Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
962 FXAK69 PAFG 292224 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 224 PM AKDT Sun Sep 29 2024 .SYNOPSIS... Ridging builds across interior Alaska through Monday before shifting north across the Beaufort Sea through the middle of next week. This pattern brings mostly clear skies and large diurnal temperature ranges (warm days/chilly nights) through Tuesday. Highs near or above 50F are expected at lower elevations - especially the Tanana Valley - through tomorrow and perhaps Tuesday too. Sub-freezing lows are expected in most locations away from more coastal portions of the YK Delta and Seward Peninsula. DISCUSSION... Analysis and Forecast Discussion... The 20Z surface analysis indicated a 986mb low over the Canadian Archipelago, a deepening 1003mb low approaching Cold Bay, and 1018+mb ridging in-between across most of Northern Alaska. A similar pattern is found aloft and is expected to amplify through tomorrow as a deep low pressure develops over the Gulf of Alaska. By Monday evening, a sub-960mb vertically stacked low to our south and a 1028+mb surface ridge over the Beaufort Sea results in a considerable pressure gradient across the state. Most of this gradient is south of the Alaska Range, but seasonably strong northeast winds are expected at Dalton and Elliott Highway summits along with breezy conditions elsewhere. The primary near-term weather maker is the ridge building across northern AK resulting in mostly sunny and warm days then mostly clear and chilly nights. Central and Eastern Interior...Much like Saturday, patchy morning fog lifted to a few stratus decks that are barely moving beneath the building ridge. Clear blue skies prevail across most of the eastern interior and North Slope with temps warming into the 40s in most spots. Despite decreasing day length and solar angle, mostly clear skies should allow for large diurnal temperature ranges (warm days and cool nights) near if not greater than 20F. This generally results in high temps within a few degrees of 50F (above 50F in sunny valley spots such as Fairbanks) and low temps mainly in the 20s through Monday. As the Gulf of Alaska low moves ashore on Tuesday, expect high level clouds to increase and shave a few degrees off high temps. If clouds fail to occur then Tuesday`s temps may be very similar to Monday. Winds will be mostly light, though northeast winds are likely to gust to around 30-40 mph for Dalton and Elliott Highway summits Monday afternoon. West Coast and Western Interior...Humid southeast flow across the YK Delta is resulting in some sprinkles/drizzle, but model soundings show a shortwave tonight and tomorrow night that should bring brief rounds of light rainfall. Expect mostly sunny skies in the Interior north of Galena through Monday and perhaps Tuesday too. Generally light southeast winds back northeasterly Monday night before veering southeasterly and increasing Wednesday night as a seasonably strong storm moves across the Bering Sea. Highs will be in the 40s with lows in the 30s. A few spots may warm to near or perhaps a few degrees above 50F Sunday and/or Monday. North Slope and Brooks Range...The CIRA Snow Cloud Discriminator RGB satellite pass at 1926Z showed two ribbons of new snow cover on Point Utqiagvik. Overnight satellite imagery showed cloud streets streaming across the area and model soundings were marginally supportive of sea-effect snowfall so that`s probably what happened. Model soundings imply a similar pattern in the easterly flow south of the ridge on Tuesday into Wednesday that may bring some light snow showers to locations between Utqiagvik and Deadhorse. However, light winds and ridging overhead imply a chilly night is in store, but increasing southeast flow may keep mixing and temperatures elevated and perhaps allowing for a rapid warm up into the 40s across the western North Slope on Monday. Coastal Hazard Potential Days 3 and 4...None. Extended Forecast For Days 4 Through 7...The extended forecast period begins Wednesday night starts with dry and calm conditions across the mainland and a weakening surface trough approaching the Seward Peninsula. Farther to the southwest, a seasonably strong low pressure crosses the Kamchatka Peninsula and deepens rapidly across the far western Bering Sea. Model spread in terms of storm intensity and storm track remains large as this system crosses the Bering Sea, but an occluding sub-970mb low near or perhaps just northwest of St. Matthew Island (roughly 61N, 176W) around 10 PM Thursday appears most likely at this time. Subjective averaging of the stronger ensemble members implies a minimum pressure between 950-960 mb, but individual ensemble members range from sub-940mb to above 980 mb. The strongest winds and largest waves are expected south of the low track implying greatest impacts across the Southern Bering Sea, but the low track and intensity should be monitored closely. Vessels planning to transit the Bering Sea next Thursday/Friday should monitor forecast updates and consider altering plans. If a stronger and farther north storm occurs then coastal flooding will also be possible. The Interior and North Slope remains dry with temps averaging above-normal quiet weather through the extended period. HYDROLOGY...No concerns. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...None. PK...Small Craft Advisory for PKZ815-861. && $$