textproduct: Fairbanks

SYNOPSIS

A strong low in the High Arctic continues to eject a series of shortwaves south across Northern Alaska, which will culminate with a cold front today into Monday building in out of the northwest. This system will continue to support widespread snow across the North Slope and Brooks Range, where a Winter Weather Advisory is in effect for central portions of the range for the Dalton Highway. Farther south, precipitation is expected to be rain in the form of scattered showers and isolated thunderstorms, with higher elevations of the Alaska Range expected to see snow.

Following showers and thunderstorms out ahead of the main front today, steadier precipitation rates are likely in a more organized band as it works southeast from the NW Arctic Coast into the Interior tonight into Monday as isolated thunderstorms shift southeast. Colder conditions will accompany this front, with below normal temperatures expected to build in early next week as lows regionwide drop the 20s/30s/40s. Looking ahead, warmer and drier conditions are expected to return midweek onward as daily isolated showers and thunderstorms persist.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Gradually cooling temperatures are expected through the weekend into early next week as increasingly scattered showers and isolated thunderstorm chances build in across the Interior.

- Scattered showers and isolated thunderstorms will be along a line from the Upper Kuskokwim to the Yukon Flats, today, ahead of the cold front pushing southeast.

- Gusty west/southwest winds will increase across the Interior today, with gusts up to around 20-40 mph through Monday.

- Dependent on clearing skies, low temperatures Monday night and Tuesday night will bottom out in the 30s and 40s for most, with coldest valleys dropping to around freezing. We will continue to monitor the potential for frost/freeze headlines for Fairbanks during this timeframe.

- More widespread showers expected across the Interior on Monday with the frontal passage. Showers will become more isolated starting Tuesday, with warmer and drier conditions building back across the Interior Wednesday onwards as daily isolated showers persist.

West Coast and Western Interior...

- Dry conditions will continue across Western Alaska through tonight, with highs cooler on the coast in the 30s/40s/50s and warmer inland in the 50s/60s/70s.

- A cold front building in out of the northwest today will support scattered rain and snow showers as a colder airmass builds in. Showers will shift inland and towards the Y-K Delta later in the day Sunday into Monday. Light snow accumulations will remain confined to the Northern Seward Peninsula and NW Arctic Coast.

- Colder and drier conditions on Tuesday will give way to a warming trend Wednesday onwards as temperatures return to more seasonable levels with highs rebounding into the 50s/60s/70s regionwide.

North Slope and Brooks Range...

- Widespread light snow is expected across the Arctic Coast/Plains, with heavier totals in the Brooks Range. A Winter Weather Advisory is now in effect tonight through Monday for the Central Brooks Range for snow accumulations of 5-10 inches and wind gusts up to 30 mph.

- Below normal temperatures continue today north of the Brooks Range with highs/lows in the 20s/30s while warmer air remains situated to the south of and in the Brooks Range where highs in the 40s/50s/60s and lows in the 30s/40s continue.

- Isolated to scattered rain/snow showers will continue to build in out of the northwest across the North Slope, expanding over the Brooks Range as a cold front passes over the region. Heaviest precipitation is expected on the northern side of the Brooks Range.

- Behind the Sunday/Monday cold front, isolated to scattered snow showers will continue for Tuesday ahead of warmer and drier conditions returning Wednesday onwards. Highs are expected to build back into the 50s/60s/70s with 30s/40s along the coast.

FORECAST ANALYSIS AND DISCUSSION

Today through Tuesday Night. Broad southwesterly flow continues across much of the state with the 505 decameter low in the Arctic. A weaker low, around 535 decameters, continues to move westerly across Gulf toward the Alaska Panhandle. Attention pivots toward a cold front, in association with the Arctic low, that will push SE from the Chukchi over the next couple of days. Today, areas out ahead of the front, specifically along a line from the Yukon Flats to the Upper Kuskokwim, will see the potential for thunderstorm formation as steeper lapse rates move in. This trough will also tighten heights, aloft, which will allow the potential for gusty winds from the West Coast to the Central Interior today. Daytime heating will also be more sufficient out ahead of the front which will further support thunderstorm chances. Model soundings along the line from the Upper Kuskokwim to the Yukon Flats show adequate amounts of speed sheer which may promote chances for small hail growth. In addition, sounds are also showing deep inverted 'V' shape from the surface to around 5000 ft. This suggests that some of these storms have the potential to produce gusty down bursts.

The upper-level trough will continue to dig south, pushing the front farther SE on Monday. This will allow for thunderstorm potential along the Eastern Interior and Upper Tanana as the front will not have passed over just yet. Rain will be the main precip type for most of the Interior. Areas over the Brooks Range will see mostly snow with the cooler temperatures still in place. In addition, this setup will provide widespread snowfall across the Brooks Range throughout the day today into the early hours on Monday. A Winter Weather advisory remains in effect for the Central Brooks Range. Total snowfall accumulations are expected to be between 5 and 10 inches. The gusty winds, mentioned earlier, mixed with the snow could produce areas of blowing snow at times as well.

