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000
AGNT40 KWNM 251202
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
802 AM EDT Thu May 25 2017

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Atlantic Ocean W of 50W from 30N to 50N.

As a triple point surface low track NE across Virginia it
continues to push a warm front N across the Nrn NT2 waters while
pulling a cold front off the Carolina coasts. Per the latest buoy
observations and with the 06Z GFS forecasting an associated 50-65
kt low level 925 mb jet, have high confidence that Sly gale force
winds are present in advance of the cold front across the Srn and
central NT2 waters. Max seas over these waters are likely in the
low to mid teens, which are in line with the 06Z Wavewatch III
and 00Z ECMWF WAM models at the moment.

Over the short term, the latest models overall remain in very
good agreement. Would favor the similar 06Z/00Z GFS and 00Z
UKMET/ECMWF solutions for the surface low to track NE towards the
Nrn mid Atlc coast later today with the warm front lifting N into
the NT1 waters, across the Srn New England coast tonight while
pulling the cold front E of the offshore waters late, then across
the Gulf of Maine Fri. Per the 06Z GFS, it looks marginal but
there is still enough justification to maintain the previously
noted Ely gales N of the warm front across the Gulf of Maine
late today/early tonight. Elsewhere, the 06Z GFS also continues
to support the previously forecasted gales in association with
the cold fropa across the NT2 waters today into Fri. Therefore,
will continue to use the previously populated 00Z GFS solution
through Fri night with only some minor additional edits mainly
in deference to the 00Z ECMWF.

In the long range, the disparity between the latest global models
increases significantly as they are showing poor run-to-run
continuity. As a weak high pressure ridge is forecast to move
offshore Sat/Sat night with diminishing conditions, the similar
06Z/00Z GFS solutions then still look reasonable. Then as a warm
front is forecast to develop and drift NE off the mid Atlantic
coast Sat night into Sun night with a frontal wave tracking E
along the front, the 06Z GFS has come in somewhat stronger than
its previous 00Z run, which brings it into better agreement with
the previously populated 00Z UKMET solution noted below. Then by
Mon/Mon night, forecast confidence falls significantly due to the
global model disparity. So for now since it has some support from
the 06Z GEFS Mean and 06Z GFS, the previously used 00Z GFS
solution then looks useable for now.




-----------------------------------------------------------------
PREVIOUS DISCUSSION...

00z global models in good agreement into Saturday night, then
diverge thereafter. Will lean towards 00z GFS through most of the
forecast period, except will switch towards the 00z UKMET between
00z Sunday and 12z Monday.

Cold front approaching the southeast coast. Latest surface
observations showing sustained winds in the 25 to 30 kt range
with some gusts to gale force. Models continue to show potential
of gales in the southerly flow ahead of the front over the NT2
waters today into tonight, with the highest winds near the gulf
stream where instability is the greatest. Will continue to
populate the first sigma winds in the unstable areas and will limit
winds to 40 kt for the most part. Will have a small area of 40 to
45 kt winds over northern NT2 waters this morning as both the GFS
and the ECMWF trying to develop a potential triple point low in
the region. Gales expected to continue mostly in and near the
gulf stream in the southwesterly winds behind the front tonight
into fri before low and conditions move east of the forecast
area.

To the north, Warm front moves north across the NT1 waters today
and tonight. Global models seem to be a bit stronger with the
easterly winds to the north of the front as it pinches up near
land. Latest GFS does indicate 10m winds to 35 kt for a brief
period in the Gulf of Maine later today into tonight. With both
the ECMWF and the UKMET showing 30 kt in the area, will go ahead
and input gales into the forecast for later today in the Gulf of
Maine.

Models continue to be in good agreement until around 00z Sunday
where models diverge in solutions in regards to a warm front off
the mid atlantic coast and potential lows developing along the
front. GFS seems to be the weakest of the models while the ECMWF
seems to be the strongest, which is very different than in its
previous run. UKMET seems to be a compromise so will lean towards
that solution for Saturday night through Sunday night. Forecast
confidence for this portion of the forecast is low due to model
differences. For Monday and Monday night, will lean more towards
the 00z GFS again as the UKMET wants a secondary low to move
across the NT1 waters during this time period.


.SEAS...WNA within a foot or two of current observations. Will
lean towards 00z WNA guidance for the wave grids through most of
the period. Will use a 50/50 blend of the WNA and the ECMWFWave
for 00z Sunday through 12z Monday to try and get higher seas in
the north quadrant of the low along the frontal boundary over the
central NT2 waters as GFS has ligher winds and WNA has lighter
seas.


.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



.WARNINGS...Preliminary.

.NT1 New England Waters...
.ANZ800...Gulf of Maine...
     Gale today into tonight.

.NT2 Mid-Atlantic Waters...
.ANZ920...Baltimore Canyon to the Great South Channel...
     Gale today into Friday.
.ANZ910...East of the Great South Channel and south of 39N...
     Gale tonight into Friday.
.ANZ828...Inner Waters from Cape Charles Light to Currituck Beach Light...
     Gale tonight.
.ANZ925...Outer Waters from Baltimore Canyon to Hatteras Canyon...
     Gale today into Friday.
.ANZ830...Inner Waters from Currituck Beach Light to Cape Hatteras...
     Gale today into tonight.
.ANZ833...Inner Waters from Cape Hatteras to Cape Fear...
     Gale today into tonight.
.ANZ930...Outer Waters from Hatteras Canyon to Cape Fear...
     Gale today into tonight.
.ANZ835...Inner Waters from Cape Fear to 31N...
     Gale today.
.ANZ935...Outer Waters from Cape Fear to 31N...
     Gale today.

$$

.Forecaster Vukits/Achorn. Ocean Prediction Center.



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