Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 710 PM EDT Fri Apr 09 2021 Valid 12Z Tue Apr 13 2021 - 12Z Sat Apr 17 2021 ...Locally heavy rain likely for parts of Southeastern Alaska next week... ...Guidance/Uncertainty Assessment... The upper pattern will be characterized by anomalous and blocky flow next week with troughing along 160W and ridging over the Bering and NW Canada/AK Panhandle. An upper low is forecast to sink south-southeastward with multiple embedded vortices around it, suggesting lower predictability on the smaller scale. Trend has been toward a slower and more amplified pattern overall, and this was supported by the 12Z ECMWF/UKMET/Canadian/Canadian ensembles and 00Z ECMWF ensembles. The GFS and its ensembles were just a bit quicker and weaker to start, especially with a deeper system moving across the Aleutians Tue-Wed, and eventually were completely out of phase with the larger consensus by the end of the week and much quicker overall. Preferred the slower and more amplified solution and used a majority deterministic weight through next Friday to maintain system details and meridional flow. ...Weather/Hazards Highlights... Southerly flow early in the week will sustain well above normal precipitable water values, perhaps nearing as high as they can reach for this time of year, as a system moves into and through the Gulf Tuesday with a stronger system early Wednesday. The former may spread modest to locally heavier rain to parts of the Panhandle while the latter may bring more widespread modest and heavier rain (higher elevation snow) to Southcentral (southern Kenai to Prince William Sound especially, in addition to the western side of Cook Inlet). Several inches of rain will be possible. Once that system lifts northeastward out of the region, upper ridging will nose in from the southeast as the upper low sinks southward through the northeastern Pacific. This should introduce a drying trend for most of the state starting Thursday into Saturday. Temperatures will trend milder as southerly flow brigs warmer air northward, especially over northern areas across the North Slope. The Panhandle may see an extension of below normal temperatures with high pressure nearby and the southerly flow mostly west/offshore across the Gulf. Fracasso Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Wed, Apr 12-Apr 14. 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