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marine weather discussion
NWS ocean prediction center Washington DC
718 am EST Thu 20 Nov 2008
.Forecast discussion: major features/winds/seas/significant
.Weather for North Atlantic ocean W of 50w from 30n to 50n.
About whether to go for gales over the nt2 wtrs S of Cape Fear
for late Fri into Fri nite prd...NAM and GFS say marg gales here
in stg caa over the Gulf Stream with support from other Med rng
mdls...so will incrs the Max winds here from 30 kt to 35 kt for
Fri and Fri nite.
06z GFS has vry gud support from ECMWF/NOGAPS/UKMET mdls...and
also from latest HPC Med rng fcstr guidance...so will cont to
favor the GFS with no signif changes planned to the current fcst
trend.
06z wna version of wavewatch iii mdl looks vry similar to the
00z run...and still looks a ltl slow to bld up the seas over the
nt2 wtrs with a dvlpg low and cold fnt during the Fri into Sat
timeframe.
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Prev discussion:
Summary...wl be dropping gales in Balto to Hague line FM last
ngt. Extnding gales into Georges Bank Fri ngt into Sat with next
sys.
GOES WV imgry indc an upr trof movg E of the ofshr wtrs
attm...and IR indc stg caa ovr the rgn behind the assoc cdfnt.
The sfc low pres sys is movg N of the area...and the ltst sfc
rprts indc no gales attm. Qscat FM 00z last ngt indc gales ovr
the ern edg of the nt2 wtrs...but the pass is old. Attm feeling
cnfdnt enuf to drop the gales in the ofshr wtrs FM last ngt.
The mdls are in gud agrmt with a wkr fast movg low pres sys movg
thru nrn nt2 tda and tngt. The GFS has been consistently indc
that this sys wl be fairly wk...which is in gud agrmt with the
rest of the guid...so xpct no chngs FM before.
The rmn in decent agrmt thrut the rmndr of the fcst pd...and
indc that a stg low wl dvlp just E of the area Fri as another
upr lvl trof movs into the rgn. The GFS indc that the stg caa
behind the assoc cdfnt wl create enuf instability and mxg to
incrs the wnds to gale frc ovr nrn nt2 Fri into Sat. The GFS has
been fairly consistent with this scenario...which is close to
the genl mdl consensus. The GFS is a ltl stgr with the low ctr
as it movs to off to the N Sat...but the ECMWF/UKMET/Gem all
indc stg wnds as the caa movs ovr the ofshr wtrs. The prev fcst
had gales consistent with the GFS...xcpt for ovr Georges Bank.
The GFS indc that the low wl track close to nt1...so feeling
attm that the wnds wl mix...so wl add gales to Georges Bank
attm. The GFS also indc gales ovr the far srn wtrs. Attm not
ruling it out...but would prefer to see anthr mdl cycle before
adding to the fcst. Otrw wl stay nr the GFS for the rmndr of the
fcst.
Seas...the 00z ww3 mdl is within a ft or so of the ltst
data...and seems fairly rsnbl. However...feel it is prob a bit
slow with building the seas with the next caa event Fri and
Sat...so wl adjust accordingly.
.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...Gale frc wnds Fri ngt into Sat...MDT confdc.
.S of New England...None.
.Nt2 mid Atlc waters...
.Hudson to balt cnyn...gale Fri ngt into Sat...MDT confdc.
.Balt cnyn to Hague line...Gale Fri thru Sat...MDT confdc.
.Balt cnyn to Hatteras cnyn...Gale Fri into Sat...MDT confdc.
.Hatteras cnyn to Cape Fear...Gale Fri into Fri ngt...MDT
confdc. .Cape Fear to 31n...gale Fri into Fri ngt...MDT confdc.
.Forecaster Scovil/Kells. Ocean forecast branch.
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