Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
251 PM EST Thu Jan 17 2019

Valid 12Z Mon Jan 21 2019 - 12Z Fri Jan 25 2019

Ensemble guidance continues to point to increased upper ridging
over western Canada late next week which will favor increased
troughing through the Bering Sea and across the Aleutians. This
will stop any eastward progress of Pacific systems and will set up
at least several days of precipitation for Southcentral into the
Panhandle. The 12Z GFS and 00Z ECMWF cluster near their ensemble
means and formed a good starting point to the forecast Mon-Thu
next week. Given the shifts in prior runs could not trust any
single deterministic model. By next Friday, ECMWF seemed too quick
with its sfc low into northern Alaska/Beaufort Sea as it can be
too quick to bring shortwaves into/over upper ridges. Though at 8
days out it still fell within the typical timing spread.

Temperatures will moderate with time as heights build and lower
level temperatures rise. This will work its way to the surface due
to sustained southerly flow aloft later next week, bringing above
freezing air to Anchorage as snow changes to rain. Precipitation
totals may be significant from the southern Kenai eastward toward
the northern Panhandle where several inches (liquid equivalent)
may fall area-wide with max values near 10 inches.

Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html