HS 100

marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 930 PM EDT Fri 24 may 2013

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

A low pres center was located over Cape Cod with a trailing cold front extending SW across south of New England and the nt2 waters. Winds E of the low and front were S to SW 15 to 25 kt except in the E 70w over Baltimore Canyon to the Hague line 25 to 35 kt. W of the low and front NW winds 20 to 30 kt N of Cape Fear and 10 to 20 kt S of Cape Fear. Seas from 9 to 17 ft N of Hatteras Canyon and 6 to 9 ft to the S.

A closed upper low will form over New England on Sat with the sfc low moving N overnight and then rotating arnd the upper center Sat and Sat night. The upper low will slowly lift N Sat and Sat night then move more rapidly sun. The low pres center will pull the trailing cold front across the waters overnight then a series of low pres troughs will move se through the nrn waters Sat and sun.

The models are in good agreement with the short term pattern. The NAM and GFS inc winds to gale force in the NW flow Sat as the first low pres trough sweeps across the NW waters. The BUFKIT soundings as well as the GFS 30m winds for unstable conditions support a gale so have inc winds for the south of New England zones. Plan to have gale Sat into Sat night. The upper low will move to the N sun. For update only change was to add gale to south of New England zone.

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Summary...a cold fnt will pass E across the ofshr wtrs this aftn thru Sat. Low pres will move NE over the srn nt1 wtrs this aftn into tonite...then turn N and pass across the nrn nt1 wtrs Sat into sun. The low will move off to the NE late sun and Mon. Rdg will bld se into the srn nt2 wtrs sun...expand over the nrn nt2 wtrs Mon...then bld across the nt1 area Tue. The rdg will shift E of the nt1 area Wed...as a warm fnt lifts NE over the nrn nt2 and srn nt1 wtrs.

Models...the 12z NAM and 12z Med rng mdls are in gud overall agreemnt thru the fcst prd...with ECMWF and GFS in closest agreemnt across the cstl/ofshr wtrs. 12z ECMWF/UKMET look a bit wkr with the S to SW flow ahd of the cold fnt into Sat...while the 12z NAM/Gem are stgr...and 12z GFS/NOGAPS are median solns wrt strength of the S to SW flow. Since the GFS has stg support from the ECMWF...and because the GFS looks like a gud median soln...will be favoring the 12z GFS for the upcoming ofshr wtrs fcst package. Am not planning to make any signif changes to the current fcst trend.

Seas...the 12z multigrid ww3 and 12z ECMWF wam both initialized well over the cstl/ofshr wtrs. These mdls are in gud overall agreemnt during the fcst prd...with only some minor diffs noted on Sat and sun. Will use the multigrid ww3...except may go with a blend of the multigrid ww3 and ECMWF wam on Sat and sun to smooth some of the diffs.

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...Gale Sat into Sat ngt...low to mod confdc.

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

.Forecaster oszajca/Scovil. Ocean prediction center.