Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 060658
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
258 AM EDT FRI MAY 6 2016

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

OVER THE SHORT TERM...AS ALL OF THE 00Z MDLS FCST THE STRONG SFC
LOW NOW JUST SW OF NOVA SCOTIA TO CONT TO MOVE OFF TO THE NE
EXPECT ANY ASCD GALE FORCE WINDS ACRS THE OUTERMOST NT1 AND NE
MOST NT2 WTRS TO DMNSH TO WELL BELOW GALE FORCE BY THE START OF
THE TODAY FCST PERIOD.

ELSWHR THE 00Z MDLS SHARE SMLR SOLUTIONS FOR THE SFC LOW NOW OFF
THE MID ATLC COAST TO ROTATE NW TO THE VCNTY OF THE DELMARVA
PENINSULA LATER TODAY...THEN CONT TO DRIFT INLAND TONITE AND
WEAKEN AS IT BCMS VERTICALLY STACKED WITH ITS ASCD CLOSED UPR
LOW...WHICH WL ALSO INDUCE ANOTHER WEAK SFC LOW TO DVLP OFF THE
NRN MID ATLC COAST. THEN SAT AS THE UPR LOW IS FCST TO WEAKEN THE
MDLS FCST BOTH SFC LOWS TO DSIPT. THE BIGGEST SHORT TERM FCST
PROBLEM IS HOW STRONG WL THE ENELY GRADIENT BCM OFF THE NRN MID
ATLC COAST TODAY AS THE SFC LOW TRACKS NW AND ITS ASCD OCCLUDED
FRONT BOWES NWD. WITH EARLIER JASON ALTIMETER PASSES SHOWING SOLID
25-30 KT WINDS ALREADY IN THIS GRADIENT...ONLY A SLIGHT TIGHTENING
OF THIS GRADIENT WL RESULT IN GALES DVLPG. THE PREV OFSHR FCST
PACKAGE FCSTD A BRIEF PERIOD OF GALES TO DVLP THIS AFTERNOON IN
THE NW PORTION OF NT2 ZONE ANZ820 AND THE W PORTION OF NT1 ZONE
ANZ815. WITH THE 00Z NAM/GFS FCSTG NR GALE FORCE 30M BL WINDS IN
THIS GRADIENT (AND THE USUALLY CONSERVATIVE 00Z ECMWF FCSTG SOLID
25-30 KT BL WINDS)...WL GO AHEAD AND MAINTAIN FCST CONTINUITY AND
LEAVE THESE BRIEF GALE WRNGS IN PLACE. THEREFORE WL POPULATE OUR
FCST WIND GRIDS WITH THE 00Z GFS 30M BL WINDS FOR TODAY INTO
TONITE...WITH SM ADDITIONAL EDITS IN DEFERENCE TO THE 00Z
NAM/ECMWF. THEN AS THE SFC LOWS ARE FCST TO DSIPT SAT...FLWD BY
THE 00Z MDLS ALL FCSTG A STRENGTHENING SWLY GRADIENT TO DVLP SAT
NITE NR THE SRN MID ATLC COAST IN ADVANCE OF THE NEXT APRCHG COLD
FRONT...WL TRANSITION TO POPULATING WITH THE WEAKER 00Z GFS 10M BL
WINDS FOR LATE TONITE THRU SAT NITE. SO AS A RESULT ANTICIPATE
MAKING ONLY MINOR SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...THE 00Z MDLS SHARE SMLR FCST TIMING FOR THE
COLD FRONT TO SWEEP OFSHR SUN/SUN NITE. PER THE 00Z GEFS MEAN
SUSPECT THAT THE 00Z GFS IS LKLY SLIGHTLY TOO FAST WITH ITS COLD
FROPA...WHICH IS ALSO EVIDENCED BY THE TIMING OF OTHER SLIGHTLY
SLOWER 00Z GLOBAL MDLS. IN RGRDS TO THE FCST GRADIENTS ASCD WITH
THIS FROPA...THE 00Z GFS RMNS CONSISTENT VS ITS PREV RESPECTIVE
RUNS IN FCSTG A STRONGER ATTENDANT SFC LOW TO PASS N OF THE AREA
WHICH RESULTS IN STRONGER GRADIENTS THAN FCST BY THE OTHER 00Z
GLOBAL MDLS (THO THE 00Z GEM IS CLOSEST TO THE 00Z GFS) WITH GALE
FORCE ASCD BL WINDS FCST TO DVLP ACRS THE NT1 AND NRN NT2 WTRS.
WITH THE GEFS MEAN ALSO INDICATING THAT THE 00Z GFS ATTENDANT SFC
LOW IS LKLY TOO STRONG...WULD FAVOR A COMPROMISE 00Z UKMET/ECMWF
SOLUTION INSTEAD FOR THIS FROPA. THEREFORE...AS WAS DONE
PREVLY...WL TRANSITION TO POPULATING WITH THE 00Z ECMWF BL WINDS
SUN THRU MON NITE...BOOSTED UP 10-15 PERCENT ON AVERAGE IN
DEFERENCE TO THE SMWHT STRONGER 00Z UKMET POSTFRONTAL GRADIENT.

