Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
255 PM EDT Sat Mar 31 2018

Valid 12Z Wed Apr 04 2018 - 12Z Sun Apr 08 2018

...Pattern Overview and Guidance/Uncertainty Assessment...

The pattern for the upcoming week will feature a cooling mid-upper
level closed low midweek over southern Alaska that will steadily
retrograde westward to surplant a highly amplified Bering Sea to
Arctic ridge aloft. This transition is well supported by guidance
overall, but surface system reflections mainly offshore on the
periphery of this flow have been offering below average model and
ensemble run-run continuity. However, the 12 UTC GFS/GEFS mean has
significantly trended the pattern evolution and embedded system
developments more in line with the 00 UTC ECMWF/ECMWF ensemble
mean, bolstering forecast confidence. The WPC Alaskan product
suite was mainly derived from a blend of these guidance pieces
days 4-8. This blend offers decent WPC continuity, albeit with
some trend for slightly faster closed low retrogression and
slightly southward suppression of lows digging well offshore to
the south of Alaska. The newer 12 UTC ECMWF seems to offer decent
continuity into at least mid-late week.


...Weather Highlights/Threats...

Expect a relatively benign threat pattern to continue for much of
Alaska next week with mainly modest precipitation potential
overall. An exception may be associated with closed low
retrogresion over the southern third of mainland Alaska where
there will be potential for unsettled wintery weather including
some locally enhanced snows despite limited moisture. High
pressure settles over the North Slope and interior in the wake of
low passage. Otherwise, a series of offshore lows cutting
underneath the Aleutians and downstream over the Gulf of Alaska
should have some depth/organization, but may be suppressed enough
to limit effects into the Aleutians and especially southern to
southeastern Alaskan coastal communities.

Schichtel