textproduct: Fairbanks

SYNOPSIS

After a very active thunderstorm day in the Central and Eastern Interior yesterday, we do expect drying from Fairbanks North Star Borough east. A narrow front is set up from Kaktovik to Aniak with isolated to scattered thunderstorms expected there today. The thunderstorm footprint will remain similar tomorrow but there will be a chance along the AlCan Border with subtle southeast flow. On Friday, southeast flow extends into the Interior with isolated storms expected across much of the Interior with the most robust being in SW AK as a low in the Bering provides a front from the southwest. These thunderstorms will be wet and provide locally heavy rain, especially in the Brooks Range and Western Interior. The North Slope will remain mostly dry other than a few showers with a cooling trend as an arctic low brings a cold front from the northwest. Otherwise temperatures remain largely in the 70s across most of Northern Alaska with 50s and 60s along the coasts.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Showers and thunderstorms exiting to the west today, but remain mostly from the Dalton Highway westward. A cool and mostly sunny day from Fairbanks north and east.

- Showers and scattered thunderstorms expected from Arctic Village to Anaktuvuk Pass southward along the Dalton and towards Tanana.

- Tomorrow and Friday are a bit warmer, in the low to mid 70s, isolated thunderstorms expected north/west of Fairbanks, as well as near the AlCan Border tomorrow, spreading to the Central Interior on Friday.

- This weekend comes with isolated to scattered storms ahead of a cold front on Saturday, then the potential for heavy rain from the Alaska Range to the Yukon River on Sunday.

West Coast and Western Interior... - Red Flag Warning for the Kobuk and lower Koyukuk Valleys for hot, dry and windy conditions through midnight tonight. Tomorrow will be near critical levels once again.

- Scattered thunderstorms today through Friday afternoon from Aniak to Ruby with isolated storms over the Nulato hills.

- High temps in the Interior will be in the mid 70s to low 80s with 50s and 60s along the coast through Friday.

- Thunderstorm chances lessen and move east this weekend with temperatures expected to drop into the 60s by Sunday. Heavy rain possible in the Western AK Range and

North Slope and Brooks Range.. - Dry and sunny today with warm temperatures. Scattered thunderstorms likely over the Central and Eastern Brooks Range with an isolated storm near Kaktovik today and tomorrow.

- An arctic front arrives Thursday afternoon and moves west to east. A few showers are possible, but the most noticeable change will be temps dropping into the 30s and 40s with areas of stratus/fog in the plains and along the coast by Friday.

FORECAST ANALYSIS AND DISCUSSION

An occluded low in the Gulf of Alaska which brought a front to the Interior yesterday remains stationary in the Central Gulf. The associated front is stationed from Kaktovik to SW AK with isolated to scattered thunderstorms developing along and to the west of it and mostly sunny skies to the east. Most of the thunderstorm activity will be in the Central/Eastern Brooks Range as well as the Western Interior. Thunderstorms in these locations will continue tomorrow afternoon as the front remains stationary. A high is stationed over the Lower Yukon Valley providing sunny skies to most of the West Coast and NW Arctic Borough today and tomorrow. This high will degrade this weekend as it gets squeezed between a low in the Bering, Gulf and Arctic. North of this, the aforementioned Arctic low is near the North Pole and dropping south tomorrow. This will usher in a cold front Thursday afternoon into Friday with colder weather behind it by Friday and into this weekend on the North Slope. There may be a couple of showers associated with the front, but the weather north of the Brooks Range should remain mostly dry and chilly through the weekend.

On the other side, the low in the Gulf of Alaska will bring weak southeasterly flow towards the AlCan Border tomorrow, allowing for a few thunderstorms to develop. These become a bit more numerous on Friday and spread towards the Central Interior. The main forcing mechanism is a fairly weak, broken down front from the southeast. Saturday looks active again for thunderstorms, especially north and east of Fairbanks. Then there is a potential for a stronger shortwave trough to move over the Central/Eastern Interior Saturday into Sunday with the possibility of heavy rain. This will be spoken about in the extended discussion. The overall trend for much of Northern Alaska will be cooler temperatures with increased chances for precipitation this weekend.

FIRE WEATHER

Primary threat for critical fire weather conditions remains in the far northwest interior, with a focus on the Upper Kobuk valley south toward the lower Koyukuk. Here anticipate afternoon high temperatures of upper 70s/lower 80s and RH near 20 to 25 percent to continue through Thursday. The biggest question Wednesday morning was forecasted wind speeds; as of 1230 AKDT a Red Flag Warning was issued over concern with sustained winds of 15mph and gusts to 20 to 25 mph into late Wednesday night. Thursday a dry arctic front slides east across the north slope, bringing slightly cooler temperatures to the Northwest Interior; however, one impact could be northerly downslope winds off the western Brooks Range Thursday evening, bringing continued low RH Friday.

For the Central Interior a moist frontal passage brought substantial rainfall from Tuesday into Wednesday morning, with some areas across the AK range reporting near 1 inch of rainfall (The Farewell RAWS reported 1.44 inches of rain in 24 hours). Currently, this front is stalled from the White mountains southwest toward the Alaska Peninsula, serving as the catalyst for extensive cloud cover, cooler temperatures, and continued thunderstorms across the western Central Interior. Thursday into Friday thunderstorms likely move in from the Alcan Border as a weak shortwave moves over, bringing more thunderstorms to the Fortymile Country and perhaps further north into the Yukon Flats. By Saturday broad upper level troughing will move off the Bering into the southwest, serving as the source for widespread daily precip, cooler temperatures, and increased RH for the Central and Eastern Interior.

The Northwest Interior looks to remain drier later into the weekend with little relief in terms of widespread wetting rains. Stay tuned.

HYDROLOGY

AK Range drainage creeks/rivers are running high with some near bankfull but there is no concern for flooding at this time. The main concern is water over gravel bars, but high water levels should recede gradually though the week. Otherwise, we are monitoring the potential for heavy rain this weekend in the Alaska Range and Interior, south of the Yukon. There are fairly high probabilities for >1" of rain (25 to 50%) in the AK Range, Tanana Valley and south of the Yukon River from Saturday into Sunday. While there is uncertainty with the placement of the heaviest rain, highest certainty is in the Alaska Range with lower certainty towards Fairbanks and points west. We will be monitoring this closely through the week.

EXTENDED FORECAST DAYS 4-7

As a large but relatively weak low moves into the eastern Bering Sea Saturday, it will push a front into Western Alaska. As this occurs, a second low in the eastern Gulf of Alaska will draw robust Pacific moisture into the Alaska Range and across the Interior. At least half an inch to an inch of rain will be possible across most of the southern Interior valleys and in the Lower Yukon/YK Delta from Saturday morning through Monday morning, with higher amounts possible in the higher terrain. In the northern Interior, there will still be potential for at least half an inch of rain, although amounts are expected to generally tend lower than farther south. The highest certainty will be in the Alaska Range and will gradually fall moving northward. Depending on the movement of a shortwave trough moving northward along the eastern border on Sunday, there could be ample thunderstorm / lightning potential as well, with at least isolated chances otherwise. By Monday evening, rain chances will spread across the eastern North Slope. Moving into mid-next week, while generally cooler weather is favored across the area with perhaps another Arctic trough brushing the Arctic coast, models have minimal agreement on the positioning of features.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Red Flag Warning for AKZ919-928. PK...Small Craft Advisory for PKZ811-857. Small Craft Advisory for PKZ812. Small Craft Advisory for PKZ858.