Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
228 PM EST Wed Mar 07 2018

Valid 12Z Sun Mar 11 2018 - 12Z Thu Mar 15 2018

Models and ensembles continue to be fairly consistent in the
synoptic scale but lack stability in the shorter wavelengths. An
upper low will eventually sink southeastward away from the Gulf of
Alaska next week as upper ridging narrows into southwestern Alaska
before flattening out. Upstream pattern over the NW/W Pacific
features a collapsing upper ridge to the northwest of Hawai'i and
the resumption of an upper low over northeastern Russia, with
inherent uncertainty to the east of the trough axis in split flow.

Spread in the ensembles starts early this weekend over the Sea of
Okhotsk and translates downstream east of Kamchatka into the
western Bering. Trend has been much weaker with a lead low and
stronger with the trailing system which results in a slower timing
of the low through the Bering. Deterministic models (minus the 00Z
UKMET) took the parent low to the Bering Strait while the
ensembles were farther south. With a bit more time for the ridge
to build downstream, a farther north track is reasonable but only
split the difference between the 12Z GFS/00Z ECMWF and their
means. Another wave on that front may then track past the central
Aleutians into the southeastern Bering Sea next Tue/Wed, dragging
a cold front eastward. By then, 00Z ECMWF was much slower with the
front than the 12Z GFS or its previous runs. Opted to rely on the
ensembles by then which would take at least part of that wave and
cold front into the Gulf by next Thu.


Fracasso