Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 261320
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
920 AM EDT TUE 26 JUL 2016

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

A 09Z RAPIDSCAT OVERPASS RETURNED W TO SW WINDS TO 25 KT ACROSS
THE GULF STREAM THROUGH OUTER ZONES ANZ910 ANZ920 AND ANZ925.
ALSO THERE WERE LIMITED 25 KT RETRIEVALS ACROSS INNER WATERS
FROM HUDSON CANYON TO CAPE CHARLES LIGHT. OPC WIND GRIDS WHICH
WERE BASED ON THE 00Z GFS WERE QUITE CONSISTENT WITH RAPIDSCAT.
OVERNIGHT MODELS CONTINUED TO BE IN GOOD AGREEMENT ACROSS THE W
ATLC FOR THE NEXT FEW DAYS. ALTHOUGH SLIGHLY LESS PROGRESSIVE
THAN ITS PREVIOUS 00Z RUN...THE 06Z GFS WAS STILL ABOUT 12 HOURS
OR SO FASTER THAN THE 00Z ECMWF/UKMET WITH THE DEVELOPING LOW
MOVING OFF THE NRN MID ATLC COAST LATE FRI NIGHT AND SAT.
PREVIOUS OPC WIND GRIDS LOOK REASONABLE THROUGH THE FORECAST
PERIOD AND WILL NOT BE MAKING SIGNIFICANT ADJUSTMENTS THIS
MORNING. THE 00Z/06Z WAVEWATCH III AND 00Z ECMWF WAM ARE WELL
INITIALIZED WITH THE W ATLC WAVE HEIGHTS THIS MORNING.

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

CRNT LGTNG DENSITY PROD INDC TSTMS ACRS NE NT2 NEAR N WALL OF
GULF STREAM IN W TO SW FLOW...AND ALSO ALONG A LOW PRES TROF
NEAR THE MID ATLC COAST. THE 00Z GFS/ECMWF INDC A MDT AMT OF
INSTABILITY OVR NT2 WITH THE PREDOMINANTLY SW FLOW INJECTING
HEAT/MOISTURE INTO THE PBL. ALSO...THE MDLS INDC A PAIR OF SFC
BNDRYS OVER THE AREA IN THE SHORT RANGE...TO ACT AS A FOCUS FOR
CONVECTION...OVR NRN NT2. THE PREV FCST CARRIED SCTRD TSTMS AND
SHOWERS IN NT2...SO PLANNING ON MAINTAINING MENTION IN THE NEXT
PKG.

OTRW...THE 00Z MDLS ALL INDC THE AFOREMENTIONED SFC TROF WL MOVE
INTO THE AREA EARLY TDA...FLWD BY A FRNTL BNDRY CRNTLY JUST SE
OF THE GREAT LAKES REGION...LATER TDA INTO TNGT. 0235Z ASCAT
WIND RETRIEVALS AND CRNT SFC RPRTS INDC WINDS CRNTLY UP TO 20 KT
IN THE SW FLOW AHD OF THE SFC TROF...AND 0235Z RSCAT WINDS
EXTEND A LTL FURTHER E OVER THE GULF STREAM AND INDC 25 KT. THE
00Z GFS WNDS ARE INIT OK WHEN COMPARED WITH THE CRNT DATA...AND
INDC THAT THE WINDS WL NOT INCRS ANY FURTHER THAN 25 KT AHEAD OF
THE TWO BNDRYS. THE 00Z GFS AGREES FAIRLY WELL WITH THE 00Z
ECMWF/UKMET/NAM/GEM MDL RUNS WITH THE TMG OF THE BNDRY...BUT IS
SLGTLY STGR THAN THE ECMWF/UKMET...AND A LTL WKR THAN THE 00Z
NAM/GEM. ATTM THE GFS SEEMS TO BE ABT THE BEST CMPRMS SOLN IN
THE SHORT RANGE...AND SEEMS MOST RSNBL...SO PLANNING ON FAVORING
IT INTO THU NGT WHICH KEEPS FCST IN LINE WITH PREV ONE.

THE BIGGEST FCST PROBLEM IS IN THE EXTENDED PD...AS THE 00Z GFS
IS A FAST OUTLIER WITH THE NEXT SYS ON FRI INTO SAT. THE GFS HAD
SLOWED SLIGHTLY TWD THE OVERALL MDL CONSNESUS WITH THE 18Z
RUN...BUT HAS TRENDED FASTER AND AWAY FM IT WITH THE 00Z RUN. IN
ADDITION...THE 00Z UKMET/GEM HAVE TRENDED TWD THE CONSISTENT
ECMWF SOLN...WHICH IS ALSO SUPPORTED BY THE 00Z GEFS/ECWMF/NAEFS
MEAN SOLNS. AS A RESULT...PLANNING ON FAVORING THE 00Z ECMWF
SOLN FROM FRI 06Z ONWARD...THO WL BOOST WINDS INVOF THE GULF
STREAM WHERE THE ECMWF WINDS SEEMS A BIT LOW.

.SEAS...BOTH THE 00Z WAVEWATCH III AND ECMWF WAM MDLS HV BOTH
INITIALIZED THE CURRENT W ATLC WAVE HEIGHTS VERY WELL...WITH WV
HTS CRNTLY 6 FT OR LESS IN THE W ATLC. THE MDLS ARE IN GOOD
AGREEMENT INTO FRI...SO PLANNING ON USING 00Z WW3 UNTIL THEN. WL
THEN SWITCH TO 00Z ECMWF WAVE SOLN BY 06Z FRI...TO REFLECT
PREFERRED WX MDL TRENDS. ALSO...WW3 BUILDS SEAS FASTER THAN THE
ECMWF WAM...AS A RESULT OF STGR WINDS WITH THE FASTER LOW...SO
PREFER TO STAY AWAY FM IT ATTM.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER CLARK/KELLS. OCEAN PREDICTION CENTER.


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