Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 260137
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
837 PM EST TUE 25 NOV 2014

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

SERIES OF SFC LOWS WERE ALONG COLD FRONT FROM OFF GA COAST TO NE
FL AND DEEPEST 1010 MB LOW OVER ERN GULF OF MEXICO AND
APPROACHING W FL COAST JUST N OF TAMPA. SFC LOW SHOULD
CONSOLIDATE SOMEWHAT LATE TONIGHT AND EARLY WED. 18Z GFS AND 18Z
NAM SEEM TO HAVE GOOD HANDLE ON UPPER TROF MOVING E THROUGH
LOWER MS VALLEY WHICH WILL SUPPORT MAIN WX PLAYER OVER FORECAST
PERIOD BEING THE DLVPG COASTAL LOW NEXT COUPLE DAYS. 18Z GFS
TRENDED SLIGHTLY W WITH TRACK FROM ITS PREVIOUS RUNS AND ALSO
WAS A BIT DEEPER. IN ADDITION OVER THE PAST FEW RUNS GENERAL
MODEL TREND HAS BEEN FASTER. WITH 12Z ECMWF NOW SLIGHTLY E OF
18Z GFS WILL NOT BE MAKING ANY CHANGES TO PREVIOUS WIND GRIDS
WED THROUGH THU. ANY SLIGHT SHIFT WITH LOW TRACK WILL AFFECT
AREA OF FORECAST STORM FORCE N TO NE WINDS WED EVENING BUT WILL
WAIT FOR 00Z GUIDANCE BEFORE MAKING ANY ADJUSTMENTS. 18Z
MULTIGRID WAVEWATCH III HAS GOOD HANDLE ON W ATLC SIG WV HGTS
THIS EVENING. WILL CONTINUE WITH ABOUT 20 TO 25 PERCENT INCREASE
IN SIG WV HGTS WED INTO THU OVER AREAS WITH HIGHEST WINDS. EVEN
THO 12Z ECWF IS WEAKER THAN 12Z/18Z GFS THE 12Z ECMWF WAVE MDL
ACTUALLY PRODUCES HIGHER SIG WV HGTS THAN MWW3...ABUOT 3 TO 5 FT
HIGHER.

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

OVER THE SHORT TERM...THE NEW 12Z MDLS OVERALL REMAIN IN GOOD
AGRMT THAT THE MOST SIG WX FEATURE OVER THE NEXT SVRL DAYS WL BE
A SFC LOW DVLPG ON A FRONT AND MOVG NE TO OFF THE SE COAST
TONITE...INTENSFYG AND TRACKING NNE OFF THE MID ATLC COAST TO NR
THE 40N70W BENCHMARK BY EARLY WED EVENING (27/00Z)...THEN CONTG
NE ACRS THE NT1 WTRS WED NITE. IN REGARDS TO THE FCST TRACK OF
THIS DVLPG LOW...OTHER THAN THE 12Z GLOBAL GEM CONTG TO LOOK LK
A TOO FAR E (AND ALSO TOO WEAK) OUTLIER...THE OTHER 12Z MDLS NOW
FCST NRLY INDENTICAL TRACKS WITH JUST MINOR TIMING DIFFERENCES.
THE 12Z GEFS MEAN INDICATES THAT THE 12Z GFS TRACK IS SLIGHTLY
TOO FAST (BY ABT 3 HRS). THEREFORE A NON-GEM 12Z MDL CONSENSUS
LOOKS FINE FOR A NOW HIGH CONFIDENCE FCST TRACK. IN RGRDS TO THE
FCST GRADIENTS ASCD WITH THIS LOW...THE 12Z GFS/GFSP/UKMET/ECMWF
ALL FCST VERY SMLR TIMING AND AREAL COVERAGE FOR THEIR GALE
FORCE ASCD BL WINDS. THE BIGGEST FCST CHALLENGE IS WHETHER THIS
SYSTEM WL ATTAIN STORM FORCE WINDS AS PREVLY FCSTD WED NITE AS
IT PASSES JUST SE OF CP COD. THO SMLR TO THEIR PREV 06Z
RUNS...THE 12Z GFS/GFSP FCST ONLY SOLID 35-45 KT 30M BL AND THE
USUALLY CONSERVATIVE 12Z UKMET FCSTG 35-40 KT BL WINDS...AM
TEMPTED TO DROP THE STORM WRNGS. BUT WITH THIS LOW FCST TO TRACK
INVOF THE W WALL OF THE GULF STREAM AS IT PASSES NNE ACRS THE
NT2 WTRS...AND THE FACT THAT THE 12Z GEFS MEAN INDICATES THAT
THE 12Z GFS MAY NOT BE FCSTG ITS LOW TO INTENSIFY FAST ENUF
(ALSO NOTING THE MR RAPID 12Z UKMET/ECMWF
INTENSIFICATION)...BELIEVE THE 12Z GFS ASCD BL WINDS MAY BE TOO
LOW. THEREFORE WL KEEP THE PREVLY FCSTD WRNGS IN PLACE WITH THIS
LOW. THEN IN THE WAKE OF THIS SYSTEM THE 12Z
GFS/GFSP/UKMET/ECMWF REMAIN CONSISTENT VS THEIR PREV RESPECTIVE
RUNS IN FCSTG A SCNDRY COLD FRONT AND/OR SFC TROF TO MOV OFSHR
ACRS THE NT2 WTRS THU/THU NITE WHICH WL CAUSE THE WNWLY GRADIENT
TO RESTRENGTHEN. A CONSENSUS OF THESE MDLS LOOKS RSNBL FOR THE
FCST STRENGTH OF THIS GRADIENT FOR NOW (GNRLY UP TO 25 OR 30
KT)...BUT WL HV TO KEEP AN EYE OUT FOR POTENTIAL GALES DVLPG IN
THE VCNTY OF THE GULF STREAM. SO WITH THE 12Z MDLS RMNG
CONSISTENT...FOR THE SHORT TERM PLAN ON CONTG TO USE THE PREVLY
POPULATED SLIGHTLY STRONGER 00Z GFS 30M BL WINDS WITH JUST SM
MINOR ADDITIONAL EDITS PER THE 12Z MDLS WHICH WL RESULT IN NO
SIG TIMING AND/OR AREAL COVERAGE CHNGS TO THE PREVLY FCSTD SHORT
TERM WRNGS.

