Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 290119
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
919 PM EDT FRI AUG 28 2015

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

THE 18Z GFS AND NAM MDLS ARE SIMILAR TO THE 12Z COUNTERPARTS THIS
EVE. WE WILL NOT MAKE SIG CHANGES TO THE PREV FCST FOR THE EVE
UPDATE. WE WILL ADJUST THE FCST AS NEEDED BASED ON THE LATE EVE
T.S. ERIKA ADVISORY FROM NHC AND ALSO ADJ GRIDS TO FIT CURRENT
CONDITIONS AND TWEAK THEM ESPEC WITH NEARBY TAFB GRIDS. OTW...
THE STNRY FRONT PERSISTS FROM SW TO NE OVR NT2 OFF WTRS PER THE
00Z PRELIM OPC SFC ANALYSIS. WK LOWS ARE STILL FCST TO TRACK NE
ALONG THE FRONT OVR THE NEXT FEW DAYS. THE LATEST SATELLITE IMGRY
AND LIGHTNING DATA INDICATES A FEW SCTD TSTMS NEAR THE FRONT
EXTENDING NE FROM COASTAL GEORGIA AND SRN SOUTH CAROLINA. LOCALLY
GUSTY WINDS AND ROUGH SEAS CAN BE FOUND IN OR NR ANY OF THE
HEAVIER TSTMS MAINLY OVR SRN AND CENTRAL NT2 OFF WTRS TONITE INTO
THE WKND.

SEAS...SEA HTS RANGE FROM 6 FT OVR SRN NT2 OFF WTRS TO 2 FT OVR
THE NRN GULF OF MAINE PER THE 00Z RA1 SEA STATE ANALYSIS. SEA HTS
OFF THE GEORGIA AND SOUTH CAROLINA COASTS ARE RUNNING A COUPLE FT
ABV MDL GUID AND THE PREV FCST. WE WILL ADJUST SEA HTS UPWARD
SLIGHTLY OVR THIS REGION AS A RESULT FOR THE EVE UPDATE. OTW...
LITTLE CHANGE CAN BE EXPECTED.

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

OVER THE SHORT TERM...THE NEW 12Z MDLS PRESENT NO SIG FCST
PROBLEMS. THE 12Z MDLS GNRLY AGREE THAT A HIGH PRES RIDGE WL
BUILD OFSHR INVOF 40N TONITE/SAT...THEN SHIFT S INTO THE SRN NT2
WTRS BY SUN NITE WITH A WSWLY GRADIENT DVLPG TO ITS N WITH MAX
ASCD WINDS RMNG ONLY IN THE 15 OR 20 KT RANGE AT MOST. AS WAS DONE
PREVLY...PLAN ON POPULATING OUR SHORT TERM FCST WIND GRIDS WITH
THE 12Z GFS 10M BL WINDS FOR TONITE THRU SUN NITE WITH SM
ADDITIONAL MINOR EDITS IN DEFERENCE TO THE 12Z UKMET/ECMWF. SO AS
A RESULT PLAN ON MAKING ONLY MINIMAL SHORT TERM CHNGS TO THE PREV
OFSHR FCSTS.

IN THE LONG RANGE...FOR THE NRN WTRS THE 12Z GFS/ECMWF AGREE THE
MOST SIG FEATURE WL BE A COLD FRONT WHICH THEY SHARE SMLR TIMING
FOR WL PUSH S ACRS THE NT1 WTRS MON NITE...THEN CONT S ACRS THE
NRN/CNTRL NT2 WTRS TUE WHL WKNG. OTHERWISE THE BIGGEST LONG RANGE
FCST PROBLEM REMAINS THE FUTURE TRACK OF T.S. ERIKA...IF SHE STILL
EXISTS BY THEN. VS ITS PREV 06Z RUN...THE 12Z GFS HAS NOW FLIP-
FLOPPED BACK TO A SOLUTION CLOSER TO ITS PREV 00Z RUN OF A WEAKER
SYSTEM TRACKING FURTHER S AND MOVG SLOWLY WNW INTO THE NERN GULF
OF MEXICO SUN INTO WED NITE WITH NO SIG IMPACTS ON THE NT2 OFSHR
WTRS. ON THE OTHER HAND THE 12Z CANADIAN GLOBAL GEM LOOKS LIKE A
TOO STRONG AND TOO PROGRESSIVE OUTLIER SOLUTION. THE 12Z UKMET
FCST TRACK IN GNRL IS SMLR TO THE 12Z GFS BUT IS SIGLY FASTER WITH
ITS FCST LOW MAKING LANDFALL OVER THE NW FLORIDA PANHANDLE ON TUE.
THE 12Z ECMWF FCST TRACK IS VERY SMLR TO THE WEAK 12Z GFS FCST
TRACK AND BY 03/12Z THE TWO MDLS FCST NRLY IDENTICAL FCST PSNS FOR
THEIR FCST LOWS OVER THE NE GULF OF MEXICO NR 29N86W. THE 12Z GFDL
REMAINS ON THE ERN SIDE OF THE FCST TRACK ENVELOPE WITH ITS FCST
LOW TRACKING N INVOF 80W MON NITE THRU TUE NITE...THEN MAKING
LANDFALL INTO S CAROLINE WED. THE 12Z HWRF TRACK IS SLIGHTLY W OF
THE 12Z GFDL...BUT IS SM 6-12 HRS FASTER. WITH SUCH A HIGH DEGREE
OF MDL DISPARITY HV VERY LITTLE FCST CONFIDENCE ON ANY ON
PARTICULAR MDL SOLUTION FOR ERIKA. BUT IF FORCED TO CHOOSE WULD
USE A BLENDED 12Z GFS/ECMWF SOLUTION. OF COURSE THO WL HV TO WAIT
FOR THE NEXT HURCN CONFERENCE CALL AND THE NEXT NHC FCST ADVSRY
BEFORE MAKING ANY SIG CHNGS TO PREV NT2 FCST. SO FOR NOW PLAN ON
TRANSITIONING TO POPULATING OUR LONG RANGE FCST WIND GRIDS WITH
THE 12Z ECMWF BL WIND SOLUTION...WHICH ACRS THE NRN WTRS IS SMWHT
LESS PROGRESSIVE THAN THE 12Z GFS AND CLOSER TO THE LATEST WPC
MEDIUM RANGE GUIDANCE...FOR MON THRU WED NITE.

.SEAS...TO MATCH THE FCST WINDS USED...WL POPULATE OUR FCST WAVE
GRIDS WITH THE 12Z WAVEWATCH III FOR TONITE THRU SUN NITE...THEN
WL TRANSITION TO THE 12Z ECMWF WAM FCST SEAS FOR MON THRU WED
NITE.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER MILLS/VUKITS. OCEAN PREDICTION CENTER.



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