textproduct: Fairbanks

SYNOPSIS

The heavy rain in the Brooks Range and North Slope has prompted a Flood Warning in Wiseman/Coldfoot as well as a Flood Advisory along the Colville and Sag River. The rain will stop this afternoon/evening and there will likely be rises in Allakaket/Bettles along the Koyukuk in the next 1 to 2 days. The Sag and Colville will likely rise as well, since the water will be draining into the headwaters and flowing downriver over the next couple of days. Otherwise, the rest of Northern Alaska is pretty quiet and cool with isolated rain showers and a chance for a couple of thunderstorms in the Upper Tanana. Tomorrow will begin a warming trend for most spots and it is expected to continue into the weekend with increasing chances for thunderstorms each day.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Temperatures a few degrees below normal today with a warming trend into the low-mid 70s beginning on Wednesday and upper 70s to near 80 by Friday.

- Isolated afternoon showers across the Interior today with a couple of thunderstorms possible in the Upper Tanana Valley.

- Thunderstorms increase in coverage Wednesday, but more noticeably on Thursday and Friday.

West Coast and Western Interior... - Generally light winds and calm weather for most of the area. A few showers possible in the Western Interior.

- A warming trend begins on Wednesday with highs in the 60s to near 70 in the Interior and 50s along the coast. Gradual warming by about 1 to 2 degrees a day continues through the week.

- Thunderstorm chances increase on Wednesday and will be isolated over most of the Interior and northern Seward Peninsula. Isolated thunderstorms persist on Thursday in the Interior then track east on Friday.

- A low moves to the West coast Wednesday night and will provide an enhanced area of showers through Thursday, especially south of the Seward Peninsula.

North Slope and Brooks Range.. - Other than some showers, the heaviest rain has ended. A Flood Advisory is in effect for the Colville River through Friday morning with Flood Watches elsewhere through at least Wednesday morning.

- Warming trend with temps ranging from the upper 40s/low 50s along the coast to the low to mid 70s in the Brooks Range valleys by Thursday.

- The warmer temps will also support chances for thunderstorms in the Brooks Range and North Slope from Wednesday through Saturday.

FORECAST ANALYSIS AND DISCUSSION

There isn't much change from the last few days as we have a ridge building over western Canada, a trough north/northwest of Utqiagvik, a ridge over the North Pacific and a low near the Eastern Aleutians. Over the next few days, ridging will take over most of Northern Alaska allowing the temperatures to warm but also introduce higher chances for showers and thunderstorms throughout the week. It will be a messy ridge as we'll have many shortwaves moving around it, acting as the main driving force for our thunderstorms in the Central/Eastern Interior and Brooks Range. For thunderstorms, this is one of the "best" patterns of the year so far with east/southeast flow, warm temperatures and plenty of lift from shortwaves. Overall, this looks like typical warm summer weather with chances for storms but given the timing, around the Midnight Sun activities, this could be particularly impactful. For those that will be outside, you will want to be weather aware this weekend as many of these thunderstorms will come with briefly heavy rain, gusty winds, hail and frequent lightning. Typically thunderstorms end during the evening as well, but with persistent energy moving into the area, thunderstorms may linger all night, especially over the Central and Eastern Interior. Otherwise, expect near to above normal temperatures for the North Slope and Central/Eastern Interior through the end of the week and into the weekend.

Out west, we'll have an upper level low moving towards the West Coast Wednesday night. This will provide stratus and some fog to the coast while bringing an enhanced area of showers south of the Seward Peninsula through the day on Thursday. It will also assist in providing thunderstorms to the Western Interior on Wednesday and Thursday. Temperatures will be near to above normal in the Western Interior but around average along the coast for much of the period. Otherwise, there are no major systems expected for the foreseeable future.

FIRE WEATHER

Relatively quiet for now on the fire weather front as we keep cool temperatures with mostly 30%+ RHs this afternoon. Tomorrow will begin a warming trend across Northern Alaska, high temperatures get into the 70s in the valleys across the Interior but RHs remain around 30% or higher. Heading through the rest of the week, most of the Central/Eastern Interior warms into the upper 70s or low 80s by Friday. Lowest min RHs look to be around 25% in the Tanana Valley and Yukon Flats, but most spots remain above 30% by Friday. The Western Interior valleys remain in the low 70s through the end of the week with RHs around 30 to 40%. Thunderstorms will be isolated across the Interior today, we've already had a couple of strikes south of Manley Hot Springs, but thunderstorms will be hit or miss. Tomorrow, coverage will expand to the Fortymile, AK Range, SW Interior, Brooks Range and northern Seward Peninsula. On Thursday, most thunderstorms will be from the Western Interior to the Western North Slope. Friday comes with chances for scattered storms across the Central/Eastern Interior.

HYDROLOGY

Most of the rain is ending on the North Slope and Brooks Range but there are plenty of flood products issued including an Advisory along the Colville and Sag and a Warning in Wiseman/Coldfoot. Watches are issued for most of the North Slope, Brooks Range and the Koyukuk River to Allakaket.

See Weather.gov/afg for the most updated flooding products and water.noaa.gov for the most updated river gauge forecasts.

Otherwise, we anticipate high water and river rises as the snowmelt continues and rain ends. Impacts may persist through the end of the week, especially on the North Slope as it takes a while for all of the water to pass through the system. The latest forecast for the Sag River along the Dalton Highway is, between mileposts 310-340, road washouts are possible especially in areas adjacent to the Sag River and in the vicinity of stream crossings if lingering ice results in culvert blockages. On the Colville from Umiat to Nuiqsut, minor flooding in low-lying areas due to rapid temperature rises and continuing rain on residual snowpack is possible. The flood crest should attenuate as it progresses downstream, but water levels are already high in Umiat and minor flooding should be expected elsewhere.

High water near Coldfoot and Wiseman will continue to recede today but it is flowing towards Bettles and Allakaket currently. The river gauge in Bettles is beginning to rise and will continue to do so through about midnight Wednesday night with a current forecasted crest around 22.70 feet. Allakaket will see their highest water about 24 hours later. Minor flooding will be possible as the water continues to rise.

EXTENDED FORECAST DAYS 4-7

A high pressure system will continue over Northern Alaska, and drive most of our upcoming weather. A series of shortwaves will provide instability to our area. We are expecting a general trend of increasing temperatures, decreasing relative humidity, and a moderate supply of CAPE present as we move into our weekend. Isolated to scattered thunderstorms are possible as we approach saturday, and with the trend of lower relative humidity values, fire weather remains a concern for the Central and Eastern interior. Wind gusts are expected to be light and variable with precipitation scatted throughout our area.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ812-831. Flood Watch for AKZ804>810. PK...None.