Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 704 PM EDT Tue Apr 8 2025 Valid 12Z Sat 12 Apr 2025 - 12Z Wed 16 Apr 2025 ...Gulf low pressure could lead to heavy precipitation for the southern coast and strong gap winds in the Alaska Peninsula this weekend/early next week... ...Overview... Guidance remains pretty consistent in showing a mean upper low over the Bering Sea by the start of the period on Saturday, with troughing extending southward across the eastern Aleutians and northern Pacific. This upper low will shift slowly southward, and eventually into the Gulf by sometime early next week. This supports surface low pressure in/around the Gulf region next week, as various shortwaves/cold fronts act to reinforce. Mean moist southerly flow near and east of the low could bring locally heavy precipitation to the southern coast of the Mainland into parts of the Panhandle, particularly over the weekend into Monday. Northerly to northwesterly winds and gap winds on the backside of the low may be brisk in the vicinity of the mid-Aleutians to Alaska Peninsula behind this low over the weekend. ...Guidance/Predictability Assessment... Model guidance is in fairly good agreement on the overall upper pattern, but with plenty of uncertainty in the timing of systems and details. There is better agreement on the positioning of the upper low over the Bering come Saturday, and its track as it moves southward across the Peninsula this weekend. The 00z ECMWF was much slower in showing this transition, tending to keep the upper low over the Bering Sea for a few days. But the 12z run this afternoon did trend a bit faster. After Monday though, there is some disagreement in how quickly the low weakens and its positioning Days 7 and 8. The main outlier was the 12z ECMWF which weakens and lifts the upper low energy more northward into mainland Alaska, which there is better consensus for energy to stay over the Gulf, with a discernible surface low. A somewhat blocky pattern looks to build through the period with upper ridging over western North America and the western Bering/Aleutians. The WPC forecast for today used a blend of the deterministic guidance Days 4 and 5. After Day 5, gradually increased influence of the ensemble means into the blend, eventually resulting in 80 percent ensemble means by Day 8. ...Weather/Hazards Highlights... Precipitation chances will be on the increase by the weekend as surface low pressure consolidates in/near the Gulf. This provides support for more precipitation, with moderate to locally heavy amounts becoming more likely from the Kenai Peninsula into Southeast Alaska for the weekend into early next week. Northerly to northwesterly winds on the backside of the low could be brisk to strong across the Alaska Peninsula for the weekend and perhaps into next Monday. The upper low in the Bering Sea should support below normal temperatures over the western part of the state, with warmer temperatures filtering in across eastern/central parts of the state underneath upper ridging. Forecast highs in the Interior should generally be in the 40s to low 50s by Sunday and beyond. Southeast Alaska is forecast to see slightly below average temperatures late this week but warm slightly above normal, especially for lows, early next week. Santorelli 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