Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
172 FXAK69 PAFG 251447 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 647 AM AKDT Tue Jun 25 2024 .SYNOPSIS... A very active pattern will bring the warmest temperatures so far this Summer to much of the Interior on Wednesday and Thursday while a highly unusual Bering Sea low pressure system brings near Gale force winds to the Yukon Delta coast on Wednesday. The heat wave will even extend to the North Slope on Wednesday and Thursday, bringing near record high temperatures to that area. Thunderstorms will continue to be active this week, with relatively dry thunderstorms possible east of Chena Hot Springs on Wednesday evening. Thursday and Friday also look to be very active thunderstorm days across Northern Alaska. && .DISCUSSION... Analysis and Model Discussion...Aloft at 500 mb, a tight closed low is retrograding northward off the Arctic Coast as a strong ridge builds over the central and eastern Interior. A vertically stacked low has now entered the western Bering Sea near Attu. This feature will track along the western Aleutians to near Adak then turn northward, reaching St. Paul Island Wednesday afternoon. As the low continues to drift north Thursday and Friday, a sharp convergence zone will form along the boundary between the ridge over the Interior and the low in the Bering Sea. This will serve as a focus areas for scattered thunderstorms on Thursday and Friday afternoons and evening. Thunderstorms will likely even drift north of the Brooks Range, especially west of Umiat. With the center of the high moving over the eastern Arctic Coast by Thursday afternoon, expect very warm temperatures all the way up to the Arctic Coast Wed/Thu/Fri. Another impactful feature will be a shortwave rotating to the southwest around the center of the upper level ridge centered over the Yukon Flats on Wednesday afternoon. With dry air at the surface, elevated instability, and lifted condensation levels as high as 8500 feet, this will likely produce widely scattered dry thunderstorms over the Fortymile Uplands and upper Tanana Valley Wednesday afternoon. Models initialized quite well when compared to obervations at the surface and aloft. We will use a blend of models for the forecast today and make a few notable changes in the Lightning Activity Level forecast including increasing thunderstorm coverage to scattered on Thursday across a large area from the Alcan border to Fairbanks to Huslia to the Western Brooks Range. We also increased rainfall amounts on Thursday in the area that we expect thunderstorms. We`ll also increase thunderstorm coverage to widely scattered today across the White Mountains, and increase easterly winds across the northern Interior on Thursday. Central and Eastern Interior...Hot and dry conditions with afternoon and evening thunderstorms continue today with highs reaching the low to mid 80s. Wednesday will be the hottest day of the week with highs in the upper 80s to near 90. Thursday will be slightly cooler, but expect an increase in thunderstorm activity especially south and west of the Yukon Flats. West Coast and Western Interior...Warm and mostly dry conditions persist. With a strong low pressure system approaching in the Bering Sea Wednesday and Thursday, expect southeast winds 15 to 25 mph from Nome south late tonight and Wednesday. The front will bring little in the way of precipitation with only light rain expected along the Yukon Delta. Thursday looks to be a very big thunderstorm day from east of Kotzebue to Huslia and southeast. North Slope and Brooks Range...Warm temperatures will extend north all the way to the Arctic Coast on Wednesday and Thursday as the ridge moves north over the Arctic Coast. Isolated thunderstorms are expected even up to the Arctic Coast on Wednesday. Thunderstorm activity will increase in the Brooks Range on Thursday. East winds around 15 mph are expected tonight along the coast. Coastal Hazard Potential Days 3 and 4...The aforementioned low pressure system in the Bering Sea will bring elevated surf 1 to 2 feet above the normal high tide line along the Yukon Delta coast as well as south facing shorelines south of the Bering Strait including Nome. Water will be elevated Wed-Fri with multiple water level peaks as storm surge values remain fairly constant and tides go in and out. && .FIRE WEATHER... A strong ridge aloft continues to build over Interior Alaska with numerous shortwaves moving through the ridge providing instability for thunderstorm activity. The most concerning of these shortwaves will move around the high center from the north on Wednesday afternoon and evening over the southeast Interior. With lifted condensation levels as high as 8500 feet along with northeast steering flow and surface RHs as low as 20%, this is an ideal setup for dry thunderstorms. Dry thunderstorms will be possible east of Chena Hot Springs, but most likely in the upper Tanana Valley from Dot Lake east to the Alcan Border. Today, expect near Red Flag conditions across the interior of the Seward Peninsula and northeast to Buckland. Highs will mostly be in the 80s in the Interior and in the mid to upper 70s out west away from the immediate coastline with min RHs dropping into the 25-35% range. Winds will likely only reach 15 mph over the interior Seward Peninsula this afternoon. Thunderstorms will be isolated across the Interior and the Eastern Brooks Range and widely scattered from McGrath to Livengood and east across the White Mountains and Fortymile uplands. Wednesday, in addition to the possibility of dry thunderstorms described above, will be the hottest and driest day of the week with highs expected to reach the upper 80s to near 90 across most of the Interior. Min RHs will be 20-25% east of Tanana and slightly higher to the west. Outside of the widely scattered dry thunderstorms east of Chena Hot Springs, expect isolated thunderstorms across the rest of the Interior. On Thursday, the ridge will shift north to the Arctic Coast as a strong low in the Bering Sea pushes further north. This will tighten the gradient and cause east winds 10 to 20 mph across the northern Interior. It will still be plenty hot and dry, so if the winds pan out, could see Red Flag conditions for hot/dry/windy in the northern Interior on Thursday. Thursday may also be the largest lightning day of the year so far as scattered thunderstorms are expected to form along a boundary between the Bering low and the Interior ridge extending from the Western Brooks Range to Fairbanks to the Alcan Border. Isolated thunderstorms are expected even up to the Arctic Coast. Friday will likely be another big thunderstorm day, with activity at this time looking the most active over the Yukon Flats. && .HYDROLOGY... Glacial fed rivers including the Tanana are beginning to rise as warming temperatures lead to increased high elevation snowmelt. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...Dense Smoke Advisory for AKZ839-840-844. PK...Small Craft Advisory for PKZ801. Small Craft Advisory for PKZ802-816. Small Craft Advisory for PKZ850. Small Craft Advisory for PKZ851. && $$ CHRIEST