121 FXAK69 PAFG 122217 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 117 PM AKST Thu Nov 12 2020 .SYNOPSIS... The relatively quiet weather pattern across northern Alaska will continue for the next several days. Gusty northeasterly winds have developed across the northwestern Arctic and will continue through tonight. The West Coast will see a mixture of rain and snow through Friday morning with parts of the Lower Yukon Valley will receiving 4 to 7 inches of snow. Colder temperatures are expected for the weekend and beyond for the Interior. && .DISCUSSION... Models...The 12/12z model suite initialized well against the 12z surface analysis and verified well against the 18z surface analysis. Model run to run consistency is reasonable and remains good between between model families in the short and medium range. Model spread is minimal through Saturday but increases Sunday and is significant Monday and beyond. Upper levels and Analysis...A broad longwave trough with multiple upper level lows remains centered over the central Bering Sea eastward over Alaska while an upper level ridge over the Western Bering Sea builds slowly north and east. The trough slowly digs south and east over the Yukon and Northwest Territories through Monday as the upper level ridge builds north and east over the Eastern Bering Sea and Western Alaska through early next week. In general the models continue to indicate a weak and short lived Omega Block setting up over Western Alaska early next week, however the position, strength and longevity of the block differs considerably in the long range among the different model families. Opted to weigh the short term and mid term forecast heavier toward the ECMWF solution which slows the evolution both in time and amplitude of a building upper level ridge over the Eastern Bering Sea and Western Alaska into a weak and fairly short lived Omega Block early next week. This in turn allows more moisture and clouds to push into the Interior and slows the infiltration of clearing skies and the subsequent colder temperatures both aloft and at the surface over the Interior until late in the weekend and early next week. With the Omega Block setting up over Western Alaska the coldest airmass aloft will now be centered over the Yukon and Northwest Territories however temperatures in the Central and Eastern Interior will fall to normal by Sunday and slightly below normal by early next week. Arctic Coast and Brooks Range...Cloudy with flurries over much of the North Slope especially to the west and south of weak front now passing through the coastal areas. Clouds and flurries will briefly diminish behind the front this afternoon and evening but this will be short lives with more low ceilings and flurries expected to develop again tonight and continue through tomorrow. Expect generally northerly winds in the 10 to 20 mph. Temperatures will remain seasonal inland and above normal along the coasts. West Coast and Western Interior...A stalled front combined with a low pressure trough over the West Coast and Western Interior continues to produce snow over Southwest Alaska. The heaviest snow continues in the Lower Yukon Valley where a Winter Weather Advisory for 4 to 7 inches of snow has been issued and will continue into tomorrow morning. Generally 1 to 2 inches expected south of Galena. Rain is mixing with the snow over the YK Delta. Cold air continues to be drawn in from the northwest behind the trough. Strong and gusty winds north east to east winds will continue in the Chukchi Sea region tonight and into tomorrow ahead of a front pushing south through the Bering Strait tonight. Strong winds are also found in zone 207 and will increase tonight and develop tomorrow for zone 213 especially through the Bering Strait. Inland winds generally light and variable. Temperatures will be cooling as temperatures aloft cool. Central and Eastern Interior...A chance of snow, mainly north of the Yukon River this evening along a stalled front will diminish tonight. Cloudy for the remainder of the area, but expect some breaks. Snowfall will be light with little accumulation. Temperatures will be slowly cooling to near normal levels through Saturday, then cooler again through the rest of the weekend and early next week. Low temperatures Friday and Saturday will drop into the single digits above and below and then drop into the teen and 20s below in the coldest locations Sunday and early next week. Coastal Hazard Potential Days 3 and 4...None. Extended Forecast for days 4 to 7...High pressure will be pushing north out of the North Pacific over the West Coast and Chukchi Sea. This pattern will generally hold as a 1034 mb high develops over the Central Interior by Monday morning. A strong low will move to the Western Bering Sea Monday and approach the West Coast Tuesday. As the high pressure build over the Interior this weekend temperatures will be falling with Central and Eastern Interior low temperatures dipping down into the teens below to start the week. && .AFG WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory for AKZ215. Heavy Freezing Spray Warning for PKZ200-PKZ215-PKZ220-PKZ225- PKZ230-PKZ235. Gale Warning for PKZ210-PKZ220-PKZ225. && $$ CCC NOV 20