textproduct: Fairbanks

SYNOPSIS

Showery and stormy conditions are expected to continue this afternoon through next week as broad troughing persists over the state. Isolated to scattered thunderstorms are likely across the Northern Interior, with the highest chances for lightning just south of the Brooks Range. Areas of fog and low stratus will continue to impact portions of the North Slope and Kotzebue Sound through the week as onshore flow continues. Strong southerly gap winds through the Alaska Range Passes return Tuesday afternoon through Wednesday morning, with near critical fire weather conditions possible near Delta Junction. Temperatures are expected to remain near seasonable norms through the week with overnight lows dipping down to near freezing at times across the Interior Valleys.

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 across the Yukon Flats this afternoon. Isolated to scattered thunderstorms will continue through next week with a trend towards drier thunderstorms possible.

- 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 50 mph are possible along the Dalton Highway Summits.

- Southerly gap winds return to the Alaska Range passes Tuesday morning and continue into Wednesday. Gusts up to 60 mph are possible. Near critical fire weather conditions for Delta Junction are possible Tuesday afternoon.

West Coast and Western Interior... - Showery conditions continue across the West Coast and Western Interior today through Monday. Isolated afternoon thunderstorms are possible in the Western Interior throughout the upcoming week, with the highest chances (~15%) expected this afternoon through Tuesday.

- Areas of dense fog have formed along the Chukchi Sea Coast, especially near Kotzebue due to onshore flow. Dense fog remains a threat through Monday morning due to west/northwest winds.

- 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 40 mph west of Wainwright.

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

FORECAST ANALYSIS AND DISCUSSION

Sunday through Tuesday night. At the start of the forecast period, broad troughing sits over Northern Alaska with weaker ridging over the North Slope. A low pressure system in the Gulf of Alaska strengthens this morning/afternoon and begins to move southeast towards the Alaska Panhandle. As this system deepens, it will work to drag the remnant broad troughing over the state down south as well, allowing for the ridging over the North Slope to briefly strengthen as troughing moves out of the region. Isolated to scattered showers are possible across the Central and Eastern Interior this afternoon, with the highest accumulations expected in the Upper Tanana Valley. With these showers, isolated to scattered thunderstorms are likely to develop just south of the Brooks Range, with the highest probabilities for thunder (~30%) expected in the Yukon Flats. Although recent thunderstorm activity has been a mix of wet and dry thunderstorms, higher relative humidity values throughout the Interior should work to limit afternoon virga and increase chances for saturation to occur and rain to reach the ground within the Interior valleys.

By Monday, a new low pressure system moves into the Bering Sea from the North Pacific. This new low pressure system will be the main driver of weather going into midweek. Isolated to scattered showers and thunderstorms persist across the Interior Monday afternoon, but the highest chances for lightning will shift towards the Western Interior and parts of the Middle Tanana Valley. Relative humidity values will start to slowly decrease across Interior Valleys Monday afternoon as well, increasing virga chances once again. As the Bering Sea low approaches Bristol Bay early Tuesday morning, the pressure gradient over the state will tighten and allow for strong southerly gap winds to return to the Alaska Range Passes Tuesday afternoon through Wednesday morning. With winds expected to increase near Delta Junction as well, near critical fire weather conditions are possible Tuesday afternoon, but will largely be dependent on how dry minimum relative humidity values will be. We will continue to monitor conditions as Tuesday approaches.

More consistent showers and thunderstorms are expected going forward as the low in the Bering Sea advects multiple shortwaves into Northern Alaska through Thursday. These showers will continue to follow a northeast to southwest orientation with a trend towards drier isolated thunderstorms throughout the week.

FIRE WEATHER

General troughing persists over Northern Alaska today and into early next week, supporting chances for scattered showers and isolated thunderstorms. The highest chances for rain are over the White Mountains, Forty Mile Country, and the Norton Sound Coast Sunday morning into the evening. Scattered showers are likely in the afternoons and evenings across most of the Interior through the week as general troughing lingers. Afternoon thunderstorms are likely throughout the Northern Interior, mainly south of the Brooks Range, and across portions of the Norton Sound Coast/Northern YK Delta throughout the week.

By Monday night, winds are expected to strengthen along the Dalton Highway Summits, near Ambler and surrounding areas, and the Seward Peninsula. Gusts could reach up to 30 mph in these areas, weakening by Tuesday morning. High temperatures are expected to remain in the mid to upper 60s throughout the week for the Interior and West Coast. Upper level ridging over the North Slope will keep high temperatures in the mid to upper 20s with warmer temperatures expected near the southern slopes of the Brooks Range. Relative humidity values are likely to dip into the 20 to 30 percent range by Tuesday afternoon over the Tanana Valley, returning to the mid 30 percent range by Thursday.

HYDROLOGY

Yukon River: The ice jam downriver from Holy Cross released Thursday evening. Water levels in Holy Cross fell several feet. Downriver at Russian Mission water levels started rising and minor flooding was observed during an overflight. Rising water levels and minor flooding were reported at Marshall on Friday. The Yukon River breakup front was likely along the stretch from Pilot Station to Mountain Village as of Friday afternoon. Reports were received of minor flooding at Marshall and moving ice at Mountain Village. As of Saturday morning there have been reports of ice moving near Emmonak, Nunam Iqua, and Kotlik.

The surge of water from the Holy Cross ice jam release will increase ice jam and flooding potential for Marshall, Pilot Station, St. Mary's, and Mountain Village. Flood Warnings remain in effect for those same communities as well as Russian Mission and Holy Cross. Flood Watches remain in effect for the rest of the Yukon River downstream of Russian Mission.

Innoko: Reports from Shageluk indicate that the Innoko River has begun to backup due to high water in the area. Currently not expecting significant impacts.

Chena: The Chena River continues to respond to warmer temperatures with higher elevation snowmelt leading to rivers running higher than normal, but likely remaining below action stage.

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

Wednesday through Saturday. High confidence continues midweek amongst long range forecast models, which show broad upper level troughing over Northern Alaska as the main 500 mb low tracks east through the Gulf of Alaska. This pattern will keep temperatures fairly stable to finish out the week, with highs keeping mostly in the 50s/60s outside of some 20s/30s/40s in the Brooks Range, along the North Slope, and across portions of the West Coast. Ample moisture and a series of shortwaves working over our region will continue to support daily isolated to scattered showers and thunderstorms with a focus in the Interior and Alaska Range where the bulk of activity is expected. Winds on Wednesday will remain elevated through Alaska Range Passes and Delta Junction in addition to the NW Arctic Coast to the Bering Strait, where gusts up to around 30 to 50 mph are expected that will subside Thursday onwards. The exception to the subsiding winds will be along the NW Arctic Coast, where gusts up to 30 mph look to continue into the weekend. Precipitation amounts through the extended forecast are expected to remain light overall, heaviest of which will be in the Eastern Alaska Range and Upper Tanana Valley.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ825. PK...None.