textproduct: Fairbanks

SYNOPSIS

Conditions will trend drier across the Interior today as attention turns to North Slope, where a series of fronts tracking E/SE will bring scattered to widespread rain/snow showers today into Wednesday farther north. Convective snow showers could lead to heavy snow at times, with highest snow accumulations through Wednesday expected in the Brooks Range and Eastern Arctic Coast. Light rain and high elevation snow showers will track southeast across the Interior later today into tonight and Wednesday associated with an Arctic front working over the Brooks Range. Out west, a strong low pressure system is expected to move into the Bering Sea midweek. Widespread moderate to heavy rain and gusty winds will build into Western Alaska Wednesday into Thursday as a warm front moves in, with those impacts pushing northeast into the Interior Thursday into Friday.

KEY MESSAGES

Central and Eastern Interior...

- Isolated rain and high elevation snow showers will continue across the Eastern Interior today. An Arctic front working southeast over the Brooks Range later today into tonight and Wednesday will support another round of scattered rain/mountain snow showers.

- Clearer skies this morning across much of the Interior has led to lows dropping to the upper 20s to low 30s, with warmer areas in the mid 30s to low 40s. Highs today will be in the upper 40s to mid 50s.

- Cloudier skies will build in tonight into early Wednesday with the Arctic front, with lows dropping to the low to mid 30s. Highs tomorrow will be in the mid 40s to low 50s. Winds out of the W/NW will pick up throughout the day Wednesday, with gusts around 20 to 30 mph.

- The first widespread hard freeze is expected across the Interior Wednesday night into Thursday morning, as clearing skies support the coldest temperatures we have seen so far this season. With lows dropping to the 20s to low 30s regionwide, Thursday morning is shaping up to the coldest in over three months.

- Atmospheric river moisture from a strong low pressure system in the Bering Sea will lift northeast into the Interior Thursday into Friday, with widespread rain and breezy gap winds through Alaska Range passes. Winds gusts at Windy Pass south of Healy and north of Isabel south of Delta could see gusts peak around 40 to 50 mph.

- A first look at rainfall amounts Thursday through Friday night shows around 0.50 to 1.00 inches for the Central Interior west of and including FNSB, and 0.10 to 0.25 inches east of FNSB. Driest conditions will be just north of the Alaska Range and Alcan Border, with dry conditions expected in the Upper Tanana/Fortymile region.

West Coast and Western Interior...

- Rain and high elevation snow showers will continue to build into Northwest Alaska and the Northern Interior today into Wednesday as a series of fronts drop southeast from the Chukchi Sea. Winds will remain breezy in this corridor out of the W/NW with gusts to around 20 to 30 mph.

- Atmospheric river moisture from a strong low pressure system in the Bering Sea will lift northeast across the West Coast throughout the day Wednesday, pushing into the Western Interior Wednesday night into Thursday. Widespread moderate to heavy rain and gusty winds are expected regionwide with this system.

- A first look at rainfall amounts Wednesday through Thursday night shows around 0.50 to 1.50 inches across all of Western Alaska, with highest totals at St. Lawrence Island and the Southern Seward Peninsula. Locally wetter spots could approach two inches.

- Strongest winds Wednesday through Thursday will be out of the E/SE, shifting to the S/SW late Thursday into Friday as winds lessen. Peaks wind gusts are expected to be around 30 to 50 mph across the West Coast (strongest at St. Lawrence Island) and 20 to 40 mph for the Western Interior.

- While minimal coastal concerns are expected as winds remain S/SE initially and favor more offshore flow, winds shifting to the S/SW late Thursday into Friday could lead to higher water around the Yukon Delta and Norton Sound region. High surf is possible in this area, with water levels potentially reaching 1 to 3 feet above the normal high tide.

- Lows in the 30s/40s and highs in the 40s/50s will see a warming trend later this week as southwest flow builds into the region.

North Slope and Brooks Range...

- Scattered to widespread rain and snow showers will continue to track east today into Wednesday as a series of fronts track across far Northern Alaska from the Chukchi Sea.

- Convective snow showers could lead to heavy snow at times, with highest snow accumulations through Wednesday expected in the Central/Eastern Brooks Range and Eastern Arctic Coast from Point Thomson to Kaktovik. Snow accumulations here are expected to be 3-6 inches above 2000 feet and 1-3 inches below 2000 feet, with a Special Weather Statement now in effect.

