Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
731 PM EDT Fri Jul 7 2023
Valid 12Z Tue Jul 11 2023 - 12Z Sat Jul 15 2023
...Overview and Weather/Hazards highlights...
An upper level trough is expected to be in place across western
Alaska at the beginning of the forecast period early Tuesday and
then across the North Slope/Northern Interior, with gradual system
weakening through early-mid next week around the periphery of an
upper ridge lingering over eastern Alaska and the Yukon. A new
low pressure system then develops over the Gulf region and then
lingers in place there through the end of the week, and this will
support modest to locally moderate rainfall chances by early-mid
next week. The guidance signal for this organized system has
increased. A second system is likely to develop over the western
Bering Sea late in the forecast period and may result in increased
rainfall chances for portions of the Aleutians. However, no
organized areas of heavy rainfall are expected during this
forecast period.
...Guidance Evaluation/Preferences and Predictability Assessment...
The 12Z model guidance suite is in very good synoptic scale
agreement across the Alaska domain and adjacent waters going
through the early to middle part of next week. In regards to the
low pressure system developing over the Gulf of Alaska by
Wednesday, the 12Z GFS is displaced a little to the southeast of
the model consensus going into the second half of the week, and
stronger with an upper low near the Arctic Coast. By the
Friday-Saturday time period, the ECMWF and CMC are close in their
depiction of the Gulf low, and also reasonably close with the
upper low over the western Bering, and the greatest model
differences by this time reside across the Arctic and northwestern
Canada. The fronts/pressures forecast was primarily derived from
a deterministic model blend for Tuesday and Wednesday, and then
ensemble means were gradually increased each day to about 50% by
next Saturday.
Hamrick
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