Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 631 PM EDT Mon Jul 5 2021 Valid 12Z Fri Jul 9 2021 - 12Z Tue Jul 13 2021 ...Overview and Guidance/Predictability Evaluation... A rather amplified and slow moving pattern is expected to exist across the Alaska domain for the medium range forecast period. A strong shortwave trough settling southward across western Alaska early in the forecast period should evolve into a closed low in the general vicinity of the Alaska Peninsula by Saturday, and then settle southward over the northern Gulf by Sunday and into Monday. A narrow upper ridge axis may try to build in between these two features across portions of the Interior for next weekend and into next Monday. The deterministic models and the ensemble means are in generally above average agreement on the synoptic scale pattern through most of the forecast period, with the exception of the Arctic where more significant timing differences on shortwaves exists. The extent of the upper level ridging over north-central Alaska is a bit less certain. In terms of model preferences, the WPC forecast was primarily derived from a deterministic model blend through Saturday night, for early next week while still maintaining some of the CMC/ECMWF/GFS. Some previous WPC continuity was also maintained through day 7. ...Weather/Threats Highlights... Given the broad upper low/trough in place, increased cloud cover and widespread showers will tend to keep temperatures below average across most of the state through Saturday, with the greatest anomalies likely for south-central Alaska with highs running 10 to 20 degrees below normal, particularly across western and southern portions of the state. A moderation trend should commence by the Sunday to Tuesday time period as the weak upper ridge builds in across much of the Interior. Another thing to monitor is the prospect for episodes of heavy rainfall from the Alaska Peninsula to western portions of the southeast Panhandle, with the potential for some 2-4 inch rainfall totals with locally higher amounts. This would be in response to enhanced onshore low-mid level flow ahead of the closed upper low, with a potential atmospheric river setting up this weekend near the Kenai Peninsula. Showers are also expected to be scattered during the afternoon hours across portions of the Interior as well. Gusty winds are likely for southern coastal regions with the unsettled weather pattern in place across the northern Gulf region. Hamrick Hazards: - Heavy rain across portions of the Alaska Panhandle and southern mainland Alaska, Sat-Mon, Jul 10-Jul 12. 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