Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
247 PM EST Fri Feb 02 2018

Valid 12Z Tue Feb 06 2018 - 12Z Sat Feb 10 2018

Upper ridging bridged across the interior from southeastern Alaska
to northwestern Alaska early next week will eventually separate
into two positive height anomalies -- one just off the BC coast
and the other near the New Siberian Islands (75N/140E). The weaker
(but still formidable) ridging in between will still help to keep
the upper low centers near the western Aleutians and over the
Canadian archipelago, maintaining a rather dry pattern for the
interior but a wet one for the coastal areas from the Aleutians to
the Panhandle.

The ensembles remain in good longwave agreement with the overall
pattern evolution but within that remains a modest or even high
spread as far as system timing/track/strength owing to rather weak
systems. A consensus approach sufficed with more deterministic
weight to start (12Z/06Z GFS and 00Z ECMWF, mostly) trending
toward an increased weight of the 06Z GEFS mean and 00Z ECMWF
ensemble mean by the middle of next week. Lead system in the Gulf
will moving into the Panhandle early Wednesday as another system
lifts into the Bering. Ridging to its north will weaken and split
it in half with the southern part moving into the Gulf later next
week.

Dry period for most of the interior with variable temperatures --
850mb temperature anomalies will be near to above average but that
may not be realized at the surface in some valley locations under
inversions. Used an ensemble blend to account for variability.
Precipitation will focus along the southern coast especially into
the Panhandle with the lead system, heaviest over the southern
Panhandle near the advancing warm front. Rain may then be heavy
over the eastern Aleutians with the second system (including
south-facing upslope-favored regions on the AkPen and Kodiak)
Wed-Fri and whatever is left of it by Saturday, including another
weaker system out of the central Pacific.


Fracasso