Marine Interpretation Message
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000
AGNT40 KWNM 271258
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
758 AM EST FRI FEB 27 2015

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

AS STRONG HIGH PRES BUILDS IN FROM THE NW...THE WTRS ARE UNDER THE
INFLUENCE OF A WEAK TO MODERATELY STRONG NLY GRADIENT WITH MAX
WINDS UP TO 20 OR 25 KT...HIGHEST ACRS THE NT2 WTRS. MAX SEAS IN
THIS GRADIENT...AS CONFIRMED BY AN EARLIE JASON ALTIMETER PASS...
ARE IN THE 10-14 FT RANGE...HIGHEST ACRS THE OUTERMOST NRN AND
CNTRL NT2 WTRS...WHICH ARE BEING HANDLED RSNBLY WELL BY BOTH THE
06Z WAVEWATCH III AND 00Z ECMWF AT THE MOMENT.

OVER THE SHORT TERM...THE DIFFERENCES BTWN THE LATEST MDLS REMAIN
MINIMAL. THE MDLS ALL FCST THE STRONG SFC HIGH TO SLOWLY MOV TWDS
THE MID ATLC COAST THRU SAT NITE WHL DVLPG A RIDGE OFSHR ACRS THE
NT1 WTRS WITH LITE ASCD CONDS THERE. TO THE S THE HIGH WL SUPPORT
A MOD STRONG (UP TO 25 OR 30 KT) NELY GRADIENT...HIGHEST ACRS THE
SRN NT2 WTRS. WITH THIS BEING COUNTER FLOW AGAINST THE GULF STREAM
OVER THESE SRN NT2 WTRS WL FAVOR THE STRONGER 00Z/06Z NAM/GFS
GRADIENTS. SO WITH THE 06Z NAM/GFS FCSTG SMLR WIND SPEEDS...WL
CONT TO USE THE PREVLY POPULATED 00Z GFS 30M BL WINDS FOR THIS
GRADIENT AND WL MAKE ONLY SM MINOR TWEAKS.

IN THE LONG RANGE...OVERALL THE LATEST MDLS ARE IN GOOD AGRMT THAT
A STRONG COLD FRONT WL APRCH FM THE NW SUN NITE...THEN PUSH SE
ACRS THE WTRS MON/MON NITE WHL AN ATTENDANT SFC LOW INTENSIFIES NE
OF THE NT1 WTRS. OTHER THAN SM SLIGHT TIMING AND TRACK DIFFERENCES
FOR BOTH THE FROPA AND SFC LOW...THE LATEST MDLS FCST SMLR ASCD
FCST GRADIENTS WITH THIS SYSTEM. BASED ON THE STRONG ASCD COLD
AIR ADVECTION AND NEGATIVE STATIC STABILITY FCST IN THE WAKE OF
THIS FROPA...WITH THE 06Z GFS RMNG CONSISTENT...SEE NO REASON TO
MAKE ANY MAJOR CHNGS TO THE PREVLY USED 00Z GFS 30M BL WINDS. SO
WL MAKE ONLY MINOR CHNGS TO THE PREV OFSHR FCSTS RGRDG THIS
SYSTEM.

FURTHER OUT IN THE LONG RANGE...THE 06Z GFS REMAINS CONSISTENT VS
ITS PREV 00Z RUN...AND IS ALSO SPRTD BY THE 00Z GEM/NAVGEM/UKMET
AND 06Z GEFS...IN FCSTG A WARM FRONT TO LIFT NE ACRS THE WTRS TUE
NITE WITH AN ASCD SLY GRADIENT STRENGTHENING TO GALE FORCE. THE
BIG FCST PROBLEM IS THE 00Z ECMWF REMAINS EQUALLY CONSISTENT IN
FCSTG A SIGLY LESS PROGRESSIVE SOLUTION. FOR NOW SINCE THIS IS DAY
5 BELIEVE A COMPROMISE BTWN THE 00Z/06Z GFS AND 00Z ECMWF
SOLUTIONS STIL LOOKS RSNBL. SO WL CONT WITH THE PREVLY USED 00Z
GFS 10M BL WINDS...TIME SHIFTED 6 HRS SLOWER AS A COMPROMISE AND
FOR NOW WL HOLD OFF ON FCSTG ANY PSBL ASCD GALES.


