Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
655 PM EDT Wed Jul 01 2020
Valid 12Z Sun Jul 05 2020 - 12Z Thu Jul 09 2020
...Guidance/Predictability Assessment...
Model guidance has a trend of increasing spread through the
extended period that is lowering forecast confidence in the
regards of amplitude and axis of the blocking ridge pattern. The
last three runs of the ECWMF have consecutively shifted the ridge
axis to the west which allows the mid/upper low over the Arctic to
drift closer to far Northeast Mainland/Yukon. The GFS runs do show
the amplitude of the ridge lessen with time but maintains the low
over the Arctic/Canada further east. The CMC favors the ECWMF
evolution, while the UKMET consistently splits the differences
between the ECWMF and GFS solutions. At this time, still favor a
slower progression with the low/trough over the Bering
Sea/Aleutians and hanging onto the ridge longer. This equated to
including the ensemble means earlier in the forecast and a heavier
weighting toward the 6/12Z GFS.
...Overview and Weather/Hazard Highlights...
Shower activity will accompany a front as it slowly moves across
the North Slope and into the Interior. Parts of West/Southwest
Alaska and central Mainland could see rain through the week.
Meanwhile, with the blocking-like pattern, the deepened low over
the Bering Sea will make very little progress; which will keep it
offshore through the coming week. The gradual westward shift of
the summer ridge axis more into western and southwest Alaska into
early next week leaves room for temperature moderating and
unsettling upper trough digging from the Arctic and northwest
Canada down through the eastern Interior and Southeast Panhandle.
Campbell
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