textproduct: Fairbanks

SYNOPSIS

It is the start of a rainy weekend for western Alaska as widespread moderate to heavy rain is making its way north across the region this morning. Along with the rain, winds will strengthen, gusting up to 40 mph in the Lower Yukon and Kuskokwim Valleys and reaching the middle Tanana Valley Saturday evening. Southerly gap winds through Alaska Range passes will gust up to 60 mph Saturday evening. In the Central and Eastern Interior, temperatures will peak in the upper 70s to mid 80s on Saturday before cloud cover begins to moderate temperatures on Sunday. Thunderstorms will develop in the Interior Saturday, which pose a threat for fire starts in the Yukon Flats where hot and dry weather has dried fuels for the past week.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Highs in the 70s and 80s are expected in Interior valleys Saturday, with a heat advisory in effect for the Yukon Flats where temperatures will reach around 85F. Temperatures will begin a cooling trend from west to east beginning Sunday.

- Saturday afternoon, thunderstorm coverage shifts back towards the Central Interior, over the Dalton Highway Summits and White Mountains north of Fairbanks with scattered thunderstorms expected over the Yukon Flats.

- Southerly gap winds through the Alaska Range will strengthen Saturday afternoon, with potential gusts up to 50 and 60 mph respectively through Isabel and Windy Pass.

- A Wind Advisory is in effect for the western portion of FNSB on Saturday, including Fairbanks, for potential gusts up to 40 mph.

West Coast and Western Interior... - Widespread wetting rain will arrive in the YK Delta this afternoon and travel north through the region through Saturday. The current track of the low supports half an inch or more in the the YK Delta and Southern Seward Peninsula on Saturday, around a quarter in the lower to middle Yukon Valley, and less than a quarter in most other regions. - Winds strengthen with the arrival of the system from the Bering. Areas along the coast will see gusts up to 35 to 45 mph. Farther into the Interior, gusts will reach 25 to 35 mph. Winds will weaken slightly on Sunday, but remain gusty through the weekend. - A wind advisory is in effect on Saturday for southern portions of the Western Interior for potential gusts up to 40 mph.

- Fog and low stratus have moved in from the Bering along portions of the West Coast and will linger through the weekend.

North Slope and Brooks Range.. - Max temperatures on the North Slope will peak around 70F through the weekend, and into the 60s on Monday. Temperatures along the coast will be cooler, in the 50s and low 60s, and in the 40s around Utqiagvik.

- Isolated thunderstorms are expected in the central and eastern Brooks Range this afternoon. The best chances will be in a similar area from Anaktuvuk Pass to Arctic Village.

- Widespread rain will reach the Western Brooks Range from the south on Saturday and will continue into the North Slope on Sunday becoming lighter.

FORECAST ANALYSIS AND DISCUSSION

A shortwave trough is currently working its way north through the western regions of Alaska, positioned over the Lower Yukon at the time of writing. The shortwave is propelled by a 542 decameter low in the Bering, due west of Nunivak Island. Along with this shortwave is almost an inch and a half of precipitable water. As a result, there will be widespread rain in the western region of Alaska throughout the weekend. Total QPF amounts through the end of the weekend will reach an inch or more on the Southern Seward Pen and along the YK Delta Coast. In addition to the rain, winds along the coast will gust in the 35 to 50 mph range. Farther inland, winds in the western Interior look like they will reach 30 to 40 mph. The center of the low will be positioned over the Seward Peninsula, so while winds will be southerly in the Western Interior, Kotzebue Sound and Norton Sound, they will be northerly through the Bering Strait Coast. The arrival of system will also lead to gusty southerly gap winds through the Alaska Range. Wind gusts should peak around 50 mph through Isabel Pass and up to 60 through Windy Pass on Saturday evening, as the front crosses the range and the upper level pattern becomes aligned south to north across the Range.

In the eastern half of Alaska on Saturday, a weak ridge will keep conditions warmer and drier. Temperatures in the 70s and 80s are expected this afternoon, with a Heat Advisory out for the Yukon Flats for temperatures in the mid 80s. There is also a Red Flag Warning for the Yukon Flats for scattered thunderstorms and dry fuels. After the recent dry and hot weather there this week, FFMCs are near maximum values.

