textproduct: Fairbanks

SYNOPSIS

Wind speeds have begun to decrease through the Alaska Range as the low over Bristol Bay continues to weaken. Active weather is expected to continue across the state as a broad area of low pressure expands eastward. This will setup increasing chances for isolated thunderstorms through the end of the weekend. another low will begin to work its way up the Aleutians along a similar track to the previous one. This will continue the showery trend and chances for thunderstorms into the early parts of next week.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Increase chance for thunderstorms toady with chances increasing to around 30% in the Central and Northern Interior by Saturday.

- Seasonably normal temperatures are expected to continue across the Interior through much of the week.

West Coast and Western Interior... - Showery conditions are expected along the Lower Yukon and Yukon Delta regions throughout the week. These showers will be mostly rain, especially nearer the Western Interior, but some periods of snow and light wintry mix are possible near St. Lawrence Island and the Bering Strait Coast.

- Increased thunderstorm potential around 15% today, lasting through the weekend. The best chances for thunderstorms will primarily around the Middle Yukon Valley and Upper Kuskokwim Valley, with highest chances increasing to 30% on Saturday.

North Slope and Brooks Range.. - Gusty northeasterly winds will gradually increase, to around 25 and 35 mph, along the Arctic Coast over the next couple of days. Gradient will begin to lighten by Friday night.

- Diurnal showers along the southern portion of the Brooks Range are expected to continue through the week. Little to no precipitation is expected for the North Slope.

- Chilly temperatures persist with highs in the 20s and lows in the teens along the North Slope. A gradient of temperatures across the Brooks Range with highs in the 50s to near 60 along the southern slopes and low 40s for the northern slopes.

FORECAST ANALYSIS AND DISCUSSION

An active pattern is expected to continue over the next several days. An area of low pressure will continue to weaken as it rotates over Bristol Bay. This will continue to provide scattered rain showers across the state through the start of the weekend. In addition, instability will be increasing across northern Alaska over the next several days. Remnants from a shortwave will continue to move up the Al-Can boarder. This will slowly push the Arctic high further north, which will gradually weaken the gradient across the state throughout the weekend. Chances for scattered snow showers will increase across the eastern Arctic Coast with the approaching bits of energy.

Meanwhile, another shortwave will be moving across the gulf which will broaden the trough across the state. This will result in easterly flow across the Interior which will help increase the chances for thunderstorms as the weekend progresses. A drier airmass is looking to move in across the Interior on Saturday which will keep the showers and thunderstorm chances very isolated. A subtle upper-level ridge will slowly materialize over the Yukon Saturday night into Sunday, helping to bring across an inverted shortwave across the SE Interior from Canada. Models are also hinting at the potential for a thermal trough to settle in under the upper-level ridge Sunday and slowly progress easterly across the Interior. All of these components will work together to support thunderstorm development. Model soundings are also showing the potential for little shear to be associated with any storms that form, which will result in short-lived storms.

Northeast flow will also begin to settle in across the Interior as another low will moves toward Bristol Bay from the Aleutians. This low is expected to take a similar track to the previous one. Unlike the previous one, a more pronounced ridge is expected to set up out ahead of the low, stretching from the Gulf to the southern portions of the state. The eastward progression of this next low will be determined by the strength of this ridge which will play a role in thunderstorm potential for next week.

FIRE WEATHER

A relatively dry day (in terms of humidity) is expected today, with highs in the Interior in the upper 50s or low 60s and min RH values in the 20s and 30s %. Isolated thunderstorms will be possible in northern and western portions of the Interior, with more broadly scattered showers possible along and south of the Brooks Range. The best chance for fire weather conditions will be from Delta Junction south, where dry conditions could yield min RH values in the low 20s with southerly winds winds continuing in the area. Potential Red Flag conditions could be limited given southerly winds in the area have weakened this morning and are expected to continue doing so through the day. Saturday will be another warm and dry day, but winds are likely to remain under 15 mph in most areas. Scattered thunderstorms will be possible along the Brooks Range and across the uplands along the eastern border, with showers and isolated thunderstorms possible across much of the rest of the Interior. Sunday will remain warm but could see min RH values increase as moisture moves in from the south. This will also bring more shower and thunderstorm chances. Isolated thunderstorms will be possible across the northeastern half or so of the Interior, with scattered thunderstorms possible along and just south of the eastern Brooks Range. Warm and dry conditions with shower and thunderstorm chances continue next week as a low moves into the southeastern Bering Sea and could bring a return of easterly winds to the Interior.

HYDROLOGY

Yukon River: The breakup front on the Yukon has passed Russian Mission. As of 12AM AKDT Thursday, a sharp increase in water level was recorded near Pilot Station, indicating that a release is possible. Then, as of 11am AKDT Thursday, an ice jam 10 miles downstream of Russian Mission has been confirmed to be releasing, according to the River Water team. Further information is needed regarding the speed of release and There is another minor ice jam downstream from Holy Cross, with water levels remaining mostly steady. The most extensive flooding is occurring at Holy Cross and in the lowlands between Holy Cross and Anvik. When the jam releases, additional rising water and flooding is likely at Russian Mission. The Yukon River breakup front moved past Marshall on Thursday and jammed about 8 miles downriver.

Flood warnings remain in effect for Russian Mission, Holy Cross, and Grayling. A Flood Advisory is in effect for Anvik. A flood watch remains in effect for communities further down the Yukon River to St. Mary's. Extensive flooding of the lower portion of Holy Cross community was occurring Tuesday, including the Holy Cross runway. Water remains high on the Yukon upriver from the breakup front due to snowmelt and the Yuki Ice Jam release. As of noon Wednesday the River Watch Team reported that the river slows down around Anvik and that the backwater from the jam seems to have extended to Anvik.

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.

EXTENDED FORECAST DAYS 4-7

To start the forecast period on Monday, warm temperatures in the low to mid 60s will be possible across the Interior and could last through the middle of next week. A low moving into the southeastern Bering Sea will bring easterly winds to much of the area beginning Monday, with sustained winds of 20 to 30 mph possible in prominent/ exposed coastal locations such as St. Lawrence Island and the western tip of the Seward Peninsula. Easterly winds will also be possible across the Arctic Coast through the middle of next week with a persistent high pressure area over the Arctic. Elsewhere, the highest sustained winds will be in elevated areas across the Interior, with gusty easterly winds in the valleys, especially during periods of maximum diurnal heating. Ahead of the low Monday afternoon, thunderstorms will be possible from the Western Interior to the Middle Tanana Valley / White Mountains areas. As the low moves eastward on Tuesday, it will rapidly weaken, but gusty winds could continue across the area, with southerly gap winds increasing through the Alaska Range passes. By Wednesday, the remnants of the Bering Sea low will have drifted into the Gulf of Alaska, with Interior winds gradually decreasing through the day, but shower and thunderstorm potential will linger across much of the Interior each day.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ826-830. PK...Brisk Wind Advisory for PKZ806. Brisk Wind Advisory for PKZ807. Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ814. Brisk Wind Advisory for PKZ815. Small Craft Advisory for PKZ854. Brisk Wind Advisory for PKZ856. Small Craft Advisory for PKZ858. Brisk Wind Advisory for PKZ860. Brisk Wind Advisory for PKZ861.