Marine Interpretation Message
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
000
AGNT40 KWNM 020024
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
824 PM EDT SUN MAY 1 2016

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

UPDATE...18Z NCEP SFC ANALYSIS SHOWS A HI PRES RIDGE OVER THE
OFSHR WTRS...EXCEPT FOR A STATIONARY FRONT ARCING SE TO NW ACROSS
ZONE 835 IN THE SRN NT2 WTRS. LATEST AVAIL ASCATB HI-RES AND RSCAT
PASSES FROM EARLIER TODAY SHOW SOME AREAS OF WINDS TO 20 KT IN THE
CENTRAL AND NRN NT2 WTRS...BUT OTHERWISE INDICATE LIGHTER WINDS OF
15 KT OR LESS ACROSS THE OFSHR WTRS. LIGHTNING DENSITY PRODUCT
DATA AT 2250Z DID NOT SHOW ANY SHOWERS OR TSTMS OVER THE OFSHR
WTRS.

MAIN WEATHER FEATURES...A WARM FRONT WILL LIFT NE OVER THE NRN NT2
WTRS TONITE...THEN CONT NE ACROSS THE NT1 AREA MON. A DVLPG LOW
WILL PASS NE OVER THE NT1 WTRS MON...THEN MOVE OFF TO THE NE MON
NITE AND TUE WHILE PULLING A COLD FRONT SE OVER THE NT1 AREA. A
SERIES OF LOW WILL PASS NE ACROSS THE SRN NT1 WTRS TUE INTO WED.
ANOTHER COLD FRONT WILL MOVE E OVER THE NT2 WTRS WED THRU THU. LOW
PRES WILL FORM NEAR THE SRN MID ATLC COAST THU NITE...THEN REMAIN
NEARLY STATIONARY THRU FRI NITE.

MODELS...THE MED RNG MDLS ARE IN VERY GUD OVERALL AGREEMNT ACROSS
THE OFSHR WTRS FOR TONITE THRU WED NITE...AND WILL BE USING THE
REPRESENTATIVE GFS SOLN TO POPULATE THE WIND GRIDS FOR THIS
TIMEFRAME. FOR THU THRU FRI NITE WITH THE LOW NEAR THE MID ATLC
COAST...GEM/GFS ARE STRONGER WITH ITS WINDS WHILE ECMWF/UKMET ARE
WEAKER...SO A 50/50 BLEND OF THE ECMWF/GFS AS A COMPRIMISE SOLN.
AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE CURRENT FCST
TREND.

SEAS...WNA VERSION OF WAVEWATCH III MDL AND ECMWF WAM ARE IN
VERY GUD AGREEMENT FOR TONITE THRU MON NIGHT. THE WNA WW3 IS 2 TO
3 FT HIGHER THAN THE ECMWF WAM AHEAD OF THE COLD FRONT TUE NITE
AND WED. DECIDED TO USE THE WNA WW3 MDL FOR TONITE THRU WED NITE
IN ORDER TO BE CONSISTENT WITH THE PREFERRED GFS SOLN...THEN WENT
WITH A 50/50 BLEND OF WNA WW3/ECMWF WAM FOR THU THRU SAT NITE FOR
THE SAME REASON.

EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

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

A HIGH PRES RIDGE ACROSS THE NEW ENGLAND AND MID ATLC OFFSHORE
WATERS WILL SHIFT E THIS EVENING AS A WARM FRONT LIFTS N AND NE
THROUGH THE MID ATLC WATERS. 12Z MODELS ARE IN GOOD AGREMEENT
WITH THE TIMING OF THE WARM FRONT REACHING THE NT1 WATERS MON
MORNING. HOWEVER WITH SHALLOW MARINE LAYER IN PLACE OVER COASTAL
AND AREAS AS WELL AS INNER WATERS THE FRONT WILL REMAIN NEARLY
STATIONARY NEAR THE VIRGINIA CAPES INTO MON AFTERNOON. TO
VARYING DEGREES THE 12Z MODELS INDICATE A WEAK SURFACE LOW WILL
DEVELOP ALONG THE FRONT AND MOVE OFF THE DELMARVA PENINSULA
TONIGHT... AND MOVE NE THROUGH THE NT1 WATERS MON INTO MON
NIGHT. OVER THE PAST SEVERAL RUNS MODELS HAVE GENERALLY TRENDED
WEAKER AND FURTHER N WITH THIS DEVELOPING LOW. THE 12Z GFS 10M
WINDS LOOK REASONABLE OVER NEXT 12 HOURS BUT THAN AS SW WINDS
BEGIN TO INCREASE LATER TONIGHT USED A 50/50 BLEND OF 12Z GFS
10M AND BOUNDARY LAYER WINDS LATE TONIGHT THROUGH MON NIGHT TO
CAPTURE THE HIGHER SW WINDS WHICH ARE LIKELY TO OCCUR OVER THE
OUTER MID ATLC WATERS ALONG THE GULF STREAM...UP TO 30 KT MON
NIGHT. 12Z GFS AND 12Z ECMWF THEN ARE IN GOOD AGREEMENT THAT A
SERIES OF SURFACE LOWS WILL TRACK NE ALONG THE SLOW MOVING COLD
FRONT TUE THROUGH WED NIGHT...STRONGEST OF WHICH SHOULD BE LATE
TUE AND TUE NIGHT. BOTH THE 12Z 1/4 DEG GFS AND ECMWF SHOW SOME
MARGINAL GALES OVER CLIMATOLOGICALLY FAVORED OUTER NORTHERN MID
ATLC WATERS NEAR GULF STREAM. AGAIN USED A BLEND OF THE 12Z GFS
10M AND BOUNDARY LAYER WINDS TUE THROUGH WED NIGHT WHICH
RESULTED IN GALES FOR OUTER ZONES ANZ905 ANZ910 AND ANZ920 TUE
INTO WED.

12Z MODELS THEN ARE IN AGREEMENT THAT THE COLD FRONT WILL PASS
JUST E OF THE OFFSHORE WATERS LATE WED NIGHT AND EARLY THU.
LATER THU THROUGH THE END OF THE WEEK MODELS NAMELY THE
GFS/ECMWF/UKMET HAVE COME INTO MUCH BETTER AGREEMENT WITH THE
AMPLIFIED UPPER TROUGH/CLOSED LOW THAT WILL DROP SE INTO THE
EASTERN US THU AND MOVE OFF THE MID ATLC COAST FRI AND FRI
NIGHT. 12Z MODELS ARE NOW ALSO IN GOOD AGREEMENT WITH THE
SURFACE LOW DEVELOPMENT OFF THE VIRGINIA CAPES LATE THU AND THU
NIGHT AS SYSTEM BECOMES VERTICALLY STACKED. 12Z GFS/GEM ARE
STRONGER WITH THE ASSOCIATED WINDS THAN 12Z UKMET/ECMWF. SO FOR
THU/FRI AS A COMPROMISE AM FAVORING A 50/50 BLEND OF 12Z ECMWF
AND 12Z GFS.

12Z WAVEWATCH III AND 12Z ECMWF WAM ARE IN EXCELLENT AGREEMENT
THROUGH MON NIGHT...THEN WITH GFS STRONGER THAN THE ECMWF WITH
INCREASING SW WINDS SE OF THE COLD FRONT TUE NIGHT AND WED...THE
12Z WW3 IS 3 FT OR SO HIGHER THAN THE 12Z ECMWF WAM. AFTER SOME
NEAR TERM EDITS TO ACCOUNT FOR LATEST OBS...USED THE 12Z WW3
THROUGH WED NIGHT...THEN A 50/50 BLEND OF THE 12Z WW3 AND 12Z
ECMWF WAM THU THROUGH SAT NIGHT.

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

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE TUE.
     GALE POSSIBLE TUE NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE TUE.
     GALE POSSIBLE TUE NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE TUE.
     GALE POSSIBLE TUE NIGHT INTO WED.

$$

.FORECASTER SCOVIL/CLARK. OCEAN PREDICTION CENTER.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.