Marine Interpretation Message
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000
AGNT40 KWNM 120126
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
826 PM EST THU FEB 11 2016

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

AS LOW PRES NR NOVA SCOTIA MOVES EWD...THE WLY GRADIENT IN ITS
WAKE PER THE LATEST SFC OBS SUPPORTS GALE FORCE WINDS (GNRLY UP
TO 35 OR 40 KT) ACRS THE NT1 AND NRN NT2 WTRS AS PREVLY FCSTD.
MAX SEAS OVER THESE WTRS ARE GNRLY IN THE 15-20 FT RANGE...HIGHEST
ACRS THE SE MOST NT1 AND NE MOST NT2 WTRS...WHICH ARE BEING
HANDLED RSNBLY WELL BY BOTH THE 18Z WAVEWATCH III AND 12Z ECMWF
WAM MDLS AT THE MOMENT.

OVER THE SHORT TERM...THE LATEST MDLS ARE IN GOOD AGRMT THAT AS
THE LOW CONTS OFF TO THE E THAT WINDS ACRS THE NRN WTRS WL DMNSH
TO SUBGALE BY EARLY FRI. THEN FRI/FRI NITE...THE 18Z NAM/GFS
REMAIN CONSISTENT VS THEIR PREV RESPECTIVE RUNS IN FCSTG A DVLPG
SFC LOW TO RACE NE ACRS THE SRN/CNTRL NT2 WTRS. PER THE SLIGHTLY
WEAKER 12Z UKMET/ECMWF SOLUTIONS IT LOOKS CLOSE AS TO WHETHER THIS
SYSTEM WL STRENGTHEN TO STORM FORCE ACRS THE OUTERMOST NT2 WTRS.
BUT WITH THE 18Z GFS/NAM STIL FCSTG STORM FORCE ASCD 30M BL WINDS
WL CONT TO USE THE PREVLY POPULATED WINDS WITH NO SIG CHNGS TO THE
ASCD WRNGS. THEN SAT/SAT NITE AGAIN THE 18Z NAM/GFS REMAIN
CONSISTENT AND IN GOOD AGRMT WITH THE OTHER 12Z GLOBAL MDLS IN
FCSTG A STRONG NNWLY GRADIENT TO DVLP THRUT MOST OF THE WTRS WITH
THE STRONGEST COLD AIR ADVECTION AND MOST INTENSE NEGATIVE STATIC
STABILITY OF THE WINTER SO FAR. IN THE WAKE OF THE ASCD CLOSED UPR
LOW PASSING ACRS THE NRN WTRS WITH AN ASCD WEAK SFC LOW OR SFC
TROF...IT LOOKS CLOSE (MAINLY PER THE 18Z GFS AND 12Z NAVGEM)
WHETHER THIS GRADIENT WL STRENGTHEN TO STORM FORCE ACRS THE ERN
MOST NT1 WTRS LATE SAT NITE/EARLY SUN. FOR NOW WITH THE OTHER
GLOBAL MDLS FCSTG SLIGHTLY WEAKER GRADIENTS THERE FOR NOW WL CONT
TO FCST STRONG GALE FORCE WINDS UP TO 40-45 KT. ALSO LATE SAT INTO
SUN CANNOT COMPLETELY RULE OUT STORM FORCE WINDS DVLPG IN THIS
GRADIENT INVOF THE GULF STREAM ACRS THE NT2 WTRS. BUT FOR NOW WL
JUST MAKE SM MINOR SHORT TERM EDITS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...AFTER THE MDLS GNRLY AGREE THAT CONDS WL DMNSH
AS HIGH PRES BLDS OFSHR LATE SUN INTO MON THE FOCUS SHIFTS TO THE
FCST DVLPMNT OF ANOTHER POTENTIALLY POTENT SFC LOW AFCTG THE WTRS
MON NITE INTO TUE NITE. IN GNRL THE LATEST GLOBAL MDLS AGREE THAT
THIS SYSTEM WL MOV INTO THE SE CONUS MON NITE...THEN TRACK NWD NR
THE COAST OR JUST INLAND TUE INTO TUE NITE. THE 12Z UKMET/ECMWF
FCSTS A MR PROGRESSIVE SYSTEM THAN THE 18Z/12Z GFS. BUT THE 12Z
ECENS MEAN INDICATES THAT THE 12Z ECMWF TRACK MAY BE TOO FAST BY TUE
NITE. WITH THE 18Z GFS RMNG CONSISTENT VS ITS PREV 12Z RUN...THO
SLIGHTLY STRONGER...FOR NOW WL CONT TO USE THE PREV 12Z GFS BL
WINDS FOR THIS SYSTEM FOR NOW. ALSO STORM FORCE WINDS ARE LKLY TO
DVLP WITH THIS SYSTEM...BUT FOR NOW DUE TO THE MDL UNCERTAINTY WL
CONT TO CAP THE ASCD WINDS AT STRONG GALE FORCE AND THEN WL SEE IF
THE 00Z MDLS LATER DICTATE OTHERWISE.





