Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
556 PM EDT Mon Jun 15 2020
Valid 12Z Fri Jun 19 2020 - 12Z Tue Jun 23 2020
...Overview and Guidance/Predictability Assessment...
Strong upper ridging over Siberia/northeastern Russia will favor
troughing to its east, centered along 150W, albeit in two pieces.
The northern component will be an upper low likely remaining over
the Arctic Ocean but perhaps swinging modest height falls across
the North Slope this weekend. The southern component will be a
lead and then secondary upper low just south of the eastern
Aleutians. This former will be associated with a front and
trailing wave development near the Panhandle that will take a few
days to push through. The latter has the potential to be a more
robust system lifting out of the northern Central Pacific toward
the Gulf by next week Mon-Tue. The 12Z guidance was in decent
agreement but differed most on the more robust system over the
Pacific, especially the 12Z ECMWF (slower and farther west/south).
The 12Z GFS clustered near the 12Z GEFS and 00Z ECMWF ensemble
mean and was the preferred deterministic model. However, it may be
too aggressive with height falls over the Beaufort/North Slope
around the upper low that it takes farther south than the
consensus.
...Weather/Threats Highlights...
Temperatures will be within several degrees of normal through the
period, with near/above normal over western/interior areas and
near/below normal from Southcentral to the Panhandle. There,
clouds/showers will temper afternoon maxes Fri-Sun until the lead
system moves on. Rainfall is not expected to be very heavy due to
weaker forcing overall. Over the interior, afternoon convection
will be possible but perhaps not widespread owing to weak ridging
between low centers to the north and south along with lifted
indices marginally sub-zero. By next week, Pacific system may
bring in more appreciable rainfall to southern coastal areas, but
confidence is low in timing/placement should a more offshore track
to the east rather than northeast materialize. Kept the hazard
depiction blank for now.
Fracasso
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
Hazards:
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