textproduct: Fairbanks

SYNOPSIS

Continued breezy and chilly along the North Slope the next few days. However sunshine will help knock off a bit of the chill and begin to lift temps a bit north of the Brooks Range. South of the range, Spring-like conditions continue with river breakup progressing downstream and temps regularly warming into the 50's and 60's. There will be a general mix of clouds and sun through the weekend with chances for scattered showers at times as storm systems to our south and west allow for some moisture transport into the region.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Easterly winds of 15 to 25 mph will remain possible over higher terrain of the Central and Northeastern Interior into tonight before weakening.

- Cooler temperatures will be possible thru Friday with increasing cloud cover and occasional showers possible. Warmer conditions will return this weekend with highs back in the mid or upper 60s with southerly flow over the Alaska Range and clearer skies possible.

West Coast and Western Interior...

- Warming temperatures are expected the next few days, with highs will rising into the mid to upper 50s or lows 60s across the Western Interior and the Interior Seward Peninsula.

- It will be generally dry for the next few days with only scattered showers expected, with better chances for rain Friday and Saturday.

North Slope and Brooks Range...

- Gusty winds will continue across the Central and Eastern North Slope through tonight. Winds will be strongest along the Eastern Arctic Coast where winds could gust to over 35 mph. Areas of fog in the area which will reduce visibility in spots.

- High temperatures on the North Slope will range from the mid 20s to the lower 30s through the weekend, potentially reaching around 40 on the north slopes of the Brooks Range.

FORECAST ANALYSIS AND DISCUSSION

While we will have lot's of moving pieces over the next few days around Alaska, impacts to sensible weather across central and northern parts of the state should be minimal. The big picture continues to show dominant ridging over the Arctic Ocean with upper troughing centered over the Bering and into southwest Alaska. In general easterly flow will persist north of the Brooks Range where winter's chill remains evident while a series of shortwaves push north over the Alaska Range and into interior and southwest Alaska.

For the North Slope there is an additional wrinkle in the flow pattern whereas a weak shortwave trough over the northern Yukon of Canada will pivot westwards around the periphery of the Arctic Ridge through Saturday before emerging into the western Beaufort. Near the surface this continues to be reflected with localized pressure gradients resulting in continued brisk east winds, especially along the eastern Arctic coastline. These winds will continue to diminish overnight tonight. Meanwhile plenty of sunshine should reach the North Slope allowing for some gradual warming.

South of the Brooks Range is where most precip chances will reside. This evening we are watching weak energy and modest moisture advection tracking into the Upper Tanana Valley and over portions of the Alaska Range as a weakening surface low shifts into the northern Gulf. Despite a fair amount of mid and high clouds over the area, enough breaks in the cloud cover will help to generally destabilize the boundary layer and convective showers with some thunder should develop. More of the same could occur across this region Friday while shower chances increase across the YK Delta and much of the Western Interior. This is due to a more prominent surface cyclone that will track along the central Aleutian Chain before spinning north into the Southern Bering by Sunday.

While enough residual moisture will remain in place for parts of the central and eastern Interior to produce a few convective showers over the weekend, the best moisture push will be across the west closer to the main surface low. So expect to see occasional showers and potentially some limited thunder across the west over the weekend. Further east southerly flow across the Alaska Range will result in some chinooking into the rest of the Interior. This will likely limit some of the precipitation potential Saturday into Sunday, while increasing gap winds and warmer temps will be common. Therefore renewed fire weather concerns may creep back into the picture over the coming days in these areas.

FIRE WEATHER

Strong May insolation will support afternoon destabilization and scattered convective shower development with potential for thunder through this evening in the Upper Tanana Valley and White Mountains. Any thunderstorm activity is expected to initiate in the White Mountains and remain unorganized and scattered. Activity is expected to stay over the region, though showers may move slightly to the south into the Upper Tanana Valley Thursday evening. The convection is expected to produce rain showers, minimizing the chance for dry lightning activity. Gusty and erratic winds are expected around where any convective shower activity develops. Any convective showers are expected to dissipate in the late evening as the atmosphere begins to stabilize after peak heating. There may be afternoon convective showers once again Friday afternoon in the region, but thunder is not expected.

