Marine Interpretation Message
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000
AGNT40 KWNM 270055
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
855 PM EDT MON SEP 26 2016

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

SATLLITE IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND
ISOLATED TSTSM OVER THE FAR SRN NT2 WATERS. THE 18Z GFS IS VERY
SIMILAR TO THE PREVIOUS 12Z GFS THROUGH THE PERIOD. THE MAIN FCST
CONCERN CONTINUES TO BE THE LOW PRES WHICH IS FCST TO MOVE OFF THE
SE COAST TUE...THEN TRACK NE ACROSS THE NT2 WATERS TUE AFTERNOON
INTO WED. THE GFS IS STILL INDICATING AREA OF GALES IN THE SW FLOW
TO THE E AND SE OF LOW TRACK. THE EXISTING GRIDS ARE BASED MORE ON
THE 12Z GFS WINDS...AND WITH THE 18Z VERY CLOSE DO NOT PLAN ON
MAKING ANY SIGNIFICANT CHANGES FOR THE EVENING UPDATE. DURING THE
EXTENDED PERIOD...THE 18Z GFS IS ALSO SIMILAR TO THE PREVIOUS 12Z
WITH THE MAIN FOCUS BEING THE E TO NE WINDS OVER THE NT1 AND FAR
NW NT2 WATERS. WILL CONTINUE TO KEEP WINDS CAPPED AT 30 KT FOR THE
TIME BEING WITH ALL THE MODELS INDICATING WINDS JUST BELOW GALE.
THE 00Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS MATCHED UP
WELL WITH THE MWW3 FCST VALUES...AND WILL ALSO NOT BE MAKING ANY
MAJOR CHANGES TO WAVE GRIDS.

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

THE LATEST GOES VISIBLE SATELLITE IMAGERY AND THE LIGHTNING
DENSITY PRODUCT INDICATES AN AREA OF SHOWERS AND TSTMS ACROSS THE
FAR SW NT2 WATERS ALONG A VERY WEAK FRONTAL BOUNDARY. CURRENT
SURFACE REPORTS INDICATE E TO NE WINDS UP TO 20 KT ALONG THE
FRONT...AND SHIFTING TO NORTH TO THE SW OF THE AREA...BEFORE
TURNING WEST MIDWAY THOUGH THE STATE OF FLORIDA. THE VISIBLE
IMAGERY ALSO INDICATES A BROAD CYCLONIC CIRCULATION OVER THE FAR
WRN ATLANTIC OFF THE SE COAST. ASCAT WINDS FM 15Z INDICATE UP TO
20 KT IN SRN NT2...WITH A FEW EMBEDDED 25 KT BARBS TO THE S OF
NT2...BUT MISSED THE AREA RIGHT OFF THE SE COAST. THE 12Z GFS
10-METER WINDS ARE INITIALIZED WELL WHEN COMPARED WITH THE
DATA...AND INDICATE THAT THE WEAK CIRCULATION WILL MOVE N THEN NE
OVER THE NEXT 12 TO 24 HOURS. THE GFS THEN INDICATES THAT THE LOW
WILL CONTINUE NE WHILE INTENSIFYING OVER THE GULF STREAM...AND THE
MODEL LOW LEVEL TEMPERATURES INDICATE THE LOW COULD MAINTAIN A WARM
CORE...WHILE MODEL PRECIPITABLE WATER AND DEW POINT TEMPERATURES
SHOW AMPLE LOW LEVEL MOISTURE IN THE UNSTABLE ENVIRONMENT OVER
THE GULF STREAM...WHICH COULD SUPPORT CONVECTION. THE 12Z GFS
INDICATES THE LOW WILL DEVELOP GALE FORCE WINDS WHILE MOVING INTO
NRN NT2. THE PREVIOUS THINKING INDICATED THAT THERE COULD BE SOME
FEEDBACK ISSES WITH THE MODEL. HOWEVER...THE 12Z ECMWF/GEM BOTH
INDICATE GALES IN THE SW FLOW. THE 12Z GEFS MEMBERS ARE CLUSTERED
TIGHTLY AROUND THE OPERATIONAL GFS SOLUTION WHICH HAS TRENDED
STRONGER...SO AT THIS TIME CONFIDENCE HAS RISEN TO THE MODERATE
TO HIGH RANGE WITH THE PROSPECT OF GALES OVER NRN NT2 FOR WED. THE
PREVIOUS FORECAST HAD GALES IN FOR WED...SO PLANNING ON CONTINUING
THEM AT THIS TIME...AND WILL EXPAND TO LATE TUE NIGHT IN A FEW
ZONES.

