marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 1012 am EDT Tue may 21 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Visible satellite imagery clearly shows cold front has move moved S into the N and central mid Atlc waters. The front continues to move S into the central and southern areas of the mid Atlc by tonight and passes S of the area by early Wed. Weak high pressure was over the S mid Atlc waters and should dissipate by early afternoon. Subtropical depression Andrea was near 31n69w this morning and stays E of the area as it moves slowly E today into tonight. Elsewhere as cold air advection increases across the New England waters postfrontal should see winds increasing to 30 kt this afternoon or by tonight over the outer New England waters into the Gulf of ME. At the moment have only seen winds to 25 kt postfrontal. With the updated forecast will be making few changes to previous forecast for now.
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IR imagery along with lightning data indicate the cold front has moved offshore New England early this morning, through the Gulf of Maine, and across Georges Bank. Earlier ascat overpasses between 0127z-0305z returned no surprises, with S-SW flow generally 20 kt or less save for locally higher 25-30 kt retrievals coincident the north wall of the Gulf Stream off the mid-Atlantic coast. Caution continues to mariners for locally higher gusts to gale force and very rough seas in or near any of the stronger convection. Much farther to the se -- about 260 nm to the SW of Bermuda -- subtropical storm Andrea continues move slowly N at about 10 kt, and will remain well E of the offshore waters today before dissipating Wednesday. See the National Hurricane Center for the most up to date and recent information.
00z guidance in good agreement in the near term as the cold front moves south across the offshore waters today, then clears the southern zones later tonight. Models still prog a secondary surge of cold air across the northern portions, either via a secondary cold front or low pressure trough. Models remain in good agreement with strongest winds generally in the 25-30 kt range across the area. Out of deference to previous forecasts, will carry highest winds to 32 kt across anz900 and anz905 by using some of the GFS first sigma layer winds. High pressure builds to the coast later tonight, moves offshore Wed and Wed night, then shifts E and se of the area Thu.
The h5 shortwave currently across aiding in the severe weather across the plains finally crests the strong ridge across the eastern conus Wed night into Thu, then digs se across New England and the Gulf of Maine Thu night into Fri. A marked trend toward a slower and farther east track is apparent in all global models, and the 00z ECMWF is the best consensus solution among all guidance this morning. In attempt to maintain some continuity in forecasts, plan to boost the ECMWF winds to maintain gale headlines across the outer zones Fri and Fri night as the 130 kt jet streak digs overhead. Confidence in gales is about average. Another high builds across the W Atlantic Fri night into Sat, then weakens and shifts se of the offshores Sat night ahead of the next boundary approaching the mid-Atlantic and New England.
Seas: both sets of wave guidance initialized seas fine on the 06z sea state analysis. In the near term will favor the ww3, then in similar fashion as the wind grids will transition the significant wave heights toward the wam Thu Onward.
Extratropical storm surge guidance: no significant positive surge events are expected during the next few days. Consult your local National Weather Service forecast for more detailed information.
.Nt1 New England waters... .anz900...Georges Bank east of 68w... gale possible Friday night.
.Nt2 mid-Atlantic waters... .anz905...the great South Channel to the Hague line... gale possible Friday night. .Anz910...East of the great South Channel and south of 39n... gale possible Friday night.
.Forecaster Rowland/Collins. Ocean prediction center.