marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 250 am EDT Thu Aug 21 2014
.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Over the short term...the new 00z mdls overall present no sig fcst problems. The mdls gnrly agree that the weak sfc low now over the NE nt2 wtrs wl slowly pass E of the nt2 wtrs today into Fri. Based on the weak upr lvl sprt fcstd wl favor the weaker 00z GFS/UKMET/ECMWF solutions vs the stronger 00z NAM/Gem solutions for this system and as a result wl hold the Max ascd fcst winds in its vcnty to gnrly in the 15-20 kt range. Then Fri nite to varying degrees the 00z mdls fcst a frontal low(s?) To move se off the mid Atlc coast along the trailing stnry front causing only slightly stronger gradients to dvlp. To mainly better match the fcst gradients of the 00z UKMET/ECMWF...plan on populating our short term wind grids thru Fri nite with the 00z GFS 30m bl winds (which are not sigly different vs the 00z GFS 10m bl winds). So since a mix of the 12z GFS 30m and 10m winds were prevly used...anticipate making only minor short term chngs in the next ofshr fcst package.
In the long range...by late Sat/Sat nite the 00z global mdls gnrly agree that the most sig frontal lows wl pass E of the nt2 wtrs whl pulling the front S as a cold front into the srn nt2 wtrs by Sat nite with a mod strong enely gradient dvlpg N of the front thrut the nt2 and srn nt2 wtrs. Then late sun/sun nite the 00z mdls all fcst the front to push S of the nt2 wtrs with the mod strong enely gradient dvlpg thrut all of the nt2 wtrs. So for this enely gradient plan on using a 50/50 blend of the 00z GFS 30m and 00z ECMWF bl winds for Sat thru sun nite which wl result in Max winds gnrly in the 15-20 kt range...smlr to the prev ofshr fcsts.
Then further out in the long range...by late Mon/Mon nite the future track of the next psbl tropical cyclone may start to impact the srn nt2 wtrs. Vs its prev respective runs...the 00z GFS now fcsts this system to turn nwd mr quickly Mon nite causing a slightly stronger (20-25 kt) enely gradient to dvlp acrs the srn most nt2 wtrs. The 00z Gem is smlr to the 00z GFS whl the 00z UKMET is mr suppressed with its fcst track and hence fcsts a weaker gradient acrs the srn nt2 wtrs. But on the other hand...smlr to its prev 12z run...the 00z ECMWF is sigly faster in turning this system nwd to just se of the se most nt2 wtrs by late Mon nite. So since this system has not even been classified yet by NHC and due to the current mdl disparity...for now wl instead just focus on the gnrly smlr gradients that the 00z GFS/ECMWF fcst acrs the ofshr wtrs and as a result wl cont to use a 50/50 blend of the 00z GFS 30m and 00z ECMWF bl winds for Mon thru Mon nite.
Seas...with the differences btwn the two mdls not exceeding 1-2 ft...plan on using a 50/50 blend of the 00z wavewatch iii and 00z ECMWF wam thru Mon nite.
.Extratropical storm surge guidance...N/A.
.Nt1 New England waters... None.
.Nt2 mid Atlc waters... None.
.Forecaster vukits. Ocean prediction center.