IN THE EXTENDED...THE 12Z MODELS INDICATE AN UPPER HIGH WILL
BUILD OVER THE WRN ATLC...AND BLOCKS A CUT OFF LOW IN THE ERN
CONUS FROM MOVING OFF SHORE THROUGHOUT THE REMAINDER OF THE
FORECAST PERIOD. THE MODELS AGREE FAIRLY WELL ON THE UPPER
PATTERN...SO CONFIDENCE IS SOMEWHAT HIGH WITH THE GUIDANCE ON
THE UPPER PATTERN. AT THE SURFACE...THE 12Z MODELS INDICATE THAT
THE AFOREMENTIONED SURFACE LOW ON WED WILL MOVE OUT OF THE AREA TO
E AND NE...AS A FRONTAL BOUNDARY FORECAST TO STALL ACROSS THE NRN
NT2 WATERS INTERACTS WITH HIGH PRES BUILDING OVER SE CANADA. ALL
SOLUTIONS INDICATE SOMEWHAT STRONG E TO NE FLOW ACROSS NT1 LATE
WED INTO SAT...WHICH SHOULD LOWER STATIC STABILITIES OVER THE
COLD SHELF WATERS. HOWEVER...THE MODELS ALL INDICATE THE
ENVIRONMENT WILL REMAIN MOSTLY STABLE...SO NOT EXPECTING STRONG
VERTICAL MIXING. AT THIS TIME PLANNING ON FAVORING THE 12Z GFS
SOLUTION...WHICH IS SUPPORTED SOMEWHAT BY THE REST OF THE 12Z
GLOBAL MODELS ON THE OVERALL PATTERN. THERE ARE SOME DIFFERENCES
ON THE DETAILS...WITH NO CLEAR TREND...SO CONFIDENCE WITH GUIDANCE
IS FAIRLY LOW THROUGHOUT THE EXTENDED PERIOD.

.SEAS...THE 12Z WAVEWATCH-III AND ECMWF WAM WERE INITIALIZED A
FOOT OR TWO LOW OVER THE SRN NT2 WATERS IN THE VICINITY OF THE
TSTMS AND SHOWERS OFF THE SE COAST. THE MODELS SEEMED A LITTLE LOW
WITH THE WAVE HEIGHTS AS THE DEVELOPING LOW MOVES NE THROUGH
NT2...SO WILL ADJUST SEAS HIGHER. OTHERWISE THE 12Z WAVEWATCH
SEEMS REASONABLE...SO WILL GENERALLY FOLLOW AS IT REFLECTS TRENDS
OF PREFERRED GFS WINDS.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID-ATLANTIC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TUE NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE WED.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE TUE NIGHT INTO WED.

$$

NOTE: ON OCTOBER 06, 2016...THE NWS FTPMAIL SERVICE WILL DISABLE
THE CURRENT EMAIL ADDRESS. THE NEW EMAIL ADDRESS IS LIVE NOW.
PLEASE TRANSITION TO IT AS SOON AS POSSIBLE TO AVOID A SERVICE
DISRUPTION.

NEW EMAIL ADDRESS...NWS.FTPMAIL.OPS@NOAA.GOV
/ALL LOWER CASE LETTERS/

FOR THE SERVICE CHANGE NOTICE...PLEASE GO TO
HTTP://WWW.NWS.NOAA.GOV/OS/NOTIFICATION/SCN16-37FTPMAIL.HTM
/ALL LOWER CASE LETTERS/

.FORECASTER KOSIER/KELLS. OCEAN PREDICTION CENTER.



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