textproduct: Fairbanks

.KEY MESSAGES

Central and Eastern Interior...

-Snow will continue in the Alaska Range, with periods of heavy snow expected through Wednesday morning. Isabel Pass will receive the most snow of about 24 to 36 inches.

-Snow is expected throughout the Interior. Gusty winds in higher elevation are possible, especially within the Upper Tanana Valley. * 4 to 7 inches expected for Nenena/Fairbanks/North Pole. * 5 to 10 inches for the Denali Borough. * 5 to 10 inches from Eielson AFB to Eagle Summit. * 6 to 12+ inches for most of the Eastern Interior with elevated terrain seeing locally higher amounts.

-Light mixed precipitation is possible for Northway and the Alcan border throughout Tuesday.

-Temperatures will drop later this week, with highs in the upper 20s and lows in the single digits. *Some portions of the Interior could see temperatures drop to 0 degrees.

West Coast and Western Interior...

-Rain and snow will continue through Tuesday afternoon. *Accumulations between 1 to 2 inches are possible from the Yukon Valley to McGrath

-A strong coastal storm is expected in the Bering Sea Friday morning, which could result in prolonged coastal impacts and strong winds late this week.

North Slope and Brooks Range... -Snow fall will be gradually decreasing through Tuesday along the Northwest Coast *Some snow showers could linger slightly longer. Accumulations will be minor.

-Temperatures will stay below freezing. Outside of the Chukchi Sea Coastline that will remain near to above freezing.

SYNOPSIS

A very active weather pattern is moving in for the northern interior, while another system lines up to impact the West for the latter half of the week. The first system, moving through Tuesday and Wednesday, will bring substantial widespread accumulating snow across the eastern interior from FNSB on east, with lower amounts for areas along the Kuskokwim Mountains. Cooler temperatures sweep in behind this system for the second half of the week, before attention turns towards a potentially impactful Bering Sea low, which could bring coastal impacts and heavy snowfall (at elevation) from Friday through the weekend.

SHORT TERM /THROUGH THURSDAY NIGHT/

The short term begins with the 996 mb low continuing to trend through the Northern Gulf. As it does, it will deepen slightly to a 980mb low by early Tuesday morning. This system will then go through a brief period of cyclogenesis,where a strong warm front associated with this storm develops and is sent north/northeast through the Interior, leaving our area through the Yukon Territories by Tuesday evening. This system will be the driving factor of the weather over the next 24 to 30 hours, and the impacts this system will bring will be dependent on the placement of its warm front. Even with the storm less then 8 hours out, there still remains discrepancy on how much snow this storm could bring. Only a 20 mile displacement of this warm front could drastically change the expected snowfall amounts within the Interior. This sensitivity in placement is why many models are still struggling to build confidence on which areas will experience the heaviest snow through Wednesday.

Although we are leaning towards the front trending more easterly, directing the bulk of the snow to the Eastern Interior, it would not take much for this system to shift more westerly. Which as a result, would create a heavier snowfall pattern for both the Central and Eastern Interior. Currently, some model solutions suggesting that the storm will remain over the YK-Delta until midday Tuesday. However, observations have already shown the storms surface low over Mainland Alaska early this morning. This discrepancy alone could make the warm front potentially trend slightly more westerly, and significantly change snowfall totals in the process. The most recent model guidance suggests that Fairbanks could accumulate 4 to 7 inches of total snowfall Monday through Wednesday afternoon, with the North Pole potentially having higher chances of exceeding 7 inches. However the total snowfall amount is subject to change depending on the fronts positioning through this time.

Due to a saturated atmosphere and weak 500mb shortwaves, there has already been some snow accumulating within the Interior. The expectation is that through Tuesday morning, lower ratio snow will persist. This is due to the temperatures at the surface remaining just at or below freezing. Warmer surface temperatures could allow for some minor melting to occur as the snow falls through the atmosphere, resulting in lower snow ratios. Along with the warmer temperatures, gusty winds within the DGZ (Dendritic Growth Zone) are expected to increase. This can cause the ice crystals in the DGZ to crash into each other, leading to larger crystals, and wetter snow accumulations. This process is known as collision and coalescence, where snowflakes grow in moisture content by colliding and sticking together as the fall through the DGZ. By midday Tuesday, temperatures will continue to drop, and winds aloft are expected to gradually decrease. Once this occurs, the probability for high ratio snow increases. The calmer wind speeds prevent the ice crystals from colliding resulting in a smaller moisture content as they fall, while the cooler temperatures prohibit the possibility of melting. Snowfall is expected to be the heaviest by late Tuesday afternoon, when the wind speeds are still relatively light in the DGZ, and there exists a substantial amount of lift available to keep the ice crystals aloft within the DGZ To grow.

