Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
653 PM EDT Wed Jun 08 2022
Valid 12Z Sun Jun 12 2022 - 12Z Thu Jun 16 2022
...Overview and Guidance Evaluation/Predictability Assessment...
The guidance generally agrees that a retrograding upper low at
high latitudes/near northwest AK will help guide systems under its
base generally south of Alaska, towards the Gulf, while mid to
upper level ridging will also build across eastern AK and the
Yukon. Guidance shows good agreement the first few days with this
pattern, but after that some uncertainties begin to arise
regarding the retrograding low towards the Bering and another deep
low moving into the domain which may impact parts of the Aleutians
by mid-next week. The 12z ECMWF seemed an outlier by day 6/Tuesday
as it becomes displaced to the south with the upper low in the
Bering, likely seeing more interaction with a low into the Gulf,
and brings another compact upper low across the Arctic/northern
Alaska. The ensemble means suggest something with more separation,
more like the 12z GFS/CMC. There are some minor differences with
the low towards the Aleutians late period, but nothing egregious
considering a day 8 time frame. The WPC forecast blended the
latest 12z deterministic guidance (GFS, ECMWF, CMC, and UKMET) for
days 4-5. For 6-8, leaned more on the ensemble means ending up
with an equal weight of the ECENS/GEFS mean with some of the GFS
and ECMWF (the CMC became fast/south with the Gulf low early on so
it was excluded from the blend after day 5). This maintained
reasonable WPC continuity.
...Weather and Hazard Highlights...
For much of the period, south-central Alaska and the Panhandle
should be fairly wet. The guidance continues to show some
disagreement on how much precipitation, but it's reasonable to
expect some precipitation, especially within the warm conveyor
belt of the departing upper low with some local terrain
enhancements. The Aleutians and northern Alaska should be mostly
rain free, until around the middle of next week when an upper low
moves towards the Aleutians. Much of Alaska should see a general
warming trend through the period as upper ridging tries to build
over parts of the region. Overall, it should be mild to warm
across central/western Alaska, and colder than normal across the
North Slope, and portions of the Panhandle/southeast Alaska.
Santorelli
No significant hazards are expected over Alaska during this
forecast period.
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
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