textproduct: Fairbanks

SYNOPSIS

Active weather is expected to continue across the state as a broad area of low pressure expands eastward. This will setup a broad area of isolated to scattered thunderstorms through the end of the weekend for the interior. A strong low will move along the Aleutians and weaken near Bristol Bay. This will continue the showery trend, increase chance for thunderstorms, and fire weather concerns for the Tanana Valley.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Increasing chances for thunderstorms going into the weekend, around 30% in the Central and Northern Interior for Saturday and Sunday.

- 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. Chances for snow and wintry precipitation are possible for St. Lawrence Island and the Bering Strait Coast, primarily for this evening.

- Increased chances for thunderstorms will primarily be 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.

- Intermittent periods of freezing rain/drizzle for the northern slope with little to no accumulation expected.

- 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

The main driver of weather for the next few days will be the occluded Bering Sea low rotating near the YK Delta, along with a stronger shortwave racing across the GoA. Easterly flow across the Interior with multiple perturbations moving along the flow will help increase the chances for thunderstorms through the weekend. 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 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. The one exception being near the Tanana Valley, which could have longer lasting storms and increased QPF.

Meanwhile, through tonight, signs of freezing drizzle are possible mixing in with snow along the north slope for Nuiqsut eastward. Likelihood remains low, primarily driven by the saturated low level inversion up to around 925-850 mb layer. With the saturated portion of the profile above -5C, the cloud profile is expected to be largely supercooled droplets. Onshore flow and slight terrain increase is expected to cause just enough lift to generate some freezing drizzle for these communities with little to no accumulation.

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. Currently expecting this ridge to hold strong until Wednesday before breaking down.

FIRE WEATHER

Primary fire concerns through the weekend continue to be the threat of isolated to scattered thunderstorms across the interior, with highest likelihood (30%) along the White Mountains and over to the Upper Koyukuk Valley both Saturday and Sunday. These days look to see a thermal trough set up in the aforementioned areas, increasing thunderstorm chances. Elsewhere in the interior, isolated showers and thunderstorms (15%) are possible through the weekend. Saturday will be another warm and dry day, but winds are likely to remain under 15 mph in most areas. Sunday will remain warm but could see min RH values increase as moisture moves in from the south.

Warm and dry conditions with shower and thunderstorm chances continue next week as a low moves into the southeastern Bering Sea and could bring additional gap winds to the Isabel Pass and Delta Junction area, raising concerns again.

HYDROLOGY

Yukon River: The breakup front on the Yukon has passed Russian Mission and is currently downstream of Marshall. The flood warning and advisory for Grayling and Anvik respectively have been cancelled, as water levels are expected or have receded below critical thresholds. The most extensive flooding is occurring at Holy Cross and in the lowlands between Holy Cross and Anvik, however, water levels are expected to drop in the following hours. When the jam releases, additional rising water and flooding is likely at Russian Mission.

The flood watch has been extended down to the delta, including communities of Mountain Village, Kotlik, Emmonak, and Alakanuk. Pilot Station, St. Mary's, and Mountain Village are the current areas of interest for potential flooding in the following days as the ice front moves downstream.

Water remains high on the Yukon upriver from the breakup front due to snowmelt and the Yuki Ice Jam release.

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 AKZ825. Flood Watch for AKZ826-830. PK...Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ814-856-860. Brisk Wind Advisory for PKZ815. Brisk Wind Advisory for PKZ861.