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000
AGNT40 KWNM 201407
MIMATN

.Marine Weather Discussion for N Atlantic Ocean
.NWS Ocean Prediction Center Washington DC
905 AM EST TUE 20 FEB 2018

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Atlantic Ocean W of 50W from 30N to 50N.

At 12Z strong high pressure was centered east of the offshore
waters near 37N 58W, while a weak stationary front extended
along the Maine coast. This pattern will persist through Wed
resulting in south to southwest return flow across the offshore
waters. The latest models are consistent in forecasting a cold
front will exit the New England and northern Mid Atlantic coast
Wed evening and Wed night. Overall, the models are in above
average agreement through most of the forecast period. By late
in the weekend, the GFS is the most amplified of the global
models with the upper level trough lifting northeast across the
lower Great Lakes and New England, and as a result in also the
strongest with the offshore surface winds associated with the
approaching cold front and possible triple point development.
The previous wind grids were largely based on the 00Z ECMWF, and
appear reasonable at this time.

---------------------------------------------------------------
...Previous Discussion...

Highly amplified pattern will persist across the CONUS for the
next several days and into the weekend. Deep mean and reloading
upper trough will persist over the Western US, while anomalous
upper ridge will remain stationary across the Eastern Seaboard.
Across the W Atlantic and OPC offshore zones, this persistent H5
ridging will yield mostly light winds and flat seas.

Overall model guidance from the 00z cycle remains in pretty good
agreement throughout forecast period. Plan on using the 00z
ECMWF into 12z Thu, and out of deference to the higher 30 kt
winds in 00z GFS guidance, intend to evenly blend the first
sigma layer winds during this time frame. Will transition to the
00z ECMWF onwards for cold front passage, then stall between
37N-38N off the mid-Atlantic coast Thu and Thu night. The ECMWF
has shown excellent run to run consistency, and represents a
consensus solution between the northern front stalls of the 00z
UKMET/GEM, and the far southern front stall of GFS guidance.
Another cold front approaches the northern areas Fri night and
Sat, then again stalls off the mid-Atlantic coast in a near
similar position Sat night. No wind warning hazards are expected
during the next week.

Seas: not surprising given such a weak pattern, but both the 00z
WW3 and 00z WAM match ongoing ship and buoy obs fairly well and
are in good agreement through Sat night. Plan on using an even
blend of the wave height guidance to iron out any minor
differences.

Extratropical Storm Surge Guidance: no major deviation from the
latest surge guidance appears necessary over the couple of days.

.WARNINGS...Preliminary.

.NT1 New England Waters...
     None.

.NT2 Mid-Atlantic Waters...
     None.

$$

.Forecaster Clark/Collins. Ocean Prediction Center.


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