marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 1014 PM EDT Wed Apr 16 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Stlt trends and new 00z NCEP sfc anal show fnt E of ofshr wtrs slowing down with srn part bcmg stnry. Near term gradients in NE flow NW of fnt as shown in mdls sprt subgale conds as fnt and hi pres rdg to N sloly wkn thru Thu night. Mdls are in good agrmt thru Thu night...with 12z/18z GFS looking rsnbl. GFS then more quickly movs low pres alg fnt NE acrs FL versus other mdls. 12z UKMET/Gem and ECMWF sprt slower track and farther W. Previous shift eventually used 12z ECMWF FM 12z Fri on as this mdl is slower but not as far W as UK/ec. 12z ECMWF is close to final wpc Med rng guidance...beginning to lift low pres out nr outer srn nt2 wtrs by day 5. It bears watching the incrg gradients ovr srn wtrs as reinforcing high pres FM Canada blds down into mid Atlc wtrs...as these situations of lows undercutting highs often produce wrngs. ECMWF dvlps nmrs 30 kt bl wnds with even a 35 kt sml area outer srn wtrs on sun...before the cndn high movs E and gradient wkns. For now will cap wnds at 30 kt for now as low lvls appr more unstable to the N where gradients are less.
Seas...comparing mdls with 00z sea state anal...12z ECMWF wam apprs best initialized ovr nt2 wtrs espcly in the S...and therefore repopulated with that mdl thru 12z Thu. Mdls bcm closer after that and used 50/50 blend of multigrid ww3 with ECMWF out to 12z Fri and then with ECMWF favored...used 12z ECMWF wam Fri and bynd. ----------------------------------------------------------------- Previous discussion...
Sfc analysis and satellite imagery indicate cold front now mostly E of the offshore waters except the far E portion of Balt canyon to Hague waters. An asact pass from 1510z indicated several areas of NW gales...one over the W portion of balt to Hatteras Canyon and Hatteras Canyon to Cape Fear...with another over srn portion of balt Canon to Hague. These area were embedded in a broad area of 25 to 30 kt winds depicted over most of area.
The 12z models area in decent agreement through the short term period...roughly from tonight through 12z Fri. From 12z Fri and beyond...the models diverge with the GFS continuing to be a clear outlier. For the short term period...will allow the gale warnings to expire as scheduled with the next fcst issuance. Still expecting winds to remain in the 20 to 30 kt range over the nrn nt2 waters overnight before diminishing Thu. Looking ahead to 12z Fri and beyond...the 12z GFS has trended closer to the ECMWF/umket/CMC...however it is further E and faster moving a low across Florida Fri night and early Sat then moving NE. At the present time...am favoring the 12z UKMET/CMC which has a slower and further W low track. These are also more in line with the previous 00z ECMWF...although the low is a bit further N. In summary...will go close to the 12z GFS through 12z Fri...then will trend to the 12z UKMET for the remainder of the period. No warning headlines will be needed through the period.
.Seas...The latest sea state analysis indicated that observed seas were within a ft of the mww3 fcst values. Will go close to the mww3 through 12z Fri. For the remainder of the period...will trend closer to the ECMWF wam which as mentioned is more in line with the UKMET/CMC.
.Extratropical storm surge guidance...N/A
.Warnings...Preliminary. Any changes will be coordinated through AWIPS 12 planet chat or by telephone:
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster Bancroft/kosier. Ocean prediction center.