National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Anchorage, AK

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-- Discussion containing changed information from previous version are highlighted. --821FXAK68 PAFC 240055AFDAFCSouthcentral and Southwest Alaska Forecast DiscussionNational Weather Service Anchorage AK455 PM AKDT Thu May 23 2024.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:Tonight through Sunday)...
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Low stratus around Cook Inlet mixed out this morning, allowing forsome daytime heating to kick off cumulus/rain shower development,especially over the southern Susitna Valley and the western KenaiPeninsula. Isolated to scattered rain showers will continuethrough the evening until the sun angle becomes too low to supportsufficient surface heating. Further east, a weakening front overYukon and extending into Interior Alaska is producing steadierrainfall north and east of the Wrangell Mountains, for locationsincluding Mentasta Lake, Nabesna, and Chisana. These locationshave seen around half an inch of rain since this morning. Thisrain will taper off through the evening hours and overnighttonight as the front exits to the north and east.The weak ridge contributing to relatively drier, sunnierconditions for most of Southcentral will shift quickly eastwardtonight, as a low tracking into southern Alaska from the BeringSea moves in behind. This will bring cloudier conditions andanother round of precipitation to Southcentral into the weekend.Rain chances return for much of the area on Friday, though theheaviest, most persistent precipitation will occur along the northGulf coast. The front will attempt to move up Cook Inlet onFriday, making rain a near certainty for much of the western KenaiPeninsula, though the front weakens through the day as it pushesnorth. As a result, Anchorage and the Mat-Su Valleys will likelysee much lighter, spottier precipitation.As a triple point low develops along the front in the Gulf onFriday, a weak coastal ridge builds. This will drive southerlywinds through the typical gaps, including Turnagain Arm, the KnikRiver Valley, and the Copper River Valley. The low shifts into thecentral Gulf Friday night, allowing the coastal ridge to relax andgaps winds to diminish. Cooler air aloft accompanies the low,which will drop snow levels to around 2500 ft through much of thecoastal mountains. The main impact will be potential for lightsnow through Thompson Pass on Friday night.The low`s front lingers along the coast, keeping these areas wetthrough Saturday, though the low weakens for Sunday, allowing forconditions to dry out. Further inland, a shift to northerly flowas the low tracks into the Gulf will lead to some drying andbreaks in the clouds heading into the weekend. The one exceptionlooks to be an upper-level easterly wave which tracks across theCopper Basin on Saturday, bringing further rainfall. The waveshears apart as it tracks west, meaning much of the precipitationdoes not look to make it past the Talkeetna/Chugach Mountains,though a chance for precipitation remains.- Quesada
-- End Changed Discussion --&&.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THEALEUTIANS (Days 1 through 3)...
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A Bering low will continue to move eastward reaching Bristol Baytomorrow and the Gulf of Alaska Saturday. Frequent rain showerswill persist in the Southwest and Alaska Peninsula throughtomorrow evening with scattered showers afterward into earlySaturday morning. Wet snow could mix in with the rain showers inMekoryuk-Toksook Bay-Kipnuk area his evening. The heaviestprecipitation through tomorrow afternoon is expected in SouthwestAlaska. The area of heaviest precipitation will shift southward tothe Alaska Peninsula afterward through Saturday morning.Widespread fog could develop this evening into tomorrow morning.Westerly wind gusts along the Aleutians will range from 35 to 45mph through tomorrow evening before becoming more northerly tonorthwesterly for Saturday. Cooler temperatures in the Aleutiansare also expected as a result of the northerly winds this weekend.Clearing skies are expected with the switch to northerly tonorthwesterly winds Saturday evening and Sunday in interiorSouthwest Alaska.A Kamchatka low will bring a front through the western Aleutiansreaching Adak as early as Sunday morning. Ahead of this,southwesterly winds will signal a warmer and less cooler periodfor Sunday in the Central Aleutians.-DJ
-- End Changed Discussion --&&.LONG TERM FORECAST (Days 4 through 7) Monday through Thursday...
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The Alaska Weather Map is under a very broad area of upper levellows, with three separated centers. The first is a weakeningcenter in the Southern Gulf of Alaska/Northeast Pacific that isdrifting Eastward. The second is a somewhat energetic centermeandering around the Bering Strait. The weakest of the three is acenter in the Western Aleutians and Bering. The main focus isalong the Southern portions of the state with additional energythat arrives via the North Pacific through the forecast period.The Northern low center contributes to weather producers overWestern Alaska. Model confidence is good with a deterministicblend changing over to a one-half ensemble blend by midweek. Theend result is an elongated areas of low pressure extending acrossthe Bering into the Gulf for Thursday.Overall looking at a good mix of sunny breaks and wetter weather.Periods of rain spread across Southcentral Alaska to just Northof the Alaska Range through Thursday. A well developed frontbrings locally heavy rain over the Aleutians and Bering, spreadinginto Southwest Alaska late Wednesday. A second well developed lowand front bring another round of locally heavy rain into theWestern Aleutians and Bering late Wednesday into Thursday.- Kutz
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PANC...VFR conditions are expected through Friday morning. Aslight increase of west to southwest winds from Cook Inlet withthe sea breeze could occur through this evening, until about 06Z.Otherwise, light south to southwest winds will prevail.
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