Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
999 FXAK68 PAFC 181326 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 526 AM AKDT Tue Jun 18 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Thursday night)... The upper level ridge that has been over the Gulf of Alaska and Southcentral is starting to edge eastward as a front is pushing northward toward the southwest Gulf. This is the start of a pattern shift with the unstable airmass that has been over Southcentral being pushed farther northward with the Copper River Basin being left as the only area with much convective potential this afternoon and evening. The Marine stratus that pushed up Cook Inlet Sunday afternoon into Monday has largely dissipated as the ridge moved eastward. there is still some patchy fog around, but this should dissipate as the day warms. Where the stratus has not dissipated in over the Gulf and Prince William Sound. The subsidence from the ridge and persistent southwest flow onto the coast will make it difficult for this stratus to clear out until Wednesday of even Thursday. Therefore expecting from Seward to Valdez to Cordova to remain under this marine stratus through tonight. It is possible for there to be a break this afternoon or evening, but it should return shortly with this pattern. By Thursday, the pattern will have shifted enough to have cleared out the low clouds, but with southeast flow aloft, more general cloudiness is expected over Southcentral for the end of the week. && .SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA/ALEUTIANS (Days 1 through 3)... Satellite shows the main low pressure rotating south of Adak will continue to bring waves of energy to the Southwest through tomorrow afternoon. South to southeasterly wind flow will continue to bring rain showers from the Central Aleutians to inland areas of the Southwest into this evening as a secondary low pressure migrating south of Sand Point moves into the Bering Sea later today. Radar shows the area of heaviest rain showers over the Alaska Peninsula/Eastern Aleutians where this secondary low continues to enhance precipitation through late this morning. Though the chance of thunderstorm and lightning activity experienced the past few days is below 5% region wide, an isolated late afternoon to mid- evening thunderstorm is possible from Sleetmute to Aniak today. Gap winds in the Alaska Peninsula ranging from 15 to 25 knots are expected this afternoon into the evening hours. The aforementioned main low will move over the Central Aleutians late tomorrow morning resulting in a brief period of light rainfall for the Central Aleutians. Southerly to southeasterly flow persists during this time though for the Eastern Aleutians, the Alaska Peninsula and most of the Southwest keeping the chance of widespread scattered rain showers and cooler temperatures over the area. Widespread isolated rain showers are expected Thursday region wide. -DJ && .LONG TERM FORECAST (Days 4 through 7: Friday through Monday)... Model agreement is pretty good until around Sunday and the GFS becomes the outlier. For Friday, mainland Alaska will be separated by low pressure over the Gulf and high pressure to the north. Any easterly waves coupled with instability over the mainland could lead to chances for convection. A progressive ridge over the Bering Sea will be moving towards Southwest Alaska where low stratus and fog will be possible. Farther west is a North Pacific low with a front transecting the Western Aleutians. Precipitation will accompany primarily small craft winds are expected. Gusts could approach gales, but are not expected at this time. By Saturday, the ridge will have moved across mainland Alaska and overall flow appears weaker, but the slight chances for showers will linger, especially over higher terrain and thunderstorms appear less likely for the weekend. Sunnier and drier weather is possible for the upcoming weekend though. Over the Aleutians, the low will move along the Aleutian Chain with the front reaching the Pribilof and the Eastern Aleutians. Model agreement falls apart later Sunday through Monday. GFS is highlighting a vigorous low into the Bering Sea, though the representative forecast is leaning towards a more mild weather with weak lows and more progressive flow that is similar to what has been occurring more recently. && .AVIATION... PANC...Some ares of stratus are still lurking around Cook Inlet early this morning. There might be a short period of MVFR ceilings in this stratus this morning, but it looks increasing likely that it should clear out by late morning. Therefore VFR conditions are expected form late this morning through tomorrow. && $$