Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EST Tue Jan 10 2023 Valid 12Z Sat Jan 14 2023 - 12Z Wed Jan 18 2023 ...Overview... The latest guidance continues to have a fair handle on the large scale pattern through the extended period. One feature will be a compact upper low that tracks just north of the Bering Strait as of early Friday which should leave lingering weakness aloft near the Arctic/North Coast. Much of the Mainland will have ridging in place through the extended period. Meanwhile, as an initially deep Aleutians storm weakens, an elongated trough will setup from the Bering Sea to portions of the northern Pacific and will feature some areas of low pressure to pass though. This large scale pattern looks to maintain itself through the extended period which will keep precipitation focused along the southern part of the mainland while lighter amounts forecast for the Southeast and the Aleutians. At the surface the mainland will remain in a gradient between strong high pressure over higher latitudes of the Arctic and the various surface lows to the south/southwest. ...Guidance/Predictability Assessment... The latest guidance continues to show persistent ridging across the Mainland with weakness expected near the northern coast. Yesterday it was noted that recent GFS runs have been a little more variable, with at least half fitting into the consensus scenario reasonably well but stray runs occasionally showing a deep low closing off over the mainland early next week. While the CMC/UKMET runs have been more erratic, pushing the ridge farther north yesterday and then suppressing it early in the period. The ECWMF was the preferred model with varied percent weightings of the GFS, CMC and UKMET. The latest ECWMF and its ensemble mean continue to be the preferred solution for this forecast with similar inclusion of the GFS, CMC and UKMET solutions. Overall this blend kept a since of run to run continuity. Guidance continues to show a lot of uncertainty for specifics of individual surface lows across the Pacific and Bering Sea. However there has been somewhat of a signal that a low could follow that general evolution albeit weaker, so a moderate input of GFS guidance reflects such a possibility. Various possibilities for individual lows exist farther eastward as well, with some potential influence on areas between the Alaska Peninsula and the Panhandle. In a broad sense a moderate majority of guidance (including the 12Z ECMWF and latest ECMWF/CMC means) suggests that Bering Sea low pressure may migrate eastward toward the end of the period next Tuesday while a separate low gravitates toward or consolidates just east of Kodiak Island. ...Weather/Hazards Highlights... Meaningful precipitation will be focused along the coastal areas from the Southeast to the Alaska Peninsula at varying times. Higher daily totals will likely focus in the vicinity of the the Kenai Peninsula and parts of the Alaska Peninsula given fairly persistent easterly low level flow. In general, rain fall intensity is expected to remain light to moderate but there may be short durations where it is moderately heavy. The compact upper low/shortwave initially brushing the northern mainland may produce light snow in its vicinity late this week. Otherwise most of the mainland away from the southern coast should stay fairly dry. The Aleutians should see unsettled conditions through the period, but with low confidence for any individual lows that could focus precipitation/wind beyond the initial deep low over the area on Friday. The gradual weakening of upper ridging over the state over the course of the period should promote a colder trend for temperatures. Lows may may still be above normal over most locations by early next week after starting out well above normal on Friday, but gradually increasing coverage of below normal highs will be possible over the interior and North Slope. Campbell/Rausch No significant hazards are expected over Alaska during this forecast period. Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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