ON THE 18Z RA1 SEA HT ANALYSIS THE SEA HTS ARE IN
THE 2 TO 5 FT RNG OVER THE NT1 WTRS AND IN THE 5 TO 11 FT RNG IN
THE NT2 AREA. THE 12Z MULTIGRID WW3 MDL INITIALIZED WELL VERSUS
THE BUOY OBS...AND HAS GUD SUPPORT OVERALL FROM THE 12Z ECMWF WAM
THRU THE FCST PRD...SO WILL USE 12Z MWW3 GUIDANCE FOR THE WAVE HT
GRIDS.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE SUN INTO SUN NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE SUN NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE SUN NIGHT.
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...
     GALE SUN INTO SUN NIGHT.
.ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR...
     GALE SUN.
.ANZ935...OUTER WATERS FROM CAPE FEAR TO 31N...
     GALE SUN.

$$

.FORECASTER VUKITS/SCOVIL. OCEAN PREDICTION CENTER.


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