textproduct: Fairbanks

SYNOPSIS

An active weather pattern will continue across Northern Alaska into early next week, as moisture from the Bering Sea continues to build into the West Coast and Interior with snow and gusty winds while a cold and very dry airmass builds in out of the north. These two airmass will meet in the Interior, setting the stage for widespread snowfall. With afternoon highs above freezing for most locations in Interior, we could see a rain/snow mix at times particularly farther south. Any wet/slushy spots will likely refreeze overnight, leading to potentially icy surfaces. Poor drainage areas could see localized pooling/ponding of water. Another system will affect the area by the middle of next week, with more snow and mixed precipitation possible, especially in Western Alaska, as temperatures broadly warm.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Scattered light snow showers will continue across the Interior today, with a front moving in Sunday into Monday bringing in more moderate, widespread snowfall through early next week.

- Snowfall totals will range from around 1-4" in the valleys and 3-8" in the mountains. Locally higher totals are expected in the Alaska Range, where around 8-16" of snow is expected for higher elevations of the Parks and Richardson Highways with locally higher totals above pass level.

- High temperatures will continue to be above freezing for most, leading to the potential for a rain/snow mix at times particularly farther south. Any wet/slushy spots will likely refreeze overnight, leading to potentially icy surfaces. Poor drainage areas could see continued pooling/ponding of water.

West Coast and Western Interior...

- A front will bring strong winds to most of the West Coast, with the strongest winds at St. Lawrence Island and through the Bering Strait, where northeast winds could gust around 50-65 mph. Areas of blowing snow could significantly reduce

- This same front also provides snow beginning this morning in the Yukon Delta and gradually traversing north and east through tonight and Sunday.

- Rain will likely mix with the snow in the Lower Yukon and Upper Kuskokwim Valleys from Mountain Village to McGrath with the best chances being Sunday afternoon.

- Prior to the rain, snow amounts will be around 4 to 7 inches. North of the mixing line, snow amounts will range between 5 to 10 inches from Ruby to Kaltag and 3 to 6 inches in the Kobuk Valley.

- Any rain across the area will change back to light snow and snow showers Monday afternoon which will linger into Tuesday.

- Winds will also gradually weaken on Monday and Tuesday. Another system looks to move into the area on Wednesday.

North Slope and Brooks Range...

- Generally quiet weather on the North Slope with below normal, cold temperatures continuing into next week.

- Light snow continues in the Central Brooks Range through this evening with only light accumulations around 1 to 2 inches expected. - Another area of snow arrives on Sunday, particularly late in the day and gradually traverses north to the coast Sunday night and Monday.

- This second round of snow will bring another 1 to 3 inches in the North-Central Brooks Range with around 1 inch on the North Slope.

UPDATE

Winter Storm Watches have been upgraded to a mix of Winter Storm Warnings and Blizzard Warnings with Winter Weather Advisories issued for the Interior. Special Weather Statements have also been put in place for areas surrounding areas. Stay tuned for updates over the coming days as an active weather pattern remains in place.

FORECAST ANALYSIS AND DISCUSSION

Today through Monday Night. Active, unsettled weather continues through next week across Northern Alaska. Elongated troughing aloft from over the Arctic (with minimum 500 mb heights of around 512 dm) extends across the North Slope and the Seward Peninsula. At the 850 mb level, temperatures are around 22C at 850 mb over the North Slope and 15C over the Seward Peninsula. Cold air associated with this area of troughing along with northerly winds will permit colder surface high temperatures today in Western Alaska; highs on the Seward Peninsula/coastal areas are expected to be in the single digits and teens above zero, with highs in the Western Interior in the mid to upper 20s from around Galena north. Scattered showers continue across an area extending from Norton Sound to the Central Brooks Range and are receiving dynamic support from a shortwave trough moving northeastward across the Interior. More numerous showers are occurring across the Alaska Range and will persist through the next few days. Snow will be heaviest on the southern side of the Eastern Alaska Range south of Trims Camp; near the Richardson Highway, some surface melting during the daytime periods followed by later refreezing could result in slick road conditions.

