030
AGNT40 KWNM 201235
MIMATN
MARINE WEATHER DISCUSSION
NWS OCEAN PREDICTION CENTER WASHINGTON DC
830 AM EDT SAT 20 MAR 2010
.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.
COLD FRNT WILL DROP SE THRU NEW ENGL TDA AND EMERGE OFFSHR TNGT
AND WILL CONTINUE TO HOLD ASSOC WINDS IN 15 TO 20 KT RANGE N OF
HUDSON CNYN. FCST CHALLENGE THEN BECOMES WHETHER ANY GALES WILL
MIX TO SFC AHEAD OF COLD FRNT MOVING OFFSHR S OF HATTERAS CNYN
LATE SUN NGT/MON. 06Z GFS WAS LESS ENTHUSIASTIC THAN ITS
PREVIOUS RUN WITH ANY PRE FRNTL GALES HERE. WITH SUCH WINDS
ALREADY IN PLACE IN NT2 FCST...WILL MAINTAIN OPC FCST CONTINUITY
AND REVISIT AFTER 12Z GUIDANCE AVAILABLE. 06Z GFS WAS THEN
SLIGHTLY SLOWER THAN PREVIOUS RUNS WITH UPPER LOW OFF MID ATLC
COAST LATE TUE AS WAS THE 00Z ECMWF WHEN COMPARED TO ITS
PREVIOUS RUN. AND AGAIN NOT PLANNING ON SIGNIFICANT ADJUSTMENTS
FROM PREVIOUS NT1/NT2 FCSTS WITH ASSOC GALES.
WITH 06Z GFS NO LONGER INDICATING AS STRONG OF NE WINDS OVER GLF
OF ME TUE NGT...06Z WAVEWATCH III ALSO BACKED OFF SIG WV HGTS BY
3 TO 5 FT FROM ITS PREVIOUS RUN.
---------------------------------------------------------------
..PREVIOUS DISCUSSION
OVER THE SHORT TERM...THE NEW 00Z MDLS RMN IN RSNBLY GOOD AGRMT
THAT A WEAK COLD FRONT WL PUSH INTO THE NRN GULF OF MAINE LATE
TODAY...STALL ACRS THE SRN MOST NT1 WTRS TONITE INTO SUN...THEN
DRIFT BACK N AS A WARM FRONT LATE SUN INTO MON. SUSPECT THAT THE
00Z NAM/GFS MAYBE A LTL TOO FAST TO LIFT THE FRONT BACK N...BUT
NOT SIGLY SO. REGARDLESS OF THE TIMING OF THIS FRONT...PER THE
00Z NAM/GFS FCST BL WINDS...DO NOT PLAN ON FCSTG ANY ASCD WINDS
IN EXCESS OF 15-20 KT AS PREVLY FCSTD. OTHERWISE NO OTHER SIG
SHORT TERM CHNGS ARE PLANNED TO THE PREV OFSHR FCST PACKAGE.
IN THE LONG RANGE...THE 00Z MDLS GNRLY AGREE THAT A CLOSED UPR
LOW WL MOV OFF THE MID ATLC COAST TUE AND PASS E OF THE OFSHR
WTRS WED. AT THE SFC THO THE MDLS CONT TO DIFFER WITH THEIR FCST
TRACKS OF THE ASCD SFC LOW(S?). THRU 84HRS THE MDLS OVERALL ARE
IN ACPTBLY GOOD AGRMT...THO BLV THE 00Z GFS/GEM ARE A LTL TOO
FAST WITH THE ASCD FRONT PUSHING OFSHR. THEN BY LATE TUE/WED THE
00Z GFS CONTS THE TREND OF ITS PREV 18Z RUN IN FCSTG ITS ASCD
SFC LOW TO MOV OFSHR ACRS THE NRN WTRS MR SLOWLY. BUT THE 00Z
GEFS MEAN INDICATES THAT THE 00Z IS STIL TOO FAST. SMLR TO ITS
PREV 12Z RUN...BLV THE 00Z UKMET LOOKS TO BCM A NWRN OUTLIER
WITH ITS SFC LOW BY WED. BY 25/00Z THE 00Z GFS/GEM/GEFS MEAN AND
12Z ECMWF CONVERGE TO WHAT LOOKS TO BE A RNSBL FCST PSN SE OF
NOVA SCOTIA. SO OVERALL PLAN ON FAVORING A BLENDED 00Z GEFS MEAN
AND 12Z ECMWF FCST TRACK FOR THIS SYSTEM. IN RGRDS TO THE ASCD
WRNGS... AS THE ASCD FRONT IS FCST TO PUSH OFSHR SUN NITE INTO
TUE...BLV ANY ASCD PREFRONTAL SLY GALES WL BE LIMITED TO THE
WARMER WTRS FM THE GULF STREAM EWD BYND THE CSTL WTR DOMAINS.
THEN IN THE WAKE OF THE SFC LOW AND POSTFRONTAL WISE...THE 00Z
GFS NOW FCSTS STORM FORCE BL WINDS TO DVLP ACRS THE GULF OF
MAINE LATE TUE. FOR NOW WITH THE OTHER 00Z GLOBAL MDLS (UNLESS
THE 00Z ECMWF COMES IN AND SPRTS THE GFS) FCSTG SMWHT WEAKER
GRADIENTS THERE WL HOLD OFF ON ANY STORM WRNGS. OTHERWISE WL
CONT WITH THE PREVLY FCSTD POSTFRONTAL GALES DVLPG THRUT THE
WTRS N OF CP FEAR. AS NOTED EARLIER IT STIL LOOKS CLOSE AS TO
WHETHER THE HDSN TO BALT CNYN WTRS WL REACH GALE FORCE LATE
TUE/EARLY WED. FOR NOW WL CONT TO HOLD OFF ON WRNGS FOR THESE
WTRS UNLESS THE 00Z ECMWF COMES IN AND SPRTS THEM. SO OVERALL NO
MAJOR LONG RANGE CHNGS ARE PLANNED TO THE PREV OFSHR FCSTS RGRDG
THIS SYSTEM.
OVERALL THE 00Z WNA WAVEWATCH III FCST SEAS LOOK REPRESENTATIVE.
BUT SINCE THE 00Z GFS WL NOT BE COMPLETELY FAVORED...WL TONE
DOWN THE MDLS FCST SEAS ACRS THE GULF OF MAINE SLIGHTLY TUE
NITE.
EXTRATROPICAL STORM SURGE GUIDANCE...THE 00Z ETSS MDL FCSTS MAX
POSITIVE SURGE VALUES IN THE 1-2 FT RANGE ALONG THE COAST BTWN
CP COD AND MATINICUS ROCK BY LATE TUE WHICH IS LKLY SLIGHTLY
OVERDONE SINCE THE STORM FORCE GFS BL WINDS WL NOT BE ACPTD FOR
NOW.
WARNINGS/FORECAST CONFIDENCE
WARNINGS ARE PRELIMINARY AND ARE
SUBJECT TO CHANGE. ANY CHANGES WILL BE COORDINATED THROUGH AWIPS
12 PLANET CHAT OR BY TELEPHONE.
.NT1 NEW ENGLAND WATERS
GULF OF MAINE...GALE TUE INTO WED
MOD CONFDC.
GEORGES BANK...GALE WED
MOD CONFDC.
S OF NEW ENGLAND...GALE TUE INTO WED
MOD CONFDC.
.NT2 MID ATLC WATERS
HUDSON TO BALT CNYN
NONE.
BALT CNYN TO HAGUE LINE...GALE TUE AND WED
MOD CONFDC.
BALT CNYN TO HATTERAS CNYN...GALE MON INTO WED
LOW TO MOD
CONFDC.
HATTERAS CNYN TO CAPE FEAR...GALE MON AND TUE
LOW TO MOD
CONFDC.
CAPE FEAR TO 31N...GALE MON
LOW CONFDC.
.FORECASTER CLARK/VUKITS. OCEAN FORECAST BRANCH.
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