Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
546 PM EDT Sun Apr 19 2020
Valid 12Z Thu Apr 23 2020 - 12Z Mon Apr 27 2020
...Overview and Guidance Evaluation and Weather/Threats
Highlights...
A lead deepened low/frontal system along with an enhanced
winds/waves/precipitation remains slated for the Gulf of Alaska
into Thursday/Friday, exiting through the Southeast Panhandle this
weekend. Meanwhile upstream, an emerging low/frontal system with
enhanced winds/waves/precipitation will dig through the Aleutians
Friday and reform/track across the Gulf of Alaska next weekend
into early next week on the heels of the lead system.
Farther inland over the state, several unsettling mid-upper level
troughs/impulses will work over the North Slope and the Interior
over the coming week, significantly cooling the current warm
spell. In this pattern expect some locally/terrain enhanced snows
will focus in vicinity of the weaknesses/lows aloft and with a
persistent and wavy surface front.
A composite blend of reasonably well clustered 12 UTC models and
ensemble means along with the 19 UTC National Blend of Models
seems to produce a good forecast starting point Thursday/Friday in
a pattern with above normal predictability. Increased the ensemble
mean weightings at longer time frames consistent with growing
forecast spread and uncertainty. Manual adjustments were applied
to produce sufficient offshore system depths consistent with upper
support, but artificially weakened by the blend process. This
Alaskan office collaborated forecast maintains good WPC continuity.
Schichtel
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
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