Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 247 PM EST Sun Nov 10 2019 Valid 12Z Thu Nov 14 2019 - 12Z Mon Nov 18 2019 Models show reasonably good consensus on a deep but gradually weakening low pressure system passing south of Kodiak Island and moving into the Gulf of Alaska Thu-Fri. The ECMWF and CMC solutions were best clustered with the current model/ensemble consensus (and the forecast for days 4-5 was based heavily on these solutions), while the GFS was a bit southeast of consensus with the low (especially on Thu). Otherwise, the flow pattern across Alaska through the remainder of the extended period will be a chaotic one, with a train of shortwave energy traversing the westerlies across the North Pacific, and additional Arctic shortwave energy diving southwestward across mainland Alaska - with the potential for interactions between the Pacific/Arctic waves. The GFS is the most aggressive solution with one of these potential interactions, developing a deep upper low and associated surface low across the eastern Bering Sea Thu-Fri, a solution which seems too strong based on the consensus of model/ensemble data. Model run-to-run variability is relatively high (and thus predictability is relatively low) during days 6-8 (Sat-Mon). Thus, trended quickly toward the ECENS/NAEFS ensemble means by later in the forecast period. There was some consensus evident among the ensembles that another low pressure system should enter the Gulf and approach mainland and southeast Alaska Sat-Sun, with another quickly following in its heels by Sun night, and yet another approaching the Alaska Peninsula by Mon. Confidence in the specific details and timing of these systems decreases quickly through time. Ryan 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 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