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

ASCAT WND RTRVLS FM 01Z INDC A STG LOW E OF THE OFSHR WTRS...WITH STORM
FRC SE OF THE LOW S CTR. THE ASCAT ALSO INDC A FEW RMNG GALES
JUST E OF THE OFSHR WTRS IN THE STG CAA BEHINS A STG FRNTL
BNDRY...THO THE GOES IR SATLT IMGRY INDC THE SYS IS MOVG QUICKLY
OFF TO THE E. CRNT SFC RPRTS INDC THE STGST WNDS ARE WELL E OF
THE OFSHR WTRS...WITH ONLY ABT 15 TO 20 KT IN THE FAR W ATLC. THE
00Z GFS/ECMWF/UKMET/GEM ALL INDC ABT 25 KT OVR FAR NE NT2...THEN
ALL DCRS THE WNDS RPDLY AS THE FAST MOVG SYS MOVES OFF TO THE E
TDA...WHILE A HIGH PRES RDG BUILDS JUST N OF NT1. THE 00Z MDLS ALL
INDC THE TAIL END OF THE FRNTL BNDRY IS XPCTD TO DRIFT SE JUST E
OF THE SRN NT2 WTRS...AND PLACES THE SRN NT2 WTRS IN N TO NE FLOW
FRI INTO SAT. THE CD SURGE BEHIND THE FRNTL BNDRY IS XPCTD TO BE
UNSTABLE...IN NE FLOW OVR THE GLF STRM. THE 00Z ECMWF/UKMET/GEM
ALL INDC A BF PD OF 25 KT SAT IN THIS UNSTABLE ENVRMT...AND THE
GFS/NAM SHOW 30 KT WITH A FEW GALES IN THE NAM. ALSO...THE GFS HAD
BEEN HOLDING ONTO THE DVLPMT OF A WK LOW JUST E OF NT2. THE
ECWMF/UKMET HAD PREV NOT SHOWN MUCH OF ANYTHING...BUT NOW HAVE
TRENDED TWD THE GFS. THIS WL ALSO HELP TO INCRS THE PRES GRAD OVR
SRN NT2...AND HELPS TO SUPPORT AN INCRS IN THE WNDS FOR NT2. WITH
THE ENVRMT UNSTABLE...PREFERRING ATTM TO USE 30M GFS WINDS OVR THE
GLF STRM...AND INCRS THE WNDS TO 30 KT IN SRN NT2. HOWEVER...THE
GALES IN THE NAM LOOK A BIT OVERDONE...ESP WITH THE ECWMF/UKMET/GEM
ALL MGRNLLY SHOWING 25 KT...SO CONFDC IS LOW WITH THE GALES AND WL
KEEP OUT OF THE FCST.

THE 00Z MDLS AGREE SOMEWHAT WELL ON THE SYNOP PTTN THRUT THE
RMNDR OF THE FCST PD...THO MINOR DIFFS APPEAR WITH THE NEXT SYS
MON. THE 00Z GFS AND UKMET BOTH TRENDED N WITH THE LOW TRACK TWD
THE ECWMF...WHICH AHS BEEN FAIRLY CONSISTENT WITH THE TRACK.
HOWEVER...THE 00Z ECWMF IS NOW SLIGHTLY FASTER WITH THE SFC LOW.
THERE ARE ONLY VRY MINOR DIFFS IN TMG OF FROPA...AND THE WND
SHIFT...SO PLANNING ATTM TO STAY WITH GFS THIS FEATURE. ALSO...GFS
WNDS AREA STGR...AND SEEM TO BETTER REFLECT THE UNSTABLE ENVRMT
CREATED BY THE STG CAA. ATTM PLANNING ON USING THE 30M WINDS FM
ABT 15Z MON TO 21Z TUE...TO ACCT FOR THE STGR MXG XPCTD IN THIS
SCENARIO. IS A NRLY OUTLIER WITH THE LOW CTR OF THIS NEXT
SYS...AND TAKES IT TO THE N OF THE NT1 WTRS. THE GFS HAS BEEN TKG
IT THRU THE GULFME ON SUBSEQUENT RUNS...THO IS THE SRN END OF THE
MDL CONSENSUS...ALBEIT MUCH CLOSER TO IT THAN THE ECWMF. DEPITE
THE SLGT DIFFS ON THE TRACK...THE GFS AND ECWMF AGREE SOMEWHAT ON
THE PRES GRAD...AND ALL AGREE WITH AT LEAST GALE FORCE OVR THE N
PTTN OF THE OFSHR WTRS MON INTO MON NGT. THE PREV FCST USED THE
GFS WINDS WITH THIS BNDRY...WHICH SEEMS RSNBL GIVEN THE WKR WINDS
OF THE ECWMF. HOWEVER...THE STG CAA WL DESTABLIZE THE ENTORE WATLC
BEHIND THE FRNT...SO PLANNING ON USING 30M WINDS TO 21Z TUE.

