textproduct: Fairbanks

SYNOPSIS

Cool and wet weather continue across Western Alaska today while the eastern half of the state experiences a warming & drying trend as an upper-level ridge over Eastern Alaska reinforces southerly Chinook flow over the state. Southerly gap winds through the Alaska Range Passes have continued to gust upwards of around 55 to 70 mph today, which will gradually weaken from this evening through Monday morning. Out west, a low sitting around Bristol Bay will support continuous rain showers along the coast well into next week. By Tuesday, the ridge over Eastern Alaska starts to break down and allows for southwest flow to set up over the state. With this new pattern, an increase in thunderstorm activity & widespread rain showers across the Interior become likely. In the meantime, we are continuing to monitor the development of another low pressure system moving into the Bering Sea for the latter half of the week for minor coastal impacts & high surf due to gusty WSW winds. There is high uncertainty with the track of this system, however, with the models placing the track anywhere between the Bering Strait to the Yukon Delta. We will publish necessary updates through the week.

KEY MESSAGES

Central and Eastern Interior... - Warming temperatures into the mid 70s/low 80s this afternoon with low to mid 80s on Monday and some upper 80s in the Yukon Flats. Temperatures cool back into the 60s and 70s again on Tuesday.

- There has been a brief lull in thunderstorm activity today with chances returning Monday and Tuesday afternoon in the Eastern Interior and north towards the Eastern Brooks Range.

- Southerly gap winds through Alaska Range Passes and Delta Junction continued today with gusts upwards of around 55 to 70 mph. Winds will gradually diminish this evening into Monday.

West Coast and Western Interior... - Widespread continuous showers are expected through early next week with the highest rainfall totals in the YK Delta, southern Seward Peninsula, & Kobuk Valleys. Rainfall totals between 0.25 to 0.50 inches, with locally higher amounts near 0.75" possible through Tuesday. - A few isolated thunderstorms are possible this afternoon over the extreme northern Seward Peninsula & western Brooks Range, shifting southward to encompass the entire Seward Peninsula by Monday afternoon. Thunderstorm chances diminish from Tuesday, onward.

- Another low making its way into the Bering Sea for the latter half of next week may support additional widespread showers & breezy winds across Western Alaska. Minor coastal impacts are possible, primarily high surf. (See the coastal section for additional information)

North Slope and Brooks Range... - Scattered showers and isolated thunderstorms are in store for the Western Brooks Range & Western Arctic Plains for this afternoon. Shower & thunderstorm coverage shifts southeastward for Monday through Tuesday.

- Temperatures warm through early next week with 70s to near 80F possible in the Arctic Plains. Cooler temperatures in the 50s/60s are expected along coastal areas through midweek.

- Areas of low stratus and patchy fog may continue to develop during the evenings & overnights along the Arctic Coast into next week.

FORECAST ANALYSIS AND DISCUSSION

The ongoing forecast remains on track with troughing out west and ridging building in the east. Wedged in between is southerly chinook flow over the AK Range and Brooks Range. Western Alaska will remain cool and wet for the foreseeable future as several shortwave troughs and weak low pressure systems move through from south to north. Wind through the AK Range Passes and in Delta Junction have been around 50 to 60 mph and will peak tonight. North of both ranges we are expecting significantly warmer temperatures in the 70s and 80s with the warmest spots being in the Yukon Flats where high temperatures approach 90 degrees on Monday. In addition to warming temperatures, we will see an increase in thunderstorm activity on Monday and Tuesday in the Interior and Brooks Range as a front lifts northward. This front will cool things down significantly from Tuesday onward, bringing a persistent cool and wet pattern once again. On the North Slope, it will remain warm through the middle of the week but the broad scale troughing will win out by the end of the week, cooling things down significantly and bringing more active weather.

Overall, the summer-like weather on the North Slope and in the Central/Eastern Interior will be short-lived as cooler and wetter weather prevails towards the middle and end of the week. The West Coast will continue to see areas of rain/showers with cool temperatures. One thing we will be monitoring, which will be elaborated on in the Extended Discussion and Coastal Hazard section below, is the potential Bering Sea low by the end of the week. Significant impacts are not expected but minor coastal impacts/high surf and heavy rain/gusty winds appear to be on the agenda right now.

