HS 100

marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 900 PM EDT Tue 21 may 2013

.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.

Note: having major awips2 problems so will be brief.

A warm/stnry front extending acrs the nt1 wtrs has Max ascd winds only in the 15-20 kt range attm with Max ascd seas gnrly in the 3-5 ft range.

Over the short term...wl use a blended 18z GFS and 12z ECMWF solution for this front very slowly lifting nwd acrs the nrn nt1 wtrs thru Wed nite. Per this blended solution wl cont to fcst a strenghtening sswly gradient dvlpg thrut all of the ofshr wtrs thru Thu with Max winds up to 25 or 30 kt. So no major short term chngs are planned for the next ofshr fcst period.

In the long range...wl use the 12z ECMWF fcst timing for a cold front movg ofshr Thu nite...then pushing slowly se acrs the ofshr wtrs Fri into early Sat. Vs its prev 12z run...the 18z GFS now fcsts a mr progressive fropa which is more in line with the 12z ECMWF and the latest wpc medium range guidance. With all of the latest global mdls fcstg sm prefrontal gale force bl winds dvlpg...per the 12z ECMWF for now wl add psbl gale wrngs for the balt cnyn to the Hague line wtrs Fri into Sat. So wl be making sm sig long range chngs to the prev ofshr fcst package.

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Low pres currently E of the nrn nt2 waters will continue moving E today while slowly weakening. Srly flow will then increase across the offshore waters by tonight. The srly flow will continue to increase into Thu as low pres moves just N of New England and a cold front approaches the E coast of the U.S.. winds up to 30 kt are still expected across the nt1 and nrn nt2 waters by Thu ahead of the front. Low pres is expected to develop along the front off the coast of srn New England by Fri and then move off to the NE Sat. High pres will then build across the offshore waters sun. Winds across portions of the nt1 and nrn nt2 waters will come close to gale force on Fri ahead of the low...but for now will keep the Max winds at 30 kt. The latest GFS and ECMWF look to be in reasonable agreement. Will continue to carry no warnings across the offshore waters during the forecast period.

The multigrid wavewatch iii looks reasonable with the seas and will be followed fairly closely during the forecast period.

Extratropical storm surge guidance...N/A.

.Warnings/forecast confidence...Preliminary. Any changes will be coordinated through AWIPS 12 planet chat or by telephone:

.Nt1 New England waters... .Gulf of Maine...none. .Georges Bank...None. .South of New England...None.

.Nt2 mid Atlc waters... .Hudson Canyon to Baltimore Canyon...none. .Baltimore Canyon to Hague line...Gale Fri into Sat...low to mod confdc. .Baltimore Canyon to Hatteras Canyon...None. .Hatteras Canyon to Cape Fear...None. .Cape Fear to 31n...None. $$

.Forecaster vukits/nolt. Ocean prediction center.