Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
637 PM EDT Sat Jun 06 2020
Valid 12Z Wed Jun 10 2020 - 12Z Sun Jun 14 2020
...Overview and Weather Highlights/Threats...
A relatively progressive flow pattern is expected to persist
across the North Pacific and into the Gulf of Alaska through the
extended forecast period, while weak and broad upper ridging
persists from the Arctic Ocean into western Canada. Meanwhile, the
Interior of Alaska will lie within a region of chaotic and
relatively weak easterly upper-level flow. Onshore flow across
southern mainland Alaska as low pressure weakens in the Gulf of
Alaska will keep the potential for precipitation up through the
middle of next week (especially across the higher terrain), while
weak easterly flow and occasional upper shortwave energy will also
keep isolated to occasionally scattered convective activity in the
picture across the Interior. A low pressure system expected to
pass near the Aleutians as it moves toward the Gulf of Alaska by
the middle to late part of next week will bring an increase in
shower and perhaps some gusty winds to the Aleutians, with
precipitation eventually increasing across the Alaska Peninsula as
well. Temperatures in this pattern are expected to be above
average through the forecast period, with highs ranging from 5 to
15 deg F above average for many areas, especially across the
Interior. Meanwhile, more clouds and precipitation will keep
temperatures several degrees below average closer to the coast.
...Guidance/Predictability Assessment...
The 12Z ECMWF was used heavily early in the extended forecast
period, with a gradual transition to more weight placed on
ECENS/GEFS ensemble means through time through the period. Similar
to yesterday, the GFS was not used this forecast cycle due to a
solution that was outside consensus over a couple areas, including
a system in the Gulf of Alaska by the middle of next week, and
across the western Aleutians late next week. Overall, forecast
confidence was was average through the extended.
Ryan
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
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