Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 654 PM EST Mon Nov 6 2023 Valid 12Z Fri Nov 10 2023 - 12Z Tue Nov 14 2023 ***Intense Gulf of Alaska low late this week to bring high winds and heavy precipitation to southeastern Alaska*** ...Guidance Evaluation and Preferences... There has been an overall slightly faster and stronger trend in the 12Z model guidance cycle for the likely storm force low over the northern Gulf for the end of the week and into Saturday, with an increasing probability of the low reaching peak intensity of <970 mb Friday night. There has also been a slight northerly trend with the major eastern Siberia low over the weekend compared to yesterday's forecast, but with a faster cold front progression across the Aleutians with a triple point low forecast to form near the Kenai Peninsula going into next Monday. The GFS and ECMWF appear to be handling the overall evolution of these systems well with good support from their ensemble means, and the UKMET was also usable through Saturday, so the model blend through Saturday incorporated these models along with some of the CMC. However, by late Sunday and beyond, the CMC begins diverging significantly from the other guidance, especially across the north Pacific where it indicates a much greater expanse of high pressure, so this model was not incorporated for early next week. Ensemble means accounted for 50-60% of the forecast blend by next Monday and Tuesday. ...Overview and Weather/Hazards Highlights... The overall weather pattern across the Alaska domain is forecast to remain quite active for the Friday through Tuesday time period, particularly across the maritime regions. The first big storm of interest will be a rapidly deepening surface low across the northern waters of the Gulf through Friday night, followed by a steady weakening trend as the upper low/trough dampens and loses strength. The resulting strong pressure gradient will increase the winds quite a bit across the coastal waters of southeast Alaska with gusts in excess of 50 knots possible, and heavy terrain enhanced snow for the coastal mountain ranges, and a cold rain for the lower coastal elevations. There will also be steep lapse rates in association with the anomalous 500mb low, so some hail and thunder are within the realm of possibility with the heavier showers. Conditions should slowly improve going into late Saturday and Sunday, but unsettled weather may make a return for early next weekend as a new but weaker low pressure systems tries to develop in the same general area. An even stronger low pressure system with storm force winds is looking increasingly likely across portions of the western Bering and eastern Siberia going into the weekend and perhaps lasting into early Monday. Although the greatest impacts are currently expected to remain well west of the mainland, portions of the Aleutians may be impacted by gale to storm force winds, and parts of the southwestern mainland may also be affected by gusty winds and increased prospects for snow. Temperatures are generally expected to be in the 10s to middle 20s for highs across most of the mainland, and 30s for the southern coastal areas. Hamrick Hazards: -High winds across portions of the North Slope, Thursday, Nov. 9 -High winds across portions of southwestern Alaska, Sunday-Monday, Nov. 12-13 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