textproduct: Fairbanks

SYNOPSIS

A low pressure over the Chukchi Sea with ridging across southeast Alaska are the primary weather features this weekend until a low pressure lifts north toward the AK Peninsula on Monday. A weak cool front shifted east across most of the interior last night and a stronger cold front is shifting east along the West Coast this afternoon. Most of interior northern Alaska is between these fronts within a weak cold air advection regime allowing for gusty west- southwest winds in the 25 to 35 mph range with temperatures in the mid 30s to mid 40s. Temperatures have dropped into the 20s behind the West Coast cold front that when combined with winds are resulting in wind chills as cold as the single digits above zero, which is similar to conditions observed across the North Slope. In terms of precipitation, there is a diurnal uptick in shower activity particularly along the West Coast cold front and Brooks Range as can be seen on satellite. While a few light showers linger into Sunday, a general drying trend is expected through midday Monday ahead of the next storm system.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Southwest winds gusting up to 45 mph through the Alaska Range passes and higher elevations of the interior including Eagle Pass diminish tonight with light winds by Sunday evening. - Scattered rain/snow showers mainly at higher elevations diminish this evening with mostly dry weather for Sunday through midday Monday. Rain chances increase north of Fairbanks on Monday.

- High daytime temperatures remain in the 50s through the weekend with lows in the 30s. Monday appears to be the warmest day with cooler temperatures Tuesday and Wednesday behind a cold front.

West Coast and Western Interior... - A cold front focuses mainly rain chances through Sunday morning, but snow is possible above ~1500 ft and immediately behind the cold front, but accumulations are not expected.

- Breezy southwest winds gusting up to 40 mph near and south of the Yukon River will continue until around sunset with light winds by Sunday morning.

- Temperatures will range from highs in the 30s along the coast to the 40s farther inland. Lows will range from around 20 across the Seward Pen and Kotzebue Sound to the 30s across the interior.

North Slope and Brooks Range... - Light snow showers spread eastward along the Brooks Range through Sunday. More significant snowfall is expected to begin for the central Brooks Range Monday evening that spreads across eastern and central portions of the North Slope on Tuesday.

- A frontal boundary tracks east to the central North Slope tonight with colder temperatures west of the front and warmer temperatures east of the front. Temperatures approach 30 east of the front with temperatures around 20 and gusty southwest winds west of the front.

FORECAST ANALYSIS AND DISCUSSION

A nearly vertically stacked low pressure system (525 dm aloft and 999 mb at the surface) over the Chukchi Sea is the primary feature controlling our generally low-impact weather through Monday. Ridging across southeast Alaska is similarly persistent through the forecast period with 576 dm ridging aloft and 1026 mb ridging at the surface. A weak frontal boundary shifted east across the interior this morning and relatively steep lapse rates are resulting in gusty winds across the southeast half of interior Alaska this afternoon. Southwesterly gusts above 30 mph have occurred in many places across the interior this afternoon, but peak gusts should fall just short of advisory criteria before diminishing quickly this evening as surface heating diminishes. The primary exceptions to that will be higher elevations ridges such as Eagle Pass along the Steese Highway and the Alaska Range Passes that will diminish more gradually by Sunday afternoon. A more potent frontal boundary is pushing east onto the West Coast this afternoon with a westerly wind shift. This front is focusing a band of precipitation with pre-frontal light rain/drizzle and post-frontal light snow and noticeably cooler temperatures/wind chills dipping into the teens and locally even single digits. This frontal boundary struggles to make eastward progress and mainly lifts northeast across the western Brooks Range/Arctic Slope tonight into Sunday before stalling on Monday.

Somewhat more impactful weather associated with a ~990 mb low pressure over the Gulf of Alaska on Monday afternoon that lifts north across the state through Wednesday morning. This system results in a strengthening band of frontogenic precipitation along the remnant frontal boundary Monday evening through Tuesday before tracking over the Beaufort Sea by Wednesday. Most precipitation falls as rain across the interior, but light low-elevation snow accumulation is possible behind the frontal boundary across the Western Interior. More impactful snowfall is expected across the Brooks Range Monday night through Tuesday night - especially above about 2000 ft elevation, including Atigun Pass - when 4-8 inches of snowfall is possible. In addition to focusing precipitation, this frontal boundary separates a late season winter air mass with 850 mb temps approaching -15C from an early spring air mass with 850 temps approaching +10C. Depending on the exact low track, there is also potential for strong winds through the Alaska Range passes but the duration would be relatively short at around 12 hours.

Persistent upper-level ridging continues over eastern Alaska as an upper-level low sits over the northwest Arctic Coast. This will allow for the continuation of southerly/southwesterly flow aloft over much of the state. At the surface, a broad area of low pressure moves up along the West Coast before overspreading the Arctic Coast this afternoon through Sunday. Temperatures will slowly start to cool across much of the West Coast and North Slope as the low sitting in the northwest Arctic Coast pulls in a colder airmass east from Siberia. Most of the Interior will stay around seasonable norms while the North Slope and West Coast can expect to see temperatures below average through mid-week. Meanwhile, widespread precipitation is expected through much of the western Interior and north through the Brooks Range and Arctic Coast through the weekend. There is a chance for some localized freezing rain/drizzle to develop near Deadhorse/Nuiqsut this afternoon, but measurable ice accumulations are unlikely. The highest snowfall accumulations are expected throughout the Brooks Range and at higher elevations above 1500 feet.

EXTENDED FORECAST DAYS 4-7

Wednesday through Saturday. Ensemble guidance is in good agreement about an upper level trough positioned across northern Alaska on Wednesday with a surface low over the Beaufort Sea. As this low tracks from the interior to the Beaufort late Tuesday night it drives a seasonably strong cold front eastward across the eastern Arctic Slope. The combination of freshly fallen snow, rapidly cooling temperatures, and a potential barrier jet developing supports potential for blowing snow concerns between Deadhorse and Kaktovik on Wednesday. This same frontal boundary shifts east toward the Canadian border Wednesday into Thursday bringing colder temperatures and rain/snow chances to the eastern interior. A shortwave pivoting around the base of the trough appears to stall the fronts eastward progress and should focus additional precipitation chances along the front (southeastern interior) later next week. There is a non-zero threat of lightning, but the best chances appear to stay in Canada where instability is greater. The lingering upper level trough interacts with another low pressure system lifting into the Gulf of Alaska Friday/Saturday, but this system doesn't appear to track as far north resulting in moderating temperatures and a drying trend.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ804. Brisk Wind Advisory for PKZ811. Brisk Wind Advisory for PKZ812-857. Brisk Wind Advisory for PKZ856. Brisk Wind Advisory for PKZ858. Brisk Wind Advisory for PKZ859. Brisk Wind Advisory for PKZ860-861.