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Weather Center


 

North Atlantic Marine Weather Discussion

AGNT40 KWNM 222033
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
333 PM EST Tue Jan 22 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 broad high pressure located 
over the eastern U.S., extended its ridging into the NT1 and NT2 
waters. The latest ASCAT high resolution data indicated 25-35 kt
winds over the western half of the NT1 waters and northern NT2
waters. 20-30 kt winds were noted over the inner central and 
southern NT2 waters. GOES IR satellite imagery continues to show 
a large area of cold cumulus across the Western Atlantic in the 
cold air advection in the wake of a strong cold front well E of 
the OPC offshore waters. 

The 12Z model guidance maintained good agreement through Fri
night, with guidance then diverging Sat through Mon in regards to
at least one low pressure system moving through the waters, with
the potential for a stronger system to move into the waters, or
be located E of the waters at the end of the period. Hence for 
this update will populate the wind grids with a 75 percent blend 
of the old 00Z ECMWF and 25 percent blend of the 12Z ECMWF winds 
through Fri night. Then for the remainder of the forecast will 
allow the ongoing grids, the 00Z ECMWF, to solely remain in 
place. Continue to expect gales to exit the last of the offshore 
waters, the NE NT2 waters, early tonight as high pressure 
continues building E across the waters. The high slides E over 
the region Wed before the next strong cold front approaches the 
waters from the W Thu. Guidance continues to remain in general 
good agreement concerning the strength and timing of the frontal 
passage with the front expected to pass E over the region later 
Thu through early Fri. Confidence in gales developing over the 
offshore waters overnight Wed into Thu is above average due to 
the consistency seen among the global guidance and NAM in regards
to this. Will continue with the mention of storm force winds in 
parts of the outer NT2 waters later Thu into Thu night in the 
vicinity of the Gulf Stream due to stronger mixing down of winds 
aloft. This is supported by model guidance with the 12Z 
GFS/ECMWF/CMC/NAM-4km each showing areas of 50 kt winds, and the 
12Z UKMET showing a large swath of 45 kt winds. Additionally the 
12Z GFS/ECMWF continue to show a strong low level jet ahead of 
the front with 70-80 kt winds at 925 mb. Confidence concerning 
these storm force winds remain slightly above average here. 

Behind this front high pressure will build over the southern half
of the NT2 waters Fri, while another cold front slides E across 
the NT1 and northern NT2 waters Fri night with good agreement
among the guidance concerning timing of the frontal passage.
While winds are anticipated to increase ahead of this front, am
not expecting anything reaching gale force as of now. By Sat day
4 and Sun day 5, anticipate one or potentially two low pressure
system to impact the offshore waters, though considerable spread
remains among the guidance. Hence the choice to continue with a
persistence forecast, consisting of 100 percent of the 00Z ECMWF
grids from overnight and this morning. On Sat guidance suggests
weak low pressure moving N or NE through the NT2 waters, though
again the timing and exact track differ. Right now guidance 
suggests winds associated with this low will remain below warning
criteria. Concerning Sun, there's indications that a separate 
and stronger low pressure system may either move into the NT2 
waters or be located not far E of the NT1 or NT2 waters. The 12Z 
GFS/ECMWF develop low pressure E of the offshore waters and moves
it N Sun, while the 12Z UKMET/CMC develops low pressure S of the
NT2 waters, then brings it N into the waters as a gale system. 
Again, like with yesterday and overnight, due to the continued 
spread in the guidance confidence remains below average 
concerning the weekend time frame.

.SEAS...Went with a blend of 75 percent of the old 00Z ECMWF WAM
and 25 percent of the 12Z ECMWF WAM given the choice to use the
same blend, model cycle wise, when it came to the ECMWF wind
grids in the forecast. 

.EXTRATROPICAL STORM SURGE GUIDANCE...No significant positive
surge events are likely over the next few days. Please monitor 
the latest more detailed information from the coastal National 
Weather Service forecast offices over the next few days.

.WARNINGS...Preliminary.

.NT1 New England Waters...
.ANZ800...Gulf of Maine...
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ805...Georges Bank west of 68W...
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ900...Georges Bank east of 68W...
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ810...South of New England...
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ815...South of Long Island...
     Gale Thursday.

.NT2 Mid-Atlantic Waters...
.ANZ820...Hudson Canyon to Baltimore Canyon...
     Gale Thursday.
.ANZ915...Hudson Canyon to the Great South Channel...
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ920...Baltimore Canyon to the Great South Channel...
     Gale Wednesday night.
     Storm Thursday.
     Storm Possible Thursday night.
.ANZ905...The Great South Channel to the Hague Line...
     Gale today.
     Gale Thursday.
     Gale Possible Thursday night.
.ANZ910...East of the Great South Channel and south of 39N...
     Gale today.
     Gale Thursday.
     Storm Possible Thursday night.
.ANZ825...Inner Waters from Baltimore Canyon to Cape Charles Light...
     Gale Wednesday night into Thursday. 
.ANZ828...Inner Waters from Cape Charles Light to Currituck Beach Light...
     Gale Wednesday night into Thursday. 
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Gale Wednesday night.
     Storm Thursday.
     Gale Possible Thursday night.
.ANZ830...Inner Waters from Currituck Beach Light to Cape Hatteras...
     Gale Wednesday night into Thursday. 
.ANZ833...Inner Waters from Cape Hatteras to Cape Fear...
     Gale Wednesday night into Thursday. 
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Gale Wednesday night into Thursday. 
     Gale Possible Thursday night.
.ANZ835...Inner Waters from Cape Fear to 31N...
     Gale Wednesday night into Thursday. 
.ANZ935...Outer Waters from Cape Fear to 31N...
     Gale Wednesday night into Thursday. 
     Gale Possible Thursday night.

$$

.Forecaster Holley. Ocean Prediction Center.

 

 



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