Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 300012
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
812 PM 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.

GLOBAL MODELS BECOME QUITE DIVERGENT AND PROBLEMATIC BEGINNING
ABT 00Z TUE AFFECTING THE NRN HALF OF THE OPC OFSHR ZNS. PREV
SHIFTS HAVE FAVORED A FLATTER/MORE SRN SOLN OF A LOW PASSING FROM
NR LONG ISLAND ENE ACRS BALT CANYON WHILE PASSING JUST S OF THE
HAGUE LINE. THIS SOLN IS SUPRTD BY THE 29/06Z GFS...28/12Z
ECMWF...AND MOST RECENTLY IS VERY CLOSE TO 12Z GEFS MEAN SOLN.
DEFERENCE TO FLATTER SOLN KEEPS PERSISTENT E-NELY FLOW ACRS NT1
AND NRN NT2 WTRS FROMM MON ONWARDS THRUT THE END OF THE PERIOD.

THAT SAID THE 18Z GFS CONTS TO TREND TWD A MORE NWARD/STGR
SOLN...MORE TWDS THE 29/12Z UKMET-GEM-ECMWF (NON-NCEP MDLS) WHICH
PULL THE LOW MUCH FARTHER N FROM THE GULF OF MAINE TO N OF NOVA
SCOTIA. SHUD THE UPCOMING 00Z GFS AND OTHER GUID CONT TO SUGGEST
A MORE NRN TRACK FOR THIS LOW FEATURE... WL LIKELY ALTER THE LONG
RANGE PORTION TMRW MORNG.

FOR NOW HWVR...WL NOT BE MAKING SIG CHANGES TO THE ONGOING FCST
THAT IS ALREADY IN PLACE. WL AWAIT 00Z GUID TO RE-EVALUATE OFSHR
FCST SPCLY IN THE LONG RANGE.

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

ASCAT-B PASS FM 1523Z SHOWED WINDS 10 KT OR LESS ASCD WITH A
SUBTRPCL RDG N OF 35N AND 10 TO 20 KT E TO NE WINDS S OF 35N AND
MORE RECENT SFC RPTS FM 18Z SHOW SIMILAR CONDS. STRONGER CONDS IN
ELY FLOW NEAR BERMUDA...UP TO 25 KT IN EARLIER PASS FM 1344Z ARE
ASCD WITH A LOW NR 26N68W. THESE WNDS ARE IN A SLOW WKNG TREND.
SEAS ARE 7 FT OR LESS...HIGHEST IN THE OUTER SRN NT2 ZONES. THESE
CONDS ARE IN LINE WITH CURRENT FCST AND 12Z GFS 10M WINDS.

OVER THE SHORT TERM...THE LATEST MDLS REMAIN IN OVERALL EXCELLENT
AGRMT THAT THE WK CDFNT ACRS THE SRN NT1 AREA AND FAR NW NT2 WTRS
WILL DSIPT EARLY TONIGHT AS THE HIGH PRES RIDGE REMAINS IN PLACE
TO THE S. ASCD GRADIENTS SPRTG LIGHT WINDS WHICH WL PERSIST INTO
SAT. THEN THE 12Z 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 SAT INTO SAT NIGHT...UP
TO 25 KT IN GLF OF MAINE SAT AND UP TO 30 KT SAT NIGHT IN N
PORTION...AS A STG LOW TRACKS E ACRS QUEBEC AND LABRADOR...WITH
PREFNTL GRADIENT DMSHG AS LOW MOVES AWAY SUN. WITH SPRT FM OTHER
12Z GLOBAL GUIDANCE WILL CONT USING 12Z GFS 10M WINDS. CDFNT THEN
PASSES S THRU NT1 AND INTO NRN NT2 WTRS LATER SUN AND SUN NIGHT
AND STALLS ALG A WSW LINE ACRS NRN NT2 AREA TO DELMARVA MON AND
MON NIGHT. 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 LATEST MDLS SHOW MARKED DIVERGENCE
WHILE TAKING DVLPG LOW FM NR DELMARVA MORE NWD INTO NEW ENGLAND
WTRS WHILE ONLY GFS IS CLOSER TO PRIOR RUNS WITH ITS MORE SRN
TRACK...BUT STILL TAKING LOW N OF 40N BY WED. LATEST 12Z GEFS
ENSEMBLE MEAN ALONG WITH 00Z ECMWF ENSEMBLE MEAN SUPPORT A MORE
SRN TRACK MORE LIKE AN OLD 12Z/28 ECMWF RUN AND CLOSE TO 06Z GFS.
WILL THEREFORE SHIFT PREFERENCE FROM 12Z GFS TO 06Z GFS ON TUE
THEN GO WITH THE OLDER 12Z/28 ECMWF GRIDS BEYOND 18Z WED...SLOWED
DOWN BY 6 HR TWD GEFS MEAN. THIS WILL YIELD 20 OR 25 KT IN NE TO
E FLOW N OF FNT AND LOW MAINLY SRN NT1 AND NRN NT2 ZONES CONTG
THRU WED NIGHT.

.SEAS...THRU MON NIGHT WL USE THE LTST 12Z WNA WVHTS...EXCP SUN
AND SUN NIGHT A M50/50 BLEND OF 12Z WNA/ECMWF WAM WVHGTS...THEN
PER TRANSITIONS TO 06Z GFS AND THEN OLD ECMWF...SHIFT PREFERENCE
TO 06Z WNA TUE AND 12Z/28 ECMWF WAM LATER WED.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER COLLINS/BANCROFT. OCEAN PREDICTION CENTER.



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