Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
700 PM EST Wed Feb 23 2022
Valid 12Z Mon Feb 28 2022 - 12Z Fri Mar 04 2022
...Overview...
A relatively mild pattern is forecast for Alaska during the first
half of next week, as southerly flow dominates in between an upper
low moving slowly across the Kamchatka Peninsula and ridging with
an axis over northwestern Canada that could migrate into Alaska
around Thursday of next week. Above average temperatures and
periods of light to moderate precipitation are expected for
coastal areas with this pattern.
...Guidance/Predictability Assessment...
Recent model and ensemble guidance is generally agreeable with the
pattern described above, but ample differences remain with the
smaller scale details, including surface and upper lows over the
northern Pacific and Gulf of Alaska for the early part of next
week. A multi-model deterministic blend yielded a surface low
position west of the Panhandle early Sunday, closest to the
ECMWF/UKMET position. Additional low pressure and frontal systems
move across the northern Pacific/Gulf during the period, with a
general trend for faster tracks of the fronts compared to the
previous forecast, but once again confidence is low with the
details.
Most guidance shows a bout of ridging briefly building over the
Aleutians next Monday into Tuesday, shunting eastward ahead of the
larger scale Kamchatka to Bering Sea upper low. At the surface,
preferred the ECMWF and CMC that were better clustered with the
ensemble mean positions of a surface low in the western Bering,
whereas the GFS runs are alone in showing the low over the
Aleutians early Tuesday. There is overall fair agreement at least
in the ensemble guidance that upper ridging may build over the
eastern mainland by the end of the period Thursday ahead of the
low/trough to the west, possibly combining the ridging influences
that tracked across the Aleutians and northwestern Canada. A
surface low associated with the upper low/trough slowly making its
way eastward across the Bering/Aleutians is then likely to affect
the Aleutians Thursday, which had okay clustering especially in
the ensemble means, with the ECMWF the closest deterministic model
to the low position. Given the deterministic model differences,
phased in the ensemble means to around 50 to 70 percent of the
forecast blend by days 7-8.
...Weather/Hazard Highlights...
Moist southerly flow is forecast to keep rain and snow chances in
the forecast particularly across coastal areas. Precipitation
could be enhanced over the Panhandle over the weekend with the
possibility for a lingering low pressure system, but with light to
perhaps locally moderate amounts, generally trending lighter with
time. Some light scattered precipitation could extend farther
north over the mainland as well. Increasing precipitation and
possibly gusty winds are then forecast for the Aleutians through
much of the workweek, with amounts and timing depending on low
pressure/frontal systems. Current forecasts show the best signal
for notable precipitation there by around next Wednesday-Thursday.
Above average temperatures will abound over Alaska through much of
next week, especially for lows. The highest anomalies are forecast
over the northern and western parts of the mainland for the
beginning of the week, with lows up to 30-40 degrees above normal
and highs 20-30 degrees above normal. Anomalies will ease with
time, reaching near to slightly below average for highs in the
Panhandle in the southeastern mainland by midweek, but remaining
above normal farther north and west for the week.
Tate
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