IN THE EXTENDED...THE MODELS SHOW ANOTHER LOW PRES SYS MOVG TWD
THE COAST FM THE W LATE TUE INTO TUE NGT...AND THE 00Z MDLS CONT
TO HAVE DIFFS ON THE TMG. THE GFS HAS BEEN A FAST OUTLIER WITH
THIS SOLN...AND INDC GALES IN THE SRLY FLOW OVR CLDR WTRS N AND W
OF THE GLF STRM. CONFDC IS CRNTLY VRY LOW WITH THE GALES...AS THE
GFS SEEMS TOO FAST TO INCRS THE WNDS...AND TOO STG IN THE SRLY
FLOW. THE PREV FCST TONED DN THE INTNSTY OF THE WINDS...AND SLOWED
DN THE FORWARD MOTION OF THE SYS FROM THE WHAT THE GFS INDCD. THIS
AGAIN SEEMS TO BE A GUD STRATEGY...SO AGAIN PLANNING ON USING A 6
HOUR TIME SHIFT TO SLOW DN THE GFS. WL ALSO BACK OFF THE WNDS
SLGTLY TO KEEP BLO GL FRC...AS CONFDC IS VRY LOW.

.SEAS...THE 00Z NWW3 AND ECMWF WAM ARE INIT A FT OR TWO LOW IN THE
WATLC...SO PLANNING ON ADJUSTING SEAS HIGHER INTIALLY. THE MDLS
STAY IN GUD AGMRT INTO ABT 12Z MON...SO PLANNING ON USING A 50/50
BLEND TO THIS POINT. THE NWW3 THEN RUNS ABT 5 FT ABV THE ECWMF
WAM...WHICH BETTER MATCHED THE STG CAA XPCTD MON. PLANNING ON
USING A 2:1 BLEND AT THIS POINT TO FAVOR THE NWW3 WHICH PICKS UP
BETTER ON THE CAA. WL THEN TIME SHIFT THE NWW3 +6 HOURS AT 21Z TUE TO
MATCH THE TIME SHIFT IN THE GFS MDL...AND WL GO BACK TO A 50/50
NWW3/ECWMF BLEND TO OFFSET THE OVERDONE NWW3.

.EXTRATROPICAL STORM SURGE GUIDANCE...WITH PREDOMINANTLY OFSHR
FLOW THRUT THE PD...THE SURGE GUID IS NEAR NEUTRAL TO NEG VALUES
THRUT THE PD...WHICH SEEMS RSNBL.

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ805...GEORGES BANK WEST OF 68W...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ810...SOUTH OF NEW ENGLAND...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ815...SOUTH OF LONG ISLAND...
     GALE POSSIBLE MON.

.NT2 MID ATLC WATERS...
.ANZ820...HUDSON CANYON TO BALTIMORE CANYON...
     GALE POSSIBLE SUN NIGHT INTO MON.
.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...
     GALE POSSIBLE SUN NIGHT INTO MON NIGHT.
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE POSSIBLE MON.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE POSSIBLE MON INTO MON NIGHT.
.ANZ825...INNER WATERS FROM BALTIMORE CANYON TO CAPE CHARLES LIGHT...
     GALE POSSIBLE MON.
.ANZ828...INNER WATERS FROM CAPE CHARLES LIGHT TO CURRITUCK BEACH LIGHT...
     GALE POSSIBLE MON.
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...
     GALE POSSIBLE MON.
.ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE HATTERAS...
     GALE POSSIBLE MON.

$$

.FORECASTER VUKITS/KELLS. OCEAN PREDICTION CENTER.



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