textproduct: Fairbanks

SYNOPSIS

A cold front continues to push SE from the Chukchi. Ahead of the front, today, a chance for thunderstorms is possible along a line from the Yukon Flats to the Upper Kuskokwim as instability increases. In addition, gusty winds can be expected across the Interior today. The associated upper-level, Arctic trough will continue to dig south through the start of the week. This will bring a brief period of seasonably colder temperatures to much of the state. Thunderstorm chances shift further SE on Monday as the front moves across the Interior, however widespread showers can be expected during the day. As the week continues, a gradual warming trend can be expected.

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 SE.

- Gusty west/southwest winds will increase across the Interior today, strongest farther north and across higher elevations where gusts up to around 30-40 mph are expected.

- 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 to the Brooks Range Sunday into Monday as a cold front passes over the region.

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

FORECAST ANALYSIS AND DISCUSSION

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.

FIRE WEATHER

Sunday, a band of vorticity being stretched from from the middle Kuskokwim Valley to the Yukon Flats will help showers and isolated thunderstorms develop over that area, with the highest likelihood in the Eastern Interior. After Sunday, thunderstorm coverage is pushed back into the Southeast corner of the Interior as a cold and dry air mass digs down over Northern Alaska through the middle of the week.

Speaking of the arctic air mass, it is presently keeping the Northwest parts of Alaska cool, highs under 60F with lows below freezing. The cold temperatures will suppress fire activity for the near future and 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 but also dry with minimum relative humidities in Interior Valleys bottoming out in the 20s after the showers end on Tuesday.

HYDROLOGY

No changes from the previous hydro forecast discussion.

Sagavanirktok, Colville, and Kuparuk Rivers

Below normal temperatures continue across the North Slope, with APRFC's breakup map continuing to show 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. 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.

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

EXTENDED FORECAST DAYS 4-7

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

AFG WATCHES/WARNINGS/ADVISORIES

AK...Winter Weather Advisory for AKZ809. PK...Small Craft Advisory for PKZ806. Brisk Wind Advisory for PKZ807-855. Brisk Wind Advisory for PKZ808-809-856. Small Craft Advisory for PKZ810.