Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 321 PM EDT Sun Jun 02 2019 Valid 12Z Thu Jun 06 2019 - 12Z Mon Jun 10 2019 Guidance continues to show persistent surface high pressure over a majority of the Bering Sea as well as portions of the Arctic (one center northeast of the mainland late in the week and early weekend possibly followed by one or more centers building north of the mainland by next Sun-Mon) associated with general ridging aloft, while surface troughing remains over the mainland. Exact details aloft are still somewhat ambiguous though. One trend of note is for the mean ridge aloft over the Bering to extend its influence farther eastward into the mainland compared to yesterday's consensus. There is also a fair degree of uncertainty over an upper low north of Siberia. Most guidance keeps it well away from the mainland but the past couple ECMWF runs bring it farther southeastward. Across the Pacific there is still decent clustering among most models and ensemble means for a leading system to drift closer to the Alaska Peninsula and Kodiak Island late in the period with a leading ridge aloft building over the Panhandle/western Canada into the mainland. The situation farther westward is much more chaotic with a wide spread of model/ensemble solutions for one or more lows whose influence could extend as far northward as the Aleutians--or remain well suppressed. Today's guidance preference maintains the approach of starting with an operational model blend early in the period and then transitioning to a model/ensemble mean blend (60 percent means by day 8 Mon). Latest consensus shows higher heights aloft over the mainland versus yesterday early-mid period and yields a slight northward adjustment for the Pacific system. By next weekend this system should bring some enhanced winds/precipitation to areas from the Alaska Peninsula and Kodiak Island eastward through the Gulf of Alaska with moisture also reaching the Panhandle. As for specific considerations by area/system: The forecast reduces 00Z ECMWF weight after day 4 Thu as its upper low north of Siberia strays farther southeast than most other guidance. The new 12Z ECMWF still shows this southeast scenario though. Ensembles as a whole are all over the place with the low, leaving the ECMWF within the full spread, but that model is far enough from the majority to favor downplaying its forecast until supported by other guidance. For the primary Pacific low of interest, the 12Z GFS is favorably slower than the 06Z run and northward of the questionably suppressed 00Z run so the new run provides the GFS input (along with the 06Z FV3 for about the first half of the period). Spread over the western Pacific favors a conservative blend/ensemble mean approach. By day 8 Mon an overwhelming majority of ensembles favor a more suppressed pattern than depicted by the 00Z ECMWF that tracks strong low pressure close to the western Aleutians. The ensemble component of the forecast leans more to the 00Z ECMWF mean relative to the 06Z GEFS as the former has better definition across most of the North Pacific. Rausch 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