HS 100

marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 905 PM EDT Sat 18 may 2013

.Forecast discussion: major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.

The 00z prelim opc sfc analysis shows a 1027mb high centered nr 40n 69w with a strny front extending from W to E ovr srn nt2 off wtrs. A few tstms are nr the front with areas of rain and showers further N off the mid Atlc coast. An eve ascat pass shows the high in this gnrl location with winds running mostly 20 kt or less ovr the off wtrs. Overall we will not make sig changes to the prev opc fcst for the eve update...just tweaking the fcst to fit current conditions and to line up with adjacent wfos and TAFB grids.

Seas...sea hts appear to be running mostly within a ft or two of the ongoing opc fcst and the latest wna ww3 mdl guid. Again... overall we will not make sig changes to the prev fcst.

---------------------------------------------------- Prev discussion...

14z and 15z hi res ascat passes extended as far W as 74w and indicated hiest winds over offshore/coastal waters were 20 kt over sern balt cnyn to Hague line...with high pres centered over new engl waters. 12z mdls are in good agreement that stnry front invof Cape Fear shud persist tngt before beginning to lift NE thru waters sun...at which time high pres ridge will shift E of new engl waters. 12z GFS 10m winds look reasonable thru next 36 to 48 hrs. Mdl preference then will switch to 00z ECMWF by early Mon...as GFS appears somewhat overdone with SW winds Mon mainly due to the suspect trple pt it dvlps and drives thru nrn glf of ME late Mon/Mon ngt.

Mdls also differ with Tue/Wed cold front with 12z GFS now more agressive in pulling frnt S into nrn mid Atlc waters which was a change from its previous run as well as the UKMET/ECMWF. Will maitain opc continuity favoring 12z UKMET/12z ECMWF which stall front over new engl waters near 40n. By Thu am favoring a 2 to 1 12z ECMWF/12z GFS blend which shud account for some of the differences with strength of upper low thru sern Canada Thu...or in the case of GFS depicting open upper wave. Blend will result in SW winds to 20 or 25 kt over waters N of Cape Fear which is slightly lower than 12z ECMWF sfc winds.

12z multigrid wavewatch sig WV hgts fit well with latest W Atlc ship/buoy obs. For Mon thru Thu will blend 12z mww3 with ECMWF wave mdl to account for the minor sig WV hgt differences.

Extratropical storm surge model...N/A.

.Warnings/forecast confidence...Preliminary. Any changes will be coordinated through AWIPS 12 planet chat or by telephone:

.Nt1 New England waters... .Gulf of Maine...none. .Georges Bank...None. .South of New England...None.

.Nt2 mid Atlc waters... .Hudson Canyon to Baltimore Canyon...none. .Baltimore Canyon to Hague line...None. .Baltimore Canyon to Hatteras Canyon...None. .Hatteras Canyon to Cape Fear...None. .Cape Fear to 31n...None. $$

.Forecaster Mills/Clark. Ocean prediction center.