HS 100

marine weather discussion NWS ocean prediction center Washington DC 800 PM EST Sat 7 Nov 2009

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

As high pres blds ofshr acrs the cntrl nt2 wtrs gnrly lite winds (15-20 kt or less) hv dvpld thrut the cstl/ofshr wtrs attm. Max seas are running in the 8-10 ft range acrs the outermost nt2 wtrs which are slightly higher than fcst by the 18z wna wavewatch iii attm.

Over the short term...the latest mdls present no major problems. Per the 18z NAM/GFS...inadvof weak cold front fropa late tonite into sun...wl cont to fcst Max SW winds up to 25 or 30 kt acrs the nrn wtrs. Otherwise no sig short term chngs are planned to the prev ofshr fcsts.

In the long range...by late Tue/Wed the latest mdls cont to offer sigly different solutions for the future path of T.S. Ida or its remnants as it is expected to interact with a strong cold front movg ofshr. Vs its prev 12z run...the 18z GFS now does not phase the srn and nrn upr streams as quickly and as a result is slower and further se with a major frontal low (remnants of ida?) Crossing the nt2 wtrs Wed/Wed nite with ascd hurcn force bl winds fcst. The 18z gefs ensemble members indicate that initially the 18z GFS is lkly too fast in the Gulf of Mexico with Ida on Tue...and then later does not show much sprt for the strong frontal low acrs the nt2 wtrs on Wed. For now with a very low level of confidence plan on favoring a blended 12z ECMWF and 18z gefs/12z ECMWF mean fcst for the strong cold fropa and any frontal wave dvlpmt which wl be in line with the latest HPC medium range guidance.

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The latest ascat pass and the latest sfc obs showed W to NW winds 10 to 20 kt...except E of 67w 15 to 25 kt across the offshore waters from Baltimore Canyon to the Gulf of Maine...variable winds 5 to 10 kt from Baltimore Canyon to Cape Hatteras and N to NE winds 10 to 20 kt from Cape Hatteras to 31n. Seas were 3 to 6 ft over nt2 W of 1000 FM...the W portion of south of New England and the Gulf of Maine and 6 to 10 ft elsewhere with the highest 9 to 10 ft E of 67w.

High pres build across the area will move E of the nt1 waters overnight while remaining across nt2. A weak cold front will move into the N waters sun stall over the central nt2 waters Sun night then lift N as a warm front Mon. A low pres center will move across central Maine Tue night. The low will pull a cold front off the coast and across the NW waters Tue night and E of the area Wed. High pres will build into the area following the front Wed and Thu. The remnants of T.S.Ida are expected to remain in the Gulf of Mexico well SW of the offshore waters.

The model are in good agreement through Tue then the GFS take Ida as an extratropical low NE along the cold front move across the area. The other models keep Ida in the Gulf of Mexico or nudge it to the SW. This will be the problem of the day with the GFS diverging from the model consensus. For this package will not use the GFS for day 4 or 5 but go with the HPC Med range and the ec. Plan to keep the gale winds for Wed but not extend into Thu for any zone. The low passing across Maine Tue night will have strong NW flow which should inc winds to gale Wed from Gulf of Maine S to Cape Hatteras...then S of Hatteras to 31n the high ridge into area set up a NE flow across the Gulf Stream. Have low confdc in low move NE into nt2 per Gem or E across FL but S of nt2.

For seas have use the previous fcst and ww3 through Tue. Then with seas building Wed have not made much of a change and for Thu will slowly diminish. The wave watch is driven by the GFS so low confdc in guidance aft Wed.

.Warnings/forecast confidence...Warnings are preliminary and are subject to change. Any changes will be coordinated through AWIPS 12 planet chat or by telephone.

.Nt1 New England waters... .Gulf of Maine...gale Wed...low confdc. .Georges Bank...Gale Wed...low confdc. .S of New England...Gale Wed...low confdc.

.Nt2 mid Atlc waters... .Hudson to balt cnyn...gale Wed...low confdc. .Balt cnyn to Hague line...Gale Wed into Thu...low confdc. .Balt cnyn to Hatteras cnyn...Gale Wed...low confdc. .Hatteras cnyn to Cape Fear...Gale Wed into Thu...low confdc. .Cape Fear to 31n...Gale Wed into Thu...low confdc.

.Forecaster vukits/oszajca. Ocean forecast branch.