Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 271306
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
906 AM EDT WED MAY 27 2015

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

HIGH PRES RIDGE CURRENTLY ACROSS THE CENTRAL AND SRN NT2 WATERS
IS FORECAST TO REMAIN IN PLACE THROUGH SUN. THE MODELS ARE IN
REASONABLE AGREEMENT THAT ONE COLD FRONT WILL APPROACH THE NT1
WATERS TODAY AND TONIGHT...THEN MOVE INTO THE OFFSHORE WATERS BY
THU NIGHT WHILE WEAKENING. STILL EXPECT SW WINDS UP TO 25 KT OR SO
ACROSS PORTIONS OF THE NT1 WATERS TODAY INTO THU AS THE FRONT
APPROACHES. SW FLOW WILL THEN RETURN TO THE NRN NT2 AND NT1 WATERS
BY LATE FRI AS THE FRONT DISSIPATES. ANOTHER COLD FRONT IS THEN
EXPECTED TO APPROACH THE NT1 WATERS BY LATE SAT. THE FRONT WILL
THEN SINK SOUTH INTO THE NRN NT2 WATERS BY EARLY MON. THE GFS
CONTINUES TO BE ABOUT 6 HOURS FASTER WITH THE SPEED OF THE FRONT
THAN MOST OF THE OTHER GUIDANCE SO WILL LEAN TOWARDS THE SLIGHTLY
SLOWER SOLUTIONS. FOR WIND GRIDS...WILL CONTINUE TO USE THE GFS
10M WINDS...EXCEPT WILL SLOW THE GFS FRONTAL SPEED DOWN BY 6 HOURS
BY SUN.

SEAS...THE NWW3 AND ECMWF WAM CONTINUE TO BE IN REASONABLE
AGREEMENT THROUGH SUN SO WILL USE A 50/50 BLEND. AFTER SUN THE
MODELS ARE SHOWING SOME DIFFERENCES SO WILL LEAN MORE TOWARDS THE
NWW3 BUT SLOW IT DOWN BY 6 HOURS SIMILAR TO THE WINDS.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

HIGH PRES RIDGE EXTENDING INTO THE CENTRAL NT2 WATERS RMNS THE
DOMINANT WEATHER FEATURE AFCTG THE OFSHR ZNS AS IT MAINTAINS LITE
WINDS THRUT THE RGN. ASCAT METOP-B PASS JUST AFTER 02Z RETURNED S
TO SW WINDS GNRLY IN THE 10-20 KT RANGE N OF THIS RIDGE ACRS NT1
WITH THE CORE OF HIEST WINDS ACRS THE SRN GULF OF MAINE. FARTHER
S ACRS SRN NT2 AND S OF THE RIDGE LITE S TO SELY WINDS WERE
RETURNED IN THE ASCAT PASSES GNRLY IN THE 10-15 KT RANGE. THESE
SFC WINDS ACRS BOTH NT1 AND NT2 WTRS MATCH WELL WITH INITIAL
OUTPUT FROM THE 00Z GFS 10M BL WINDS.

OVER THE SHORT TERM...THE 00Z MDLS REMAIN IN GOOD AGRMT THAT LTL
CHNG WL OCCUR IN THE PATTERN WITH THE HIGH PRES RIDGE FCST TO RMN
IN PLACE ACRS THE CNTRL NT2 WTRS THRU THU MAINTAINING THE MOD
STRONG (UP TO 20 OR 25 KT) SWLY GRADIENT ACRS THE NT1 WTRS. THEN
LATE THU/THU NITE THE MDLS WITH SLIGHT TIMING DIFFERENCES ALL FCST
A WEAK CDFNT TO MV OFSHR INTO THE NT1 WTRS. IN COMPARISON WITH THE
00Z UKMET/GEM...THE 00Z GFS LIKELY FCST THIS FRONT TO PUSH A LTL
TOO FAR S...BUT BY FRI MORNING ITS ASCD FCST GRADIENTS BCM SO WEAK
THAT THE LTST 00Z GFS 10M BL WINDS STILL LOOK REASONABLE.

IN THE LONG RANGE...THE LATEST GLOBAL MDLS AGREE THAT THE MOST SIG
WEATHER FEATURE WL BE ANOTHER SMWHT STRONGER CDFNT MOVG OFSHR INTO
THE NRN WTRS SAT NITE INTO SUN NITE. THE 00Z GFS RMNS THE FASTEST
SOLN AS COMPARED TO THE 00Z NON-NCEP UKMET/GEM/ECMWF SLOWER SOLNS
AND IS 6-12 HRS SLOWER COMPARED TO THE GEFS MEAN. AS ALLUDED TO
IN THE PREV DISCUSSION WL TIME SHIFT THE 00Z GFS 10M BL WINDS 6
HRS SLOWER TO A PSN JUST S OF THE NT1 WTRS BY LATE SUN NITE TO
BETTER MATCH THE SLOWER CONSENSUS WITH THE FROPA.

.SEAS...SIG WVHTS WILL BE POP USING A 50/50 BLEND OF THE 00Z WW3
WNA AND 00Z ECMWF WAM THRU UNTIL 18Z SUN TO SMOOTH OUT ONLY MINOR
DIFF BETWEEN THE TWO WV MDLS. WL THEN USE 00Z WNA WITH 6 HR SLOWER
TIME SHIFT TO MATCH THE PREFERRED SLOWER FROPA ACRS NT1 SUN AND
SUN NITE.

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



.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER NOLT/COLLINS/VUKITS. OCEAN PREDICTION CENTER.


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