Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
608 PM EDT Tue Jun 16 2020
Valid 12Z Sat Jun 20 2020 - 12Z Wed Jun 24 2020
...Overview and Guidance/Predictability Assessment...
Strong upper ridging over Siberia/northeastern Russia and
northwest of the Paphanaumokuakea Marine National Monument will
favor troughing 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
northwestern/northern areas next week. The southern component will
be the remains of system through the Yukon early Saturday with a
more robust system south of the Aleutians. The 12Z guidance was in
decent agreement but differed on the speed and track of the
Pacific system that should steadily curl into the Gulf by next
Tue-Wed. The consensus trend has been a bit slower but mostly
aligned in a similar track to continuity. The 12Z deterministic
models had varying degrees of resemblance to the ensemble means
and none was preferred overall, though the ECMWF was perhaps a
contender for the Mon-Wed period. Before that, the 12Z GFS was
comparable though still perhaps a bit stronger with height falls
than the others. To the south, the GFS was like the ECMWF/Canadian
with the system into the Gulf but lagged well behind the
ECMWF/Canadian with another system to its southwest. Overall
favored the ensemble consensus to limit daily changes to the
forecast.
...Weather/Threats Highlights...
Temperatures will tend to be near to below normal for most of the
state, with near/above normal temperatures over western areas
under weak ridging. Over the interior, afternoon convection will
be possible but perhaps not widespread after Saturday owing to
weak ridging between low centers to the north and south along with
lifted indices marginally sub-zero. Old occlusion on Saturday may
focus more rain/convection north of the Brooks Range. By next
week, Pacific system may bring in more appreciable rainfall to
southern coastal areas, perhaps not until late next Tuesday.
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