Marine Interpretation Message
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AGNT40 KWNM 221858
MIMATN

Marine Weather Discussion for N Atlantic Ocean
NWS Ocean Prediction Center Washington DC
258 PM EDT Sat Jul 22 2017

.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 12Z models in general agree that a
front will remain quasi-stationary in the vicinity of 40N today
through Mon night. But, at the same time the 12Z models have both
timing and forecast strength differences in regards to a series
of surface lows forecast to track E along the front then. Due to
the expected short wave lengths between these frontal lows,
continue to have relatively low forecast confidence in the
forecast solution of any individual model for these lows. The 12Z
GFS has become more consistent versus its previous 06Z run and
has the support of the 12Z GEFS Mean. Therefore, since they
forecast similar frontal positons, would favor a solution closest
to the 12Z GFS/ECMWF. Therefore, similar to the previous
offshore forecast package, as a compromise will populate our
forecast winds grids with a 50/50 blend of the 12Z GFS 10m and
12Z ECMWF boundary layer (BL) winds for tonight into Mon night.

In the long range, with some timing differences, the 12Z global
models agree that the last significant frontal low will pass E
of the NT1 waters late Mon night into Tue night and pull the
front S as a cold front across the N/central NT2 waters. In
comparison to the other 12Z models, the 12Z GFS looks to become a
slow outlier in regards to the southward progression of this
cold front. Therefore, would favor the similar 12Z UKMET/ECMWF
cold fropa. Then by Wed/Wed night, all of the 12Z global models
forecast the front to stall across the central NT2 waters Wed/Wed
night with its associated gradients weakening as a high pressure
center passes E across the NT1 waters. Then Thu/Thu night would
favor the 12Z ECMWF solution of the front slowly returning N as a
warm front with weak associated gradients persisting. So plan on
populating with all 12Z ECMWF BL winds on Tue through Thu night.

Seas...The 12Z Wavewatch and 12Z ECMWF WAM have both initialized
the current seas equally well. Since a compromise 12Z GFS/ECMWF
solution will be used, will populate our forecast wave grids with
a 50/50 blend of the two wave models for tonight through Mon
night. Then since the 12Z ECMWF solution will become favored,
will transition to populating with all 12Z ECMWF WAM seas on Tue
through Thu night.

.Extratropical Storm Surge Guidance...N/A.

.WARNINGS...Preliminary.

.NT1 New England Waters...
     None.

.NT2 Mid-Atlantic Waters...
     None.

$$

.Forecaster Vukits. Ocean Prediction Center.



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