Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
614 PM EDT Mon Jun 01 2020
Valid 12Z Fri Jun 05 2020 - 12Z Tue Jun 09 2020
...Overview and Guidance/Predictability Assessment...
Quasi-zonal flow across much of the North Pacific will encounter a
pair of upper lows near Alaska later this week. Low over the
Bering Strait is forecast to sink southeastward into next week as
a persistent upper high slowly retreats into the Canadian
archipelago. To the south, a system over the North Central Pacific
will lift northeastward and perhaps interact with the Bering upper
low moving across Bristol Bay. The models/ensembles were in good
agreement through about 24 hours ago but have departed a bit from
a consensus. This stemmed from the handling of both the northern
stream upper low and the mid-latitude system and how they may
interact (and at what longitude). Preferred to stay near the
larger 12Z consensus and continuity rather than the 00Z ECMWF
ensemble mean which shifted abruptly westward with the Pacific
system in line with its deterministic counterpart at 00Z. With a
farther east 12Z ECMWF, used the 12Z GEFS to smooth out some
timing/track differences but added some detail with the 12Z
Canadian that kept the system on an eastward trajectory until next
Mon/Tue when it may attempt to lift into the Gulf. Confidence was
no better than average given the model/ensemble changes.
...Weather Hazards/Threats...
Near to above average temperatures will remain for northwestern
mainland Alaska to the northeast of the upper low. That will bring
cooler temperatures to southwestern areas as it crosses Bristol
Bay. Weak mid-level flow near the Alaska Range to the Tanana
Valley will promote scattered showers and some convection through
the period, some of which could be locally modest in amounts.
Temperatures will be within several degrees of normal between the
Alaska and Brooks Range, but near to below normal over
Southcentral to the Panhandle. By next week, the system over the
central North Pacific will spread at least more cloudiness toward
the coast but at this point appears to keep most rain over the
water, except for maybe parts of the southern Panhandle.
Fracasso
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Much above normal temperatures across portions of northwestern
Alaska, Thu, Jun 4.
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html