Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 251346
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
846 AM EST THU DEC 25 2014

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

11Z OBS FM FRYING PAN SHOALS BUOY REPORTED W 25-29 KT GUSTS 35 KT
BEHIND CDFNT MOVG OFFSHORE MID ATLC AND SE CST. 06Z NAM40
STABILITY GUIDANCE SHICH SHOWS BETTER REPRESENTATATION OF GLF STRM
INDICATES 975 MB BL WNDS COULD REACH 35 TO AS HIGH AS 40 KT BY
EARLY THIS AFTN OVER NRN NT2 ZONES 920 AND 925 IN CAA BHND FNT.
HAVE MADE MINOR WND GRID EDITS TO BOOST WNDS ABT 10 PCT TO 35 KT
IN THOSE TWO ZONES BY 18Z. CURRENT WORDING OF THOSE OFSHR ZONES
IMPLIES THIS. AFTER 12Z WND GRIDS BCM BASED ON HIGHER GFS 30M WNDS
AS CAA BHND FNT MOVS OFFSHORE PRECEDED BY INCRG LOW LVL JET MOVG
OVR OUTER NT2 AND ERN NT1 ZONES ZONES FAVORING PREFNTL GALES IN
THOSE AREAS.

PRESENT FCST WAS BASED ON 00Z GFS THRU SAT NIGHT DURING PERIOD OF
BEST MDL AGRMT...AND 06Z GFS SHOWS LTLCHG. BYND SAT NIGHT 00Z
ECMWF IS FAVORED WITH 00Z GFS FASTER THAN NON-NCEP MDLS IN HNDLG
OF LOW TRACKING ACRS SE CANADA. WITH 06Z GFS TRENDING SLOWER TWD
00Z ECMWF/UKMET/GEM SEE NO NEED TO REPOPULATE WITH 06Z GFS THRU
FCST PRD. ALSO MEDIAN 00Z ECMWF FAVORED BETWEEN FARTHER N CNDN GEM
AND FARTHER S AND SUPPRESSED GFS FOR TRACK OF LOW OR LOWS ALG A
STALLED FNT OFF CAROLINAS MON AND MON NIGHT.

BASED ON RECENT STLT...RADAR AND LATEST SREF TSTM GUIDANCE GOING
WITH CONTINUITY OF PREVIOUS FCST SPRTG TSTMS ALG FNT NE INTO SE
NT1 AREA.

SEAS...THE 00Z/06Z WNA WW3 AND 00Z ECMWF WAM GUIDANCE ARE SIMILAR
INTIALLY AND ARE WI A FOOT OF 12Z OBS AND 10Z ALTIMETER PASS. FOR
THE UPDATE PLAN TO FAVOR THE SLGTLY HIGHER 00Z ECMWF WAM OVR
WARMER WTRS FOR THE TODAY PERIOD IN DVLPG STG CAA THEN
TRANSITIONING TO PREVIOUSLY POPULATED 50/50 BLEND OF MDLS
TONIGHT...AND THEN TO ECMWF WAM SUN.
-----------------------------------------------------------------
PREVIOUS DISCUSSION...

NEAR TERM...AN ASCAT PASS FROM LAST EVE INDICATED MAX WINDS OF 30
KT OFF THE MID ATLC COAST...OR OVR ZONES 920 AND 925. ELSEWHERE S
AND SW WINDS UP TO 25 KT WERE NOTED AHEAD OF A STRONG COLD FRONT
CURRENTLY MOVG E FROM NEAR THE GEORGIA COAST N TO CENTRAL PA TO
WRN NY STATE TO STRONG LOW PRES CENTER OVR ERN ONTARIO.
SATELLITE...RADAR...AND LIGHTNING DATA INDICATES LOCALLY HVY
TSTMS FROM E AND SE OF CAPE HATTERAS SOUTHWARD TO WELL OFF THE
GEORGIA COAST. THIS TSTM ACTIVITY IS MOVG NE AHEAD OF THE COLD
FRONT...AND PER THE LATEST SREF TSTM GUID WILL CONT TO DVLP AND
EXPAND NE AHEAD OF THE FRONT TDA...OVR MOST OF THE NT2 OFF
WTRS...AND PSBLY N INTO PARTS OF THE NT1 WTRS AS WELL. LOCAL GUSTS
EXCEEDING GALE FORCE CAN BE EXPECTED IN OR NEAR ANY HVY TSTMS OVR
THE OFF WTRS TDY. MORE WIDESPREAD GALES ARE STILL FCST TO DVLP
EARLY TDA JUST AHEAD OF THE FRONT...TO THE E OF LONG
ISLAND...WHERE A STRONG LL JET MAX WILL CROSS THE WTRS. THE GALES
ARE THEN FCST TO EXPAND TO THE E AND N INTO NT1 AND NE NT2 WTRS
DURING THE DAY INTO TNGT AS FAIRLY STRONG COLD AIR ADV DVLPS OVR
THESE WTRS IN THE WAKE OF THE STRONG COLD FRONT. OVERALL...LITTLE
CHANGE WILL BE MADE FOR THE EARLY AM PACKAGE FROM THE LAST FEW
OPC FCSTS. WE WILL RELY ON THE 00Z GFS FOR THE EARLY AM PACKAGE
INTO THE UPCOMING WKND AS IT HAS REMAINED FAIRLY CONSISTENT AND
IS IN DECENT AGREEMENT WITH THE NON-GFS MDL GUID. INITIALLY WE
WILL USE A BLEND OF THE 10M AND 30M GFS WINDS OVR THE OFF WTRS AS
THESE LVLS SEEM TO FIT WELL WITH THE LATEST OBS AND EARLIER
SCATTEROMETER DATA. FOR MOST OF TDA THRU FRI NGT WE WILL SWITCH
TO USING THE 30M GFS WINDS FOR THE FCST AS THIS WILL MAINTAIN
CONTINUITY FROM THE PREV FEW OPC FCSTS...AND ALSO FIT WELL WITH
THE COLD AIR ADV AND UNSTABLE WIND FIELD DVLPG BEHIND THE STRONG
COLD FRONT TDA THRU TNGT INTO FRI. HIGH PRES WILL EXPAND FROM THE
SE STATES NE INTO THE NT2 WTRS DURING FRI. THE HIGH WILL PERSIST
OVR THE NT2 OFF WTRS FRI NGT...AND MOVE E OF THESE WTRS SAT INTO
SAT NGT. AS THE COLD AIR ADVECTION WEAKENS BY EARLY SAT WE WILL
THEN USE THE 10M GFS WINDS FOR SAT INTO SAT NGT...WITH LITTLE
CHANGE FROM THE PREV FEW OPC FCSTS AS CONDITIONS IMPROVE OVR MOST
OF THE OFF WTRS.

