textproduct: Fairbanks

SYNOPSIS

Pleasant spring-like conditions will persist for most areas south of the Brooks range for several more days while winter's chill hangs on north of the range. Meanwhile the active storm track looks to remain south of our area as storm systems traverse from the southern Bering Sea into the northern Gulf. These systems will manage to push moisture onto the West Coast as well as portions of the Interior at times resulting in occasional scattered showers. Otherwise mainly dry conditions will continue to be the norm.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Easterly winds up of 15 to 25 mph will be possible over higher terrain of the Central and Northeastern Interior and could last into Thursday night before weakening.

- Much warmer temperatures are expected the next few days, with highs today rising into mid to upper 60s in the Middle and Upper Tanana Valleys today, with upper 60s to low 70s possible in the far eastern Interior. - It will be mainly dry for the next couple of days; however, some scattered showers will be possible near the Alaska Range slopes and across the Upper Tanana Valley this evening and Thursday.

West Coast and Western Interior...

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

- Generally dry for the next few days with only scattered showers expected, more likely Friday and Saturday.

North Slope and Brooks Range...

- Gusty winds will continue across the North Slope through tonight. Winds will be strongest along the Eastern Arctic Coast where winds could peak upwards of 40 mph and are producing blowing snow. There are also areas of fog in the area which will reduce visibility in spots.

- Cold conditions will persist throughout the North Slope for a couple of more days before temps begin to warm a bit over the weekend.

FORECAST ANALYSIS AND DISCUSSION

Currently a broad and persistent high pressure ridge centered over the Arctic Ocean continues to act as a block across northern Alaska, forcing multiple low pressure systems to track eastward beneath it. One such low is currently stretched out from the southern Bering into the western Gulf. The resulting pressure gradient between this low and the Arctic high continues to produce gusty winds across the higher terrain of the northern Interior. At the same time, the Arctic Ridge continues to maintain a colder and drier air mass over the North Slope while another area of lower pressure along the northern Canadian Arctic coast has helped enhance local pressure gradients near the Brooks Range and the eastern Arctic coast where blowing snow will continue to reduce visibilities from Deadhorse to Point Thomson through tonight.

Despite the organized synoptic pattern that is in place, precipitation looks to remain relatively scattered and convective in nature across much of the Interior the next few days as deeper moisture and strongest large-scale forcing remain displaced further south and west around the primary lows. As the Gulf low weakens and shifts eastward Thursday into Friday, a new low develops and strengthens over the Bering Sea southwest of the YK Delta, gradually becoming the dominant feature influencing western Alaska. This transition will weaken the winds temporarily across portions of the Interior while increasing southerly flow sets up heading into the weekend as the Bering low approaches.

Meanwhile, colder air aloft lingering beneath the broader trough pattern the next couple of days will combine with increasing May solar heating to promote afternoon destabilization, favoring the aforementioned scattered convective showers and isolated thunderstorms rather than widespread precipitation. In conjunction with this, embedded shortwaves rotating through the larger-scale pattern will further enhance shower development for the western Interior, Upper Tanana, and areas near the Alaska Range the next few days.

FIRE WEATHER

Across areas of the Interior, colder air aloft combined with strong May insolation will support afternoon destabilization and scattered convective shower development through Thursday. The greatest convective potential appears focused across portions of the Western Interior, Upper Kuskokwim region, and terrain surrounding the Upper Tanana Valley where thunderstorms could develop this evening. Instability remains relatively modest overall so thunderstorm coverage should remain scattered and terrain-driven rather than widespread or organized. Most convection is expected to remain rain- producing, reducing the threat for dry lightning or significant holdover activity. Even so, the convective nature of the showers could still produce localized gusty outflow winds near heavier cells despite otherwise light ambient winds. As the pattern evolves, more widespread precipitation is expected across areas of the Western Interior as a band of precipitation moves across the region with limited instability reducing any thunderstorm concerns.

Winds are expected to remain elevated through this evening as the low pressure system south of the Aleutians continues to move eastward maintaining a tighter pressure gradient and stronger southeasterly winds over the YK Delta. As this system moves eastward, winds are expected to weaken substantially reducing large- scale wind-driven fire spread potential. As we enter the weekend, a new Bering Sea low begins to tighten the gradient once again across the YK Delta leading to a slight increase in winds. Overall fire risk remains low across most of the region with main threats in areas of stronger winds associated with the passing of the low as well as localized gusty outflow winds near convective showers.

HYDROLOGY

Koyukuk River: An ice jam on the Koyukuk River 9 miles downstream of Hughes has released as of Wednesday morning. As a result, water levels have started to drop at Hughes. Therefore the Flood Warning that was scheduled to expire Wednesday evening has been allowed to expire early.

Yukon River: As of early Wednesday morning, flooding was occurring at Stevens Village. It was reported that water levels had risen by 5 feet since midnight. While no homes were being inundated, water levels are expected to continue rising. Given the rapid rise in water levels, this flooding is likely being caused by an ice jam. Impounding water due to the ice jam will cause rapid river rises upstream.

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, with minor flooding occurring in the Big Eddy area as of Tuesday evening. A Flood Advisory has been issued for this flooding.

A long run of bank-to-bank ice was observed nearly 100 miles upstream of the breakup front and likely extended further beyond the view of the River Watch team. The river was reported to be mostly open between Tanana and Galena, although an ice run was seen moving through near Rampart Tuesday evening.

In Galena, the ice sheet in front of new town shifted downstream some Tuesday morning, although intact ice remains in place above and below Galena, including at the entrance of Bishop Rock. Below Bishop Rock, the river had a stretch of open water with degraded in place ice below to Koyukuk. A FLood Watch has been issued for Galena for the potential for ice jam flooding from an ice jam downstream, including near Bishop Rock.

Porcupine River: Water levels in the Porcupine River are rising due to snowmelt which is pushing water into the Sucker River near Ft. Yukon. The Sucker River is starting to flow over low lying roads near the NE end of the runway. Water levels could keep rising for several days as the snowmelt pulse in the Porcupine makes its way into the Yukon River. Residents of Ft. Yukon should monitor water levels through the end of the week. A Flood Watch has been issued for potential snowmelt flooding for the Fort Yukon area.

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

Salcha River: The Salcha River is expected to reach action stage later this week as warmer temperatures lead to increased snowmelt.

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

Over the weekend the pattern will be dominated by an upper level high over the Arctic Ocean and a very large region of upper level low pressure across the southern Bering Sea and Gulf of Alaska. As these upper level features slowly weaken the pattern early next week will become less certain. Most of the forecast variance remains south of the region, but the weakening upper level features allows for a wider range of possible solutions to develop. By Sunday another low approaches the Alaska Peninsula, but there is still uncertainty in exactly how far north the low gets. Further north solutions would favor stronger winds across the region and more widespread showery conditions. A more southerly solution would favor weather more similar to this week with relatively mild conditions across Northern Alaska.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ829-833. PK...Heavy Freezing Spray Warning for PKZ812. Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ813-815-860-861. Gale Warning for PKZ814. Brisk Wind Advisory for PKZ858. Brisk Wind Advisory for PKZ859.