Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
972 FXAK68 PAFC 191333 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 533 AM AKDT Wed Jun 19 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Friday)... The upper level ridge continues to slide east with its axis over the Alaska Panhandle this morning. This eastward progression of the ridge will allow for the development of a more southerly flow across the Gulf of Alaska that will advect a more stable airmass over the southern half of Southcentral as well as drive a surface front from the western gulf to the northern Gulf through Friday. Weak upper-level waves will move through the southerly steering flow between the exiting ridge and an advancing upper-level trough. The first of these will move across the Copper River Basin later today, allowing for the development of showers and isolated thunderstorms across the northern and western periphery of the basin. This trough should also allow for gap winds to develop later this afternoon. Along the coast, a marine stratus deck continues to hold over the northern Gulf and immediate Prince William Sound coast. These clouds should lift and become less expansive in coverage through the day and into Thursday as influence from the aforementioned ridge wanes. By Thursday, the pattern will have shifted enough to have cleared out the majority of very low clouds, but with southeast flow aloft, more general cloudiness is expected over Southcentral for the end of the week. The stable stratus marine layer clouds over the northern Gulf of Alaska to be replaced by stratiform clouds from the incoming trough, although enough instability may remain in place along the Alaska Range for another round of showers and isolated thunderstorms for Thursday afternoon. Southerly gap winds will likely return for Thursday afternoon and evening as well. All-in-all little change is expected for places like Kodiak, with persistent easterly winds, clouds, and periods of light rain. -TM/CL && .SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS (Days 1 through 3)... A North Pacific low will remain south of the area and reach the Gulf by week`s end. Weak surface lows moving through the Aleutians will bring continued southerly to southeasterly winds, fog and scattered rain showers today there. A ridge will build in the Central Aleutians tomorrow reaching the Eastern Aleutians Friday morning with another low south of Adak as early as Friday evening. Scattered rain showers and a mostly cloudy sky is expected for most of Southwest Alaska and the Alaska Peninsula today. The North Pacific low working its way through the Pacific could cause a weak wave of instability through the Alaska Range and Kuskokwim Delta tomorrow afternoon. A few breaks in cloud cover could occur tomorrow afternoon and evening resulting in a return of isolated thunderstorms in this area. Though the thunderstorm chance is greater (10%) for locations such as Sleetmute and Aniak compared to Bethel (3%), some uncertainty exists for the amount of cloud cover that will remain tomorrow afternoon and evening. Friday afternoon and evening, a grater chance of scattered thunderstorms, less cloud cover, increased CAPE and greater instability, is likely in the Western Alaska Range and and isolated thunderstorm in the Kuskokwim Delta. Elsewhere in the Southwest, scattered rain showers are expected. -DJ .LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)... Mainland Alaska remains under the influence of an upper level ridge extending from Northwestern Canada through the forecast period. Warmer than normal temperatures are expected over the Southern half of the Mainland. On the surface, thermal troughs support widespread convection. Arctic areas continue under a broad low, with the Northwestern Bering low looping back into Siberia for Tuesday. A very broad low stretches from Kamchatka across the Aleutians and Bering into the Gulf of Alaska and Eastern North Pacific. Model guidance continues in good confidence through most of the period, but outliers develop into the new week. A series of troughs slip along the Aleutians, spreading showers over the Alaska Peninsula Southwest Alaska and Kodiak Island through Tuesday. In the far West, a better organized front moves into the Central Aleutians and Bering through Tuesday. A trough from the Eastern North Pacific low brings showers to coastal locations from the Canadian Border to Prince William Sound for the weekend. -Kutz && .AVIATION... PANC...VRF conditions will prevail with westerly winds by late morning becoming more southerly for late afternoon through evening. Winds should remain 10 kts or less through the TAF period; however, gusts to 20 kt are possible later this afternoon and evening. Any gusts will diminish overnight when day-time heating is lost. && $$