A more widespread swath of precipitation is expected under the front itself, bringing another round of showers across the Interior on Monday. Colder temperatures will accompany the front as it works its way south, with lows regionwide in the 20s/30s/40s. We will continue to monitor the potential for frost/freeze headlines for Fairbanks during this timeframe, which will be centered around Monday night and Tuesday night when temperatures are expected to be coldest. This will be followed by a gradual warmup through the rest of the week. More on this in the extended portion of the AFD.

EXTENDED FORECAST DAYS 4-7

Wednesday through next Sunday. On Wednesday, the big upper low over the Arctic will loosen its grip as a ridge over Canada and the Aleutians begins to merge. This brings a warm up to most of Northern Alaska through next weekend. While ridging usually means warm and dry, this will be a bit of a dirty ridge since there is a remnant low in the Gulf. This means there'll likely be clouds around with showers and storms across the region. Exact details with the placement of showers and storms are uncertain as numerous shortwaves meander around Northern Alaska. Then towards the weekend, there is a bit more uncertainty with what happens with the ridge over Canada. However, compared to yesterday, there is more consensus that the ridge will set up along or just to the west of the CONUS west coast late next week and into the weekend. This leaves room for a low around the Alaska Peninsula or western Gulf of Alaska which would continue to provide southerly flow to much of Northern Alaska. What all of this is saying is, a return of summer-like weather is expected in the extended period with more widespread showers, thunderstorms and warmer temperatures. Speaking of temperatures, there may be a prolonged period of mid 60s to mid 70s, potentially warmer, in the Interior with 50s/60s along the West Coast and 40s to 60s from the North Slope to the Brooks Range.

Coastal Hazard Potential Days 3 and 4...None

FIRE WEATHER

Sunday afternoon will have the best chances for scattered showers and isolated thunderstorms across the southern and eastern Interior for the next few days. Areas around McGrath, to Fairbanks, to the Yukon Flats, will see convective showers developing and tracking eastward through the evening with an occasional thunderstorm mixed in. The greatest chance for lightning appears to be in the Eastern Interior, as storms that trigger off the White Mountains move east. Mixing heights for these storms are generally above 5000 feet which may facilitate gusty winds near downdrafts and dry lightning. Westerly winds will be particularly strong for most areas on the West Coast and in the Interior through Tuesday evening as a series of troughs orbiting the main arctic low slide west to east across the Brooks Range. Gusts up to 35 mph will increase spread potential if any surface fires develop.

A cold front will begin to swing southeast across the state on Monday. As it does, it will bring widespread, light showers through the day Monday. Behind the front, temperatures will be cool, low 60Fs of below for most of Northern Alaska, but also dry with minimum relative humidities in Interior valleys bottoming out in the 20s after the showers end on Tuesday with similar conditions on Wednesday.

Temperatures in the Interior should warm back up to near average, upper 60s near 70F, by Wednesday and continue to gradually warm as a ridge builds in through the latter half of the week. The ridge will also suppress precipitation chances. However, lighter winds and positive moisture advection should help mitigate fire weather conditions.

HYDROLOGY

Sagavanirktok, Colville, and Kuparuk Rivers

Below normal temperatures continue across the North Slope, with APRFC's breakup map showing some open to mostly open water on the Sag, Colville, and Kuparuk Rivers outside of immediately along the Arctic Coast where mostly ice remains in place. Fresh Eyes on Ice reports indicate that there could be some minor ice jams forming near the coast, but impacts remain limited at this time and is more just backing up water.

Colder temperatures will remain in place through early next week with warming temperatures expected Tuesday onwards. By as soon as Thursday and Friday, highs in the 50s and 60s will be in place across the Arctic Plains with 30s/40s along the Arctic Coast. This will likely accelerate snowmelt and lead to rises on North Slope rivers. With the recent cooldown and drop overall in most river levels, this will likely give enough room for new snowmelt to join the channels and help mitigate any significant flooding concerns at this time. Stay tuned.

For the latest breakup information, visit weather.gov/aprfc.

AFG WATCHES/WARNINGS/ADVISORIES

AK...Winter Weather Advisory for AKZ809. PK...Small Craft Advisory for PKZ804. Small Craft Advisory for PKZ806. Gale Warning for PKZ808. Gale Warning for PKZ809. Small Craft Advisory for PKZ810. Brisk Wind Advisory for PKZ855. Brisk Wind Advisory for PKZ856.