Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
277 FXAK69 PAFG 202306 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 306 PM AKDT Thu Jun 20 2024 .SYNOPSIS... Upper-level ridging extending across northern Alaska will continue to bring warm temperatures and thunderstorm chances across portions of the Interior. High temperatures will hover in the 70s across the Interior through Sunday, with cooler temperatures along the coast. Isolated to widely scattered thunderstorms shift from the Eastern Interior this afternoon to along the Alaska Range and into the Western and Central Interior for Friday through Sunday. A Dense Smoke Advisory remains in effect for visibility one mile or less in smoke along the Richardson Highway between Salcha and Birch Lake until northeasterly winds develop on Friday. For the North Slope, high pressure will promote intermittent fog and stratus along the coast. && .DISCUSSION... Upper Level Analysis... A ridge extends northwest from Western Canada, across Interior Alaska, into the Chukchi Sea, promoting fairly warm and dry conditions across much of northern Alaska this afternoon. A potent shortwave trough lifting into Southcentral Alaska is providing divergence aloft which is supporting widely scattered thunderstorms over the Eastern Interior. Further north, a digging trough is slowly traversing southward across the Brooks Range, bringing drier air aloft over the NE Interior. Surface Analysis... A thermal trough extends west from Yukon along and north of the Alaska Range, displaced slightly southward from the upper-level ridge. Surface high pressure is present in the Chukchi Sea with a ridge along the Arctic coast. Between these features, generally light northeasterly winds have developed across the forecast area. Some locations in the higher terrain east of Fort Yukon have observed 15 mph winds, while gap winds through the Brooks Range have gusted as high as 35 mph. A brief, weak southeasterly wind brought smoke from the McDonald Fire into Fairbanks this morning, leading to decreased air quality. A drier air mass moving in off the Arctic Ocean has aided the midday sun in clearing out stratus and fog on the North Slope. Warm conditions with temperatures in the 70s with dew points in the 40s have allowed for the development of ongoing scattered to widespread rain showers and widely scattered thunderstorms across much of the Interior. Central and Eastern Interior... Temperatures will peak broadly in the mid to upper 70s again this afternoon/evening across the Central and Eastern Interior. Temperatures in the Yukon Flats will be somewhat cooler than yesterday as a trough dipping slowly across the Brooks Range brings cooler air southward. Widely scattered thunderstorms continue this evening primarily over the high terrain of the White Mountains, Fortymile Country, the northern foothills of the Alaska Range, as well as portions of the Central Interior. More isolated thunderstorm activity is ongoing along the south side of the Brooks Range. There is potential for thunderstorms to drift slowly off the high terrain this evening into the Tanana Valley. Increased mid-level moisture brought by a series of troughs lifting into the SE Interior will lead to the potential of heavy rain in localized areas from showers and thunderstorms. Rainfall totals of half an inch up to one inch per hour will be possible in localized areas. This could contribute to rapid rises on creeks in steep terrain along the Alaska Range and in the Goodpaster, Upper Charlie, and Upper Fortymile River Basins. High pressure along the Arctic coast has brought a shift to northeasterly winds in the Yukon Flats today, and northeasterly flow will spread across the rest of the Central and Eastern Interior tonight into Friday. Wind gusts up to 25 mph remain possible this evening and Friday in the higher terrain east of Fort Yukon. Dense smoke in the Harding Lake area will begin to clear out along the Richardson Highway as northeast winds develop Fri afternoon and continue through Saturday. The upper-level trough digs south of the Brooks Range into the Eastern Interior on Friday, pinching off the ridge and relegating the best thunderstorm potential to a corridor along and just north of the Alaska Range, with some isolated storms remaining possible in the Central Interior. The pattern remains similar into the weekend, though convective potential looks to be even lower as the thermal trough dips south of the Alaska Range and drier air moves in. West Coast and Western Interior... With the upper-level ridge now extending across the NW Interior, high temperatures in the 70s are expected across much of the Western Interior, including the Kobuk and Noatak Valleys, as well as interior valleys of the Seward Peninsula. Warm temperatures continue through at least Sunday. Warmer temperatures and increased instability will