FIRE WEATHER

With broad troughing to the west and ridging to the east, strong southerly flow continues to work over the Alaska Range. Warmer and dry conditions are expected for areas just north of the Alaska Range with strong gusty winds up to 65 mph expected through the passes and up to 55 mph in Delta Junction. Peak observed gusts so far today have been up to 62 mph in the passes and 53 mph at Delta. Wind Advisories remain in effect for this region tonight into Monday. Another round of southerly gap winds through Alaska Range passes is expected late Tuesday into Wednesday and Wednesday night.

Temperatures have already begun warming across the Interior north to the Arctic Coast, which are expected to peak on Monday as highs climb well into the 70s/80s. Heat Advisories remain in effect for Monday for the Yukon Flats and Fortymile Country for highs around 85- 90F and the Arctic Plains for highs up to around 80F. Minimum RHs through Monday will drop to around 25-35% across much of the Interior north to the Brooks Range and Central Arctic Plains, with improvement expected Tuesday onwards. There is a limited overlap of critical wind and low RH expected, with elevated conditions possible where the warmest and dries conditions overlap with breezy winds.

Dry conditions across the Interior today through Monday morning with will give way to isolated to scattered showers and thunderstorms lifting north along a NW to SE oriented front that will build in Monday afternoon and shift north on Tuesday. The best thunderstorm chances Monday afternoon and evening will be from the Upper Tanana Valley northwest to the Central Brooks Range, with isolated activity continuing Monday night for the Yukon Flats and Brooks Range. Tuesday is shaping up to see the highest thunderstorm coverage across the Yukon Flats north through the Brooks Range, peaking during the afternoon and evening.

Across Western Alaska, isolated to scattered showers and very isolated thunderstorms will continue through Monday, with heavy precipitation expected in the Western Alaska Range. A closed low moving into Southwest Alaska on Tuesday will bring steadier rain for the Y-K Delta and Southwest Interior north to the Seward Peninsula.

Looking ahead, a coastal storm is expected to move into Western Alaska Wednesday into Thursday, with widespread precipitation and gusty winds moving across all of Northern Alaska mid to late week. Colder temperatures will accompany this system as widespread highs in the 50s/60s return, with locally colder conditions farther north.

HYDROLOGY

No concerns at this time.

EXTENDED FORECAST DAYS 4-7

WEDNESDAY THROUGH SUNDAY Wednesday afternoon an approximately 540 decameter closed off low will move towards St. Lawrence Island. Accompanying this low will be gusty winds, heavy rain, and minor coastal concerns. The 12z model guidance is in good agreement that the surface low should be around 990 mbs. This would allow for wind gusts of 30 to 50 mph being possible across the West Coast and Western Interior. Attached to the low pressure system, a stout atmospheric river will also be pushed into the West Coast. This additional moisture could produce widespread moderate to heavy rainfall across the West Coast. As the low moves east on Thursday, this rain will move east and north towards the Brooks Range and Eastern Interior.

Looking towards the weekend there is large model uncertainty regarding the pattern. A ridge axis extending north into the Interior from the North Pacific High is the source of this uncertainty. Depending on the strength of the ridge axis would dictate how far into the Interior an arctic trough is able to dig southwards. This arctic trough will move onto the North Slope Saturday morning, bringing very cold 850mb temperatures. These temperatures are introducing the possibility of light to moderate snowfall in the Brooks Range on Saturday and Sunday. If the ridge axis is on the weaker side than snow chances could be possible in the higher terrain of the Interior. On the flip side of that if the ridge holds than it would just be more rain.

Coastal Hazard Potential

We have issued a Special Weather Statement for potential coastal impacts later this week from a Bering Sea storm. The main things we are monitoring are the track and strength of the storm but there is uncertainty with both of these. The good news is, the storm doesnt look to intensify too much and impacts should be minor. The West Coast from the Yukon Delta to Kivalina should monitor the latest forecasts at weather.gov/afg to stay aware of potential impacts from this storm.

Current coastal flood guidance is hinting at high surf and potentially minor flooding. Fortunately, significant impacts are not expected. We will continue to update as necessary.

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ837-847-849. Heat Advisory for AKZ833-835. Heat Advisory for AKZ806-808. PK...None.