textproduct: Fairbanks

SYNOPSIS

Relatively quiet weather persists across Alaska this week as high pressure and ridging remain overhead. The few exceptions to the benign conditions will be across portions of the West Coast and North Slope where periodic chances exist for light snow and windy conditions. Well above normal temperatures for this time of year continue with highs ranging from the teens to mid 30s. Coldest spots are in Interior valleys and low lying areas while higher elevations above the inversion and along the west coast have the best chance of getting above freezing. Added a Special Weather Statement for the West Coast to account for the possibility of a wintry mix or rain within scattered upslope snow showers. Periods of blowing snow and gusty winds are likely over the Arctic coast today then again Thursday into Friday as a few systems ride over the ridge. Watching later this weekend into early next week for a brief cool down back below zero for much of the region.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Well above normal temperatures continue with highs in the teens and 20s. Coldest spots remain in the valleys, warmer at higher elevations.

- Fog and low stratus to continue in interior valleys

West Coast and Western Interior...

- Mild with widespread high temperatures in the 20s to low 30s continue for the next several days.

- Mainly dry, but a few snow showers and potentially some freezing drizzle along south-facing slopes Tuesday and Wednesday, especially around Nome and southern facing slopes

- More widespread precipitation moves into West and NW Coast Thursday into Friday. Rain may mix in at times with temperatures rising above freezing.

North Slope and Brooks Range...

- Increasing easterly winds along the Arctic coast with gusts to 30 mph at times. Visibility may decrease at times due to blowing snow.

- Warming trend through the week with highs ranging from the teens to lower 30s

- More widespread snow expected Friday for the North Slope

FORECAST ANALYSIS AND DISCUSSION

Satellite imagery this morning shows a strong ridge over the state, diverting the storm track around the Bering and up over the high arctic. Despite southerly flow across the interior, surface high pressure has kept a strong surface inversion in place, keeping valleys significantly colder than surrounding areas and low fog and stratus trapped at the surface. Fog and low stratus continues for these areas over the next several days as high pressure remains with light winds and little change in airmass to mix out that lower layer. Subtle differences in topography/elevation of as little as 100ft agl can mean the difference between 10-20 degrees and sunny skies or stuck under the low clouds.

High pressure becomes centered over the West tomorrow into the end of the week switching low level flow around to the north across the interior, decreasing downsloping flow off the Alaska range and helping 850mb temperatures cool slightly. This should weaken the inversion, potentially helping areas stuck under low clouds to clear out. Stronger low level southerly flow today keeps moisture and higher clouds streaming northward from the Pacific, but as this shuts off tomorrow, expect a clearing trend for mid and upper level clouds as well.

A weak frontal boundary along the north slope increases NE winds along the Arctic coast today to 10-20 mph with gusts as high as 30-35 mph. Brief reductions in visibility due to blowing snow are possible at times.

While the main storm track has shifted well to the west around the ridge, the west coast remains in a southerly flow pattern with weak disturbances riding up the ridge. A weak shortwave along a front extending east from a low in the Bering may increase snow shower activity along southern facing slopes on the Seward Peninsula and in the western Brooks range today. With strong warm air advection, rain/freezing rain may mix in at times along the Seward Peninsula. Most precipitation should be confined to upslope favored areas, with locations further away from higher mountains likely to remain warmer and drier.

EXTENDED FORECAST DAYS 4-7

High pressure remains in place over the Interior mid to late week; however a pattern change is on the horizon. By the end of the week, longer range guidance has been consistent in showing a strong storm system developing and moving along the top of the ridge in the Chukchi sea and high arctic. This system will have numerous impacts to sensible surface weather and the overall weather pattern. While confidence is lower on the finer details, confidence is increasing that a strong system pushes eastward near the arctic coast Thursday into Friday bringing a period of strong winds, low visibility, and widespread snow to the NW Coast and North Slope...with deteriorating conditions possibly as far south as the Seward Peninsula depending on how the storm system evolves. The rest of the interior remains relatively quiet in the extended with temperatures slowly cooling down this weekend.

This system impacts the anomalously strong ridge in place over the week, creating a weakness along the top of the ridge, allowing a deep trough over NW Canada to push westward into the Interior of Alaska this weekend. High confidence exists in this pattern change by the weekend with a much colder airmass advecting in with 850mb temps back into the -20s once again. The ridge aloft becomes centered over the Bering and Siberia as troughing takes hold of the state. A few day period of temperatures in the 0 to -30 range are likely, especially for the Eastern Interior where the core of the colder air will be. Mild, above average temperatures hold on a few days long along the west coast, before the arctic airmass pushes west. Expect northerly gap winds to significantly increase across much of the state this weekend as strong high pressure sets up over the high arctic behind the late week system.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Brisk Wind Advisory for PKZ812. Brisk Wind Advisory for PKZ813. Brisk Wind Advisory for PKZ814-860. Brisk Wind Advisory for PKZ815. Brisk Wind Advisory for PKZ816-854. Brisk Wind Advisory for PKZ817. Brisk Wind Advisory for PKZ851. Brisk Wind Advisory for PKZ858. Brisk Wind Advisory for PKZ859. Brisk Wind Advisory for PKZ861.