Marine Interpretation Message
Issued by NWS

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AGNT40 KWNM 021449
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
1049 AM EDT THU OCT 2 2014

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

THE SAT IMG HAS MOST OF THE CONV OVR THE NRN WTRS WHERE THE
LGHTNG INTSTY IS THE STRONGEST. THE RADAR HAS STRONG TSTMS EMBDD
IN THE CONV CLDS OVR THE BALT CNYN WTRS. AT 1200Z LOW PRES 1012 MB
OVR THE BALT CNYN WTRS HAS WRM FRNT XTMDG NE AND CLD FRNT SE. HGH
PRES 1030 MB CNTRD OVR NOVA SCOTIA HAS A RIDGE STRETCHNG SW ACRS
NEW ENGL INTO ANOTHER HGH PRES 1022 MB CNTRD OVR THE MID ATLC
STATES. THE PRES GRNT IS NOT AS TIGHT AND THE MAX OBS WINDS ARE 30
KT IN THE NW SECTOR OF THE LOW. THE LAST ASCAT PASS WAS AT 0115Z
AND IT HAD INDCTD MAX WINDS OVR THE WTRS ADJ TO NW ENGL. THE SEAS
ARE ALSO HGST OVR THE NRN WTRS WITH 13 FT PEAKS. SEAS SUBSIDE TO 2
FT OVR THE FAR SRN WTRS. THE LAST JASON PASS AT 0622Z PASSED TRU
THE ERN PARTS FO THE REGION AND HAD INDCTD HGR SEAS TO 11 FT OVR
THE BALT CNYN WTRS. THE NWW3 MULTI GRID WV MDL FITS VERY WELL WITH
THE OBSVD SEAS PATTERN AND SEEM TO BE ON PAR WITH THE FRCST AND SO
WILL SWITCH TO NWW3 FOR THE SEAS.

THERE IS SOME ENRGY OVR THE NRN WTRS THAT WILL FEED THE LOW PRES
AND DEEPEN IT TO FORCE A TIGHTER PRES GRDNT AND RSULT IN GALE
FORCE WINDS OVR THE NRN WTRS ESPCLY IN THE NW QUADRNT. ANOTHER SIG
WAVE OF ENERGY OVR THE MID WEST WILL REACH THE NRN HALF OF THE
REGION OVR THE WEEKEND BUT RIDGING TO THE SE WILL PREVENT ITS FULL
ENERGY TO BE DAMPED ON THE WTRS AND SO THE WTRS WIL BE SPARED OF
GALE FORCE WINDS AFTER THE CURRENT EPISODE.

THE 1200Z RUN SHOW THAT MDLS HV AGRRED ON MOST OF THE SYNOP
FEATURES OVR THE WTRS IN THE SHORT TERM. THE MNR DIFFS ARE MAINLY
IN THE STRGNTH OF THE PRES GRDNT OVR THE NRN WTRS. OTHERWISE WILL
GO WITH GFS FOR THIS UPDATE SINCE IT INITIALIZED THE 12Z MAP
BETTER THAN THE ECMWFHR. IN THE SHORT TERM THE LOW PRES WILL
SLIGHTLY MOVE SE WHILE THE HGH PRES OVR THE MID ATLC STATES MOVES
CLOSER TO THE WTRS. A RIDGE WILL REMAIN TO THE NW AND AS PRES
FALLS OVR THE WTRS THE PRES GRDNT WILL BECOME TIGHTER AND ALLOW
GALE FORCE WINDS.

