textproduct: Fairbanks

SYNOPSIS

Showery and stormy conditions expected across the Interior Sunday with southwestward storm motion. Showery and stormy conditions become more concentrated in the Western Interior Monday. Late Monday strong easterly winds develop across the Northern Interior, particularly across the Dalton Highway Summits which weaken Tuesday morning. Strong southerly winds once again return to the Alaska Range Passes Tuesday which, along with drier conditions, elevates the fire weather concerns for Delta Junction.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Isolated thunderstorms and scattered showers are expected across most of the Interior with the highest chances of thunderstorms (~30%) expected Sunday afternoon from the Yukon Flats south to the White Mountains and Fortymile Country. Isolated to scattered showers and isolated thunderstorms will continue through this week becoming more isolated after Tuesday.

- Gusty east/northeast winds return to the Interior late Monday through Tuesday with gusts possibly reaching 20 to 30 mph across most areas. Stronger gusts up to 55 mph are possible along the Dalton Highway Summits Monday night.

- Southerly gap winds return to the Alaska Range passes Tuesday morning and continue into Wednesday. Gusts up to 55 mph are possible. Elevated fire weather conditions for Delta Junction are expected Tuesday afternoon.

West Coast and Western Interior... - Isolated to scattered showers and isolated afternoon thunderstorms continue across the Western Interior throughout the week. The heaviest showers are expected Monday. The highest chances for thunderstorms (15%) are expected Sunday through Tuesday.

- Patchy dense fog is expected Monday morning across the West Coast. West/northwest facing coasts are most likely to see morning fog.

- Gusty northeast winds return to the West Coast late Monday. The strongest winds are expected from St. Lawrence Island through the Bering Strait to the Lisburne Peninsula with gusts of 30 to 40 mph possible.

North Slope and Brooks Range... - Slightly cooler than normal temperatures are expected with highs in the upper 20s to mid 30s and lows in the upper teens to mid 20s along the North Slope. Highs will be in the low 40s across the northern Brooks Range with slightly warmer temperatures expected in the southern Brooks Range around the upper 50s to low 60s.

- Easterly winds increase across the Arctic Coast Monday night with gusts up to 30 mph possible east of Point Barrow and up to 35 mph near Point Lay. Winds then weaken Tuesday night.

- Low clouds and patchy fog continue across the North Slope through midweek.

FORECAST ANALYSIS AND DISCUSSION

For Sunday through Wednesday. At the start of the forecast period Sunday, the pattern is in a transition stage between 2 main low pressure systems. The first is in the Gulf of Alaska and is pulling what remains of the low over southwestern Alaska to the south and east. As this system moves southeast a weak ridge over the North Slope is able to strengthen slightly and expand into the Northern Interior. As this system pulls away from the region convective potential increases across the Interior causing Sunday to be more showery. Thunderstorm potential also increases with isolated thunderstorms possible across the Interior, but most likely from the Yukon Flats to the White Mountains and Fortymile Country. Northeast to southwest storm motion could pull some of the longer lasting showers/storms from the higher terrain northeast of the Tanana Valley into that same valley.

A weak ridge in the North Pacific separates the departing low from the incoming one. This next low rides along the Aleutians Sunday night and settles near Bristol Bay by Monday evening. It's approach tightens the pressure gradient across the state and sends forth a south to north moving front Monday afternoon. The greatest convective potential Monday moves into the Western Interior. Ahead of the front strong easterly winds are expected across the northern portions of the Interior. The strongest gusts from this front are expected overnight Monday along the Dalton Highway Summits. Behind the front southerly winds increase through the Alaska Range yet again.

This second low does not linger in Bristol Bay as long as previous systems have and begins moving towards the Gulf of Alaska Wednesday. This transitions our pattern once more into more of a broad troughing pattern for the end of the week.

FIRE WEATHER

Expect isolated but widespread thunderstorms across the Interior Sunday afternoon as clear skies and generally weak upper-level troughing will allow convective showers to develop. Showers and thunderstorms are most likely to trigger off of higher terrain, however mid-level flow will direct them generally southwestward over lower lying areas. Chances for thunderstorms lessen through the start of this week, with a greater focus on the Western Interior on Monday.

The weather pattern of the past week will continue as a new low approaches Alaska from the southwest along the Aleutians. As it gets closer Monday afternoon, easterly winds across Interior and Western regions will strengthen. Areas of higher terrain in the Interior will see gusts up to 55 mph from Monday night through Tuesday afternoon. The combination of warmer temperatures and dry northeast winds will drop minimum RHs in the Yukon Flats into the low 20s on Monday. Southerly gap winds through the Alaska Range will strengthen Tuesday morning as the surface low squeezes into Bristol Bay and upper-level flow turns perpendicular to the range. The strong winds combined with lower relative humidities from downslope winds into the Tanana Valley will result in enhanced fire weather conditions around Delta Junction on Tuesday.

HYDROLOGY

Yukon River: As of 7pm Saturday the Riverwatch team reported that the breakup front was located approximately 12 miles downriver of Mountain Village. The breakup front is slowly moving into the remaining in-place ice. Flooding is ongoing for the communities of Pilot Station, St. Mary's, and Mountain Village. Water is receding for Holy Cross, Russian Mission, and Marshall. Flood Warnings remain in effect for Mountain Village, St. Mary's, Pilot Station, Marshall, Russian Mission, and Holy Cross.

Observer reports indicate that ice is moving slowly but smoothly down Kwig Pass near Emmonak Additional reports indicate that ice is moving at Nunam Iqua and Kotlik as well. For the Yukon Delta, water levels are expected to be the highest since 1989. Flooding is likely at Emmonak and Alakanuk, and possible at Kotlik. A Flood Watch remains in effect for the Yukon Delta.

Innoko: Reports from Shageluk indicate that high water levels are receding.

Additional Information: Visit www.weather.gov/aprfc for the latest hydro information.

Please report observed flooding to local emergency services, law enforcement, or to the National Weather Service when you can do so safely.

EXTENDED FORECAST DAYS 4-7

For late Wednesday through next Sunday. At the start of the extended forecast period late Wednesday, the pattern is primarily defined by a low in the Gulf of Alaska sitting at the bottom of broad troughing over most of the state. A ridge in Canada and high pressure in Siberia flank the trough and keep the pattern relatively stable until the weekend. This upcoming weekend confidence in the pattern falls as these higher pressure features shift somewhat unpredictably.

For the first half of the extended forecast period expected weather remains familiar with seasonable temperatures across the West Coast and Interior, slightly cooler across the North Slope, and afternoon showers with isolated thunderstorms across the Interior. Over the weekend confidence decreases which may allow for a more drastic pattern change. The most drastic potential change is the strengthening of the Canadian ridge to cover more of Alaska which would support a warmer and drier pattern. It is however a bit more likely that the region remains subject to the trough, although its shape will almost certainly have shifted considerably.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ849. Wind Advisory for AKZ837. Flood Watch for AKZ825. High Wind Watch for AKZ832. PK...Brisk Wind Advisory for PKZ814-815. Small Craft Advisory for PKZ816-817-851-854.