Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
604 PM EST Fri Jan 10 2020
Valid 12Z Tue Jan 14 2020 - 12Z Sat Jan 18 2020
...Overview...
Upper ridging and a closed high will migrate toward the North
Slope next week as the cold remains over eastern/southeastern
portions of the state. Milder air will push into
western/northwestern areas as height rise. Precipitation will be
below average with a suppressed storm track.
...Guidance/Predictability Assessment...
The 12Z GFS/ECMWF/Canadian offered reasonable clustering with the
00Z ECMWF ensemble mean to start the period, Tue-Thu, with high
pressure shifting to the eastern interior, maintaining the cold
there and to the Panhandle. By Thu, GFS started to be on the
quicker side of the spread with system south of the Aleutians,
though it did later pair well with the ECMWF by next Sat. Canadian
was much farther south and not preferred. To the north, ensemble
trend suggested more support for a closed high to drift toward the
North Slope compared to 24 hrs ago, but the 12Z ECMWF was farther
north than most guidance. Trended toward the ensemble means, with
more weight on the ECMWF ensemble mean, for next Fri/Sat which
tempered the northward extent of the upper high.
...Weather/Hazards Highlights...
Much of eastern/southeastern Alaska will have lingering much below
normal temperatures as arctic high pressure ~1040mb only slowly
retreats into NW Canada. To the west, with increased southerly
flow after Tuesday, milder air will lift northward and push
eastward with time as upper heights rise, but staying west of
about 150W as higher pressures remain. Precipitation will be light
given the storm track well to the south, focused over the
Aleutians (heavier farther west), the western coastline, and over
Kodiak and the southern Kenai peninsula.
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:
- Much below normal temperatures across portions of the Alaska
Panhandle and mainland Alaska, Mon-Tue, Jan 13-Jan 14.
- Much below normal temperatures across portions of the Alaska
Panhandle, Mon-Thu, Jan 13-Jan 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