textproduct: Fairbanks

SYNOPSIS

A low in the Bering Sea will continue to bring gusty winds and moderate to heavy rain to western Alaska as a ridge of high pressure over the eastern Interior and Yukon Territory brings warmer and drier conditions farther east. Addition rainfall amounts through Thursday are expected to be highest around the Norton Sound, Lower and Middle Yukon Valleys, and southern slopes of the western Brooks Range where around 0.5 to 1.5 inches of rain is expected. Winds will also remain elevated through Alaska Range passes through Thursday, with gusts peaking around 30 to 45 mph. As the low in the Bering shifts northeast later this week, precipitation chances will work northeast across the Interior and North Slope Thursday into Friday, where isolated thunderstorms will be possible. The most active thunderstorm corridor is expected to extend northwest from the Fortymile Country and Alcan Border to the Brooks Range and Arctic Plains. Looking ahead, a ridge of high pressure is expected to fill in behind the exiting low into the Beaufort Sea as another low enters the Bering from Siberia. This setup will favor warmer and drier conditions returning across much of northern Alaska for early next week, with best rain chances staying farther west.

KEY MESSAGES

Central and Eastern Interior...

- Warmer and drier conditions will make a return today across much of the Interior. Daytime highs will rise into the mid to upper 70s with possibly a few low 80s farther east will stick around for the next couple of days.

- Winds will remain elevated through Alaska Range passes with gusts of 30 to 45 mph continuing through Thursday, strongest of which will be through Windy Pass along the Parks Highway.

- Outside of isolated showers through Wednesday farther west, those chances will expand east on Thursday with accompanying isolated thunderstorms. Best thunderstorm chances will be Thursday afternoon and evening along the Alcan Border north of the Tanana Valley northwest to the Brooks Range. Very isolated dry thunderstorms will also be possible.

- Temperatures will cool slightly for most on Friday and Saturday with highs in the 60s to mid 70s as isolated showers persist.

- Conditions will trend warmer and drier earlier next week under the increasing influence of high pressure.

West Coast and Western Interior... - Another front will be moving through the region today, bringing gusty winds and moderate to heavy rainfall. This front is expected to stall along the West Coast, leading to higher rainfall totals farther west through Wednesday and Thursday

- Addition rainfall amounts through Thursday are expected to be highest around the Norton Sound, Lower and Middle Yukon Valleys, and southern slopes of the western Brooks Range where around 0.5 to 1.5 inches of rain is expected. Lighter amounts are expected elsewhere.

- Gusty winds across western Alaska with gusts to around 25 to 35 mph will continue through tonight and Wednesday before dropping off Wednesday night into Thursday.

- As the front and associated low off the West Coast lift northeast Thursday into Friday, warmer and drier conditions will build in out of the southwest for Friday into Saturday under increasing high pressure.

- We are tracking another low to move into the Bering Sea over the weekend with another round of breezy winds and rain expected. This system is not favored to be as strong as the one earlier in the week.

North Slope and Brooks Range... - Temperatures will rapidly warm today across the region with the coastal communities being 50s to mid 60s and the Arctic Plains in 60s to low 70s. These warmer temperatures will continue until Friday when they will begin to cool.

- Gusty southerly winds will continue to strengthen across the Brooks Range, with wind gusts of 25 to 35 mph being possible across the range including Anaktuvuk and Atigun Passes. These elevated winds will weaken on Wednesday.

- Steady rain will continue for the western Brooks Range north of the Kobuk Valley today and Wednesday. Showers and isolated thunderstorms will lift northeast on Thursday across the Brooks Range and North Slope as a Bering Sea low tracks towards the Arctic Coast.

- As the Bering Sea low works over the North Slope Friday into Saturday, expect cooler and wetter conditions to finish out the week as winds remain light overall.

- Conditions will trend warmer and drier earlier next week under the increasing influence of high pressure as showers become increasingly isolated.

FORECAST ANALYSIS AND DISCUSSION

Today through Thursday Night. A fully occluded low is continuing to slowly move east into Norton Sound where it will stall and completely weaken. The wind field for this low is roughly 25 to 50 miles further east than what the models were depicting during the 00Z model runs yesterday afternoon. This shift while doesn't have many impacts, it does influence how high the waters will get along the coast. With a smaller fetch of wind pushing water towards the Southern Seward Peninsula than it will struggle to get above the 3 feet mark, this led us to cancel the high surf advisory for the Southern Seward Peninsula early.

As the occluded front makes its way through the West Coast and Western Interior today we will see another round of moderate to heavy rainfall. Through this morning the rain will be fairly widespread and stratiform, but as the afternoon progresses drier and cooler air aloft will encroach into the region. This will cause the rain to become showery in nature. Chinook flow will continue across the Central and Eastern Interior allowing the region to continue to dry out and warm up.

