Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 050107
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
907 PM EDT WED MAY 4 2016

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

MULTIPLE WEAK LOWS ON A FRONT DRAPED SW-NE ACRS THE CNTRL/NRN NT2
WTRS ARE SUPPORTING AN ENELY GRADIENT GNRLY UP TO 20 OR 25 KT TO
ITS N AND A SSWLY GRADIENT UP TO 25 OR 30 KT...HIGHEST ACRS THE
ERN MOST NT2 WTRS. MAX SEAS THRUT ARE LKLY IN THE 8-10 FT
RANGE...HIGHEST ACRS THE OUTERMOST NRN NT2 WTRS WHICH ARE IN LINE
WITH THE 18Z WAVEWATCH III AND 12Z ECMWF WAM AT THE MOMENT.

OVER THE SHORT TERM...THE LATEST MDLS IN GNRL ARE IN AGRMT THAT
THE MOST SIG FEATURE WL BCM A DVLPG SFC LOW MOVG NE OFF OF FLORIDA
TONITE...RACING NNE ACRS THE OUTER NT2 WTRS THU...ACRS THE ERN NT1
WTRS THU NITE...THEN OFF TO THE NE FRI WHL ANOTHER WEAKER SFC LOW
FORMS OFF THE MID ATLC COAST. THE PREV FCST PACKAGE USED THE 12Z
ECMWF SOLUTION FOR THIS DVLPG LOW...WITH ITS WINDS BOOSTED UP 10-15
PERCENT ON AVERAGE. WITH THE 18Z GFS COMING IN WITH A TRACK SMLR
TO THE 12Z ECMWF...AND WITH AN ASCD SLY 65-75 KT LOW LEVEL 925 MB
JET FCST TO DVLP THU...WL CONT WITH THE PREV STORM WRNG ACRS THE
OUTERMOST NRN NT2 WTRS WITH WDSPRD GALES ELSEWHR. SO DO NOT
ANTICIPATE MAKING ANY MAJOR SHORT TERM CHNGS TO THE PREV OFSHR
FCSTS.

IN THE LONG RANGE...PER THE 18Z GEFS MEAN...THE 18Z GFS SOLUTION
FOR A COLD FROPA ON LATE SUN/SUN NITE LOOKS TOO STRONG. WULD
INSTEAD FAVOR A SOLUTION CLOSER TO THE 12Z GFS/ECMWF. SO SINCE THE
12Z ECMWF WAS PREVLY POPULATED FOR THIS FROPA AGAIN DO NOT
ANTICIPATE MAKING ANY SIG ASCD CHNGS.




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

THE 12Z SFC ANALYSIS INDICATED LOW PRES JUST OFF THE DELMARVA
COAST WITH STATIONARY FRONT EXTENDING NE ACROSS THE NRN NT2
WATERS...AND EXTENDING SW INLAND. SATELLITE IMAGERY AND LIGHTNING
DATA CONTINUE TO INDICATE SCT TO NUMEROUS TSTMS OVER LARGE PORTION
OF NT2 WATERS S OF FRONT. ASCAT PASS FROM LATE WED MORNING SHOWED
THE FRONTAL BOUNDARY VERY WELL WITH NE WINDS 15 TO 20 KT N OF
BOUNDARY AND WINDS MOSTLY S TO SE 15 TO 25 KT S OF FRONT. THERE
WERE SOME 30 KT NOTED NEAR STRONGER CONVECTION.

