Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 225 PM EDT Wed Jul 17 2019 Valid 12Z Sun Jul 21 2019 - 12Z Thu Jul 25 2019 Flat flow aloft will transition into a more amplified pattern with time across the region which evolves into a Rex Block pattern extending from Alaska/Yukon (closed deep layer high) into the northeast Pacific (closed deep layer low). Broadly, the guidance is agreeable but detail issues continue to cloud the picture. In order to deal with the system crossing Alaska Saturday night, and maintain as good of continuity as possible, used the 06z GFS outright Thereafter, a blend of the 00z Canadian/06z GFS/00z ECMWF/00z UKMET/00z ECMWF ensemble mean/00z NAEFS mean was used, with increasing percentages of the ensemble means with time as the UKMET and Canadian percentages dropped off. This led to a quicker/weaker eastern AK system early on and a slower progression with the system moving through western and central Alaska early to mid next week. Confidence is no better than average in the forecast by mid next week. Mild to warm temperatures are forecast for the state this period -- temperatures remain on pace for record warmth for the month of July across south-central AK. North and Northwest AK have the highest rain chances this weekend (where moderate to heavy rainfall is expected) before the low moving eastward through the northeast Pacific increases rain chances for southeast AK and the AK panhandle early to mid next week. Roth 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