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


THRU 12Z/12 - 12Z GFS 30M WINDS:

WIDESPREAD GALES WILL CONT TO EXPAND IN AREAL EXTENT ACROSS THE
NRN NT2 AND NT1 WATERS THIS EVENING AS LOW PRES INTENSIFIES E OF
THE OPC AOR JUST S OF NOVA SCOTIA. THE LOW WILL PULL E AND GAIN
DISTANCE FROM THE WTRS ULTIMATELY EASING THE PRES GRADIENT AND
EVENTUALLY ALLOWING WINDS TO ABATE TO BLO GALE THRESHOLD. WITH
GOOD AGREEMENT AMONG REGIONAL 12Z 4KM NAM AND 16Z HRRR EXPECT
WARNING WINDS TO DIMINISH BY 12Z FRI.

FRI INTO EARLY MON (12Z/12 - 12Z/15) - 50/50 12Z GFS/ECMWF
BLENDED SOLN - HOWEVER SLIGHT BOOST TO BLENDED SFC WINDS BY ABOUT
10 PERCENT:

ALL 12Z GUIDANCE DEVELOPS LOW PRES OFF THE SE COAST BY ABOUT 12Z
FRI...THEN SHARE SIMILAR TRACKS RACING THE LOW NE WHILE QUICKLY
INTENSIFYING. THE 12Z GFS REMAINED IN CONCERT WITH ITS PREV
SEVERAL CYCLES AND IS WELL SUPPORTED BY THE EXPERIMENTAL 00Z AND
06Z GFS. INTENSITY/TRACK SOLNS ARE ALSO WELL SUPPORTED BY ALL 12Z
NON-NCEP MODELS INCLUDING THE 00Z ECMWF EPS AND 12Z GEFS MEANS.
PRIMARY CHANGE TO UPCOMING FORECAST WILL BE TO INTRODUCE A PERIOD
OF STORM FORCE WINDS - ALBEIT BRIEFLY - ACROSS THE FAR E/SE
PORTIONS OF ZNS 930 AND 925 BEFORE THE LOW CLEARS E OF THE WTRS.
GEFS MEAN AND DETERMINISTIC ECMWF EACH OUTPUT 45 KT BL WINDS...
WHILE THE GFS/NAM OUTPUT 50 KT STORM. MODELS HAVE A KNOWN BIAS TO
BE SLOW IN DEVELOPING SFC WIND FIELDS IN AREAS OF RAPID
CYCLOGENESIS...AND WITH THIS IN MIND WILL TREND FORECAST
FASTER/INTRODUCE THESE HIER WINDS IN THE OFFICIAL FCST. THE
DEPARTING LOW WILL HELP PULL AN ARCTIC FRONT AND SECONDARY SURGE
OF COLD AIR ACROSS THE WATERS SAT INTO SUN...WITH WHAT WILL END UP
BEING THE COLDEST AIR AND HIGHEST NEGATIVE STATIC STABILITIES SO
FAR THIS SEASON. LATE SAT NIGHT INTO SUN 12Z GFS/ECMWF ROTATE AN
UPPER LOW - AND AN INVERTED SURFACE TROF - ACROSS THE GULF OF
MAINE ENHANCING THE ALREADY STRONG PRES GRADIENT IN THE CAA. WILL
CONT TO BOOST BL WINDS BUT CAP AT 45 KT HERE - BUT WOULDNT BE
SURPRISED IF SUBSEQUENT SHIFTS ADD THE 3 KTS AND HOIST STORM
WARNINGS AT SOME POINT.

