Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 291329
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
930 AM EDT FRI 29 APR 2016

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

AT 12Z SOME STRONG TO POSSIBLY SEVERE TSTMS WERE LOCATED ALONG A
LINE ABOUT 100 NM SE OF CAPE HATTERAS TO 100 NM SE OF CAPE FEAR.
STRONGEST WINDS WERE LIKELY INVOF 33.7N74.7W WHERE OVERSHOOTING
TOP AND LIGHTNING DENSITY PRODUCTS INDICATING STRONGEST UPDRAFTS
OCCURRING. LATEST HRRR AND RAP NOT INITIALIZED VERY WELL BUT DO
SHOW CELLS WEAKENING THROUGH THE AFTERNOON. MODELS ARE IN GOOD
AGREEMENT OVER THE NEXT COUPLE DAYS...FIRST WITH SURFACE LOW
CURRENTLY ABOUT 200 NM E OF NORFOLK VA SLOWLY MOVING E TODAY AND
TONIGHT BEFORE A HIGH PRES RIDGE MOVES OFF THE COAST SAT AND
CONTINUES E ACROSS THE WATERS SAT NIGHT INTO SUN. BY EARLY NEXT
WEEK 00Z ECMWF AND 00Z UKMET ARE IN GOOD AGREEMENT IN MOVING
ANOTHER SURFACE LOW S OF LONG ISLAND AND THROUGH THE NT1 WATERS.
GFS IS S OF THE UKMET AND ECMWF TRACK...WHILE THE GFSX SUPPORTS
THE UKMET/ECMWF TRACK. GFS HAS BEEN CONSISTENTLY STRONGER THAN
ECMWF/UKMET WITH WINDS SUN NIGHT INTO MON NIGHT. 00Z ECMWF/UKMET
ALSO SUGGESTING POSSIBILITY OF GALES OVER OUTER HUDSON TO
BALTIMORE WATERS AND GEORGES BANK ANZ900. WILL WAIT FOR FULL 12Z
GUIDANCE SUITE BEFORE ADDING ANY GALES.

BOTH THE 06Z MULTIGRID WAVEWATCH III AND THE 00Z ECMWF WAM HAVE
BEEN WELL INITIALIZED WITH THE W ATLC WAVE HEIGHTS THIS MORNING.
THESE MODELS ARE IN VERY GOOD AGREEMENT THROUGH SUN NIGHT. THEN
WITH GFS STRONGER THAN ECMWF WITH MON/MON NIGHT WINDS THE
WAVEWATCH III 3 TO 5 FT HIGHER WITH WAVE HEIGHTS NORTHERN NT2
AND GEORGES BANK AT THAT TIME.

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

SUMMARY...00Z NCEP SFC ANALYSIS SHOWS A STATIONARY FRONT EXTNDG
E TO W ACROSS THE CENTRAL NT2 WTRS...WITH A HI PRES RIDGE OVER
THE OFSHR WTRS S OF THE FRONT AND ANOTHER RIDGE BUILDING SE
TOWARDS THE NT1 AREA. LATEST AVAIL ASCATB HI-RES AND RSCAT
PASSES FROM EARLIER TONITE SHOW A SWATH OF 20 TO 30 KT WINDS IN
SW FLOW OVER ZONES 910 AND 920 IN THE NRN NT2 WTRS. LIGHTNING
DENSITY PRODUCT DATA AT 0630Z SHOWS A BROAD LINE OF SHOWERS AND
TSTMS EXTNDG E TO W ALONG THE STATIONARY FRONT OVER THE CENTRAL
NT2 WTRS.

MAIN WEATHER FEATURES...A COUPLE OF WEAK LOWS WILL PASS E ACROSS
THE CENTRAL NT2 WTRS TODAY. A DVLPG LOW WILL MOVE NE OVER THE
NRN NT2 WTRS SUN NITE AND MON...THEN MOVE OFF TO THE NE MON NITE
AND TUE WHILE STRENGTHENING.

MODELS...THE 00Z MED RNG MDLS ARE IN GUD OVERALL AGREEMNT THRU
THE FCST PRD...EXCEPT THE 00Z GFS IS FASTER WITH THE DVLPG LOW
FOR MON INTO TUE...WHILE THE 00Z GEM IS A BIT MORE NW WITH THE
TRAJECTORY OF THIS LOW. ALSO THE 00Z GFS 30M SOLN LOOKS OVERDONE
WITH STRENGTH OF THE SW FLOW S OF THE LOW FOR MON INTO TUE. ATTM
BELIEVE THE BEST MEDIAN MDL SOLN IS THE 00Z ECMWF...AND IT WILL
BE USED TO POPULATE THE WIND GRIDS THRU THE ENTIRE FCST PRD.

SEAS...BOTH THE WNA VERSION OF THE 00Z WAVEWATCH III MDL AND 00Z
ECMWF WAM INITIALIZED WELL ACROSS THE OFSHR WTRS...AND ARE IN
GUD AGREEMENT THRU SUN NITE. THE WNA WAVEWATCH III LOOKS
OVERDONE FOR MON INTO TUE...SO WILL JUST USE THE ECMWF WAM THRU
THE ENTIRE FCST PRD.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER CLARK/SCOVIL. OCEAN PREDICTION CENTER.



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