Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 011312
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
912 AM EDT SAT AUG 1 2015

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

GOES VIS IMGRY AND THE LGTNG DENSITY PROD INDC A FRNTL SYS OVR
NT2 WITH SHOWERS AND TSTMS ALNG THE BNDRY...WITH A WAVE JUST E OF
NE NT2. RSCAT FM 0800 UTC INDC A LRG AREA OF 30 KT JUST SE OF NRN
NT2 WTRS...WITH A VRY SML AREA OF GALES. CRNT SFC RPRTS INDC WNDS
TO 30 KT INVOF THE FRNT...AND 06Z GFS WNDS ARE INIT OK WHEN
COMPARED WITH THE DATA. THE MDL INDC THE FRNTL WAVE WL MOV OFF TO
THE NE TDA...THO THE TAIL END OF THE BNDRY WL STALL OVR C NT2 AND
WKN OVR THE NEXT 24 HRS. THE REST OF THE 00Z/06Z MDLS AGREE WELL
WITH THE GFS IN THE SHORT TERM WITH THIS FEATURE...AND THE 06Z GFS
HAS NOT CHANGED MUCH FM THE 00Z RUN...SO NOT PLANNING ON MKG ANY
SIG CHANGES IN THE SHORT TERM.

THE GOES WV INDC AN UPR RDG OVR THE WRN AND C ATLC...AND A TROF
MOVG INTO THE GRT LKS RGN. THE MODIS RGB IMGRY RM 03Z INDC WK H5
ENERGY ASSOC WITH THE UPR TROF...AND THE LTST NCEP SFC ANALYS A WK
BNDRY MOVG INTO NEW ENGLAND...HEADING TWD THE COAST. THE MDLS ALL
INDC THE WK FEATURE WL PASS THRU NT1 TNGT AND SUN...WITH ONLY
MINOR DIFFS ON THE TMG...SO PLANNING ON STAYING WITH GFS ON THIS
SYS.

OTRW...THE MDLS STILL HAVING TMG ISSUES FM TUE THRU THE END OF THE
PD...WITH THE GFS A LTL MORE PRGSV THAN THE ECWMF/UKMET WITH THE
NEXT SHRTWV TROF PASSING THRU THE AREA. THE GFS CONT TO INDC A
SLGTLY FLATTER C ATLC RDG THAN THE REST OF THE MDLS...WHICH ALLOWS
THE SHRTWV TO PRGRS ABT 6 HRS FASTER THAN THE ECWMF. THE PREV FCST
USED THE GFS...WITH A +6 HOUR TIMESHIFT TO CMPRMS TMG DIFFS. THIS
STILL SEEMS LIKE A RSNBL STRATEGY...SO WL CONT WITH IT FOR THE
UPDATE PKG.

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

OVER THE SHORT TERM...AN EARLIER 0129Z RAPIDSCAT SCATTEROMETER
PASS CONFIRMED THAT THE SFC LOW MOVG NE OVER THE CNTRL NT2 WTRS
HAD MARGINAL ASCD GALE FORCE WINDS ACRS THE OUTERMOST CNTRL NT2
WTRS. PER A CONSENSUS OF THE 00Z MDLS EXPECT THE LOW TO TRACK FAR
ENUF NE THAT ITS ASCD GALES WL SHIFT E OF THE NT2 WTRS BY THE
START OF THE TODAY FCST PERIOD. OTHERWISE THE 00Z MDLS ARE IN
RSNBL GOOD AGRMT THAT A WEAK COLD FRONT WL MOV TO THE NEW
ENGLD/NRN MID ATLC COASTS BY LATE TODAY...MOV OFSHR TONITE...THEN
DSIPT SUN. ELSWHR THE MDLS ALL FCST A HIGH PRES RIDGE INVOF
BERMUDA TO GRADLY STRENGTHEN THRU SUN NITE WHICH WL RESULT SPRT A
WEAK...TO AT TIMES MODERATE...SSWLY GRADIENT TO DVLP THRUT ALL OF
THE CSTL/OFSHR WTRS. OVERALL BLV THE 00Z GFS SOLUTION LOOKS
REPRESENTATIVE FOR THIS GRADIENT THOUGH BLV AT TIMES IT IS HAVING
SM CONVECTIVE FEEDBACK PROBLEMS (THE 00Z GEM IS HAVING EVEN WORSE
FEEDBACK PROBLEMS) WHICH RESULTS IN IT FCSTG PULSES OF HIGHER
WINDS ACRS THE NT2 WTRS WHICH ARE LKLY OVERDONE. THEREFORE WL
POPULATE OUR SHORT TERM FCST WIND GRIDS WITH THE 00Z GFS 10M BL
WINDS FOR TODAY THRU SUN NITE...BUT TO TWEAK DOWN THE PULSES OF
HIGHER WINDS ACRS THE NT2 WTRS WL MAKE SM ADDITIONAL FURTHER EDITS
IN DEFERENCE TO THE 00Z UKMET/ECMWF. SO AS A RESULT ANTICIPATE
MAKING ONLY MINOR SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...WULD FAVOR THE MR CONSISTENT 00Z GFS SOLUTION
WHICH IS MR IN LINE WITH THE LATEST WPC MEDIUM RANGE GUIDANCE FOR
A COLD FRONT MOVG OFF THE NEW ENGLD COAST MON NITE/TUE...WASHING
OUT TUE NITE...FLWD BY A SCNDRY COLD FRONT MOVG OFSHR INTO THE NRN
WTRS LATE TUE NITE/WED...THEN BCMG STNRY ACRS THE NRN NT2 WTRS WED
NITE. THE 00Z ECMWF IS SMLR TO THE 00Z GFS BUT IS SLOWER WITH THE
FIRST FRONT AND THEN LOOKS A LTL TOO PROGRESSIVE WITH SECOND FROPA
ON WED NITE. THE 00Z GEM/UKMET AT VARIOUS TIMES IN THE LONG RANGE
BOTH LOOK TO CONT TO BE HAVING CONVECTIVE FEEDBACK PROBLEMS WITH
THE SFC LOWS THEY SPIN UP IN THE SWLY GRADIENT ACRS THE NT2 WTRS
AND HENCE WL BE DISREGARDED. THEREFORE WL CONT TO POPULATE OUR
LONG RANGE FCST WIND GRIDS WITH THE 00Z GFS 10M BL WINDS...BUT IN
DEFERENCE TO THE SLOWER 00Z ECMWF SOLUTION FOR THE MON NITE/TUE
FROPA...WL TIME SHIFT THESE FCST WINDS 6 HRS SLOWER LATE MON NITE
AND BEYOND. SO SINCE A SMLR TIME SHIFTED VERSION OF THE PREV GFS
WAS USED...DO NOT PLAN ON MAKING MAJOR LONG RANGE CHNGS TO THE
PREV OFSHR FCSTS.

SEAS...OVERALL THE 00Z WAVEWATCH III AND 00Z ECMWF WAM MDLS HV
INITIALIZED THE CURRENT SEAS WELL. THEREFORE WL USE A 50/50 BLEND
OF THE TWO MDLS FOR TODAY INTO MON NITE. THEN SMLR TO THE FCST
WINDS WL GO ALL 00Z WAVEWATCH III FCST SEAS TUE INTO WED
NITE...TIME SHIFTED 6 HRS SLOWER ALSO.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER KELLS/VUKITS. OCEAN PREDICTION CENTER.


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