Following this storm, cooler arctic air is will to return to the Interior, which could drop temperatures through the weekend. This is expected once a brief ridge builds in after the storm, leading to clear skies, fresh snow, and light winds, which can lead to strong inversions developing. Highs are expected to be in the upper 20s, and lows potentially reaching the single digits/zero degrees.

Looking further ahead, confidence grows in potential significant impacts from a coastal storm tracking to the Bering Sea late this week. This system has the potential to bring prolonged coastal impacts, gusty winds, and another round of precipitation throughout most of our area. This storm will be further discussed in the extended forecast section.

LONG TERM /FRIDAY THROUGH MONDAY/

The big story in the long term is the strong Bering Sea low in the late week that will likely bring with it coastal flooding concerns for the west coast and respectable snow accumulations for many areas at elevation across the western and central interior.

Ensembles have rapidly fallen into line around a strong low entering the Bering Sea on Thursday, before moving N into the Gulf of Anadyr through the weekend. A ridge ahead of the low will be unable to halt its advance, and will swiftly be displaced into eastern Alaska. Strong south/southwest flow along with a strong frontal band will sweep out ahead of the low and into the West Coast beginning on Friday. This will result in the potential for widespread coastal flooding impacts along much of the West Coast, in a broad arc ranging from the YK Delta up to Fort Wainwright. Water levels will rise on Friday and could remain elevated through much of the weekend depending on the final track, speed, and strength of the low. Confidence is also growing in the potential for accumulating snow - especially for more inland parts of the Western Interior and even moreso for areas at elevation including the Western and Central Brooks Range, the Nulato Hills, the Ray Mountains, and the interior Seward Peninsula. Gusty winds are also likely, with especially strong winds possible for places like Point Hope, the Western Seward Peninsula and St. Lawrence Island. Unfortunately, the steering flow will continue to direct storms into the Bering through the upcoming week, with another low arriving hot on the heels of the first system in time for late Sunday into Monday. In addition, ensembles have also started to hint at another possible Bering Sea low for the latter half of next week. Additional information on these upcoming lows will be provided as more details become available.

Further east across the Central and Eastern Interior, a much different picture will play out. Drier weather will be the name of the game early on, with cold early season temperatures will be temporarily ameliorated through the weekend as warm air advection streams northward, ahead of the low in the Bering. 850 mb temperatures across parts of the central interior will rally back into +1C to +2C values, and high temperatures will likely get back above freezing. The advancing front from the low in Bering Sea will weaken as it travels East, with snowfall totals diminishing as the front moves through the central interior on Saturday, and expect only chances of some showers by the time it arrives in the FNSB area on Sunday, although parts of the central Brooks Range could still see more respectable snowfall totals. Some breezy downsloping winds are also likely along the AK Range during this timeframe, as southerly flow wraps around the far eastern flank of the Bering Sea Low.

Coastal Hazard Potential...

Guidance has rapidly consolidated around a strong low pressure system entering the Bering Sea by Thursday of this week. This system will bring strong southeasterly winds as the system nears Alaska's West Coast, turning south/southwesterly through the weekend. While exact timing is not yet set in stone, confidence is growing that the strongest gusts are likely to occur Friday morning into Friday afternoon, with average gusts ranging from 45 to 70 mph. Most models are pointing towards the majority of the West Coast likely seeing gusts up to 60 mph. Coastal flooding concerns do exist, as the anticipated strength of the winds and the prevailing wind direction (south to southwest) would be favorable for water levels above the normal high tide line. Currently, concerns are greater for coastal flooding and erosion across nearly all of the west coast. Water levels will be monitored throughout the week as the system is slow-moving with strong onshore winds. By early next week, another low could bring additional rain, snow, strong wind and persistent coastal flooding or high surf concerns. Stay tuned for additional updates.

AFG WATCHES/WARNINGS/ADVISORIES

AK...Winter Storm Warning from 10 AM this morning to 4 PM AKDT Wednesday for AKZ833-834-838>840-843. Winter Storm Warning until 4 PM AKDT Wednesday for AKZ835>837. Winter Weather Advisory from 10 AM this morning to 4 PM AKDT Wednesday for AKZ841-842-844-845. Winter Weather Advisory until 4 AM AKDT Wednesday for AKZ847- 848. Winter Storm Warning until 4 AM AKDT Thursday for AKZ849-850. MARINE...Small Craft Advisory until 7 AM AKDT this morning for PKZ850- 853.