textproduct: Fairbanks

SYNOPSIS

Active weather returns to the Bering Sea coastline late tonight through Sunday as broad southerly flow spreads north across the remainder of Northern Alaska. A warm front is lifting north across the Brooks range early this afternoon then from southeast to northwest across the North Slope/Arctic Coast tonight and Sunday. This front brings the warmest air mass of the season so far ahead of a rapidly deepening low pressure that tracks into the southern Bering Sea this evening. An occluded front shifts northeast along the West Coast and St. Lawrence Island on Sunday bringing a 6-12 hour of steady rain/snow mix and easterly winds gusting up to 45 mph. Another wave of energy tracks north on Tuesday bringing a cool front resulting in mainly rain showers and slightly cooler temperatures for Wednesday into Thursday before southerly flow returns by Friday. A few inches of wet snow are possible with that cool front, mainly above ~2500 ft elevation.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Persistent chinook flow keeps highs near to above average, in the 50s and low 60s across the interior valleys.

- A cool front brings scattered rain showers Tuesday afternoon with the most intense cells bringing potential for graupel and perhaps the first few lightning strikes of the season.

- Southerly gap winds gradually increase on Sunday with gusts up to 50 mph possible Sunday night before diminishing on Monday.

West Coast and Western Interior... - Another Bering Sea low brings easterly winds gusting up to 45 mph for the YK Delta Coast and southern Seward late Saturday night before subsiding Sunday night with wet snow at higher elevations.

- Easterly winds up to 45 mph bring potential for an ice shove (ivu) across Maknik Lagoon on Sunday or Sunday night combined with up to 3 inches of wet snow for much of St. Lawrence Island.

- Rain and snow showers persist through the week. High temperatures range from the 40s and low 50s in the Interior to mid and upper 30s along the coast.

North Slope and Brooks Range...

- Areas of light snow and east wind gusts up to 35 mph in Point Lay today. Wind weakens tonight then return Sunday evening.

- High temperatures in the southern Brooks Range rise into the 40s to near 50. The northern Brooks Range will range from the mid 20s to mid 30s. The Arctic Coast will be in the low to mid 20s with Point Hope being in the upper 30s to near 40.

- A cool front brings snow chances from west to east Tuesday afternoon through Wednesday with accumulations possible for Atigun Pass.

FORECAST ANALYSIS AND DISCUSSION

The overall pattern won't be changing much over the next week. An upper low will remain over the Bering Sea with an upper high over western Canada. However, there are two frontal systems bringing more focused wind/precipitation chances over the next 5 days. The first front is an occluding front that moves onto the YK Delta coastline early Sunday morning ahead of a deeply wrapped up ~955 mb low across the southern Bering Sea. The second frontal system is more of a cold front associated with an energetic shortwave pivoting around the Bering low that lifts across northern Alaska Tuesday/Wednesday.

The occluding frontal system weakens as it moves into our area and is moving into a seasonably warm air mass suggesting lesser impacts. However, the combination of 6+ hours of steady cold rain or perhaps very wet snow and easterly winds gusting up to 45 mph confirm that it will be lousy weather as the front moves across the YK Delta, Seward Peninsula, and St. Lawrence Island. The potential for an ice shove (ivu) continues to be monitored across Maknik Lagoon. The southwest cape up to Powooilak Camp is also exposed, but sea ice is farther offshore and may not be able to reach the coast before winds weaken.

The next front brings mainly rain chances to many of the same locations Monday and Monday night before shifting northeast across the remainder of northern Alaska Tuesday through Wednesday. The upper level disturbance is energetic and negatively tilted implying strong dynamic forcing that could support convective showers with charge separation for the first lightning strikes of the season. Even if thunderstorms don't materialize, graupel is definitely possible with the stronger cells Tuesday afternoon/evening. Further south across the Alaska Range, southerly gaps winds and high elevation snow are looking more likely. Snow levels appear to be 2500-3000 ft suggesting the Parks/Richardson highways won't be impacted, but heavy wet snow and strong winds may overload the existing snow pack resulting in some avalanche potential.

EXTENDED FORECAST DAYS 4-7

The extended forecast continues to feature troughing across the Bering and ridging across western Canada resulting in southerly flow over most of the state. The two most noteworthy features appear to be the frontal boundary lifting across the Brooks Range Tuesday night into Wednesday and the second is a low pressure system tracking north near the YK Delta Wednesday night and Thursday. EFI guidance is highlighting potential for unseasonable QPF and snowfall across portions of the Brooks Range and North Slope with the frontal boundary Tuesday night/Wednesday. EFI guidance indicates a similar combination of unseasonable QPF/snowfall potential across the YK Delta and St. Lawrence Island Wednesday night through Thursday night. Elsewhere, southerly winds across the Central Interior/West Coast and gusty winds through the Alaska Range passes remain possible, especially Thursday/Friday when the WPC is highlighting potential for high winds.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Brisk Wind Advisory for PKZ801-802-817-853. Brisk Wind Advisory for PKZ803-805-806-852. Small Craft Advisory for PKZ816. Brisk Wind Advisory for PKZ850. Gale Warning for PKZ851. Gale Warning for PKZ854.