- Temperatures will hold steady or see a cooling trend through Thursday, with highs in the 30s/40s and lows in the 20s/30s. High elevations of the Brooks Range tonight and Wednesday night could drop to around 10-20F with wind chills down around 0-10F.

- A Bering Sea low will send a warm front into far northern Alaska Thursday into Friday, with widespread precipitation and warmer temperatures expected courtesy of southwest flow.

- A first look at rainfall/QPF amounts Thursday through Friday night shows around 0.25 to 0.75 inches for the Brooks Range, and 0.10 to 0.25 inches across the Arctic Coast/Plains. Colder temperatures out ahead of this system will support a rain/snow mix at higher elevations.

SHORT TERM

Today through Thursday Night. Early morning satellite shows a 990 mb surface low in the Gulf of Alaska, a 522 dam upper level low around 75N over the High Arctic, and a 595 dam upper level ridge centered over the North- Central Pacific. Off to the west of the Aleutians, a 550 dam upper level low has begun to slowly lift north towards the Western Bering Sea. The main impacts from the low now in the Gulf are behind us this morning, with residual moisture on the back end of the low leading to isolated showers across the Eastern Interior and Alaska Range today. Up north, that broad H5 low in the High Arctic continues to eject a series of shortwave troughs and associated fronts into Northwest Alaska with scattered to widespread rain/snow showers. The leading edge of the Arctic front is currently situated over the Central North Slope, draped southwest over the Seward Peninsula. This front will continue to track southeast today into tonight and Wednesday, supporting increasing coverage of isolated to scattered rain/mountain snow showers across the Interior while more persistent precipitation chances remain focused in the Brooks Range north.

The latest forecast for this Arctic front remains on track with respect to snow, with the bulk of accumulations expected across the North Slope and Brooks Range, with lighter amounts across higher elevations of the Interior and Alaska Range. Have gone ahead with a Special Weather Statement for the Central/Eastern Brooks Range and Eastern Arctic Coast between Point Thomson and Kaktovik for more widespread moderate snowfall amounts, with amounts ranging from 1 to 3 inches below 2000 feet and 3 to 6 inches above 2000 feet with locally higher totals above pass level. High confidence supports these totals with northerly upslope flow and colder temperatures supporting snow ratios up to around 15:1 across the higher elevations as summit temperatures drop to the teens. An initial rain/snow mix along this section of the Arctic Coast will see a transition over to all snow tonight into Wednesday. Farther west across the North Slope, ocean effect rain/snow showers from the Chukchi Sea will continue to build into the Western Arctic Coast/Plains, with convective snow showers leading to locally heavy bands of snow. Snow accumulations in this corridor have lower confidence given more marginal temperatures along the coast, but just inland we are expecting totals closer to that SPS amount above.

As this midweek Arctic front works southeast across the Interior later today into tonight and Wednesday, clearing skies behind the front will help lead to the coldest night for most since May for Wednesday night particularly across the Central/Eastern Interior. 850 mb temperatures around 0C to -5C will support low temperatures by Thursday morning dropping to the 20s to low 30s.

Looking back west towards the Bering Sea, confidence continues to increase that the low entering the Bering will intensity as it forms a triple point low, which will eject a strong warm front into Western Alaska Wednesday into Thursday. This system will be tapping into atmospheric river moisture from as far south as 20-30N, which will lead to moderate to heavy rainfall potential across Western Alaska, extending northeast into the Interior and towards the Brooks Range. Rain will first reach the Yukon Delta throughout the daytime hours Wednesday, lifting northeast across the West Coast and into the Interior Wednesday night into Thursday and Thursday night. Strongest winds Wednesday through Thursday will be out of the E/SE, shifting to the S/SW late Thursday into Friday as winds lessen overall. Peaks wind gusts are expected to be around 30 to 50 mph across the West Coast (strongest at St. Lawrence Island) and 20 to 40 mph for the Western Interior. A first look at rainfall amounts Wednesday through Thursday night shows around 0.50 to 1.50 inches across all of Western Alaska, with highest totals at St. Lawrence Island and the Southern Seward Peninsula. Locally wetter spots could approach two inches. For forecast details and amounts across the Interior, see the long term discussion below, as the bulk of impacts shift into this region later Thursday into Friday. Another driving force with this system will be prevailing southwesterly flow, allowing for warming temperatures regionwide as we finish out the week.

