textproduct: Fairbanks

KEY MESSAGES

Central and Eastern Interior

- Light rain and snow chances will continue Monday through Wednesday. Snow accumulations are most likely at higher elevations of the Northern Interior.

- Gusty winds will persist in Isabel Pass through Monday afternoon with gusts up to 35 mph possible.

- A front is expected to bring another 1-3 inches of snow to lower elevations across the Northern Interior and 4-8 inches of snow to higher elevations in the Alaska Range Tuesday through Wednesday.

West Coast and Western Interior...

- Strong east to northeast winds will continue along the Bering Strait coast and St Lawrence Island through Tuesday evening with gusts up to 35 mph.

- Colder conditions spread across the Western Interior, with highs falling into the upper 20s to 30s by Wednesday.

- A strong low moves into the Western Bering Sea Thursday. It attempts to move towards the West Coast Friday through the weekend, but there is still a great deal of uncertainty in impacts. Most likely there will be periods of strong gusty winds, rain/snow, and some elevated water levels along portions of the West Coast.

North Slope and Brooks Range...

- Accumulating snow will be the primary impact through midweek, especially east of the Dalton Highway, with accumulations of 4-8 inches in the Eastern Brooks Range and 1-3 inches possible across the Eastern North Slope. Accumulations of 2 to 5 inches possible near Atigun Pass.

- Gusty east/northeast winds will continue to affect the Western Brooks Range and Lisburne Peninsula Monday through Tuesday evening. Gusts in the 25 to 35 mph range expected near the coast with gusts up to 45 mph possible at higher elevations.

- Temperatures will continue to fall Monday through Tuesday, with coastal highs dropping to the low 20s to low 30s by Tuesday.

SYNOPSIS

Relatively mild weather expected early in the week ahead of a large storm system in the Western Bering Sea later in the week. Rain and snow chances are expected Monday through Wednesday across the eastern portions of Northern Alaska with clearer skies and higher pressure moving in from the West. A large storm system develops in the Western Bering Sea Wednesday into Thursday which is expected to cause impacts for Western Alaska through the weekend.

SHORT TERM /THROUGH THURSDAY/

At the start of the forecast period, Monday, the pattern is dominated by broad troughing across the state with 2 notable surface lows moving through the state. The first was a large low pressure system that moved through the southern Bering Sea and is moving into the Gulf of Alaska as of Monday morning. The second is a low that was previously in the Gulf of Alaska and is being displaced to the north as the first low moves east. This second low continues north through the Central and Eastern Interior towards the Brooks Range Monday into Tuesday. The low's northward movement brings a brief period of gusty southerly winds to the Alaska Range Passes Monday and increased snow chances to much of the Northern Interior Monday through early Wednesday.

In the wake of the first low atmospheric ridging pushes north into the Bering Sea and starts to displace the broad troughing pattern Tuesday. Higher pressure extends over much of Western Alaska Tuesday and stalls the second low's movement. As the higher pressure continues to build and push east, the remnants of that second low connect with a upper level low near the top of our trough over the Arctic Ocean and reverses course, becoming a southeast moving front that will shift east towards the Canadian Border. This will enable even move snowfall accumulations across the Northeastern Interior and Eastern Brooks Range through Wednesday as the last of that moisture is pushed east into Canada.

High pressure dominates most of Northern Alaska Wednesday as the ridge attempts to settle over the state. A warming and drying trend is expected under the ridge. More notably, Wednesday sees the development of the next major system for Western Alaska. A strong low pressure system in the Sea of Okhotsk begins to move east over the Kamchatka Peninsula and into the Western Bering Sea. This system splits across the Kamchatka Peninsula and becomes disorganized Wednesday. The remnant of a tropical system moves south of the Aleutians and furthers the development of the eastern portion of the split low on the Bering Sea side. This strengthens it enough to ingest the rest of the split low and much of the energy from the tropical remnant forming a very large storm system around 945-960 millibars in strength. A front from this developing storm system is expected to reach the West Coast late Thursday, but there remains considerable uncertainty due to the messy way that these features try to phase with each other. Additionally uncertainty remains for how this large system will interact with the ridge that builds over mainland Alaska. More in the Long Term Section.

LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/

At the start of the long term forecast, late Thursday, a strong 945-960 millibar low spins in the Western Bering Sea and attempts to extend a front towards the West Coast. High pressure, around 1020-1030 millibars, sits under an atmospheric ridge over Mainland Alaska. There is considerable uncertainty regarding the interactions between the low and ridge. The low will attempt to push east towards the Eastern Bering Sea, but will have to push the ridge out of the way to do so. There are 2 main extremes of model solutions amongst the spread of ensembles with most other points existing as less extreme versions of these 2.

The first would be that the ridge holds firm and keeps the low in the Western Bering. In this solution gusty southeast winds are expected across the West Coast with higher pressure holding firm over the Interior. Fronts from the low will attempt to push over the West Coast and bring periods of increased winds and rain. There could be some high surf coastal concerns as these fronts pass, especially for areas vulnerable to south or southeasterly flow. The low and ridge would weaken each other through the end of the week and significantly limit impacts.

The second would be that the low overwhelms the ridge and moves much farther east into the Bering Sea. This solution would carry greater impacts for the West Coast with stronger southerly winds, periods of rain and snow pushing farther inland, and the possibility of some areas seeing minor coastal flooding concerns. Gusty southerly winds through the Alaska Range Passes would be expected as well as additional rain and snow for the Central Interior.

Current analysis of the model ensembles suggest that something closer to the first solution is more likely than the second, at around 30% to 20%. The remaining 50% probability is tied up in solutions that range between those two extremes, but currently still favors the stronger ridge and slower eastward progression of the low. We will continue to monitor this storm as it evolves.

Coastal Hazard Potential... There are no coastal concerns before Thursday. Thursday through the weekend, a strong storm system in the Western Bering Sea will attempt to push east towards the Central and Eastern Bering Sea, but will be limited by an area of higher pressure. Given uncertainty in the position of the storm system, there is uncertainty in the extent of coastal impacts. A front from this storm system is expected to approach the West Coast Thursday which will increase water levels along portions of the West Coast, especially areas vulnerable to southerly or southeasterly flow. Current forecasts suggest that impacts Thursday into Friday lean closer to high surf and beach erosion than coastal flooding, but some minor coastal flooding impacts are possible. As the low pushes east it weakens considerably and makes impacts more difficult to predict for the weekend. We will continue to monitor this storm system and update as the forecast becomes more certain.

HYDROLOGY

There are no concerns at this time.

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. MARINE...Small Craft Advisory from 10 PM this evening to 6 AM AKDT Tuesday for PKZ801. Small Craft Advisory from 1 AM to 6 AM AKDT Tuesday for PKZ802. Small Craft Advisory from 7 AM this morning to 6 AM AKDT Tuesday for PKZ806. Small Craft Advisory until 6 AM AKDT Tuesday for PKZ807-854. Small Craft Advisory until 1 AM AKDT Tuesday for PKZ810-856. Small Craft Advisory until 7 PM AKDT this evening for PKZ811. Small Craft Advisory from 1 PM this afternoon to 4 AM AKDT Tuesday for PKZ816. Small Craft Advisory until 6 AM AKDT Tuesday for PKZ817. Small Craft Advisory from 4 PM this afternoon to 6 AM AKDT Tuesday for PKZ850-853. Small Craft Advisory from 7 PM to 10 PM AKDT this evening for PKZ851.