706
AGNT40 KWNM 291338
MIMATN
MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
0936 AM EDT THU APR 29 2021
FORECAST DISCUSSION
MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.
AT 12Z, A STATIONARY FRONT EXTENDED FROM CENTRAL LONG ISLAND, NEW
YORK, TO NEAR 40N68W TO NEAR 39N65W OVER THE NE NT2 WATERS. A
HIGH PRESSURE RIDGE WAS LOCATED OVER THE REMAINDER OF THE NT2
WATERS. GOES-EAST SATELLITE IMAGERY AND THE LIGHTNING DENSITY
DATA PRODUCT REVEALED PRECIPITATION FROM ROUGHLY 37-38N AND
NORTHWARD.
WITH THE 06Z GFS IN AGREEMENT WITH THE 00Z SUITE OF MODELS
THROUGH AT LEAST THE MIDDLE OF THE PERIOD, I SEE NO REASONS TO
MAKE ADJUSTMENTS TO THE ONGOING FORECAST IN PLACE. HENCE, CURRENT
WARNING HEADLINES WILL REMAIN AS IS, IN THIS INTERMEDIATE
FORECAST PACKAGE.
PLEASE REFER TO THE PREVIOUS MARINE WEATHER DISCUSSION BELOW FOR
ADDITIONAL INFORMATION.
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PREVIOUS DISCUSSION...
THE LATEST NCEP SURFACE ANALYSIS SHOWS A FRONTAL BOUNDARY ACROSS
THE NT1 OFFSHORE WATERS THIS MORNING, AND A HIGH PRESSURE RIDGE
OVER THE SRN NT2 ZONES. IN BETWEEN THE TWO FEATURES, THE
ANALYSIS
SHOWS A TIGHTENED PRESSURE GRADIENT ACROSS THE NRN NT2 WATERS,
INDICATING ENHANCED SW FLOW ACROSS THE GULF STREAM. ASCAT WIND
RETRIEVALS FROM 02Z LATE LAST NIGHT SHOWED WINDS TO 30 KT IN
THE REGION AHEAD OF THE FRONT WITH THE HIGHEST CONDITIONS OVER
THE GULF STREAM. THIS MATCHES UP WELL WITH THE PREVIOUS WIND
GRIDS, AND THE 00Z MODELS AGREE ON 30 KT MAX WINDS IN THIS
REGION FOR TODAY AS A FRONTAL WAVE DEVELOPS TO THE E OF THE
REGION. THE MODELS DO SHOW HIGHER WINDS JUST ABOVE THE SURFACE
OVER THE WARMER SSTS, WITH GFS/ECMWF 925 MB WINDS INDICATING 40
KT OVER THE GULF STREAM IN NRN NT2. ALTHOUGH WOULD NOT RULE OUT
AN OCCASIONAL GALE FORCE GUST MIXING TO THE SURFACE, AM NOT
EXPECTED SUSTAINED GALES FOR TODAY WITH THIS WAVE AS THE MODELS
ARE NOT SUPPORTING THAT SCENARIO. AS SUCH, AM PLANNING ON
KEEPING
MAX WINDS AT 30 KT FOR TODAY.
THE 00Z MODELS THEN SHOW AN ACTIVE PATTERN CONTINUING OVER THE
OFFSHORE WATERS THROUGH THE REMAINDER OF THE FORECAST PERIOD,
WITH THE GUIDANCE HAVING A STRONG SIGNAL FOR THE DEVELOPMENT OF
GALE FORCE CONDITIONS IN THE SW FLOW AHEAD OF THE NEXT COLD
FRONT TONIGHT AND FRI, AND THEN IN THE COLD AIR ADVECTION BEHIND
THE FRONT FRI NIGHT AND SAT. THE PREVIOUS FORECAST HAD GALE
HEADLINES UP WITH THIS SYSTEM CONSISTENT WITH THE GFS WINDS, AND
CONFIDENCE REMAINS ABOVE AVERAGE WITH THEM AS A RESULT OF THE
STRONG CONSENSUS. AS SUCH, AM PLANNING ON CONTINUING WITH THEM
IN
THE NEXT FORECAST PACKAGE. ALSO, AM PLANNING ON STAYING NEAR THE
PREVIOUS GRIDS INTO SAT WITH ONLY MINOR CHANGES.
