Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 620 PM EDT Wed Jun 16 2021 Valid 12Z Sun Jun 20 2021 - 12Z Thu Jun 24 2021 ...Guidance/Predictability Evaluation... The WPC Alaskan medium range product suite was primarily derived from a composite blend of relatively well clustered guidance of the 12Z GFS/CMC/ECMWF, along with some previous WPC continuity and 00Z ECMWF. Guidance forecast spread continues to indicate above normal predictability on the synoptic scale pattern. Some more of the GEFS and EC means was incorporated for next Wednesday and Thursday to account for increasing model spread by this time. ...Weather/Threats Highlights... The first storm system during this forecast period is expected to affect the Gulf of Alaska region on Sunday, which will likely produce unsettled maritime conditions along with periods of rain from the Alaskan Peninsula to the southeast panhandle. A stronger storm system builds south of the Aleutians and should track slowly to the east for the beginning to middle part of next week. This would result in an emerging maritime and regional threat to monitor as an occluded surface low will most likely impact areas from the Aleutians to the Alaskan Peninsula in a potentially much wetter pattern toward the middle of next week for coastal areas. The weather pattern is expected to become more amplified by the Tuesday to Thursday time period as an upper level ridge builds in across eastern Alaska, which is in response to the meandering upper level gyre over the Aleutians. This will result in warm temperatures across much of the Interior next week, especially for those areas that have mostly clear skies. Hamrick Hazards: 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 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