LONG TERM

Friday through next Tuesday. The extended period begins with a 500mb pattern ideal for southwest flow into the Interior. An upper-level ridge extends northward from the north Pacific with the ridge axis over eastern Alaska. Meanwhile a low in the Bering Sea is directing moisture from the tropics into Interior Alaska. As mentioned in the short term, a large amount of the rain associated with these features will fall in Western Alaska. Still, models depict a swath of precipitable water up to 1.25 inches coming into the southern Interior Friday morning. Rain amounts in the Kuskokwim Valley and even as far inland as the White Mountains could see around a quarter to half an inch of rain on Friday with higher totals expected near the source of the moisture in the southwest Interior. Another push of moisture on Saturday appears to take a more northerly track across South Central into the Interior, but with similar rain amounts once again spread across the western and central Interior, a quarter to half an inch. In total through Friday and Saturday, areas of higher terrain in the Central and Western Interior will likely see between 0.75 and 1 inch. Other parts of those regions could get between 0.25 and 0.75 inches. Fortymile Country to the Yukon Flats look to get between 0.1 and 0.25 inches, and the Tanana Valley southeast of Delta Junction looks to remain mostly dry, especially southeast of Tok. The West Coast will also receive rain amounts between a tenth to a quarter, and up to a half inch in the Southern Seward Peninsula is possible during this time.

In addition to the rain it should be warmer than it has been recently, with generally southerly flow bringing a warmer air mass to Alaska. Temperature should warm up to around or above seasonal normals by the weekend. The warmest temperatures will be in the southeast Interior, where temperatures near 70F are within the realm of possibility this weekend.

Conditions should be less wet on Sunday, but there is another low making its way along the eastern Aleutians on Sunday morning that models are unsure whether to send east towards the Gulf, or more north into Western Alaska. Its trajectory will also have an effect on southerly gap winds in the Alaska Range, which look to strengthen as the low nears Bristol Bay Sunday night. Regardless, the pattern of unsettled weather coming in from the Pacific doesn't look to end any time soon.

COASTAL HAZARD POTENTIAL

With respect to our next coastal storm moving into Northern Alaska, minimal coastal concerns are expected associated initially as the strongest winds remain S/SE and favor more offshore flow. Winds shifting to the S/SW late Thursday into Friday however, could lead to higher storm surge around the Yukon Delta and Norton Sound region. High surf is possible in this area, with water levels potentially reaching 1 to 3 feet above the normal high tide.

FIRE WEATHER

The best chance for wrap around precipitation into the Upper Tanana Valley was earlier Tuesday morning, as a low dropped from South Central Alaska into the Gulf. However, light showers will linger, diminishing through the Tuesday morning. Northwest winds follow a similar trend. Their peak was Monday with the passage of the low into the Gulf, but breezy conditions will persist through Tuesday. More cool days are ahead of us as an Arctic air mass descends from the north into the Interior on Wednesday. Along with the passage of the cold front, there will be light showers, generally less than a tenth of an inch, and gusty west/northwest winds which will funnel through the Tanana Valley, gusting up to 25 mph Wednesday afternoon. Thursday morning will see chances for temperatures below freezing across the Interior. Temperatures increase going into the weekend as the cold air gets replaced by warmer, and wetter, air from the south. Maximum temperatures should go from the 40s on Wednesday, to mid/upper 50s on Thursday, to the 60s on Friday and through the weekend. Relative humidity should be lowest on Thursday, as temperatures rise but the moister air hasn't arrived in the southeast Interior. Minimum RHs may be as low as the 30s on Thursday before increasing going into the weekend.

HYDROLOGY

Overall rainfall amounts Wednesday through Friday night continue to have increasing confidence, showing around 0.5 to 1.5 inches across the Central/Western Interior, Brooks Range, and Western Alaska. Locally higher totals up to around 2 inches will be possible across the West Coast. Expect water level rises on area rivers and streams as a result of this rainfall, but no flooding is anticipated at this time.

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. MARINE...Small Craft Advisory from 1 AM to 6 AM AKDT Wednesday for PKZ851.