Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 260027
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
827 PM EDT WED MAY 25 2016

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

UPDATE...18Z NCEP SFC ANALYSIS SHOWS A LOW PRES TROF EXTNDG S AND
SW FROM THE SRN COAST OF NOVA SCOTIA AND ALONG THE ERN EDGE OF THE
NRN NT2 WTRS. ALSO SHOWN IN THE SFC ANALYSIS IS A LOW PRES CENTER
OVER NRN NEW BRUNSWICK WITH AN ASSOCD COLD FRONT EXTNDG SW OVER
THE SAINT LAWRENCE RIVER VALLEY AND INTO THE GREAT LAKES REGION. A
HI PRES RIDGE WAS ANALYZED OVER THE SRN AND CENTRAL NT2
WTRS...WITH ANOTHER LOW PRES CENTER SE OF THE NT2 AREA NEAR
26N68W. LATEST AVAIL ASCAT HI-RES AND RAPIDSCAT PASSES FROM
EARLIER TODAY SHOW WINDS TO 20 KT GUSTING TO 25 KT IN SW FLOW
OVER CENTRAL AND NRN NT2 WTRS W OF 70W. LIGHTNING DENSITY PRODUCT
DATA AT 2310Z DID NOT SHOW ANY SHOWERS OR TSTMS OVER THE COASTAL
OR OFSHR WTRS.

MAIN WEATHER FEATURES...THE LOW PRESENTLY CENTERED NEAR 26N68W IS
EXPCTD TO MOVE NW AND APPROACH THE NT2 WTRS TONITE THRU EARLY
SAT...CONTINUE MOVG NW OVER THE NT2 AREA LATER SAT THRU SUN...THEN
STALL NEAR THE GEORGIA COAST SUN NITE THRU MON NITE. GIVEN THE
LOCATION OF THIS LOW...NHC MIAMI IS CARRYING IT AS A LOW PROB
TROPICAL SUSPECT AREA WITH A 30 PERCENT CHANCE OF DEVELOPMENT INTO
A TROPICAL OR SUBTROPICAL CYCLONE WITHIN THE NEXT 48 HRS. THE
COLD FRONT WILL PASS SE OVER THE NT1 WTRS TONITE INTO THU. A WARM
FRONT WILL LIFT NE OVER THE NT1 AREA FRI AND FRI NITE. ANOTHER
COLD FRONT WILL MOVE SE AND APPROACH THE NEW ENGLAND COAST
SAT...THEN PASS S OF THE NT1 AREA SAT NITE INTO SUN. ANOTHER WARM
FRONT WILL LIFT NE OVER THE NT1 WTRS LATER SUN AND SUN NITE. A
THIRD COLD FRONT WILL MOVE SE AND APPROACH THE NEW ENGLAND COAST
MON NITE.

MODELS...THE MED RNG MDLS ARE IN GUD AGREEMNT OVER THE OFSHR WTRS
DURING THE FCST PRD...EXCEPT THE GEM/UKMET LOOK FASTER WITH THE
LOW NEAR THE SE COAST FOR LATER SUN THRU MON NITE...TAKING IT UP
INTO NORTH CAROLINA INSTEAD OF STALLING IT NEAR THE GEORGIA COAST
AS IS BEING DONE BY THE ECMWF/GFS MDLS. SINCE THE ECMWF/GFS ARE IN
THE BEST AGREEMNT THRU THE FCST PRD AND ALSO BECAUSE THEY HAVE
BEEN THE PREFERRED MDL SOLNS...WILL USE A BLEND OF THE ECMWF/GFS
FOR THE WIND GRIDS DURING THE FCST PRD. AM NOT PLANNING TO MAKE
ANY SIGNIF CHANGES TO THE CURRENT FCST TREND.