After the initial shortwave on Saturday, several other shortwave troughs will spin around the main trough in the Bering and over Alaska, resulting in further rounds of precipitation and eventually pushing the weak ridge off to the east. Rain should abate somewhat on Sunday as the next shortwave takes a track towards South Central Alaska. However, cloudier and cooler weather should engulf most of Alaska, keeping temperatures below 80F, staying warmest in the Eastern Interior where the ridge is strongest.

On Monday, the pattern looks favorable for the shortwave that went into South Central to pivot and ,move north through the Central Interior. As the upper-level, pattern aligns south to north and we should see another round of southerly gap winds through the Alaska Range, which could stick around longer than the winds on Saturday. The shortwave will also support the return of thunderstorms in the Interior on Monday.

FIRE WEATHER

Upper level ridging over Eastern Alaska continues to push east today as a Bering Sea low moves ashore. As the Bering Sea low pushes the ridge further east through the weekend, a strong southerly Chinook pattern takes hold over the central/eastern portion of the state, leading to warmer and drier conditions. A Heat Advisory was issued for the Yukon Flats today as high temperatures are expected to near 85F this afternoon. Elsewhere, temperatures will rise into the upper 70s this weekend with slightly cooler temperatures expected early next week. Strong southerly gap winds through the Alaska Range passes strengthen early this morning, with gusts as high as 50 to 60 mph expected. Despite the strong gusty winds this afternoon, critical fire weather conditions are not likely due to previous rainfall amounts keeping fuels wet and moist. Periods of gusty southwesterly winds are possible in Fairbanks today as well, gusting up to 40 mph.

Across the West Coast, widespread rain showers are expected to persist well into next week as the Bering Sea low taps into large amounts of moisture from the Gulf. These showers will continue to move from south to north from the YK Delta up towards the Western Brooks Range through the weekend. Rainfall totals between 0.25" to 0.50" are possible. Due to cooling temperatures and widespread wetting rains across the West Coast and Western Interior, fire weather conditions will be severely limited through most of next week.

Isolated to scattered thunderstorms remain possible this weekend, mainly over the Yukon Flats and Central/Eastern Brooks Range where strong outflow boundaries and frequent lightning are expected. Outflow gusts may reach as high as 40 to 50 mph at times. By Sunday, thunderstorm coverage will mostly be limited to the Eastern Brooks Range and Eastern Arctic Plains, but thunderstorm activity should ramp down a bit going into next week.

EXTENDED FORECAST DAYS 4-7

Tuesday through Thursday a Bering Sea low pressure system remains in place over the West Coast. Disturbances rotate up into the Alaska Range and over the Interior in a south-southwest flow aloft. Bands of stratiform rain will continue to move up into the Kuskokwim Valley and the Western Interior during this time. The unseasonably cool air and showers will eventually move up into the Central and Eastern Interior...even getting up into the Yukon Flats. The southerly winds off the Alaska Range should produce a local downslope effect in the upper Tanana Valley. Gap winds similar to today will continue to be monitored through the Alaska Range passes. Generally a cooling trend should occur across Northern Alaska this week with highs falling into 60s and mid 50s. Thunderstorm activity will be minimal during this time...isolated coverage in the favored Eastern Brooks Range. By Friday ensemble solutions have some temporary ridging building over the North Slope and Brooks Range as the mean West Coast trough weakens a bit. This should increase thunderstorm activity down into the White Mountains and Fortymile.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ849. Wind Advisory for AKZ830-852. Heat Advisory for AKZ833. Red Flag Warning for AKZ933. Wind Advisory for AKZ841-844-845. Wind Advisory for AKZ847. PK...Gale Warning for PKZ801. Small Craft Advisory for PKZ802. Small Craft Advisory for PKZ803-805-852. Small Craft Advisory for PKZ804-807-854. Gale Warning for PKZ806-856. Small Craft Advisory for PKZ809-811-857. Small Craft Advisory for PKZ810. Small Craft Advisory for PKZ816. Small Craft Advisory for PKZ817. Gale Warning for PKZ850.