Marine Interpretation Message
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
AGNT40 KWNM 310104
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
904 PM EDT THU JUL 30 2015

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

A LOW PRES CENTER OVER THE SRN NT2 WTRS HAS MAX ASCD WINDS GNRLY
IN THE 20-30 KT RANGE OVER ITS SE QUADRANT PRETTY MUCH AS PREVLY
FCSTD. ELSWHR A GNRLY WEAK SSWLY GRADIENT PERSISTS THRUT MUCH OF
THE RMNG CSTL/OFSHR WTRS. MAX SEAS THRUT ARE ASCD WITH THE SFC LOW
AND ARE UP TO 7-12 FT...HIGHEST OVER THE SE MOST NT2 WTRS...WHICH
ARE HIGHER THAN FCST BY EITHER THE 12Z ECMWF WAM OR 18Z WAVEWATCH
III...SO WL HV TO ADJUST THE IMMED SHORT TERM FCST SEAS THERE.

OVER THE SHORT TERM...THE LATEST MDLS ARE IN RSNBLY GOOD AGRMT
WITH THEIR FCST TRACK OF THE SFC LOW...S ACRS THE SRN NT2 WTRS
TONITE...THEN TURNING NE ACRS THE CNTRL/NE NT2 WTRS FRI/FRI NITE.
BUT THEY CONT TO DIFFER IN THEIR FCST STRENGTH OF THE LOW WITH THE
18Z/12Z GFS SMLR TO THE SMWHT WEAKER 12Z ECMWF...WHL THE 12Z
GEM/UKMET FCST A SMWHT STRONGER AND IDENTIFIABLE SFC LOW. AS A
COMPROMISE WL CONT TO USE THE PREVLY POPULATED 12Z GFS 30M BL
WINDS AND WL CONT WITH LOW FCST CONFIDENCE MARGINAL GALES DVLPG IN
NT2 ZONE ANZ925 ON FRI. ELSEWHR WL TONE DOWN THESE GFS 30M BL
WINDS SMWHT OVER THE COLDER NT1 WTRS IN DEFERENCE TO THE 12Z ECMWF
THRU THE SHORT TERM. SO PLAN ON MAKING JUST SM SMALL SHORT TERM
CHNGS IN THE NEXT OFSHR FCST PACKAGE.

IN THE LONG RANGE...THE LATEST GLOBAL FCST A RELATIVELY QUIET
PATTERN TO PERSIST. THE MOST SIG FEATURE WL BE A COLD FRONT FCST
TO APRCH FM THE NW MON/MON NITE...THEN DRIFT OFSHR INTO THE NT1
AND NWRN NT2 WTRS TUE/TUE NITE. THE NEW 18Z GFS LOOKS A LTL TOO
FAST WITH THIS FRONT SO WL CONT TO FAVOR THE SMLR 12Z GFS/ECMWF
FROPA TIMING. FOR THE MOD STRONG SSWLY GRADIENT FCST BY ALL OF
THE MDLS TO DVLP INADVOF THIS FRONT...WULD ALSO FAVOR A 50/50
BLENDED 12Z GFS 10M AND 12Z ECMWF BL WIND SOLUTION. THE ONLY TWEAK
TO THE PREV FCSTS WL BE TO START TO USE THIS BLEND SOONER...MON VS
THE PREVLY FCST MON NITE (THE SAME WL BE DONE WITH THE 50/50 BLEND
OF THE 12Z WAVEWATCH III AND 12Z ECMWF WAM WAVE MDLS). SO
OTHERWISE NO SIG LONG RANGE CHNGS ARE PLANNED TO THE PREV OFSHR
FCSTS.


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

SUMMARY...12Z NCEP SFC ANALYSIS SHOWS A STNRY FNT ARCING ACROSS
THE CNTRL NT2 AREA...WITH ANOTHER STNRY FNT EXTNDG NW TO SE OVER
THE GULF OF MAINE AND GEORGES BANK WTRS...AND A TROF EXTNDG S FROM
CAPE HATTERAS TO 31N. OTHERWISE WEAK HI PRES RIDGING PREVAILS
OVER THE OFSHR WTRS THIS MRNG. LATEST AVAIL ASCATB PASSES FROM
THIS MRNG SHOW A SWATH OF 20 KT WINDS IN W TO SW FLOW OVER THE
OUTER GEORGES BANK WTRS. OTHERWISE...ASCAT ONLY SHOWS LIGHT WINDS
OF 15 KT OR LESS OVER THE OFSHR WTRS. WEAK COLD FNTS WILL MOVE
ACROSS THE NT1 AND NRN NT2 WTRS FRI AND FRI NITE...THEN AGAIN SAT
NITE INTO SUN. A STGR COLD FNT IS EXPCTD TO MOVE E AND APRCH THE
ERN SEABOARD LATE MON NITE...THEN MOVE OFSHR TUE AND TUE NITE.

MODELS...THE 12Z MED RNG MDLS ARE IN GUD OVERALL AGREEMNT ACROSS
THE OFSHR WTRS THRU THE FCST PRD. ALTHO THERE ARE SOME MINOR
STRENGTH DIFFS WITH THE SW FLOW OVER THE NT2 WTRS ON FRI AND FRI
NITE...SOME OF THE MDLS INDICATE MARG GALES IN AND ARND THE GULF
STREAM...MAINLY THE 12Z GEM AND 12Z NAM...SO WILL KEEP THE GALE
WRNGS UP FOR THE NT2 WTRS. THE GFS HAS BEEN VRY REPRESENTATIVE
THE PAST FEW DAYS AND HAS ALSO SHOWN VRY GUD RUN TO RUN
CONSISTENCY...PLUS IT ALSO HAS GUD SUPPORT FROM THE LATEST WPC MED
RNG FCSTR GUIDANCE. THE 12Z GFS 30M SOLN LOOKS LIKE A GUD FIT
BTWN THE STGR 12Z GEM AND THE WEAKER 12Z ECMWF...SO IT WILL BE
USED FOR THE WIND GRIDS FOR TODAY THRU MON. A 50/50 BLEND OF THE
GFS 30M/ECMWF APRS TO BE THE MOST REPRESENTATIVE SOLN FOR MON
NITE THRU TUE NITE...SO IT WILL BE USED FOR THIS TIMEFRAME.

SEAS...THE WNA VERSION OF THE 12Z WAVEWATCH III AND 12Z ECMWF WAM
BOTH INITIALIZED WELL ACROSS THE OFSHR WTRS. WILL BE MATCHING THE
SEA HT MDLS WITH THE ATMOS MDLS...SO THE 12Z WNA WW3 WILL BE USED
TO POPULATE THE SEA HT GRIDS FOR TODAY THRU MON THEN WILL SWITCH
TO USING A 50/50 BLEND OF WNA WW3/ECMWF WAM FOR MON NITE THRU TUE
NITE.

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


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...
     GALE FRI.

$$

.FORECASTER VUKITS/SCOVIL. OCEAN PREDICTION CENTER.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.