THE 00Z GFS THEN SHOWS ANOTHER STRONG COLD FRONT MOVING ACROSS
THE W ATLC SUN AND SUN NIGHT, AND AGAIN SHOWS ANOTHER ROUND OF
GALES DEVELOPING AHEAD OF IT. HOWEVER, THE REST OF THE 00Z
MODELS ARE WEAKER WITH THE WINDS THAN THE GFS, WHICH HAS ALSO
TRENDED A LITTLE WEAKER FROM THE 18Z RUN. AS SUCH, CONFIDENCE IS
BELOW AVERAGE ON THE PROSPECT OF GALES WITH THIS SYSTEM. THE
PREVIOUS FORECAST WENT UP TO 25 KT FOR SUN AND SUN NIGHT, WHICH
SEEMS REASONABLE CONSIDERING THE LARGE SPREAD IN THE MODELS. AS
SUCH, AM PLANNING ON STAYING NEAR THIS INTENSITY FOR THE NEXT
FORECAST PACKAGE, AND WILL BE BLENDING THE 00Z GFS AND ECMWF
WITH
THE PREVIOUS WIND GRIDS FROM SAT NIGHT THROUGH THE REST OF THE
FORECAST PERIOD AS A COMPROMISE SOLUTION.
SEAS
IN ORDER TO MATCH UP WITH THE WIND GRIDS, AM PLANNING ON
STAYING NEAR THE PREVIOUS WAVE HEIGHT GRIDS INTO SAT. WILL THEN
TRANSITION TO A BLEND OF THE 00Z GFS WAVE AND ECMWF WAM MODELS
WITH THE PREVIOUS WAVE HEIGHT GRIDS THROUGH THE REST OF THE
FORECAST PERIOD.
EXTRATROPICAL STORM SURGE GUIDANCE
NO SIGNIFICANT POSITIVE
SURGE EVENTS ARE EXPECTED DURING THE NEXT COUPLE OF DAYS. PLEASE
MONITOR PRODUCTS FROM COASTAL NATIONAL WEATHER SERVICE OFFICES
FOR DETAILED WATER LEVEL INFORMATION.
WARNINGS
PRELIMINARY.
NT1 NEW ENGLAND WATERS
ANZ805...GEORGES BANK WEST OF 68W
GALE FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ810...SOUTH OF NEW ENGLAND
GALE FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ815...SOUTH OF LONG ISLAND
GALE FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
NT2 MID-ATLANTIC WATERS
ANZ820...HUDSON CANYON TO BALTIMORE CANYON
GALE TONIGHT.
GALE FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL
GALE TONIGHT INTO FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL
GALE TONIGHT INTO FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE
GALE TONIGHT INTO FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N
GALE TONIGHT INTO FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ825
INNER WATERS FROM BALTIMORE CANYON TO CAPE CHARLES
LIGHT...
GALE TONIGHT.
GALE FRIDAY NIGHT.
ANZ828
INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK BEACH
LIGHT...
GALE TONIGHT INTO FRIDAY NIGHT.
ANZ925
OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS
CANYON...
GALE TONIGHT INTO FRIDAY NIGHT.
GALE POSSIBLE SATURDAY.
ANZ830
INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE
HATTERAS...
GALE TONIGHT INTO FRIDAY.
ANZ833...INNER WATERS FROM CAPE HATTERAS TO CAPE FEAR
GALE TONIGHT INTO FRIDAY.
ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR
GALE TONIGHT INTO FRIDAY.
.FORECASTER HOLLEY/KELLS. OCEAN PREDICTION CENTER.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
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