While the surface low will begin to stall and fall apart on Wednesday the 500 mb low remains closed off. This will provide support for scattered to widespread rain showers to continue across the West Coast and Western Interior. The closed off 500 mb low is nearly stationary due it being situated between a ridge axis over the Bering Sea and Western Canada. With enough moisture remaining in the Interior and cold air aloft we could see some very isolated thunderstorms to develop today through Wednesday, with best chances developing on Thursday.

By Thursday evening, a low coming off Eastern Siberia will be the force that begins to shift the weather pattern a bit. The biggest changes will be that persistent Bering Sea low off the West Coast lifting north, with rain chances lifting northeast through the Brooks Range and North Slope, but to a lesser degree across the Eastern Interior. What will change farther east will be increasing chances for isolated thunderstorms, with most active convective corridor expected to extend northwest from the Fortymile Country and Alcan Border to the Brooks Range and Arctic Plains.

FIRE WEATHER

The weather pattern becomes stalled as a low enters the Bering Strait and a ridge holds over the AlCan border. As a result, we see rainy and windy conditions in western Alaska and dry and warm weather in the Interior. This general pattern looks consistent through Thursday morning, with minor changes in the position of these two features. However, the low will weaken through the period, gradually decreasing its influence. South winds will weaken from gusts near 25 mph to 10 to 15 mph by Wednesday afternoon. Another quarter to half an inch of rain is expected for the Western Interior through Thursday with a few areas seeing another inch or more.

Due to the heavy rain in the west, fire weather focus is on the southeast Interior, particularly around the Upper Tanana Valley and Fortymile Country. This area saw little to no rain Sunday/Monday, resulting in some of the highest fuel indices in our area. South winds across the Alaska Range will weaken to less than 20 mph Wednesday morning, but light downsloping will continue to lower RHs in the Tanana Valley. Max temperatures in the Interior will be in the mid to upper 70s through Thursday afternoon. Relative humidity will bottom out in the 30 to 40 percent range for most of the Interior, except in the area of concern in the southeast, where it will be in the 20s. These warm and dry conditions will set the stage for Thursday. A shortwave will ride north along the ridge on Thursday, resulting in the best chances for thunderstorm development in some time. Isolated thunderstorms will most likely develop in the higher terrain north of the Tanana valley and along the AlCan border, as well as in the Central and Eastern Brooks Range. Although storms should stay north of the Tanana Valley, the close proximity and dry conditions there provide some threat for dry lightning strikes. After Thursday, thunderstorm potential diminishes again.

Thursday, the low in the Bering Strait will begin to move to the northeast, bringing light showers farther inland to the Central Interior. However, models are coming into better agreement on the track taking it over the Brooks Range and out over the western Arctic Coast. This will reduce the chances for showers in southern sections of the Interior and allow temperatures in the Southern to remain warmer going into the weekend.

HYDROLOGY

Over the past 48 hours there has been 1 to 3 inches of rainfall across the West Coast and Western Interior. As another low moves through the region today through midweek it will bring an additional 0.5 to 1.5 inches of rainfall. This could exacerbate the conditions in the smaller creeks and streams. No flooding is currently expected, but river rises are anticipated and smaller creeks and streams could become bankfull.

EXTENDED FORECAST DAYS 4-7

Friday through Monday. The upper level trough that was responsible for the active weather that began this week will start to lift northeast across the state on Friday. This low will continue to support scattered showers across the Western Interior, Brooks Range, and North Slope, with the greatest coverage shifting north and east with the center of the system. Extensive cloud cover beneath the upper low should keep temperatures near to slightly below seasonal norms across the Central and Western Interior, although some warming is expected over the weekend as the system departs and heights begin to gradually rise.

Attention then turns to the Bering Sea once again where guidance indicates another upper low dropping south out of Eastern Siberia during the weekend. As this feature drives south, clouds and shower chances are expected to increase once again for the West Coast, however model guidance diverges on exact placement of this low at this time. The GFS favors this new low remaining further out in the Bering as it drives south, minimizing precipitation chances to just a few isolated showers, with highest rainfall rates likely to remain offshore and across St Lawrence Island. The ECMWF, however, favors this new system driving further southeast, bringing more widespread rain to parts of the Seward Peninsula and YK Delta. Farther east across the Central and Eastern Interior, conditions should remain warmer with little to no precipitation expected at this time.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ801-850. Small Craft Advisory for PKZ803. Small Craft Advisory for PKZ804-805. Small Craft Advisory for PKZ807-856. Small Craft Advisory for PKZ808. Small Craft Advisory for PKZ809-855. Small Craft Advisory for PKZ810. Small Craft Advisory for PKZ852.