THE MAIN FCST CONCERN DURING THE UPCOMING FCST PERIOD IS THE SHORT
TERM...SPECIFICALLY DURING THE THU/THU NIGHT TIMEFRAME. AT THE
MID/UPPER LEVELS...LOW WILL CLOSE OFF OVER THE MID ATLANTIC REGION
THU AND PERSIST INTO SAT NIGHT WITH A NUMBER OF SYSTEMS ROTATING
AROUND THE UPPER LOW. THE MOST SIGNIFICANT OF THESE FEATURES WILL
BE A LOW WHICH WILL MOVE OFF THE E COAST OF FLORIDA JUST N OF
BAHAMAS LATER TONIGHT...THEN TRACK RAPIDLY NE THU AND THU NIGHT.
THE 12Z GFS/GEM ARE SIMILAR TO THEIR PAST FEW RUNS MOVING LOW TO
NRN NT2 ZONES BY EARLY THU AFTERNOON...THEN NE ACROSS GEORGES BANK
LATE THU AFTERNOON AND TO SRN NOVA SCOTIA BY LATE THU NIGHT. THE
12Z UKMET HAS TRENDED FURTHER W AND CONSIDERABLY STRONGER THAN THE
00Z RUN. MEANWHILE...THE 12Z ECMWF IS REASONABLY CLOSE TO THE 00Z
RUN...ALBEIT A MB OR TWO DEEPER. FOR COMPARISON...BY 00Z FRI THE
UKMET IS 12 MB DEEPER AND ABOUT 120 NM W OF GFS POSITION.
CONSIDERING THE ECMWF HAS BEEN MORE CONSISTENT...AND ALSO APPEARS
TO BE A DECENT COMPROMISE BETWEEN THE WEAKER GFS/GEM AND STRONGER
UKMET PLAN ON USING THE ECMWF DURING THIS PERIOD. USING THE BOOST
ECMWF TOOL BRINGS WINDS UP TO STORM OVER ANZ910 THU NIGHT WHICH
DOES NOT SEEM THAT UNREASONABLE GIVEN PROXIMITY TO GULF STREAM.
OVERALL CONFDC IS MDT GIVEN THE MDL DIFFERENCES. THEN LOOKING
AHEAD TO FRI THROUGH SAT NIGHT...ANOTHER WEAKER LOW WILL DRIFT N
ACROSS THE NRN/CENTRAL NT2 WATERS WITH COLD FRONT TO MOVE OFFSHORE
SUN AND SUN NIGHT. THE ECMWF HAS ALSO BEEN MORE CONSISTENT WITH
THIS FRONT THE PAST FEW DAYS AND HAS DECENT SUPPORT FROM UKMET.
WEAK HIGH PRES WILL THEN BUILD INTO AREA MON/MON NIGHT. IN
SUMMARY...WILL POPULATE WIND GRIDS USING THE ECMWF WINDS...WITH
BOOST TOOL INCORPORATED THROUGH 09Z FRI. FOR THE REMAINDER OF
PERIOD...WILL USE ECMWF WINDS.

.SEAS...THE 18Z SEA STATE ANALYSIS INDICATED THAT OBSERVED SEAS
WERE WITHIN A FT OF THE MWW3/ECMWF WAM. SINCE WILL BE USING THE
ECMWF WINDS THROUGHOUT...ALSO PLAN TO USE ECMWF WAM FOR THE FCST
PERIOD. WILL MAKE A FEW EDITS TO BUMP UP SEAS A FEW FT OVER
WARNING AREAS THU/THU NIGHT.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
.ANZ800...GULF OF MAINE...
     GALE THU NIGHT.
.ANZ805...GEORGES BANK WEST OF 68W...
     GALE THU NIGHT.
.ANZ900...GEORGES BANK EAST OF 68W...
     GALE THU NIGHT.
.ANZ810...SOUTH OF NEW ENGLAND...
     GALE THU NIGHT.

.NT2 MID ATLC WATERS...
.ANZ915...HUDSON CANYON TO THE GREAT SOUTH CHANNEL...
     GALE THU.
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE THU.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE THU INTO THU NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE THU.
     STORM THU NIGHT.
.ANZ925...OUTER WATERS FROM BALTIMORE CANYON TO HATTERAS CANYON...
     GALE TONIGHT INTO THU.
.ANZ830...INNER WATERS FROM CURRITUCK BEACH LIGHT TO CAPE HATTERAS...
     GALE TONIGHT.
.ANZ930...OUTER WATERS FROM HATTERAS CANYON TO CAPE FEAR...
     GALE THU.
.ANZ935...OUTER WATERS FROM CAPE FEAR TO 31N...
     GALE TONIGHT INTO THU.

$$

.FORECASTER VUKITS/KOSIER. OCEAN PREDICTION CENTER.


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