marine weather discussion NWS ocean prediction center Washington DC 709 am EST Thu 4 Dec 2008

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

The latest qscat pass was showing light SW winds 15 kt or less across the area with only the Gulf of Maine and far W and NW portion of Hudson Canyon to Baltimore Canyon and south of New England having winds 15 to 25 kt. The seas fit the wind pattern...generally 3 to 5 ft across the area with higher seas 6 to 8 ft se of Long Island and 6 to 10 ft over the N Gulf of Maine.

High pres across the waters this morning will drift to the se later today and overnight. A cold front now extending from Lake Erie se to the Tennessee Valley will move E to the coast late this aft then E across the waters tonight and Fri. High pres will build into the area following the front Fri and Fri night then weaken Sat. The next front will move across the area Sat night and sun.

The GFS develops a low on the first front and intensifies it as it moves NE just E of the offshore waters. The other models prefer a 3 pt low on the second front. The models having close timing with the second front and agreement with gale force winds sweeping across the area. For the update will continue to go with a blended solution for the warnings sun into Mon. Think the GFS is develop too strong a low on the first front. Have not made any sig changes from previous package.

-------------------------------------------------------------- Previous discussion

Short term fcst...the new 00z mdls present no major fcst problems. The 00z NAM/namp/GFS rmn in good agrmt that a high pres area crossing the srn and cntrl nt2 wtrs wl maintain light conds today in the srn wtrs while the swly return flow increases ahd of next cdfnt. Then late today/tonight the 00z NAM/namp/GFS maintain smlr timing for pushing the cold front se acrs the nt1 and nrn/cntrl nt2 wtrs...then stalling the fnt SW-NE acrs the srn nt2 wtrs by late Fri. Per the 12z NAM/GFS bl wind fcsts and stability guidance plan on contg to fcst Max prefrontal winds up to 25 or 30 kt and Max postfrontal winds 20 or 25 kt. So overall no sig chngs are planned to the prev ofshr fcsts rgrdg this fropa.

In the long range...the latest global mdls cont to gnrly agree that a sgfnt S/W trof wl dig to the vcnty of the E CST by early sun...then mov ofshr sun into Mon...whl svrl embd sheared S/W trofs rotate thru its base. The 00z NAM/namp/GFS/Gem and old 12z ECMWF Fri nite fcst a frontal low(s) to form over the srn nt2 wtrs and then track NE nr the outermost nt2 wtrs Sat. Due to the strong swly upr lvl flow fcst over the nt2 wtrs during this timeframe do not hv a high level of confidence in the exact fcst track...nor strength...of these frontal waves. But due to the sheared upr flow one wuld expect they wuld rmn rel weak. Therefore plan on using a blended solution favoring the 00z GFS/ECMWF and wl keep the ascd winds subgale.

Then by 12z sun...the 00z cndn global and 12z ECMWF cont to fcst more consolidated low nr Georges Bank in response to digging shrtwv movg offshore alg with incoming Arctic fnt accompanied by strengthening W to NW gradient in its wake as the low conts NE twd mrtms. GFS has similar idea but holds onto a nrn strm cntr movg off New England. Using a blend of these mdls (the HPC medium range guidance looks most smlr to the 12z ecmwf) and noting the strong cold air advection and negative static stabilities fcst to dvlp in this nwly gradient...plan on contg with the prev fcst wrngs. Tho per the 12z GFS/Gem gales may not dvlp in the Gulf of Maine/Georges Bank until sun nite vs the prevly fcst sun...but for now it looks too close to chng the timing as using term late sun can imply sun ngt. Also per the 00z Gem/ECMWF gales may not extend S of hat cnyn...but again it looks close enuf to leave the wrng in place for The Hat cnyn to cp fear wtrs given GFS takes brf swipe at Cape Fear area outer wtrs with gales. Given that sun is day 4...per the 00z GFS/Gem and 12z ECMWF cont to hv above avg confidence that gales wl dvlp in the wake of this system... especly thrut the S of new engld to hat cnyn wtrs. Then per the 00z GFS/Gem and 12z ECMWF wl fcst the gales to end FM SW to NE Mon as a high pres rdg is fcst to bld twds the CST. So attm unless the 00z ECMWF is radically different no major long range chngs are planned to the prev ofshr fcst package.

Overall the 00z wna wavewatch iii looks representative and for now do not plan on deviating sigly FM its fcst seas.

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

.Nt1 New England waters... .Gulf of Maine...gale late sun into Mon...MDT confdc. .Georges Bank...Gale late sun into Mon...MDT confdc. .S of New England...Gale sun into Mon...MDT confdc.

.Nt2 mid Atlc waters... .Hudson to balt cnyn...gale sun into Mon...MDT confdc. .Balt cnyn to Hague line...Gale sun into Mon...MDT confdc. .Balt cnyn to Hatteras cnyn...Gale sun into Mon...MDT confdc. .Hatteras cnyn to Cape Fear...Gale sun...low to MDT confdc. .Cape Fear to 31n...None.

.Forecaster oszajca/Bancroft. Ocean forecast branch.