marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 322 PM EDT sun may 3 2015
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
The ltst GOES IR imgry indc a low pres sys E of the ofshr wtrs...and the WV imgry a somewhat flat upr rdg just W of the area...movg to the E. Crnt sfc rprts indc wnds up to 15 kt ovr the ofshr...as the ltst NCEP sfc analys indc high pres ovr the rgn. However...the ascat FM 15z indc 25 kt ovr the far NE nt2...in the caa assoc with the low E of the area. Attm planning on starting with 20 kt for early tngt as the stgr wnds are xpctd to be movg E of the area...then wl gl with vrbl wnds to 15 kt as hgih pres blds in later tngt.
The 12z mdls are init OK with the pttn...and agree well with the high bldg ovr the area. The GFS indc a cdfnt wl mv thru nt1 and nrn nt2 Mon ngt and Tue...with the stgst wnds ahd of the bndry. The GFS indc 30 kt...ovr the vry stable nt1 zones N of the glf strm. The mdls indc gales at 925 mb...but not xpctg them to mix dn with the stable envrmt...and confdc is vry low for gales. The prev fcst went up to 25 kt...with a few sml areas of 30 kt ovr far NE nt2 as the sys moves ovr the less stbl envrmt ovr the glf strm. The rest of the 12z mdls agree well with overall GFS tmg...so planning on using 10m GFS wnds N of the glf strm...and the 30m wnds to the S and E of it to better reflect the lower static stability.
In the extended...the biggest fcst is with low pres that forms S of 30n Wed...then moves into the nt2 wtrs Thu and Fri. The GFS has bcm a bit of an outlier soln...altho remains consistent with the track W of the the rest of the mdls. The GFS is also a bit stgr than the ecwmf/UKMET...and indc 35 kt as it moves into nt2 Fri. However...the 12z ECMWF/UKMET/Gem all take the low to the E of the GFS track...before indcg it wl drift back to the W. The mdls all basically indc an h5 rdg ovr the low...with not much in the way of steering. With the high uncertainty from mdl diffs...uncertainty is fairly high on the track and intnsty of this sys. For now planning on using the 12z ecwmf which is more in line with the rest of the guid...and wl keep wnds blo wrng criteria...as confdc with gales is low.
Seas...12z mww3 and ecwmf wam are init within a ft or two of crnt data in the ofshr wtrs....and seem rsnbl in the short while remaining in decent agrmt...so planning on using a 50/50 blend in the short. Otrw the mdls start differing by 00z Wed...so planning on staying nr the 12z ecwmf wam...which reflects the preferred wx mdl trend of the ecwmf.
.Extratropical storm surge guidance...Na.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster Kells. Ocean prediction center.