LONG TERM...BY SUN INTO NEXT WK THE 00Z MDLS BEGIN TO DIVERGE IN
THEIR SOLUTIONS OVR THE REGION. THE OPERATIONAL 00Z GFS APPEARS TO
BE A FAST OUTLIER IN BRINGING LOW PRES E OVR SE CANADA AND THE
CANADIAN MARITIMES. THE 00Z ECMWF APPEARS TO OFFER A MIDDLE OF THE
ROAD SOLUTION...BETWEEN THE FAST GFS AND THE SLIGHTLY SLOWER
CANADIAN GEM SOLUTION. THE 00Z ECMWF IS IN GOOD AGREEMENT WITH
THE 00Z UKMET. AS A RESULT THE NEXT COLD FRONT EXPECTED TO IMPACT
THE OFF WTRS IS FCST TO CROSS NT1 AND NRN NT2 WTRS SUN NGT INTO
MON. THE FRONT WILL LKLY STALL OVR SRN NT2 WTRS MON NGT WITH WK
LOW PRES AREAS TRACKING NE ALONG THE FRONT AT THAT TIME. OVERALL
BY USING THE 00Z ECMWF FOR THE PERIOD SUN THRU MON NGT...LITTLE
SIG CHANGE WILL BE MADE FOR THE EARLY AM PACKAGE FROM THE PREV FEW
OPC FCSTS.

.SEAS...THE 00Z WNA WW3 MDL GUID APPEARS TO STILL BE RUNNING UP
TO A COUPLE FT ON THE HIGH SIDE OVR NRN NT1 WTRS...AND PERHAPS A
FT OR TWO ON THE LOW SIDE OFF THE CAROLINA COAST. THE 00Z ECMWF
WAM WV GUID APPEAR SIMILIAR INITIALLY. THE 00Z ECMWF WAM DOES
BUILD SEAS A LITTLE FASTER IN THE CAA OVR NRN NT2 AND NT1 WTRS BY
LTR TDA AND TNGT. AS A RESULT...WE WILL USE A 50-50 BLEND OF THE
WNW WW3 AND ECMWF WAM FOR THE FCST TDA INTO SAT NGT...AND THEN
TRANSITION TO ALL ECMWF WAM FOR SUN THRU MON NGT AS THE USE THE
00Z ECMWF WIND FIELD FOR THAT PORTION OF THE FCST.

.EXTRATROPICAL STORM SURGE GUIDANCE...THE LATEST ESTOFS AND ETSS
MDLS CONT TO INDICATE A NEG SURGE UP TO 1.5 FT DVLPG FROM THE NRN
MID ATLC N TO THE GULF OF MAINE LTR TDA INTO EARLY FRI. THE ETSS
SURGE VALUES ARE SLIGHTLY LOWER AND THE AREA IS MORE CONFINED TO
THE N MID ATLC AND SRN NEW ENGLAND WATERS. OVERALL...LITTLE
DEVIATION FROM THE ESSG APPEARS NEEDED INTO THE UPCOMING WKND
WITH NO MAJOR SURGE EVENT EXPECTED.

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     GALE TODAY INTO TONIGHT.
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE TODAY.

.NT2 MID ATLC WATERS...
.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TODAY.
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TODAY.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE TODAY.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE TODAY.
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...
     GALE TODAY.

$$

.FORECASTER BANCROFT/MILLS. OCEAN PREDICTION CENTER.



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