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AGNT40 KWNM 060802

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
302 AM EST Sat Mar 6 2021

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

Summary...ASCAT overpasses from last evening indicated winds
approaching gale force off the coast of Maine, with widespread
winds of 25 to 30 kt covering most of the offshore waters roughly
from E of Cape Hatteras northward, with winds of 20 kt or less S
of Cape Hatteras. The latest observations indicate winds that
winds have relaxed slightly since the evening ASCAT overpasses,
with winds generally in the 20 to 25 kt, with gusts around 30 kt,
range from off the Delmarva coast northward, with winds of 20 kt
or less to the S. The 06Z OPC-NCEP preliminary surface analysis
shows a cold front E and S of the offshore waters, a low pressure
trough crossing the New England waters, and a large high
building SE from the northern plains states. Overall, there are
no major changes indicated by the 00Z guidance from the past few
OPC forecasts. A series of troughs or weak cold front will
continue to pass SE over the New England waters into Sun as a
large upper level low spins over eastern Canada. Low pressure
organizing to the SW of the region will remain S and then pass E
of the waters through Sun into Mon as the high builds further E
and finally moves off the east coast later Mon. The high will
then cross the Mid-Atlantic or NT2 waters Mon night into Tue as a
weak cold front approaches and then crosses the New England or
NT1 waters. The front will stall over the far northern NT2 waters
and weaken Tue night with high pressure then covering most of
the region by Wed as the front dissipates. The high will then
slowly slide E of the waters later Wed into Wed night.

Hazards and model guidance...As far as hazards are concerned,
there is still a slim chance for gales developing mainly over the
gulf stream waters later Sun and Sun night as the pressure
gradient strengthens between the high building SE toward the
coast and low pressure passing S and then E of the offshore
waters. For now, we will continue to show winds to 30 kt off the
SE coast at that time, with the latest guidance indicating that
any gales would occur closer to the low, and remaining E of the
offshore waters later Sun into Mon. Otherwise, there appears to
be no significant threat for hazard levels winds over the region
into next week. To maintain continuity, we will populate grids
for the early morning package closer to the well initialized 00Z
WARW winds for today into Sun, transition to a 3:1 blend of the
previous grids and 00Z GFS first sigma layer winds for Sun night
into Wed, and then populate grids closer to the consistent 00Z
ECMWF bias-corrected winds for Wed night and Thu. Overall,
forecast confidence levels are slightly above average over the
region for the next 5 days.

Seas: The ongoing wave height grids remain in excellent
agreement with the latest west Atlantic observations, and still
appear quite reasonable across the region today into Wed. To
refresh the grids during the next few days we will blend in up to
10 percent of the 00Z Wavewatch to the ongoing grids for the
early morning package into Wed, and then transition grids closer
to the 00Z ECMWF WAM for Wed night and Thu to match the wind
forecast noted above. Wave heights somewhat above the latest
guidance are still forecast by Sun night off the SE coast where
enhanced winds are forecast, as described above.

Extratropical Storm Surge Guidance: No significant positive
surge events are expected during the next several days. Please
monitor products from coastal National Weather Service offices
for detailed water level information.


.NT1 New England Waters...

.NT2 Mid-Atlantic Waters...


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