Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
151 PM EDT Wed Jun 06 2018

Valid 12Z Sun Jun 10 2018 - 12Z Thu Jun 14 2018

Medium range forecast for central/northern Alaska has become quite
uncertain over the past 24 hrs due to a change in the ensembles
regarding an upper low moving across the North Pole in the short
range. While some models previously showed the upper high near
Wrangel Island moving into northern Alaska, most now take the
upper low toward the North Slope late this weekend. Not ready to
jump to that solution but a stronger upper high over northeast
Russia (per the latest ensembles) next Monday could support a
deeper upper low sinking southward to its east. For now, opted to
use the 12Z GFS with the 00Z ECMWF ensemble mean and 00Z GEFS mean
which were much less extreme than earlier GFS runs or the 00Z
ECMWF.

To the south, the model/ensembles were much better behaved and a
blend of the guidance would suffice. This would take a system
eastward south of the Gulf before lifting northeastward around
Tue/Wed as a trough, followed by another system south of the
Aleutians that may turn northeastward sooner. Ensembles do suggest
building ridging along 140W near 50N by next Thursday, which would
block that system from moving east. However, given the uncertainty
in the day 4-7 time frame, would take that forecast with a grain
of salt.

Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html