IN THE LONG RANGE...THE 12Z GLOBAL MDLS GNRLY AGREE THAT HIGH
PRES WL BLD TWDS THE MID ATLC COAST FRI...MOV OFSHR FRI
NITE/SAT...THEN MAINTAIN A RIDGE ACRS THE SRN NT2 WTRS SAT NITE
INTO SUN NITE WITH STRENGTHENING SSWLY RETURN FLOW DVLPG ACRS
THE NRN WTRS. IN COMPARISON TO THE OTHER 12Z GLOBAL MDLS IT
LOOKS LK THE 12Z GFS IS FCSTG THIS RETURN FLOW TO STRENGTHEN TOO
QUICKLY. THEN ON SUN/SUN NITE...TO BE MR IN LINE WITH THE LATEST
WPC MEDIUM RANGE GUIDANCE...WL FAVOR THE SLOWER 12Z
GFSP/UKMET/ECMWF SOLUTION FOR A COLD FRONT APRCHG FM THE NW AND
MOVG OFSHR INTO THE NRN WTRS LATE SUN NITE. THEREFORE IN THE
LONG RANGE WL GO WITH A BLEND THE CURRENT 00Z GFS 30M BL WINDS
AND 12Z ECMWF BK WINDS FOR FRI/FRI NITE...THEN WL TRANSITION TO
ALL 12Z ECMWF BL WINDS FOR SAT THRU SUN NITE. SO AS A RESULT NO
MAJOR LONG RANGE CHNGS ARE ANTICIPATED FOR THE NEXT OFSHR FCST
PACKAGE.

SEAS...WITH THE 12Z WAVEWATCH III AND 12Z ECMWF WAM RMNG
CONSISTENT THRU THE SHORT TERM WL NOT REPOPULATE THE PREVLY USED
FCST WAVE GRIDS THRU THU NITE. THEN WL BLEND THE CURRENT GRIDS
WITH 50 PERCENT OF THE 12Z ECMWF WAM FOR FRI/FRI NITE...AND THEN
WL TRANSITION TO ALL 12Z ECMWF WAM FOR SAT THRU SUN NITE.

.EXTRATROPICAL STORM SURGE GUIDANCE...AS THE DVLPG LOW TRACKS NE
UP THE COAST THE 12Z ETSS AND 12Z ESTOFS REMAIN WITHIN .5 FT OF
EACH OTHER IN FCSTG A MAX SURGE GNRLY IN THE 1.0 TO 1.5 FT RANGE
TO DVLP FROM DELMARVA TO CP COD BAY WED INTO WED NIGHT WHICH
OVERALL LOOKS REASONABLE.

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     STORM WED NIGHT.
     GALE THU.
.ANZ805...GEORGES BANK WEST OF 68W...
     GALE WED.
     STORM WED NIGHT.
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE WED NIGHT.
.ANZ810...SOUTH OF NEW ENGLAND...
     GALE WED.
     STORM WED NIGHT.
.ANZ815...SOUTH OF LONG ISLAND...
     GALE WED INTO WED NIGHT.

.NT2 MID ATLC WATERS...
.ANZ820...HUDSON CANYON TO BALTIMORE CANYON...
     GALE WED INTO WED NIGHT.
.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...
     GALE WED INTO WED NIGHT.
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE WED INTO WED NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE WED INTO WED NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE WED INTO WED NIGHT.
.ANZ825...INNER WATERS FROM BALTIMORE CANYON TO CAPE CHARLES
LIGHT...
     GALE WED INTO WED NIGHT.
.ANZ828...INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK
BEACH LIGHT...
     GALE WED.
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS
CANYON...
     GALE WED INTO WED NIGHT.
.ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE
HATTERAS...
     GALE WED.
.ANZ833...INNER WATERS FROM CAPE HATTERAS TO CAPE FEAR...
     GALE TONIGHT INTO WED.
.ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR...
     GALE WED.
.ANZ835...INNER WATERS FROM CAPE FEAR TO 31N...
     GALE TONIGHT INTO WED.
.ANZ935...OUTER WATERS FROM CAPE FEAR TO 31N...
     GALE WED.

$$

.FORECASTER CLARK/VUKITS. OCEAN PREDICTION CENTER.


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