|
marine weather discussion
NWS ocean prediction center Washington DC
634 am EST Sat 22 Nov 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 a broad area of gale winds
from Georges Bank S to E portions of Cape Fear to Cape Hatteras.
The 12z sfc analysis has a deepening low pres system over E Nova
Scotia. This low was move to the N. The gradient between the
high pres building into the area from the W and the deepening
low will keep gale force winds across the area into sun. For the
update will let the gale end S of Cape Fear and change the
wording for Cape Fear to Cape Hatteras to keeps the gale up
early then end later in the afternoon.
For seas...in the coastal 3-6 ft over the W portions of the
offshore 6-9 ft and E portions from 9 to 21 ft. For 12z have an
observation with 21 ft over the W portion of Baltimore Canyon to
the Hague line. This observation looks high but fit the qscat
pattern and previous analysis. Also 06z GFS has area of gale
winds in the vicinity and SST has a warm eddie.
The warnings are up and verifying so no other changes to
previous package.
--------------------------------------------------------------
Previous discussion
An earlier 00z ship report of 60 kt along with a 2312z Quikscat
pass with numerous hurricane force wind vectors indicated that
hurricane force winds were present over the ern balt cnyn to the
Hague line wtrs immed NW of the rpdly dvlpg sfc low then S of
Georges Bank. Tho the 00z NAM/namp/GFS hv not initialized this
low deep enuf...there fcst tracks over the short term look rsnbl
and wl be acptd. Per the 00z NAM/namp/GFS fcst gradients in the
wake of this system...the low shuld be far enuf away FM the
ofshr wtrs to start the today fcst period with gale force winds
as prevly fcstd. Then with the 00z NAM/namp/GFS rmng consistent
with their prev respective runs...wl fcst all the gale wrngs to
end sun as prevly fcstd. So other than tweaking the prev fcsts
to reflect the latest obsrvd conds...no sig short term chngs are
planned to the prev ofshr fcst package.
In the long range...the 00z GFS rmns quite consistent with its
prev 12z/18z runs in fcstg a triple point sfc low to form invof
srn new engld late Mon nite then dumbbell NNW around its ascd
closed upr low Tue whl pulling a fairly strong cold front ofshr.
The 00z global Gem/UKMET gnrly sprt this GFS solution whl the
old 12z ECMWF was slower...especly with the cold front movg
ofshr. The latest HPC medium range guidance is in line with the
00z GFS so wl favor its solution for the next fcst package. With
the 00z GFS maintaining smlr timing vs its earlier favored
runs...do not plan on making any sig chngs to timing of the
prevly fcst gale wrngs for this system. Per the 00z GFS/Gem bl
wind fcsts... prefrontal storm force winds looks psbl Tue acrs
the ern balt cnyn to Hague line and the NE most Gulf of Maine
wtrs. With the Gulf Stream along with a warm eddy present...blv
there wl be enuf low level mixing to go ahead with storm wrngs
for the ern balt cnyn to Hague line wtrs Tue. But for the Gulf
of Maine...wl hope that the S-sely storm force bl winds fcst by
the GFS/Gem wl hv trouble mixing down to the sfc...so wl just
fcst strong gale force winds dvlpg there as prevly fcst. Then on
Wed the 00z GFS/Gem/UKMET differ in how fast the upr low and the
ascd vertically stacked sfc low wl mov E. The 00z gefs ensemble
members on Wed are too wdly scattered to draw any definite
conclusions abt the 00z GFS. For now wl favor the slower 00z GFS
solution which is smlr to the latest HPC medium range guidance
and wl cont to broadbrush with subgale wly winds thrut much of
the ofshr wtrs. So no other major long term chngs are planned to
the prev ofshr fcst package.
Due to the 00z GFS initialization problems and the strong cold
air advection...the 00z wna wavewatch iii seas are running
slightly too low attm so wl adjust its fcst seas acrdgly over
the short term. Otherwise its fcst seas look representative and
wl not be sigly deviated FM.
.Warnings/forecast confidence...Preliminary. Any changes will be
coordinated through AWIPS 12 planet chat or by telephone:
.Nt1 New England waters...
.Gulf of Maine...gale this aft into sun..hi confdc. Gale
Tue...MDT confdc.
.Georges Bank...Gale this aft into sun...hi confdc. Gale
Tue...MDT confdc.
.S of New England...Gale this aft into tngt...hi confdc. Gale
Tue...MDT confdc.
.Nt2 mid Atlc waters...
.Hudson to balt cnyn...gale this aft...hi confdc. Gale Tue...MDT
confdc.
.Balt cnyn to Hague line...Gale this aft into sun...hi confdc.
Gale Mon...MDT confdc. Storm Tue...MDT confdc.
.Balt cnyn to Hatteras cnyn...Gale this aft into tngt...hi
confdc. Gale late Mon into Tue...MDT confdc.
.Hatteras cnyn to Cape Fear...Gale early this aft...hi confdc.
Gale late Mon into early Tue...low to MDT confdc.
.Cape Fear to 31n...Gale late Mon into early Tue...low confdc.
.Forecaster oszajca/vukits. Ocean forecast branch.
|
