Marine Interpretation Message
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AGNT40 KWNM 251436
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
1036 AM EDT SUN SEP 25 2016

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

HE SAT IMG INDC MOSTLY CLOUDY AREAS OVER THE CENTRAL AND FAR SRN
WATERS WITH LIGHTNG OVER THE SRN REGION WHILE HIGH PRES IS
DEPICTED OVER THE NRN WATERS. THE LATEST OBSERVATION SHOW
RELATIVELY HIGHER WINDS OVER THE ERN PARTS OF THE BALTIMORE
CANYON. OTHER WISE N TO NW WINDS 10 TO 20 KT OVER THE NRN WATERS
AND N TO NE WINDS 5 TO 15 KT OVER THE SRN WATERS. THE 12Z NCEP MAP
HAS A COLD FRONT ACROSS THE SRN WATERS AND INLAND HIGH PRES WITH
ITS RIDGE INTO THE WATERS N OF THE FRONT AND THE PRES GRADIENT IS
QUITE SLACK. THE SEAS ARE ALSO SMALL WITH PEAKS TO 8 FT OVER THE
BALTIMORE CANYON. SEAS RANGE BETWEEN 2 AND 6 FT ELSEWHERE. NWW3
AND ECMWFWAVE MODELS HAVE BOTH INITAILIZED WELL WITH THE 12Z SEAS
PATTERN AND THEY AGREE WELL THRU MOST OF THE PERIOD. WILL CONTINUE
SEAS STAYING CLOSE TO NWW3.

IN THE UPPERLEVEL THE MODELS HAVE INDICATED SOME ENERGY OVER THE
FAR NRN WATERS WILL PUSH DOWN IN THE NEXT DAY AND THAT WILL BE
FOLLOWED BY A STRONG UPPERLEVEL RIDGE WITH LITTLE TO NO ENERGY.
MORE ENERGY EMBEDDED IN AN UPPERLEVEL TROF FARTHER NW WILL THEN
FORCE THE RIDGE TO SHIFT E AND STRENGTHEN AND FORCE A CLOSED HIGH
PRES TO PERSIST E. THE STRENGTHENING OF HIGH TO THE E WILL FORCE
THE ENERGY TO STALL NEAR THE NRN WATERS IN THE EXTENDED PERIOD.

THE MODELS GFS/CMC/UKMETHR/ECMWFHR/NOGAPS HAVE INITILAIZED WELL
WITH THE 12Z OBSERVATIONS AND ARE IN DECENT AGREEMENT IN THE SHORT
TERM. THE ONLY FDIFFERECES ARE ON THE TIMING OF THE COLD FRONT
THAT SLATED TO REACH THE WATERS FROM THE W ABOUT TUE. OTHERWISE
MODELS ARE ARE IN GENERAL AGREEMENT ON THE MAJOR SYNOP FEATURES.
WILL STAY WITH GFS FOR THIS UPDATE.


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

OVER THE SHORT TERM...THE NEW 00Z MDLS PRESENT NO MAJOR FCST
PROBLEMS. THE MDLS SHARE SMLR FCST TIMING FOR THE COLD FRONT NOW
DRIFTING S ACRS THE CNTRL NT2 WTRS TO PUSH S INTO THE SRN NT2 WTRS
LATER TODAY...THEN PASS S OF THE WTRS TONITE WHILE A HIGH PRES
RIDGE BUILDS TO THE COAST SUPPORTING A MOD STRONG (GNRLY IN THE
15-25 KT RANGE) NLY POSTFRONTAL GRADIENT...WHICH WL BE STRONGEST
ACRS THE ERN NT1 AND NE NT2 WTRS. TO BETTER ACCOUNT FOR THE MOD
STRONG ASCD COLD AIR ADVECTION AND NEGATIVE STATIC STABILITY FCST
IN THIS NLY GRADIENT...SMLR TO THE PREV OFSHR FCST PACKAGE WL
POPULATE OUR FCST WINDS GRIDS WITH THE SMWHT HIGHER 00Z GFS FIRST
SIGMA LEVEL BL WINDS FOR TODAY AND TONITE...WHICH WL RESULT IN MAX
ASCD WINDS CONTG UP TO PRIMARILY 20 OR 25 KT. THEN THE 00Z MDLS
REMAIN IN GOOD AGRMT THAT THE RIDGE WL MOV OFSHR MON...THEN PASS E
OF THE OFSHR WTRS MON NITE WHILE A COLD FRONT APRCHS FROM THE W
CAUSING A STRENGTHENING SLY PREFRONTAL GRADIENT TO DVLP OFF THE
MID ATLC AND SRN NEW ENGLD COASTS. FOR THIS RIDGE PASSAGE AND SLY
GRADIENT WL TRANSITION TO POPULATING WITH THE REPRESENTATIVE AND
WEAKER 00Z GFS 10M BL WINDS ON MON AND MON NITE. SO AS A RESULT OF
THESE FCST WINDS DO NOT ANTICIPATE MAKING ANY MAJOR SHORT TERM
CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...THE SMLR 00Z NAM/GFS/ECMWF SOLUTIONS FOR THE
COLD FRONT TO SLOWLY MOV OFSHR ACRS THE NT1 AND NRN/CNTRL NT2
WTRS TUE/TUE NITE LOOK LIKE PERHAPS A RSNBL COMPROMISE BTWN THE MR
PROGRESSIVE 00Z UKMET AND SLOWER 00Z GLOBAL GEM SOLUTIONS.
THEREFORE FOR TUE/TUE NITE WL POPULATE WITH A 50/50 BLEND OF THE
00Z GFS 10M AND 00Z ECMWF BL WINDS. THE 00Z NAM/GFS/ECMWF ALSO
FCST SVRL LOWS TO DVLP ON THE FRONT AS ITS MOVES OFSHR TUE INTO
WED. BUT BASED ON THE LACK OF SUPPORT FM THE 00Z GEFS AND PER ITS
ASCD 6 HRLY PRECIP FCSTS...SUSPECT THAT THE 00Z GFS IS LIKELY
SUFFERING FM CONVECTIVE FEEDBACK AND AS A RESULT THE FRONTAL LOW
IT FCSTS TO TRACK NE ALONG ITS FRONT ACRS THE NRN NT2 WTRS TUE
NITE/EARLY WED WITH GALE FORCE ASCD BL WINDS IS LIKELY TOO STRONG.
THEREFORE WULD FAVOR THE WEAKER 00Z ECMWF SOLUTION BY WED/WED NITE
AND AS A RESULT WL TRANSITION TO POPULATING WITH ITS BL WINDS
THEN.