support isolated to widely scattered thunderstorms each day across the Western Interior as the upper level ridge is pinched off to the east and centers over Western Alaska. At the surface, a ridge builds into the northern Bering Sea this weekend, promoting stronger westerly flow along the coast. This will increase the potential for stratus/fog on the West Coast for Saturday and Sunday and contribute to more moderate temperatures. North Slope and Brooks Range... High pressure along the Arctic coast will keep northwesterly winds blowing onshore, keeping stratus and fog a persistent feature along the coast each night. During the day, the greatest solar heating during midday will help lift fog and clear the skies. Isolated thunderstorms are likely to develop each day along the south side of the Brooks Range. High pressure along the coast will weaken this weekend, causing onshore winds to diminish as an upper-level low moves in to take its place by Sunday. A front may begin to move in off the Arctic on Sunday, bringing increased chances of rain and snow to the North Slope. Extended Forecast Days 4-7... Generally expecting continued warmer and drier than average conditions for the first half of next week, with ridging over southern Alaska, leading to continued fire weather concerns and thunderstorm potential across Interior Alaska. There is increased model agreement with an upper-level low lingering somewhere along the Arctic coast next week, bringing wetter conditions to the Brooks Range, with higher precipitation amounts focused in the eastern half. Uncertainty remains with the placement of this feature, however, and some model runs, such as the 12z EC, show limited thunderstorm potential as the upper low advects cooler, more stable air in from the west and the warmest, most unstable air is pushed into Yukon and the Northwest Territories, especially by midweek. A low, potentially gale force, also looks to track northward through the Bering Sea. For Wednesday and Thursday, its front lifts along the West Coast, bringing southerly to southeasterly winds and elevated chances of precipitation for the West Coast and Western Interior. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Temperatures will peak broadly in the 70s across the lower elevations of the Interior through the weekend, with RHs generally remaining above 25 percent through Friday. Widely scattered thunderstorms continue this evening primarily over the high terrain of the White Mountains, Fortymile Country, the northern foothills of the Alaska Range, as well as portions of the Central Interior from Tanana northward. More isolated thunderstorm activity is ongoing along the south side of the Brooks Range, and there is potential for thunderstorms to drift slowly off the high terrain this evening into the Tanana Valley as well. Increased mid-level moisture brought by a series of troughs lifting into the SE Interior will lead to the potential of heavy rain from showers and thunderstorms, leading to increased chances for wetting rains in the area today and again on Friday. A shortwave trough dipping south of the Brooks Range will combine with high pressure along the Arctic coast to bring northeasterly winds with drier air spreading southward. Gusty winds will be possible in and around the Yukon Flats, especially over the higher terrain east of Chalkyitsik, where sustained winds could exceed 15 mph during this afternoon/evening and Friday. Some areas could approach red flag conditions, though there is increased confidence in winds remaining below 15 mph at lower elevations where temperatures may reach 75 degrees, and higher elevations are likely to be cooler and more moist. As a result, hot, dry, and windy conditions are not currently expected to coincide. For Friday, widely scattered thunderstorms will be limited to a corridor along and just north of the Alaska Range, with some isolated storms remaining possible in the Western and Central Interior. As the upper-level trough continues to push south of the Brooks Range, the thermal trough retreats south of the Alaska Range for the weekend and drier air spreads across the Interior. The Eastern Interior could see RHs drop as low as 20 percent. As a whole, this weekend will see lower thunderstorm potential focused primarily in the Western and Central Interior which will sit under a weak ridge of high pressure. && .HYDROLOGY... Showers and thunderstorms in the SE Interior may produce heavy rainfall rates of half an inch, up to one inch per hour in localized areas. This could contribute to rapid rises on creeks in steep terrain along the Alaska Range and in the Goodpaster, Upper Charlie, and Upper Fortymile River Basins this evening and again on Friday. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...Dense Smoke Advisory for AKZ839-840. PK...Small Craft Advisory for PKZ801-812-858. && $$ Quesada