Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
617 PM EDT Fri Apr 15 2022
Valid 12Z Tue Apr 19 2022 - 12Z Sat Apr 23 2022
...Deep cyclone transitioning from western Pacific Typhoon Malakas
to affect the Aleutians early next week...
...Overview...
The main focus of significant systems during next week will be
near the Aleutians and over the northeastern Pacific, but storm
activity should eventually focus more into the Gulf of Alaska.
Deep low pressure originally associated with Typhoon Malakas
should track over and then southeastward from the Aleutians early
next week, bringing strong winds/enhanced precipitation and
maritime threats. Another potentially strong system could track
near the Aleutians later in the week. This system has lower
confidence in the details, but the guidance signal has improved.
Meanwhile an area of mean low pressure will likely exist south of
the Panhandle for most of the period, with an initial system
ultimately being replaced by a somewhat weakened form of the
leading Aleutians storm. The combination of these features may
bring some moisture northward into the Panhandle. Farther north,
an upper ridge centered near the northern coast of the mainland
should weaken somewhat but lingering ridging could persist into
late week, while lower heights with troughing/one or more weak
upper lows may prevail near the southern coast.
...Guidance/Predictability Assessment...
A blend of decently clustered guidance from the 12 UTC
GFS/ECMWF/UKMET/Canadian seems to provide a good forecast basis
for days 4/5 (Tue/Wed). Forecast spread growth into longer time
frames seems to favor increasingly incorporating 12 UTC GEFS/ECMWF
ensemble means that stay compatible into days 7/8. Manual
adjustments were applied to ensure sufficient depth for a later
period offshore low that seems to have the good closed upper
trough support off the Aleutians. Individual models and ensemble
members are naturally more varied, but many now have some deep
solutions and the 12 UTC GFS/ECMWF happen to share a similar
depiction for day 7/next Friday.
...Weather/Hazard Highlights...
The extratropical reflection of Typhoon Malakas tracking near the
Aleutians Monday into Tuesday will produce a broad area of strong
winds/maritime threats and precipitation from the Bering Sea
through the North Pacific early next week. Another strong storm
may track near the Aleutians next Thursday-Friday with associated
enhanced winds and precipitation. This system should extend its
influence to the Alaska Peninsula and eventually onward into next
weekend with slowing downstream progression over the Gulf of
Alaska under a mean upper low/trough. Relative to the first
system, there is greater uncertainty with details of the late week
system so continue to monitor latest forecasts for updated
information. After Monday a couple surface systems to the south
of the Panhandle may push moisture far enough north to bring
precipitation to portions of the region. Confidence is fairly low
for exact amounts/coverage, but most activity should be on the
lighter side. Much of the mainland should be fairly dry with at
most very light/scattered precipitation. In general expect above
normal temperatures over most of the northwestern half of the
mainland and below normal readings over the southeastern half of
the mainland and the Panhandle. Some areas may see slightly
warmer anomalies for morning lows relative to daytime highs.
Schichtel
Hazards:
- Heavy precipitation for parts of mainland Alaska and the
Aleutians, Thu-Fri, Apr 21-Apr 22.
- Heavy precipitation across portions of the Aleutians, Mon, Apr
18 and Thu-Fri, Apr 21-Apr 22.
- High winds across portions of mainland Alaska and the Aleutians,
Thu-Fri, Apr 21-Apr 22.
- High winds across portions of the Aleutians, Mon, Apr 18 and
Thu-Fri, Apr 21-Apr 22.
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