Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 291347
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
947 AM EDT FRI MAY 29 2015

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

RAPIDSCAT PASSES FM ABT 0935Z AND 1110Z SHOW ANTICYCLONIC LIGHT
FLOW OVR CENTRAL NT2 AREA NWD INTO NT1 WTRS WITH HINT OF A WK FNTL
BNDRY/WSHFT IN GLF OF MAINE. STRONGER WNDS APPEAR E OF OFSHR WTRS
IN ELY FLOW AROUND N SIDE OF A LOW IN PRELIM ANAL NEAR 26N68W AT
12Z. SEAS AT 12Z ARE 6 FT OR LESS...HIGHEST IN SRN OUTER
WTRS...WI A FOOT OF 6 HR FCST OF WNA WW3.

LATEST MDLS ARE IN EXCELLENT AGRMT THRU MON NIGHT. WITH GFS
CONSISTENT IN THIS TIMEFRAME WITH 06Z RUN SHOWING LTLCHG...SEE NO
NEED TO REPOPULATE CURRENT WND GRIDS WHICH ARE BASED ON 00Z GFS
10M WNDS. FOR TUE AND TUE NIGHT MDL CONSISTENCY DECLINES WITH
NEWER RUNS OF MDLS SUCH AS ECMWF/UKMET AND CMC GLOBAL GEM SUDDENLY
BREAKING DOWN RDG ACRS NT1 WTRS TOO QUICKLY TUE AND TUE NIGHT
ALLOWING LOW PRES NT2 WTRS TO TURN N. 06Z GFS IS MORE LIKE OLD
28/12Z ECMWF IN MOVG LOW PRES ALG STALLED FNT E OF NRN NT2 WTRS
INSTEAD OF MOVG IT N OF 40N. WILL LEAVE EXTENDED GRIDS BASED ON
OLD ECMWF UNCHANGED...WHICH IS ALSO SIMILAR TO DAY 4/5 WPC PRELIM
GUIDANCE. MAX WINDS UP TO 25 OR 30 KT IN E TO NE FLOW BETWEEN THE
FRONT AND HIGH PRES BLDG IN FM THE N.

SEAS...CURRENT WAVE GRIDS BASED ON 00Z WNA WW3 INITIALIZE WI A
FOOT OF 12Z SEA STATE ANAL. NO CHANGES ARE ANTICIPATED TO FCST
BASED ON 00Z WNA WW3 THEN 28/12Z ECMWF WAM AFTER 12Z TUE.

....................................................................
PREVIOUS DISCUSSION...

RAPIDSCAT PASS JUST AFTR 03Z HAD RETURNED GOOD CVRG OVR THE
MAJORITY OF THE OFSHR ZNS. A WK CDFNT HAS PUSHED INTO THE FAR NRN
NT1 WTRS AND BISECTS THE GULF OF MAINE...SEEN WITHIN THE RSCAT
VECTORS AS A SLIGHT WIND SHIFT BETWEEN S-SWLY 15-20 KT TO W 5-10
KT OVR THE NW PORTION. FARTHER S LITE 5-15 KT S-SWLY WINDS PREVAIL
ACRS THE REST OF NT1 AND NRN NT2. THEN S OF ABT 37N/RMNDR OF ZNS
E TO SELY WINDS IN THE 10 TO 20 KT RANGE WERE RETURNED ALONG THE
SWRN EXTENT OF A SUBTRPCL HIGH THAT HAS BEEN THE DOMINANT FEATURE
ACRS MOST OF THE OFSHR WTRS FOR SVRL DAYS NOW.

OVER THE SHORT TERM...THE LATEST MDLS REMAIN IN OVERALL EXCELLENT
AGRMT THAT THE WK CDFNT ACRS THE GULF OF MAIN WILL DSIPT OVR SRN
NT1 AREA TDA AS THE HIGH PRES RIDGE REMAINS IN PLACE TO THE S.
ASCD GRADIENTS SPRTG 20 KT OR LESS TDA WIL WKN WITH WK GRADIENTS
PERSISTING INTO FRI NIGHT. THEN THE 00Z GFS REMAINS CONSISTENT
WITH TIMING AND GRADIENTS ASCD WITH A STRONGER COLD FRONT EXPECTED
TO ONCE AGAIN INCREASE THE RETURN SW FLOW OVER NRN WTRS...UP TO 25
KT IN GLF OF MAINE SAT INTO SAT NIGHT AS A STG LOW TRACKS E ACRS
CANADA WELL TO THE N WITH PREFNTL GRADIENT DMSHG AS LOW MOVES AWAY
SUN. WITH SPRT FM OTHER 00Z GLOBAL GUIDANCE WILL CONT USING LATEST
00Z GFS 10M WINDS...UP TO 25 KT.

IN THE LONGER RANGE...CDFNT MOVS S THRU NT1 AND INTO NRN NT2 WTRS
LATER SUN AND SUN NIGHT AND STALLS OFF DELMARVA MON THRU RMNDR OF
FCST PERIOD. PRES GRADIENT BTWN THIS CLD/STNRY FNT AND HIGH BLDG
IN FM N STILL EXPECTED TO PRODUCE NE WNDS TO 25 KT. THEN LOOKING
BYND MON NIGHT THE LTST 00Z GFS/UKMET/GEM ALL FAIRLY AGGRESSIVE IN
DVLPG A LOPRES ALONG THE STNRY FRONT OVR BALT CANYON...THEN MVG
THE LOW NE WHILE INTENSIFYING TO A PSN OUT OF THE WTRS BY LATE
TUE NITE. WHILE THE 00Z MODELS HAVE TRENDED STGR OVRNITE WITH THIS
FRONTAL WAVE...WL NOT BITE OFF JUST YET ON THIS STGR SOLN UNTIL
MORE DATA AND MORE CONTINUITY IN FUTURE CYCLES SUPPORTS THIS STGR
SOLN. AFTER 00Z TUE WL ESSENTIALLY LV THE GRIDS AS IS...WHICH USED
THE 28/12Z GFS INTO 12Z TUE...THEN 28/12Z ECMWF THEREAFTER. DESPITE
THE MDL DIFFS WITH NE FLOW DVLPG OVR NRN NT2 AREA N OF THE FNT
WHERE CONDS ARE EITHER NEUTRAL OR SLGTLY UNSTABLE THE 10M ECMWF
WNDS WL BE BOOSTED BY 10 PCT TUE AND TUE NIGHT PRODUCING WNDS AS
HIGH AS 30 KT IN NE NT2 AREA.

.SEAS...THRU MON NITE WL USE THE LTST 00Z WNA WVHTS INTO ABT 12Z
TUE...THEN TRANSITION GRIDS TO 28/12Z ECMWF WAM.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER BANCROFT/COLLINS. OCEAN PREDICTION CENTER.


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