The primary weather maker for the next few days will be an extratropical cyclone over the southern Bering Sea. The minimum central pressure of the low-pressure center of this system is estimated to be around 960 mb. While the surface low will be fairly strong (and vertically-stacked with its corresponding upper low), it will not directly affect land at this intensity; the primary impacts will instead occur along the leading warm front well east of the low, where brisk easterly to northeasterly winds will blow across the northern Bering Sea and adjacent coastal areas. In the Bering Strait and through the Chukchi Sea, they will have a more northerly orientation. The front will move ashore over the YK Delta by this afternoon/evening and with it, a broad line of precipitation will begin to affect the area while moving in a consistent southwest-to-northeast direction. Ridging over the eastern Aleutians ahead of this system will push eastward, with meridional flow setting up over southcentral Alaska. By this afternoon and evening, snow showers in the southern Alaska Range should dwindle. Tonight into tomorrow, ahead of the upcoming front, additional showers will develop in the Central/Eastern Interior and may be convectively driven, with many forming off the higher terrain. These showers will likely continue through Saturday evening, and their precipitation type could be diurnally- driven in the valleys, with rain more likely during the afternoon/evening hours. Heavy snow on the south side of the Alaska Range will likewise resume tonight, with upslope flow supporting high snowfall rates at times. There could still be some messiness, with potential icy/slick conditions again possible.

The front itself will largely affect the Western and Central Interior from Sunday through Tuesday. In these areas, liquid- equivalent precipitation could range significantly, with lower totals around 0.2 inches on the margins to higher totals of ~0.7 inches near the center of the main band. In spite of some briefly warmer temperatures with the initial warm front, temperatures even in valleys locations in the Western Interior will remain fairly cool, with most precipitation falling as snow. The best chances for any daytime rain mixing in with snow will be in the Lower Upper Kuskokwim and Lower Yukon Valleys. Snow ratios could be high; models soundings indicate potential for saturated dendritic growth zones which could support ratios of 15:1 or higher at times. This will allow for many areas to potentially receive 6 inches or more of snow through Tuesday morning, especially between the Lower Yukon Valley and Bettles. The Dalton Highway Summits, White Mountains, and Yukon Uplands could also potentially see several inches of snow accumulation. There is uncertainty on snow totals for the Middle and Upper Tanana Valleys, but ensemble guidance supports the potential for at least a few tenths of an inch of liquid equivalent precipitation with numerous showers in the area, especially Sunday night into Monday morning. If this were to verify, multiple inches of snow would be possible in the area (although this could be affected by melting during afternoon periods).

While snow totals across much of the West Coast/St. Lawrence Island will likely be lower than inland, blowing snow will be possible where fresh or especially falling snow can combine with strong winds. Blizzard conditions are possible over both the YK Delta and St. Lawrence Island, but potential will depend on how much snowfall either area can get (and how winds coincide with falling snow). On Sunday, while there will generally be zonal flow aloft over the Alaska Range, which is not usually supportive of gap winds, there will be a strong surface pressure gradient of about 6 to 8 mb across the mountains. This will permit breezy/gusty winds through the passes. Easterly winds will also pick up on the eastern Arctic Coast from Sunday into Monday night as high pressure develops over the Beaufort Sea.

EXTENDED FORECAST DAYS 4-7

Tuesday through next Saturday. Tuesday in Wednesday, cold air with the Arctic trough will again dip into Western Alaska, dropping highs below freezing. It will then wrap eastward behind the last remaining snow showers in the Interior from the previous system and cause high temperatures on Tuesday to fall into the mid or low 30s even in the warmer valley areas. This will be short-lived, as another system entering the eastern Bering Sea pushes a warm front across the area which will push the cold air back out. Along the front, as with the previous system, winds will generally be easterly and strongest over the water. It will also bring another round of precipitation, with better chances for rain or rain/snow mix in the Western Interior than with the first system given the warmer airmass. The precipitation band moves in a more south-to-north direction, which will also limit the precipitation in the Central/Eastern Interior to a greater extent while allowing for much more to fall over the western North Slope. By the late week period, highs in parts of the Interior could rise into the 50s, with highs on the West Coast rising back above freezing and highs on the North Slope rising into the teens above.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ849. Winter Storm Warning for AKZ829-850. Winter Storm Warning for AKZ830-852. Winter Storm Warning for AKZ824. Winter Storm Warning for AKZ825-826. Blizzard Warning for AKZ827. Winter Weather Advisory for AKZ832-834-838-842-843-846. Winter Weather Advisory for AKZ848. PK...Brisk Wind Advisory for PKZ801. Gale Warning for PKZ802-853. Gale Warning for PKZ803-852. Brisk Wind Advisory for PKZ804-805. Brisk Wind Advisory for PKZ806-807-810-811-856-857. Gale Warning for PKZ816-817. Heavy Freezing Spray Warning for PKZ816. Gale Warning for PKZ850. Storm Warning for PKZ851. Storm Warning for PKZ854.