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

NONE OF 00Z MDLS ARE VERY WELL INITIALIZED WITH EITHER SFC LOW
OVER THE W ATLC...FIRST NEAR 40N61W AND SECOND OVER NERN PORTION
OF GULF STREAM 38N69W. MAINLY MDLS ARE NOT NEARLY STRONG ENOUGH
WITH WINDS ASSOCIATED WITH THESE LOWS. 0030Z HI RES ASCAT-B
RETURNED MAX WINDS OF 45 KT OVER NW QUAD OF ERN LOW WHILE 0115Z
HI RES ASCAT-A INDICATED 25 TO 35 KT ASSOCIATED WITH WRN LOW
ALONG A 40N69W TO 38N70W LINE. HRRR IS ONLY MDL WHICH SHOWS ANY
GALES WITH LOW OVER GULF STREAM. 1/4 DEG ECMWF SEEMS TO HAVE
BEST HANDLE ON UPPER SHRTWV WHICH IS AIDING IN ROBUST TSTM
DVLPMNT OVER NERN MID ATLC ANZ905 WATERS PAST FEW HRS. OVER THE
NEAR TERM FORECAST AM FAVORING NON GFS CONSENSUS AS 12Z/01 ECMWF
AS WELL AS 00Z UKMET/GLOBAL GEM ALL SEEM TO HAVE BETTER HANDLE
ON SFC LOW OVER GULF STREAM. OVER THE NEAR TERM WILL LIKELY
BLEND IN 00Z ECMWF TO EXISTING GRIDS BUT CONTINUE TO BUMP UP
STRONGEST N TO NE WINDS BY 10 TO 20 PERCENT GIVEN LATEST ASCAT.
WITH THIS UPWARD ADJUSTMENT OF ECMWF WINDS PLAN TO EXPAND GALES
TO AT LEAST ANZ805 ANZ810 AND ANZ915 ZONES TDA INTO TNGT. AS
NEXT LOW RETROGRADES W TOWARD GEORGES BANK AND NERN MID ATLC
WATERS TDA THRU FRI WILL CONTINUE WITH MARGINAL GALES ANZ900 AND
ANZ905 WATERS LATE NGT INTO FRI BUT WITH BELOW AVG FORECAST
CONFIDENCE.

MDLS ACTUALLY COME INTO SOMEWHAT BETTER AGREEMENT LATER FRI THRU
THE WEEKEND AS COMPLEX UPPER VORT GETS EJECTED E OF OFFSHORE
WATERS AHEAD OF DEEP UPPER TROF APPROACHING COAST THIS WEEKEND.
THERE IS DECENT AGREEMENT WITH TIMING OF ASSOCIATED STRONG COLD
FRONT...AND STRONG ENSEMBLE SUPPORT FOR 00Z GFS AND 00Z ECMWF.
00Z UKMET IS ONLY SLIGHTLY SLOWER. WILL CONTINUE TO USE A 50/50
BLEND OF ECMWF AND GFS AND INCLUDE WIDESPREAD WINDS UP TO 25 KT
SAT INTO SUN. BY LATER SUN HIGH PRES WILL BUILD OFF THE MID ATLC
COAST AND ESTABLISH A RIDGE NE ACROSS THE NEW ENGL WATERS. 00Z
MDLS ARE IN GOOD AGREEMENT THAT RIDGE SHOULD SLOWLY DRIFT E OVER
NEW ENGL/MID ATLC WATERS MON AND MON NGT.

.SEAS...SIG WV HGTS ARE ALREADY RUNNING HIGHER THAN 00Z MWW3 OR
12Z/01 1/4 DEG ECMWF WAVE MDL OVER NRN MID ATLC AND NEW ENGL
WATERS...AS WELL AS S OF NOVA SCOTIA WHERE BUOY 44137 WAS UP TO
15 FT AT 06Z. ALSO 44013 JUST E OF BOSTON HAD 9 FT REPORT AT
06Z. WITH PREFERENCE FOR 00Z ECMWF WINDS OVER NEXT 36 TO 48 HRS
WILL BE USING 00Z ECMWF WAVE MDL BUT BASED ON RECENT OBS WILL
CONTINUE TO ADD 15 OR SO PERCENT TO THESE SIG WV HGTS. THEN WILL
POPULATE WITH 50/50 BLEND OF MWW3 AND ECMWF WAVE MDL FRI NGT
THRU MON NGT.

.EXTRATROPICAL STORM SURGE GUIDANCE...WHEN SURGE TAKEN INTO
ACCOUNT FROM ESTOFS OR ETSS WATER LVL ANOMALIES HAVE BEEN
RUNNING ONE HALF TO 1 FT ALONG DELMARVA AND NJ COASTS. OVER NEXT
36 HRS OR SO BOTH 00Z ESTOFS AND 00Z ETSS ARE LIKELY UNDERDONE
WITH SURGE VALUES FROM CAPE COD TO DE/MD COASTS.


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE TONIGHT INTO FRI.

.NT2 MID ATLC WATERS...
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE TONIGHT INTO FRI.

$$

.FORECASTER MUSONDA/CLARK. OCEAN PREDICTION CENTER.


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