Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 322 PM EDT Thu May 30 2019 Valid 12Z Mon Jun 03 2019 - 12Z Fri Jun 07 2019 Flow over the high latitudes will feature a blocking pattern with slowly moving features. The majority of models have kept yet another upper low north of Wrangel Island and retrograde the circulation west with time. The model differences appear starting Monday with The 12z GFS and 00z ECMWF showing much different behaviors. The differences fro the 06-12z GFS, GFS FV3, and 06-12z GEFS Mean in the trough phasing/location/intensity underlie a low confidence forecast. A blended solution giving more weight to the GFS/GEFS Mean was used, with more weighting on the mean days 7-8. The 00z ECMWF was most aggressive in moving height rises south from the Arctic Ocean, in turn shunting the upper trough south from northern to southern AK next week. The 00z ECMWF Ensemble mean n was much slower to increase heights over northwest AK, allowing the trough to move more slowly south like the GEFS Mean and various GFS runs. The blended approach washed out the lower heights aloft in the 12z run of the GFS, which was deeper than each of the other models and broke continuity. On next Tue 04 Jun the models mostly show a new cyclone developing in the northern central Pacific to the southwest of the lower Aleutians. There are latitude differences with the 06z GFS north of the low positions/track vs the further south 00z ECMWF/ECMWF Ensemble Mean/Canadian. The 12z GFS trended south, increasing clustering of solutions. There is above average agreement on the development of a low. Given the typical fast GFS bias in moving closed lows too quickly, greater weighting to the 06z GEFS/00z ECMWF Ensemble means should bias correct the forecast. Mon 03 Jun an upper low is forecast to be south of the central Aleutians. The 00Z-06z suite of guidance (ECMWF/Canadian) clustered fairly well together and close to the ensemble means (00Z ECMWF ensemble mean and 06z GEFS Mean/00z Canadian mean) in moving the low east, possibly reaching the coast of southwest Canada 06 Jun. The consensus of these solutions stayed close to the prior forecast/ continuity, so the consensus was used. Early next week, Temperatures will average above normal in northern AK, and cool in southern coastal areas. As the week progresses, inland areas trend cooler if an upper trough develops. The most likely area to stay above normal would be the Aleutian Islands. Rainfall will generally be light but locally moderate in favored areas in windward terrain, focused on the southern half of mainland AK next Wed/Thu. Petersen 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 No significant hazards are expected over Alaska during this forecast period. 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