marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 803 am EDT Mon Oct 5 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Update...06z NCEP sfc analysis shows a warm fnt extndg NE to SW across the nt2 wtrs to a low cntrd near the Georgia coastal wtrs. A hi pres ridge lies over the nt1 wtrs. Hurcn Joaquin was cntrd about 90 nm NW of Bermuda...near 34n65w at 5 am EDT...and was movg N NE at 11 kt. Refer to latest NHC advisory for addtl info on Joaquin. Latest avail ascat hi-res passes from last nite showed a swath of 25 to 30 kt winds over Georges Bank...30 to 35 kt winds over the NE zones of the nt2 area...and also an area of 25 to 35 kt winds in the ofshr wtrs off the Carolinas. Lightning density product data at 1100z shows an area of sct showers/tstms over the inner ofshr wtrs near Cape Fear.
Models...the GFS has contd to show gud run to run consistency. The Med rng mdls are in vry gud overall agreemnt across the ofshr wtrs thru the fcst prd...except there are some relatively minor timing diffs with a cold fnt movg ofshr into the nt1 wtrs late Fri or Fri nite. The GFS looks vry representative thru the entire fcst prd...so it will be used for the wind grids. Am not planning to make any signif changes to the current fcst trend.
Seas...both the wna version of the wavewatch iii mdl and ECMWF wam initialized well...and with their diffs generally in the 1 to 2 ft range...will populate the sea ht grids with a 50/5o blend of the two mdls for today thru Thu nite. Then since the stgr GFS soln is favored for the Fri/Fri nite cold fropa...will go with an 80/20 blend of wavewatch iii/ECMWF wam for that timeframe.
Extratropical storm surge guidance...in the persistent NE flow over the srn nt1 and mid Atlc wtrs for today into Tue...etss conts to fcst a slightly higher pos surge than estofs...which looks reasonable.
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Over the short term...an earlier 0155z high resolution ascat-b pass showed that gale force winds in the nely gradient extend well NW of hurcn Joaquin into the far NE nt2 wtrs (zone anz910). As the new 00z mdls fcst Joaquin to cont to mov off to the NE today/tonite expect the winds in this nely gradient over these wtrs to dmnsh below gale force by this evening. Otherwise the short term focus wl be on a sfc low now just off the se coast which also returned sm gale force winds over its immed N quadrant in a 0239z ascat-a pass. Overall the 00z mdls share smlr fcst tracks for this sfc low movg slowly E then NE acrs the srn nt2 wtrs today into Tue nite (the 00z gefs mean sprts the 00z GFS fcst track). As the low tracks ofshr the 00z mdls all fcst the strong high pres ridge N of the wtrs to gradly weaken so expect the nely gradient to gradly weaken. Overall believe the 00z GFS fcst gradient looks representative and as a result wl populate our short term fcst wind grids with its 30m bl winds for today thru Tue nite. So as a result anticipate making only minor short term chngs to the prev ofshr fcsts.
In the long range...the 00z global mdls fcst a mr quiet wx pattern to dvlp. The mdls are in good agrmt that a weakening cold front wl race ofshr acrs the nrn wtrs Wed nite into Thu (with the 00z GFS fcstg a smwht stronger fropa than the other 00z global mdls)...flwd by a high pres ridge bldg ofshr Thu/Thu nite. Then late Fri/Fri nite the 00z GFS/Gem/UKMET hv come into better agrmt timing-wise for another smwht stronger cold front movg ofshr acrs the nt1 and nrn/cntrl nt2 wtrs. At the same time the 00z ECMWF solution looks a ltl too weak and slightly too slow with this fropa. Thererfore overall believe the 00z GFS solution looks representative in the long range and as a result wl populate our fcst wind grids with its smwht mr conservative 10m bl winds (mainly to compromise with the smwht weaker cold fropas fcst by the 00z UKMET/ecmwf) with sm additional minor edits in deference to the 00z UKMET. So as a result do not plan on making any major long range chngs in the next ofshr fcst package.
Seas...over both the 00z wavewatch iii and 00z ECMWF wam mdls hv both initialized well and with their differences gnrly rmng in the 1-2 ft range...plan on populating with a 50/5o blend of the two mdls for today thru Thu nite. Then since the stronger 00z GFS solution wl be favored for the Fri/Fri nite cold fropa...wl transition to an 80/20 blend of the 00z wavewatch iii and 00z ECMWF wam then.
.Extratropical storm surge guidance...In the persistent ENE gradient today into Tue...the 00z etss conts to fcst a slightly higher positive surge than the 00z estofs which looks reasonable.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... .anz910...east of the great South Channel and south of 39n... gale early today into today. .Anz833...Inner waters from Cape Hatteras to Cape Fear... gale today.
.Forecaster Scovil/vukits. Ocean prediction center.