marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 940 PM EST sun Jan 25 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
The IR Sat img show some conv clds just moving into the NW parts with no lightng. The radar indct no tstms cells ovr the region. At 0000z strng low pres 948 mb NE of Nova Scotia with hurcn force winds has a cld frnt strchng SW into the balt canyn wtrs then leaves the wtrs ovr srn NJ shore and continues inland. Dvlpg low pres 1003 mb nr KY/WV states has frnt strchng SW. Hgh pres 1023 mb ovr Canada xtnds a weak ridge se acrs the grst lakes region. The pres grdnt is just tight ovr the region. In the short term the low pres ovr KY will move acrs the mid Atlc states into the cntrl region wtrs and that will force the pres grdnt to become very tight and generate storm force winds. Will stay with GFS in the hsort term then ecmwfhr in the xtndd prd.
----------------------------------------------------------------- Previous discussion...
Over the immed short term...in response to a secondary cold front movg ofshr the wnwly gradient acrs the Gulf of Maine has strengthened pretty much as prevly expected with marginal gales (per buoy 44027 at 17z with 280/33 g 39 kt) now present. Per a consensus of the new 12z mdls...as the front pushes further ofshr blv this gradient wl weaken to subgale by the start of the tonite fcst period. Then after a weak high pres ridge builds ofshr into the nrn wtrs tonite/early Mon with dmnshg ascd conds the focus shifts to the nt2 wtrs where a clipper type sfc low is fcst to aprch the mid Atlc coast tonite.
At the upr lvls...the 12z mdls remain consistent in fcstg a strong upr S/W trof to dig twds the coast tonite...move ofshr Mon and gain negative tilt...transition into a closed upr low off the nrn mid Atlc coast Mon nite ...then drift NE acrs the nt1 wtrs Tue into early Wed whl gradly wkng. At the sfc...the 12z mdls share smlr solutions for the ascd sfc low movg off the mid atcl coast Mon...intensify whl tracking NE to nr the 40n70w benchmark early Mon nite...then driftg slowly NE acrs the rmng nt1 wtrs Tue into Tue nite whl bcmg vertically stacked with the upr low and gradly wkng. In rgrds to the fcst track of this system...the 12z GFS remains very consistent vs its prev respective runs...tho the 12z gefs mean indicates that the 12z GFS is lkly slightly too fast. By late Tue/Tue nite the speed at which this system wl mov NE bcms complicated because multiple low centers look lkly to dvlp. For now believe a 12z gefs mean track looks lk a rsnbl compromise btwn the slightly slower 12z ECMWF and faster 12z GFS/UKMET (and is sprtd by the 12z NAM/gem). In rgrds to the fcst intensity of this low and its ascd fcst gradients...overall believe the 12z GFS solution looks representative and that its stronger 30m bl winds look mr rsnbl especly as the enely gradient pinches against the coast. Therefore plan on populating our short term wind grids with the 12z GFS 30m bl winds thru Tue nite...time shifted 3-6 hrs slower in deference to the 12z gefs mean and 12z ECMWF fcst timing. So as a result wl not be making any major timing and/or areal coverage chngs to the prevly fcstd mod/hi confidence wrngs with this system but wl be beefing up the ascd winds smwht.
In the long range...the 12z global mdls are in rsnbly good agrmt that in the wake the strong short term low that dmnshg conds wl dvlp thrut the wtrs Wed into Thu as a high pres ridge blds to the coast Wed/Wed nite...then passes ofshr Thu/Thu nite. For Wed/Wed nite wl cont to populate with the 12z GFS 30m bl winds time shifted 3-6 hrs slower. Then in response to the next digging nrn stream upr trof...to varying degrees the mdls fcst another dvlpg clipper-type sfc low to aprch the nrn mid Atlc coast Thu nite...then mov ofshr Fri/Fri nite. Wl disregard the 12z Gem solution as being too weak. Overall the 12z GFS/ECMWF fcst smlrly strong solutions...but the 12z GFS is approx 12 hrs faster than the 12z ECMWF. Therefore as a compromise wl populate with the 12z ECMWF bl winds for Thu thru Fri nite...time shifted 6 hrs faster.
.Seas...Through the short term and early long range...wl blend use a 50/50 blend of the likely too low 12z wavewatch iii...time shifted like its respective 12z GFS winds wl be...and the likely too high 12z ECMWF wam seas thru Thu. Then wl transition to all 12z ECMWF wam for Thu nite thru Fri nite time shifted faster like its bl winds.
.Extratropical storm surge guidance...By late Mon into Tue in the strong enely gradient fcst to dvlp N of the dvlpg sfc low...both the 12z estofs and 12z etss fcst sig positive surge values ( up to 2.5-3.5 ft) to dvlp along the coasts FM the Delmarva N into the SW Gulf of Maine which overall look representative (if anything they may be too low).
.Nt1 New England waters... .anz800...Gulf of Maine... storm Mon night into Tue. Storm possible Tue night. Gale possible Wed. Gale possible Fri night. .Anz805...Georges Bank west of 68w... storm Mon night into Tue. Gale possible Tue night into Wed. Gale possible Fri night. .Anz900...Georges Bank east of 68w... storm Mon night. Gale Tue. Gale possible Tue night into Wed. .Anz810...South of New England... storm Mon night into Tue. Storm possible Tue night. Gale possible Wed. .Anz815...South of Long Island... gale Mon. Storm Mon night into Tue. Gale possible Tue night.
.Nt2 mid Atlc waters... .anz820...Hudson Canyon to Baltimore Canyon... gale Mon. Storm Mon night. Gale Tue. .Anz915...Hudson Canyon to the great South Channel... gale Mon. Storm Mon night. Gale Tue. Gale possible Tue night. Gale possible Fri night. .Anz920...Baltimore Canyon to the great South Channel... gale Mon into Tue. Gale possible Fri night. .Anz905...The great South Channel to the Hague line... storm Mon night. Gale Tue. Gale possible Tue night into Wed. Gale possible Fri night. .Anz910...East of the great South Channel and south of 39n... gale Mon into Tue. Gale possible Fri into Fri night. .Anz825...Inner waters from Baltimore Canyon to Cape Charles Light... gale Mon night. .Anz925...Outer waters from Baltimore Canyon to Hatteras Canyon... gale Mon into Mon night. Gale possible Tue night. Gale possible Fri night. .Anz930...Outer waters from Hatteras Canyon to Cape Fear... gale Mon into Tue. Gale possible Tue night. .Anz835...Inner waters from Cape Fear to 31n... gale Mon into Tue. .Anz935...Outer waters from Cape Fear to 31n... gale Mon into Tue.
.Forecaster musonda/vukits. Ocean prediction center.