THEN FURTHER OUT IN THE LONG RANGE...TUE/TUE NITE...THE 00Z GFS
NOW FCSTS A MR SIG FRONTAL WAVE TO MOV OFSHR NR 40N WITH THE
WSWLY GRADIENT TO ITS S STRENGTHENING TO MARGINAL GALE FORCE TUE
NITE. WITH LITTLE SUPPORT FROM THE 00Z GEFS MEAN...BELIEVE THE 00Z
GFS IS LKLY TOO PROGRESSIVE WITH THIS FRONTAL WAVE AND WULD
INSTEAD FAVOR THE LESS 00Z GEM/ECMWF SOLUTIONS WHICH ARE ALSO MR
IN LINE WITH THE LATEST WPC MEDIUM RANGE GUIDANCE. THEREFORE WL
POPULATE WITH THE 00Z ECMWF BL WINDS FOR TUE/TUE NITE.

.SEAS...THE SLIGHTLY HIGHER 00Z ECMWF WAM HAS INITIALIZED
SLIGHTLY BETTER THAN THE 00Z WAVEWATCH III...BUT BY THE START OF
THE TODAY FCST PERIOD THE DIFFS BTWN THE TWO MDLS BCM MINIMAL.
THEREFORE WL POPULATE OUR FCST WAVE GRIDS WITH A 50/50 BLEND OF
THE TWO MDLS FOR TODAY THRU SAT NITE. THEN SINCE THE 00Z ECMWF
SOLUTION WL BCM FAVORED...WL TRANSITION TO ALL 00Z ECMWF WAM FCST
SEAS FOR SUN THRU TUE NIGHT.

.EXTRATROPICAL STORM SURGE GUIDANCE...IN THE WNWLY POSTFRONTAL
GRADIENT FCST TO DVLP SUN AND PERSIST INTO MON NITE...THE 00Z
ESTOFS CONTS TO FCST A SLIGHTLY MR SIG NEGATIVE SURGE THAN THE 00Z
ETSS. SINCE THE OOZ GFS IS LKLY OVERFCSTG THE STRENGTH OF THIS
GRADIENT WULD FAVOR THE LOWER VALUES FCST BY THE 00Z ETSS.

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ815...SOUTH OF LONG ISLAND...
     GALE TODAY.

.NT2 MID ATLC WATERS...
.ANZ820...HUDSON CANYON TO BALTIMORE CANYON...
     GALE TODAY.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE POSSIBLE SUN NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE POSSIBLE SUN INTO SUN NIGHT.

$$

.FORECASTER VUKITS. OCEAN PREDICTION CENTER.



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