Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
243 PM EDT Sun Oct 07 2018

Valid 12Z Thu Oct 11 2018 - 12Z Mon Oct 15 2018

The amplified pattern will still have its grip over the Alaska
region through Thursday but will finally break down by Friday. 
The upstream ridge over Japan will weaken and shift, allowing for
a more zonal flow west of the Dateline by the weekend. Overall,
models were in agreement with the pattern through day 7.

The 00Z GFS and 00Z ECMWF were in great agreement for the overall
pattern.  The 500 mb closed low will continue to sit over the
Bering Sea, allowing for multiple systems to rotate along its
base. On Thursday, an occluded front will approach Southeast
Alaska and bringing an increased chance of precipitation. From
Friday through the first half of the weekend, another system will
skirt the Aleutians as it enters the Gulf of Alaska by Saturday.
The strong system will begin moving through the far western
portions of the Aleutians on Saturday--while slowly moving across
the chain of islands and beginning to move into the Gulf of Alaska
by Monday.  The 12Z GFS aligned more with its 06Z run with this
system--placing the associated 500 mb low farther south on Day 7
(Sunday), and then ended up being much faster by Day 8 in
comparison to the 00Z ECMWF.  The 00Z CMC seemed to favor the
northern solution--however, the CMC was too far north (in the
Bering Sea). The 00Z GFS was comparable to the 00Z ECMWF even by
day 8.  Thus, WPC used a blend of the 00Z ECMWF/GFS with more
weight on their means by the end of the medium range period.

On Thursday, precipitation chances will increase along the
Southeast/Inside Passage of Alaska with that approaching frontal
system. However, for the rest of Alaska--drier conditions are
expected through Friday. By the weekend, the wet pattern will come
back and areas from the Aleutians eastward into southeast portions
of the region should expect an increase in precipitation as
multiple boundaries move across the Aleutians and into the Gulf of
Alaska. Temperatures will be near average through most of the time
period--with highs in the upper 40s to low 50s across most of
Alaska with far north region of Alaska seeing highs in the upper
20s.


Reinhart



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