Current anomalously warm and humid conditions and a very weak frontal passage will support weak localized convection in the southern Seward Peninsula and higher elevations in the central Seward Peninsula on Friday afternoon/evening. Gusty and erratic winds are expected around any convective shower activity that develops. Chances for convection will diminish Friday night as the front passes and there is no longer any convergence to initiate storms.

While gusty winds will be possible around thunderstorms in the Upper Tanana Valley Thursday evening and on the Seward Peninsula Friday, elsewhere winds will calm remain rather light Friday. Wind speeds should pick up again at high elevations in The Interior as well as in the Alaska Range passes on Saturday afternoon. An upper and surface level low will move over the Alaska peninsula on Saturday, tightening the north-south gradient across the state. Southerly flow aloft will support mountain wave activity in the Alaska Range, and with it the potential for southerly gusts through the Alaska Range passes. Gusts between 40-50 mph are possible in the Alaska Range passes, Dalton Highway Summits, and higher elevations around Tanana.

As southerly flow returns and daytime temperatures increase through the Interior on Saturday, as well as downslope flow causing drying, relative humidities may dip below 20% on Saturday and Sunday.

HYDROLOGY

Koyukuk River: The ice jam on the Koyukuk River downstream of Hughes flushed out Tuesday night, allowing water levels to fall back to near normal with no flooding observed in the community. The river was nearly ice free for at least 20 miles downstream of Hughes as well as upstream of the village.

Yukon River: An ice jam at the Yukon River breakup front, about 20 miles downstream of Ruby at the mouth of the Yuki River, has caused water levels to rise upstream in Ruby and the Big Eddy area. In the Big Eddy area, several structures were observed surrounded by floodwaters. In Ruby, water levels rose by several additional feet and were just below River Road. Downstream of the jam, water levels in Galena leveled off and slowly fell through the day. Little movement was observed in the intact ice sheets downstream to Bishop Rock. A Flood Watch has been issued for Galena for the potential for ice jam flooding from an ice jam downstream, including near Bishop Rock.

High water levels on the Porcupine River continues moving downstream along the Yukon River. Heavy runs of bank-to-bank ice were seen moving past Rampart all day Wednesday. A Flood Watch for potential snowmelt flooding in the Fort Yukon area and a Flood Warning for high water levels near Stevens Village remain in effect.

Chena River: The Chena River has begun to respond to warmer temperatures with increased snowmelt leading to rivers running higher and gages getting closer to or reaching 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

Approaching the extended forecast period, the pattern remains dominated by a strong upper level high over the Arctic Ocean. A strong upper level low in the Bering Sea is prevented from moving east towards the Gulf by a ridge extending over the Gulf and into the Yukon. All the while a weak upper level low that split off from a low far to the east in Canada slowly moves west across the state. Unfortunately this somewhat chaotic collection of upper level features complicates how the pattern will evolve early next week. Generally speaking most solutions favor higher pressure to the north and east and lower pressure to the south and west. The majority of the variance in the overall pattern lies south of the region, but there is enough variance to keep the forecast uncertain. Should the upper level high over the Arctic Ocean continue to remain steadfast in its position, then the weather over the majority of the region will remain similar to this past week with generally mild conditions and occasional bouts of showers. Should this high be pushed aside or weaken, the influence of the low in the Bering Sea will be felt further inland increasing east to northeasterly winds across the Interior and causing more widespread showers as well as possible thunderstorms.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ829-833. PK...Brisk Wind Advisory for PKZ813. Gale Warning for PKZ814. Gale Warning for PKZ815. Brisk Wind Advisory for PKZ860. Brisk Wind Advisory for PKZ861.