marine weather discussion

NWS ocean prediction center Washington DC

730 am EST Mon 23 Nov 2009

.Forecast discussion: major features/winds/seas/significant

.Weather for North Atlantic ocean W of 50w from 30n to 50n.

At 12z the latest sfc observation showed E to NE winds 15 to 25

kt from Baltimore Canyon N to the Gulf of Maine and over the NW

corner of Baltimore Canyon to Hatteras Canyon. The stronger

winds also extending SW from Cape Hatteras to Cape Fear over the

coastal and far W offshore waters. Elsewhere winds were se to S

10 to 15 kt. Seas were 9 to 11 ft between Cape Cod and Baltimore

Canyon...3 to 6 ft over the Gulf of Maine and 6 to 8 ft S of

Baltimore Canyon.

A developing low pres center at 12z located to the se of Cape

Lookout will move NE to Cape Hatteras by evening then continue

NE to SW Georges Bank by Tue morning. The low will exit Georges

Bank early Wed. Dragging a cold front E across the nt2 waters.

The models have the general pattern with the NAM not on board

with the low moving into Georges Bank Tue. No plan to use the

NAM today. The ec...UKMET and Gem are slower then the 06z GFS.

In addition the GFS has a somewhat elongated area of low pres

with the other models favoring one center. Plan to keep the gale

up for E to NE flow arnd the low but think it will be marginal.

No charges for the update.

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Previous discussion

Large high pres conts to build se across the nrn waters...

supporting mod NE flow of 20 to 25 kt ovr most of the offshore

waters tngt...xcpt except far NW waters 15 to 20 kt. Models cont

to fcst low pres to dvlp offshore and move to E of the VA CAPES

by late aftn...then cont to deepen and move low NE tngt thru

Tue. GFS has been fairly consistent with this fcst...only latest

runs are deeper. Ll vort fields indct GFS is having minor

convective feedback prblms. The gfsp is smlr to the op

GFS...though just a bit more tepid on deepening the low. The

ECMWF/UKMET/cdn are smlr...with all the models arriving at a

fcst of the sfc low over ern Georges Bank at 00z Wed.

Oddly...the GFS ensmbl mean is se of all global models. The GFS

is 3 to 4 mbs deeper than the other models. The NAM...never

catches on and takes a very weak low and moves it

eastward...then northward and is discarded.

Will cont with E gales dvlpng at 00z tngt S of New England

waters...then across the rmndr of the nrtrn waters tngt. Xpct

gales to end Tue and Tue ngt. Will stay with minimal gales...

instead the higher 40 ro 45 kt fcst by the overdone GFS.

Next fcst prblm is late Thu and Fri. Models cont to have prblms

in timing of dvlpng cut off upr low ovr the Ohio vlly late

Thu... then bringing large upr low eastward. The GFS and ECMWF

are the most alike while the cdn and esp the UKMET conts to be

too progressive. On the sfc...a sig cyclone is likely to affect

the offshore waters Fri. Details are dffclt at this point with

confidence lacking. Wl fcst a mix of the new GFS and ECMWF...

leaning more twds the latter. The GFS ensmbl members are

scattered about and offer little...except to confirm that

confidence should be low. Best bet for gales attm is for late

Fri...early Sat in unstable caa in wake of sfc low off the mid

Atlc coast. But owing to low confidence...wl kp winds checked at

30 kt maximum.

Seas...currently...obsrvtns compared with the W Atlc wave watch

model are running 2 to 3 ft above the models off the NC and SC

coast. Seas here shld gradu subside as winds veer to s'rly and

dmnsh today. And over balt cnyn...seas are 1 to 2 ft abv gdnc...

and do not see much of a reason to change. Elsewhere...wl fllw

wave watch guidance...xcpt low seas 1 or 2 ft in assn with

slgtly overfcst low. Also...late Fri...wl trim back seas 20 to

25 pct ovr the outer offshore waters.

Extratropical storm surge...fcst lvls reach just over 1 ft along

the NJ coast 12z Tue. Since GFS winds are overdone...these hgts

may be a lttl too high.

.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 tngt into Tue...low confdc. Gale Fri...low

confdc.

.Georges Bank...Gale this aft into Tue...low to MDT confdc.

.S of New England...Gale this aft into Tue...low to MDT confdc.

.Nt2 mid Atlc waters...

.Hudson to balt cnyn...none.

.Balt cnyn to Hague line...Gale this aft into tngt E part...low

to MDT confdc. Gale Fri E part...low confdc.

.Balt cnyn to Hatteras cnyn...None.

.Hatteras cnyn to Cape Fear...None.

.Cape Fear to 31n...None.

.Forecaster oszajca/prosise. Ocean forecast branch.