marine weather discussion for N Atlantic Ocean NWS ocean prediction center Washington DC 448 PM EDT Sat Aug 24 2019
.Forecast discussion...Major features/winds/seas/significant .Weather for the North Atlantic ocean W of 50w from 30n to 50n.
Per the 18z NCEP surface analysis a cold front extended from just off the coast of South Carolina and NE across the central and northern nt2 waters. The latest GOES-east IR satellite imagery and lightning density data indicates continued scattered thunderstorms occurring near and to the S of the cold front over the southern nt2. The possibility remains for locally strong winds, possibly near or exceeding gale force, and very rough seas occurring in and near locally strong thunderstorms. All marine interests should continue to use caution in and around any of the stronger thunderstorms that impact the waters over the next few days. The latest asct high resolution data revealed 10-20 kt winds across the nt1 and nt2 waters.
The ongoing forecast continues to remain highly dependent on the evolution of low pressure near Florida, in terms of whether or not it obtains tropical or sub-tropical characteristics as it moves NE across the nt2 waters Sunday through mid-week. The 2 PM tropical weather outlook from the National Hurricane Center continues to give the low a 70 percent chance of tropical or sub- tropical cyclone formation within the next 48 hours, and a 90 percent chance through day 5. Concerning the 12z guidance, the 12z GFS/ECMWF/UKMET solutions, while not in exact agreement, did have somewhat favorable agreement concerning the track of the low through the se nt2 waters into into Tuesday and Tuesday night. Afterwards guidance begins to diverge with the 12z ECMWF showing a faster and further E solution than that of the 12z GFS/UKMET which remain somewhat in agreement through Thursday, though the 12z UKMET is a tad faster than the 12z GFS. With the continued uncertainty noted in the forecast in regards to the exact track and whether or not the low develops tropical or sub-tropical attributes, I feel making significant changes to the ongoing forecast isn't warranted as of yet. Hence, for this forecast package I will populate the grids with a 2:1 blend of the old grids and 12z GFS through Monday 00z. I will then keep the ongoing grids after, however make hand edits to the grids through Thursday 12z, mainly in the vicinity of the low expected to move NE into the waters, to closely match TAFB and the WFO grids. Lastly, the day 5 grids will remain untouched. All marine interests should continue to closely monitor the latest information from the National Hurricane Center (nhc), the latest forecasts and discussions from opc, and the coastal National Weather Service offices through the weekend into early next week.
.Seas...I will continue with the ongoing grids throughout the forecast period but with edits made through Wednesday 12z, mainly in the vicinity of the low, to match tafbs grids at the opc/TAFB boundary area.
.Extratropical storm surge guidance...A minor to moderate positive surge up to 0.5 ft or so appears likely from near Cape Hatteras northward to the Jersey Shore by into tonight as NE winds persist and increase to the N of the cold front. These surge values from the estofs model may increase towards a ft or so and expand along the coast from Long Island southward to Georgia by Sun night as NE winds increase and expand. For the remainder of the period the surge will become mostly dependent on any future development and track of the tropical or sub-tropical cyclone which could impact the waters by later sun into Wed of next week, with this surge guidance and possible watches or warnings likely issued by the storm surge unit from NHC, if necessary. Please see the latest guidance and forecasts from your local National weather forecast office for additional information.
.Nt1 New England waters... None.
.Nt2 mid-Atlantic waters... None.
.Forecaster Holley. Ocean prediction center.