Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
640 PM EDT Fri Jun 05 2020
Valid 12Z Tue Jun 09 2020 - 12Z Sat Jun 13 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 will keep potential for precipitation up
through the period, 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. The GFS
was not used this forecast cycle due to a solutions that were well
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
No significant hazards are expected over Alaska during this
forecast period.
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