marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 817 PM EST Thu Nov 26 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
No sig changes to the fcst expected attm.
Latest sfc obs showing sustained winds to 25 kt...with some gusts to 30 kt over the se portions of the nt2 waters in the strong gradient between a stationary front to the E and strong high pres ridge to the N and NW. Conditions should not change during the overnight and into Fri morning as the front slowly retrogrades W towards the region.
To the N...return sly flow on the backside of the ridge observed over the glf of ME. Current sfc obs showing sustained winds in the 20 kt range...with some gusts to 25 kt...and elevated platforms showing some gusts in the 30 kt range. With cooler SSTs...do not know if these 30 kt winds will make it to the sfc. Will let fcst ride for now and make any necessary changes in the morning package.
Seas...wna version of wwiii a little underdone over the glf of ME...but seems to be more in line with current obs in the srn zones. Will make necessary adjustments to the fcst to reflect initial conditions. Otw...model within a ft or two elsewhere across the cstl/offshr waters.
----------------------------------------------------------------- Previous discussion...
First feature of concern is NE to SW stationary front located 350 nm E of Bermuda this mrng. Models continue to fcst this front westward as a large trough...but disagree on its evolution. By Fri aftn...both the GFS and UKMET dvlp a sfc low W of Bermuda... though a 150 nm apart...then mv the low SW thru Sat while wkng it. The ECMWF is inbtwn the GFS and UKMET solutions. The NAM and Gem are smlr to the GFS...but tracks the low farther S. By 12z Sat... the GFS and Gem bring thw close enough to the srn waters to rpduce NE gales in the outer waters...where the UKMET argues for winds closer to the 15 to 25 kt range...while the ECMWF again compromises and fcst 10m winds to 30 kt ovr the outer offshr waters...which looks good...so wl fcst NE winds to 30 kt as the highest.
For the nrn waters...models fcst next cold front to move se off the New England coast Fri night. The UKMET hangs the front W to E across the waters...but will instead fllw the comsensus of the GFS/ECMWF/NAM/Gem which pushes the front S while it washes out the front. GFS 30m winds look ovrdn in the prefrntl SW flow...but winds today are more representative these slgtly strngr winds... so stay with GFS 30m winds.
By late sun...the GFS builds high pres ovr the waters FM the NW as next high advncs. Aloft...the GFS downplays S/W mvg se to the new engladn area sun ngt/Mon and is thus bcms too progressive. The UKMET/Gem/ECMWF are less prgress and also instead dvlp a cold front ovr the waters ahd of the high building ovr ont and que. By 12z Mon...wl fllw the UKMET/ECMWF with a dvlpg N to NE surge of 20 to 30 kt winds immed fllwg dvlpg cold front...which wl push to about 36n by 12z Mon...and just S pof httrs cnyn by 00z Tue. The front wl bcm stnry nr here Tue as the strong high slides off to the NE...whilch wl allow winds to veer E to se and dmnsh slgtly. For Wed and Wed night...expect front to wkn while mvg N as low pres appchs New England wl stay with the ECMWF. The UKMET/Gem and a few GFS essmbl members try and dvlp a low nr the enew gnlad coast...confidence is low in this ftr and wl stay with ECMWF in dvlpg as mod srly flow. For grids...wl blend in the ECMWF 50/50 with the GFS 30m winds Sat thru sun before switching to the ECMWF winds by 00z Mon.
.Seas...The wna version of wavewatch iii model initlzd well today with seas within a ft of guidance...except in the strng NE flow where seas were about 2 ft underdone ovr the outer srn waters. The ECMWF wam was smlr. For gdnc...wl fllow the wavewatch but incrs seas by 10 pct in the NE flow thru the weekend. Wl fllw wind gdnc and switch to the ECMWF wam beginning 00z Mon.
.Extratropical storm surge guidance...The etss has a neg surge of 1 to 2 off the coast N of Nantucket tngt that spread ns to the VA CAPES Fri before dmnshg by early Sat. The estofs shows around a 1 ft surge off the GA and SC coast tonight in the NE flow...then dmnshs late Fri adn Fri ngt.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster achorn/prosise. Ocean prediction center.