166
AGNT40 KWNM 292052
MIMATN
MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
0450 PM 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 18Z, A STATIONARY FRONT EXTENDED FROM OVER CAPE COD,
MASSACHUSETTS, SE ACROSS GEORGES BANK AND THE FAR NE NT2 WATERS.
OTHERWISE A HIGH PRESSURE RIDGE WAS LOCATED OVER THE REST OF THE
NT2 WATERS. GOES-EAST SATELLITE IMAGERY AND THE LIGHTNING DENSITY
DATA PRODUCT REVEALED PRECIPITATION FROM ROUGHLY 37-38N AND
NORTHWARD, WITH A CLUSTER OF THUNDERSTORMS NEAR 38N66W, IN THE
VICINITY OF THE GULF STREAM. AVAILABLE HIRES ASCT DATA REVEALED
5-15 KT WINDS OVER THE FAR SE GEORGES BANK AND FAR NE NT2 WATERS,
INCREASING TO 15-25 KT OVER THE N NT2 WATERS S OF 40N AND E OF
69W. 5-15 KT WINDS WERE ALSO NOTED OVER THE FAR SW NT2 OFF THE
SOUTH CAROLINA AND GEORGES COASTS.
OVERALL, THE 12Z GLOBAL MODELS WERE IN GOOD AGREEMENT THROUGH MON
DAY 4, WITH DIFFERENCES ARISING ON TUE DAY 5, MAINLY IN REGARDS
TO THE EVOLUTION OF LOW PRESSURE OR LOW PRESSURES THAT COULD
IMPACT THE NT1 AND N HALF OF THE NT2 WATERS HENCE, FOR THIS
FORECAST PACKAGE I WILL FAVOR A 2:1 BLEND OF THE OLD GRIDS AND
12Z GFS/ECMWF THROUGH SUN 00Z, THEN A 1:1 BLEND OF THE 12Z
GFS/ECMWF THROUGH TUE DAY 4, THEN ALLOW THE DAY 5 FORECAST TO
REMAIN AS IS GIVEN THE MODEL SPREAD. MODELS CONTINUE TO AGREE
THAT LOW PRESSURE WILL MOVE NE ACROSS THE GULF OF MAINE AND
GEORGES BANK TONIGHT THROUGH FRI, THEN NE ACROSS NOVA SCOTIA AND
NEWFOUNDLAND LATER FRI THROUGH SAT. A STRONG COLD FRONT WILL
ACCOMPANY THE LOW MOVING E ACROSS THE WATERS TONIGHT THROUGH FRI,
WITH A SECONDARY COLD FRONT MOVING E THE NT1 AND NT2 WATERS FRI
NIGHT THROUGH SAT. ANOTHER LOW PRESSURE TROUGH MAY SWING E
THROUGH THE NT1 WATERS LATER SAT AS WELL. WE CONTINUE TO HAVE
ABOVE AVERAGE TO HIGH CONFIDENCE ON GALES DEVELOPING OFF THE
CENTRAL NT2 WATERS TONIGHT AND SPREADING NE AHEAD OF THE STRONG
COLD FRONT INTO SAT, WITH GALES THEN PERSISTING OVER THE N AND
PERHAPS CENTRAL NT2 WATERS INTO SAT NIGHT IN THE STRONG COLD AIR
ADVECTION EXPECTED BEHIND THE INITIAL COLD FRONT AND THE
SECONDARY COLD FRONT.
THE PATTERN REMAINS ACTIVE BEHIND THIS FIRST SYSTEM WITH A COLD
FRONT, ASSOCIATED WITH ANOTHER LOW MOVING E THROUGH EASTERN
CANADA SAT NIGHT INTO MON, MOVES E OR SE ACROSS THE NT1 WATERS
LATER SUN INTO MON. RIGHT NOW WE ARENT CARRYING ANY WARNING
LEVEL WINDS WITH THIS FRONT AND GENERALLY HAVE WINDS CAPPED AT NO
MORE THAN 25 OR 30 KT. BY LATER MON A WARM FRONT, ASSOCIATED WITH
A LOW MOVING TOWARDS THE EAST COAST, IS EXPECTED OVER THE N NT2
WATERS, WITH GUIDANCE SUGGESTING LOW PRESSURE DEVELOPING ALONG
THE FRONT AHEAD OF THE MAIN LOW. WHILE GUIDANCE SHOWS THIS
FEATURE THEY DIFFER IN TERMS OF THE TRACK WITH THE 12Z
ECMWF/UKMET MOVING THE LOW E ACROSS THE GULF OF MAINE AND THE 12Z
GFS/CMC/NAVGEM FARTHER S MOVING THE LOW THROUGH GEORGES BANK.
WITH IT BEING DAY 5, THERES ENOUGH TIME TO LET THE CURRENT DAY
5 FORECAST SIT AND AWAIT FUTURE MODEL RUNS TO SEE WHICH WAY THE
GUIDANCE TRENDS AND IF THEY COME INTO A BETTER CONSENSUS ON THE
TRACK.
THIS IS THE FINAL NORTH ATLANTIC/PACIFIC OCEAN MARINE WEATHER
DISCUSSION (MIM). REFERENCE THE NATIONAL WEATHER SERVICE SERVICE
CHANGE NOTICE:
HTTPS://WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN21-35MIN_DISCO
NTINUE.PDF
SYNOPSES FOUND IN OFFSHORE FORECASTS AND FORECASTS DESIGNED FOR
U.S. COAST GUARD BROADCAST, SUCH AS THE NAVTEX AND VOBRA, WILL
CONTAIN INFORMATION ABOUT BASIC WEATHER FEATURES AND ALL OF THE
WARNING INFORMATION WHICH WAS FOUND IN THE MIM.
YOU CAN ALSO FIND OCEAN PREDICTION CENTER INFORMATION AT:
HTTPS://OCEAN.WEATHER.GOV/
SEAS
I WILL ALLOW THE EXISTING WAVE FORECAST TO REMAIN AS IS
THROUGH SUN 00Z, AS EVEN WITH THE BLENDING OF THE WINDS THROUGH
THAT TIME, I FEEL THE ONGOING SEAS STILL ARE A GOOD
REPRESENTATION, GIVEN THE EXPANSE OF GALES EXPECTED. AND
SOMETIMES BLENDING THE SEAS, LIKE WITH THE WIND, CAN DAMPEN OUT
EXISTING HIGHER SIGNIFICANT WAVE HEIGHTS IN THE GRIDS AND I
WANTED TO AVOID THAT. BEYOND SUN 00Z A 1:1 BLEND OF THE OLD GRIDS
AND 12Z NOAA WAVEWATCH III/ECMWF WAM WILL BE USED THROUGH DAY 4,
WITH THE DAY 5 FORECAST LEFT AS IS GIVEN MODEL SPREAD.
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
ANZ810...SOUTH OF NEW ENGLAND
GALE FRIDAY NIGHT.
ANZ815...SOUTH OF LONG ISLAND
GALE FRIDAY NIGHT.
NT2 MID-ATLANTIC WATERS
ANZ820...HUDSON CANYON TO BALTIMORE CANYON
GALE FRIDAY NIGHT INTO SATURDAY.
ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL
GALE TONIGHT INTO SATURDAY.
ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL
GALE TONIGHT INTO SATURDAY.
ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE
GALE TONIGHT INTO SATURDAY.
ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N
GALE TONIGHT INTO 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.
ANZ925
OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS
CANYON...
GALE TONIGHT INTO 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.
ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR
GALE TONIGHT INTO FRIDAY.
.FORECASTER HOLLEY. OCEAN PREDICTION CENTER.
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