Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 655 PM EDT Wed May 10 2023 Valid 12Z Sun May 14 2023 - 12Z Thu May 18 2023 ...Guidance Evaluation/Predictability Assessment... 12 UTC ECMWF/UKMET/Canadian guidance seems best clustered and provides reasonable continuity Sunday into Tuesday, with the latest and more eastwardly progressive GFS seemingly serving as a less likely outlier considering ensembles and amplified nature of the flow. The ECMWF then seems best compatible with the GEFS/ECMWF ensemble means thru next midweek. Forecast spread and run to run sensitivity has increased compared to yesterday, lowering forecast confidence to a degree. Prefer a composite blend to mitigate, consistent with predictability, smaller scale variances. Applied manual edits to ensure sufficient surface low pressure center depths and wind speeds, muted by the blending process and forecast spread, as consistent with upper support signals. ...Overview and Weather/Hazard Highlights... A lingering Gulf of Alaska/northern Pacific deep layered low will steadily lose influence by early next week. Expect a warming/drying trend over Southeast Alaska with ridging at the surface and aloft coming in by early next week, then persisting through the week. Upper ridging and warmer temperatures are also forecast to build farther north into the Interior and North Slope by next week, which could increase the rate of snowmelt runoff and river ice breakup and eventually lead to potential flooding threats. To the West, the slow advance and uncertain splitting of supporting upper trough energies will meanwhile act to bring additional low pressure systems across the Bering Sea and with leading triple point development into the northwestern Gulf of Alaska. This combination will spread moderate rains and some gusty/enhanced winds from the Aleutians and the Alaska Peninsula to coastal Southcentral, but also well northward, especially across western Alaska. Guidance does not show very heavy amounts, but it is worth monitoring that the increasingly deep feed of moisture and Gulf system energies expected to forced northward in a channeled conduit into the mainland between the Bering system and the building downstream upper ridge may prove more efficient, especially for favored coastal terrain. Expect some showers will also be scattered across the Interior next week as well. Schichtel 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 outlook 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