textproduct: Fairbanks

SYNOPSIS

A broad area of troughing moving over the interior will continue to be the primary driver of a rainy, and at times windy, week across Alaska. Generally cooler weather continues as shortwaves rotating around the trough axis bring rounds of rain and rain showers sweeping through. A particularly robust wave pushing up from the SW through the first half of the week will bring periods of moderate rain, especially to the southwestern interior and through the Alaska Range concurrent with strong gap winds through the Alaska Range and the Brooks Range. Some isolated thunderstorms in th eastern interior and N of the Brooks Range through the first half of the week, before chances diminish.

KEY WEATHER MESSAGES

Central and Eastern Interior...

-Rain showers move through the Interior, but conditions will generally be drier than wetter. Highest shower chance is north/west of Fairbanks each afternoon. A stronger front will bring more widespread showers on Tuesday and Wednesday.

-An isolated storm in the Tanana Valley is possible on Wednesday.

-Winds become increasingly elevated Tuesday and Wednesday as a stronger front moves through. Gusts of up to 70 mph in isabel Pass are likely, and up to 60 mph possible for Windy Pass and other areas prone to gap wind flow. A High Wind Warning is in force for Isabel Pass, and a Wind Advisory for Windy Pass.

-Temperatures remain seasonably cool, with highs in the 60s up to the low 70s, with the warmer temperatures towards the ALCan Border.

West Coast and Western Interior...

-Periods of rain showers associated with two distinct systems through the first half of the week. A decaying low in the vicinity of Diomede brings showers through the remainder of Monday before a stronger system brings periods of moderate rain Tuesday and Wednesday.

-Breezy winds diminish through Monday night, and prevailing S flow turns out of the East on Tuesday. An advancing low turns turns the flow out of the SW or (for the Seward Peninsula) the W, Tuesday night.

-High temperatures in the 50s and 60s through the week.

North Slope and Brooks Range..

-Best chances of rain will be anchored around the Brooks Range as short waves move through, with some isolated showers possible for areas north.

-Isolated chances of thunderstorms linger through Tuesday, especially for areas E of Utqiagvik.

-Breezy E winds on Monday will briefly turn out of the SW Tuesday morning before flipping back to prevailing NE flow by late Tuesday, and then remaining NE through the remainder of the week.

-High temperatures in the 60s and low 70s on Tuesday diminish to the 50s and 60s from Wednesday through the remainder of the week.

FORECAST ANALYSIS AND DISCUSSION

The upper level pattern continues to progress with troughing over Northern Alaska and a weak, subtle ridge hanging on to the AlCan Border. The main driver of our weather is the broad, longwave trough which is providing rain, heaviest in the higher terrain as well as wind through the Alaska Range and in the Brooks Range. A High Wind Watch has been upgraded to a High Wind Warning in Isabel Pass from Tuesday morning through Wednesday morning for wind gusts up to 75 mph. We have also added a Wind Advisory for Windy Pass for wind gusts up to 65 mph for the same time period. Sticking to the wind, the Brooks Range will be gusting up to 40 mph through tonight, then gradually weaken through Tuesday and Wednesday.

Looking at rainfall amounts, the West Coast, Western Interior and Alaska Range will be in the cross hairs for the heaviest rain moving through midweek. Rainfall totals south of the Yukon River through Thursday morning will be around 0.50 to 1.00 with localized amounts up to 1.50 while the southern slopes of the Alaska Range will around 1.00 to 3.00. Elsewhere across the Interior, the rainfall will be mostly showery activity resulting in totals largely less than 0.50. The North Slope will also see a front move through this afternoon but chinook flow will follow thereafter which dries it out. Temperatures across the Central/Eastern Interior remain in the 60s to near 70, while the Western Interior and West Coast stay in the 50s and low 60s for the next few days. Up on the North Slope, chinook flow will make it mild through Wednesday, but it may cool down thereafter as chinook flow weakens. In the grand scheme of things, this pattern has a lot going on but most of the weather coming with it is marginally impactful.

FIRE WEATHER

Monday, a broad trough is becoming firmly established over the Bering, serving as the source for continued wet/cool for much of the coast into the western Interior. It is becoming increasingly likely that the fire season is shutting down from Nenana west to the coast. However, there are still some localized areas for continued, albeit weaker, fire weather concerns. Primary forecast challenges are: - What areas in the central/eastern Interior are likely to see wetting rains? -How warm and dry will the Upper Tanana/Yukon Flats be through the next 24 to 36 hours? -High winds for Isabel/Delta Tue/Wed.

Starting on points 1 and 2, the parent trough across the Bering will continue steering moist south to southwest flow into the state but large portions of the Tanana and Yukon Flats see low chances for widespread wetting rains until Wed/Thur, in large part to downslope effects of the AK Range. This means at least another 36 hours of more areas of dry than wet with the potential for some isolated holdovers to start showing themselves in the Yukon. Moving into the Upper Tanana, this morning we saw excellent cloud cover with some very light rain showers out and about. But as of 1030 AKDT, clearing skies and some southerly winds have allowed RH to start dropping.

Now this leads us to point number 3: high winds in the AK Range, particularly in Isabel Pass. As a wave moves across the state tonight, it will lead to strong gap winds through the major passes, with a High Wind Warning out from Tue AM to Wed AM for 70mph wind gusts in Isabel. The forecasted winds, and the clearing skies over Delta Monday morning cause us to pause and reassess; however through conversations with our fire partners, we are missing the critical component of more receptive fuels near Delta Junction.

HYDROLOGY

Periods of moderate to heavy rain are expected Tuesday and Wednesday as a system moves through. Between 0.5 to 1.5 inches of rain are possible for more westerly and southwesterly sites, with the heaviest expected totals along the Southern Alaska Range. In the southern Alaska Range, 2 to 3 inch totals are expected, which will cause some rises along rivers and streams, but no flooding is expected at this time.

EXTENDED FORECAST DAYS 4-7

Thursday through Monday

The extended period begins with troughing covering most of Northern Alaska, bringing widespread cooler temperatures and showery conditions in the region. The GFS ensembles still anticipate a ridge building into the Eastern Interior on Friday, though the feature is slightly weaker in more recent runs. If ridging is able to break into the Eastern Interior, temperatures will warm up and widespread shower activity will be replaced by the potential for isolated to scattered thunderstorms. The Euro ensembles still keep the ridge in the Yukon for now, which will keep cooler than normal and showery conditions through the weekend. Regardless of the outcome this weekend, both ensembles are in agreement that ridging will build into the Central and Eastern Interior by this time next week, which will bring a return to summerlike conditions, including widespread highs in the low- to-mid 70s and isolated thunderstorms.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...High Wind Watch for AKZ849. Wind Advisory for AKZ809. PK...Small Craft Advisory for PKZ804-852.