Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
552 PM EST Mon Feb 10 2020
Valid 12Z Fri Feb 14 2020 - 12Z Tue Feb 18 2020
...Guidance and Uncertainty Assessment...
The 12 UTC ECMWF is the deterministic model that offers a solution
Friday/Saturday that seems best aligned today with the ensemble
means and WPC continuity. This solution still seems reasonable.
Accordingly and after collaboration with local WFO offices, it was
also agreed that the forecast starting point for the WPC Alaskan
product suite would then be mainly derived from the compatable 12
UTC NAEFS mean and especially the 12 UTC ECMWF ensemble mean
Sunday-next Tuesday. Guidance from the 19 UTC National Blend of
Models was also included in these composite blends. The overall
pattern evolution seems less predictable than normal, so only
modest forecaster adjustments were applied to add increased detail
consistent with individual weather feature predictability.
...Weather Pattern and Hazards Highlights...
Frigid air deeply settling over the Interior and North Slope may
prove slow to moderate over the next week as Arctic stream upper
troughing digs back over the region. Meanwhile, a powerhouse storm
will focus a threat of heavy precipitation/winds/seas across the
Aleutians/Bering Sea by Thursday. The deep low will gradually
weaken Friday/Saturday as a developing triple point low is
expected to progress eastward across the northern Gulf of Alaska
and offer a moderate precipitation threat into the southern and
southern Alaskan tier. There is an increasing guidance signal that
additional systems feeding into the Gulf in this stream will offer
some potential to phase with Arctic stream energies more ernestly
in about a week. Stream phasing is not very predictable at long
lead times, but could support deep northern Gulf low development
along with unsettled seas and a heavy precipitation threat into
southern and southeast Alaska.
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
Hazards:
- Heavy precipitation for parts of the Alaska Panhandle and
mainland AK, Mon, Feb 17.
- Much below normal temperatures for parts of mainland Alaska,
Thu-Sun, Feb 13-Feb 16.
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