THEN THE DISPARITY INCREASES SIGLY BTWN THE 00Z GLOBAL MDLS ON
THU INTO THU NITE. VS ITS PREV 18Z RUN...IN RESPONSE TO A CLOSED
UPR LOW FCST TO DRIFT SE FM THE ERN GREAT LAKES TWDS THE MID ATCL
COAST WED NITE INTO THU NITE...THE 00Z GFS CONTS TO FCST AN ASCD
SFC LOW TO FORM OFF THE NRN MID ATLC COAST WED NITE...THEN DRIFT
SLOWLY ENE TWDS THE SRN NEW ENGLD COAST THU/THU NITE WHILE SLOWLY
PULLING A COLD FRONT E ACRS THE WRN NT2 WTRS. IN GNRL THE 00Z
GLOBAL GEM SUPPORTS THIS 00Z GFS SOLUTION BUT FCSTS A STRONGER SFC
LOW TRACKING FURTHER N. BY FCSTG A LESS PROGRESSIVE CLOSED UPR LOW
DIGGING FURTHER S TWDS N CAROLINA BY THU NITE...THE 00Z UKMET
FCSTS AN ASCD SFC LOW TO DVLP FURTHER S OFF THE CAROLINA COASTS
THU...THEN RETROGRADE INLAND OVER THE CAROLINAS LATE THU/THU NITE
WHILE A STRONG HIGH PRES RIDGE BUILDS IN FM THE N WHICH RESULTS IN
A MOD STRONG (UP TO 20-30 KT) NELY GRADIENT DVLPG OFSHR N OF A
STNRY FRONT...BCMG STRONGEST ACRS THE SRN NT1 AND NRN NT2 WTRS.
THE 00Z ECMWF HAS COME IN WITH A SOLUTION SMLR TO THE 00Z UKMET
WITH ITS ASCD SFC LOW FORMING NR THE N AND S CAROLINA BORDER WED
NITE...THEN RETROGRADING NWD FURTHER INLAND THU/THU NITE.
THEREFORE MAINLY SINCE ITS BEEN MR CONSISTENT... WITH LOW FCST
CONFIDENCE WL CONT TO POPULATE OUR FCST WIND GRIDS WITH THE 00Z
ECMWF BL WINDS ON THU/THU NITE.

.SEAS...A COMPROMISE BTWN THE SLIGHTLY HIGHER 00Z ECMWF WAM AND
00Z WAVEWATCH III LOOKS TO HV INITIALIZED THE CURRENT SEAS BEST
AT THE MOMENT. WITH THIS IN MIND AND WITH THEIR ASCD 00Z GFS/ECMWF
SOLUTIONS BEING SMLR...WL POPULATE OUR FCST WAVE GRIDS WITH A
50/50 BLEND OF THE TWO WAVE MDLS FOR TODAY INTO TUE NITE. THEN
SINCE THE 00Z ECMWF SOLUTION WL BCM FAVORED...WL TRANSITION TO
POPULATING WITH ALL 00Z ECMWF WAM FCST SEAS FOR WED THRU THU NITE.

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



.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID-ATLANTIC WATERS...
     NONE.

$$

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
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FOR THE SERVICE CHANGE NOTICE...PLEASE GO TO
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.FORECASTER MUSONDA/MUSONDA/VUKITS. OCEAN PREDICTION CENTER.


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