MON THRU TUE NIGHT (12Z/15 - 12Z/17) - 12Z GFS:

AFTER A BRIEF PERIOD OF RELATIVELY CALM CONDS LATE SUN INTO MON
AS HIGH PRES MOVES E ACROSS THE OFSHRS...VERY INTERESTING SETUP
IN THE MEDIUM TO LONG RANGE AS THE SOUTHERN STREAM REGAINS CONTROL
DEVELOPING A LOPRES ACRS THE ERN US. TAPPING INTO THE GLFMEX
MOISTURE AN APPROACHING S/W TROF WILL AMPLIFY CONSIDERABLY...
INTENSIFYING INTO A SIG STORM OFF THE MID-ATLC COAST AFFECTING
ALL ZNS OVER THE WRN ATLC. THIS S/W FEATURE HASNT MOVED INLAND
INTO THE PAC NW YET...WHICH NOT SURPRISINGLY HAS LED TO DRASTIC
TIMING/TRACK/INTENSITY DIFFERENCES AND A LARGE SPREAD AMONG MODELS
AND ENSEMBLES. DEFERENCE TO THE 12Z GFS KEEPS CONTINUITY WITH THE
PREVIOUS FORECAST AND REMAINS SOMEWHAT CLOSE TO THE WPC MEDIUM
RANGE GUIDANCE WHICH PREFERRED THE 00Z ECMWF EPS MEAN. THE 12Z GFS
IS SLIGHTLY S OF THIS OUTPUT...SLIGHTLY SW OF 12Z GEFS MEAN...AND
A DECENT COMPROMISE BETWEEN THE MUCH FASTER/FARTHER INLAND
UKMET/ECMWF AND SLOWER/SOUTH/WEAKER GLOBAL GEM. TAKEAWAY FOR MON
INTO TUE: WITH LIMITED RUN TO RUN OR MODEL AGREEMENT CONFID IS
LOWER THAN AVERAGE AT THIS TIME AND WILL LIMIT WINDS TO STRONG
GALES AT THE MOMENT (ALL GLOBAL MODELS OUTPUT STORM FORCE AND
BORDERLINE HF WINDS AHEAD OF APRCHG CDFNT).

SEAS...SIMILAR TO PREV SHIFTS WILL GENERALLY USE A 50/50 BLENDED
WNA/WAM SOLN INTO 12Z MON BFR TRANSITIONING TO WNA THRUT. WILL
INCRS SIG WVHTS A FEW FEET IN OUTER ZNS 925/930 WHERE STORM FORCE
WINDS ARE EXPECTED AND SEAS TEND TO LAG IN MODEL OUTPUT OF QUICKLY
DEEPENING LOWS. WILL ALSO INCREASE SIG WVHTS BY 2-4 FT ACROSS THE
GULF OF MAINE SAT NIGHT INTO SUN IN AREAS OF STRONG 45 KT GALES.

EXTRATROPICAL STORM SURGE GUIDANCE...STRONG OFFSHORE FLOW
CONTINUES OFF THE MID-ATLC AND 12Z ESTOFS OUTPUTS VALUES -1 TO -2
FT FROM NEAR NANTUCKET S TO NEAR CAPE HENRY...WHILE THE 12Z ETSS
VALUES SHOW NEG SURGE VALUE TO ABOUT -1 FT IN SIMILAR AREAS. STILL
BELIEVE A COMPROMISE OR THE AVERAGE BETWEEN THE TWO IS LIKELY
BEST AT THIS POINT.


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     GALE TONIGHT.
     GALE SAT.
     GALE POSSIBLE SAT NIGHT INTO SUN.
     GALE POSSIBLE TUE NIGHT.
.ANZ805...GEORGES BANK WEST OF 68W...
     GALE TONIGHT.
     GALE SAT.
     GALE POSSIBLE SAT NIGHT INTO SUN.
     GALE POSSIBLE TUE NIGHT.
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE TONIGHT.
     GALE SAT.
     GALE POSSIBLE SAT NIGHT INTO SUN.
     GALE POSSIBLE TUE NIGHT.
.ANZ810...SOUTH OF NEW ENGLAND...
     GALE TONIGHT.
     GALE SAT.
     GALE POSSIBLE SAT NIGHT INTO SUN.
     GALE POSSIBLE TUE NIGHT.
.ANZ815...SOUTH OF LONG ISLAND...
     GALE TONIGHT.
     GALE SAT.
     GALE POSSIBLE SAT NIGHT INTO SUN.
     GALE POSSIBLE TUE NIGHT.

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

$$

.FORECASTER VUKITS/COLLINS. OCEAN PREDICTION CENTER.


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