SEAS...WNA VERSION OF THE WAVEWATCH III MDL AND THE ECMWF WAM BOTH
INITIALIZE WELL OVER THE OFSHR WTRS...AND ARE IN DECENT AGREEMNT
THRU THE FCST PRD WITH ONLY A FEW MINOR DIFFERENCES NOTED. USED
THE WNA WW3 TO POPULATE THE WAVE HT GRIDS FOR TONITE THRU
THU...THEN WENT WITH A 50/50 BLEND OF THE WNA WW3/ECMWF WAM FOR
THU NITE THRU THE REST OF THE FCST PRD.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

1350Z AND 1440Z ASCAT OVERPASSES EXTENDED ACROSS OFFSHORE WATERS
E OF 69W AND RETURNED 25 KT JUST SE OF THE WATERS...AND UP TO 20
KT ACROSS THE ANZ910 AND ANZ905 ZONES. 12Z MODELS ARE IN GOOD
AGREEMENT OVER THE NEAR TERM THAT THE UPPER LEVEL LOW JUST E OF
GEORGES BANK WILL CONTINUE TO WEAKEN AND MOVE NE TODAY AND
TONIGHT. 12Z GUIDANCE THEN SHOWS THE WEAK UPPER SHORTWAVE OVER
SOUTHERN QUEBEC WILL MOVE ACROSS THE GULF OF MAINE TONIGHT AND
SUPPORT A WEAK COLD FROPA THROUGH EASTERN NT1 WATERS. WILL
CONTINUE TO INCLUDE WINDS TO 20 KT S OF THE FRONT TONIGHT INTO
EARLY THU. MID AND UPPER LEVEL HEIGHTS WILL THEN BUILD SLIGHTLY
ALONG THE NEW ENGLAND AND MID ATLC COASTS LATE TONIGHT INTO THU
NIGHT AS WEAK UPPER RIDGE DEVELOPS. FRONT SHOULD THEN STALL AND
WEAKEN ACROSS NT1 AND NORTHEASTERN NT2 WATERS THU NIGHT AND
SLOWLY LIFT NE FRI/FRI NIGHT. OTHERWISE A HIGH PRES RIDGE WILL
PERSIST ACROSS THESE NORTHERN WATERS THROUGH SAT NIGHT. MODELS
HAVE SEEM TO BE COMING INTO A BETTER CONSENSUS WITH A SURFACE
LOW DEVELOPMENT ALONG A LOW PRES TROUGH JUST SE OF THE SOUTHERN
NT2 WATERS. LATEST GOES VISIBLE IMAGERY SUGGESTING THAT A
SURFACE LOW MAY HAVE ALREADY DEVELOPED NEAR 26N67W ALONG THE
STATIONARY FRONT OR LOW PRES TROUGH. NHC INCREASED THEIR
TROPICAL FORMATION CHANCE THIS MORNING...TO 50 PERCENT OVER THE
FIVE DAYS. ALTHOUGH THE MODELS ALL INDICATE LOW WILL TRACK NW
TOWARD THE GEORGIA COAST THU THROUGH THE WEEKEND...WITH THE
EXCEPTION OF THE GEM AND NAM THE MODELS ARE NOT PARTICULARLY
ENTHUSIASTIC ABOUT STRENGTHENING THE SYSTEM. HOWEVER MARINERS
SHOULD CLOSELY MONITOR SUBSEQUENT FORECASTS AND NHC TROPICAL
OUTLOOKS OVER NEXT FEW DAYS. BOTH THE 12Z GFS AND 12Z ECMWF WERE
WEAKER AND SLOWER THAN THEIR RESPECTIVE PREVIOUS RUNS. FOR
OFFSHORE WINDS USED A 2:1 BLEND OF THE PREVIOUS GRIDS AND 12Z
ECMWF. FURTHER BUMPED UP THESE BLENDED WINDS TO GET SOME AREAS
TO 25 KT S OF HATTERAS CANYON FRI THROUGH THE WEEKEND. WIND
GRIDS OVER THE SOUTHERN WATERS IN THE MEDIUM RANGE ARE HIGHER
THAN 12Z MODELS.

.SEAS...BOTH THE 12Z WAVEWATCH III AND THE 12Z ECMWF WAM ARE
WELL INITIALIZED WITH W ATLC WAVE HEIGHTS THIS AFTERNOON AND ARE
GENERALLY IN GOOD AGREEMENT OVER THE OFFSHORE WATERS FOR THE
NEXT SEVERAL DAYS. USED A THE 12Z WW3 THROUGH THU...THEN A 50/50
BLEND OF THE PREVIOUS GRIDS WITH THE 12Z ECMWF WAM THU NIGHT
THROUGH THE REMAINDER OF THE FORECAST PERIOD. WAVE HEIGHTS OVER
THE SOUTHERN WATERS NT2 WILL OBVIOUSLY HINGE ON ANY POSSIBLE
TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER SCOVIL/CLARK. OCEAN PREDICTION CENTER.



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