Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
419 PM EDT Wed Aug 15 2018
Valid 12Z Sun Aug 19 2018 - 12Z Thu Aug 23 2018
Models and their ensembles agree reasonable well with the synoptic
pattern evolution around Alaska through the middle of next week.
A deep occluded cyclone approaching the Alaska Peninsula on Day 4
Sunday is forecast to weaken rapidly as an old occluded cyclone
drifts into the picture across the Bering Sea early to middle of
next week. A combination of the 00Z ECMWF, 06Z GFS, and the 12Z
GFS were used to derive the WPC Alaska medium range weather grids.
More of their ensemble means (i.e. 00Z EC mean and 06Z GEFS mean)
were used toward Day 8 Thursday to handle the longer range
uncertainties. The resulting pressure fields show good continuity
with yesterday's WPC Alaskan grids.
Sensible weather wise, stormy conditions over the Alaska Peninsula
this weekend should abate early next week as the occluded cyclone
weakens rapidly. But unsettled weather is expected to linger
across the Aleutians and coastal southern Alaska through the
middle of next week as an old occluded cyclone approaches the
region. Farther to the north, a cool air mass from the Arctic
Ocean should settle southward across the Brooks Range into central
Alaska toward the middle of next week.
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at: