textproduct: Fairbanks

SYNOPSIS

As we move into the holiday weekend, most of Northern Alaska will see isolated showers and thunderstorms as well as warming trend. This warming trend will be paired with isolated to scattered rain showers and thunderstorms chances across the Interior. Most of the storms will remain in the higher terrain, but weak steering flow could move them into the valleys. A low moving into Bristol Bay will be the main culprit for the showers and thunderstorms. As this low moves southeast into the Gulf it will open up for high pressure to move into the region later this weekend. This high pressure will keep temperatures and thunderstorm chances elevated through most of next week.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Temperatures will steadily rise across the Interior with mid to upper 70s expected in the valleys by Sunday. With the rising temperatures RHs should remain moderated to due to the influx of cloud cover and low level moisture.

- Showers and thunderstorms will be possible today across the region. The highest chances for showers will be in the Alaska Range, White Mountains, and Dalton Highway Summits.

West Coast and Western Interior... - Gusty northerly winds from St. Lawrence Island to Point Hope will continue through today with wind gusts up to 40 mph possible.

- Rain showers will continue across the Yukon valley south of Kaltag and the Upper Kuskokwim Valley through tomorrow. Later this afternoon we could see scattered thunderstorms across the area, particularly in the Kuskokwim Mountains.

- Temperatures will remain fairly static until Sunday when we will start to see a widespread warming trend begin.

North Slope and Brooks Range.. - Patchy fog will continue across the Beaufort Sea coastline this morning ahead of an arctic trough. As the arctic trough moves closer to the area, the fog and low stratus should lift.

- Gusty northerly winds in the Brooks Range will continue until early Sunday morning. These winds could be as high as 30 mph.

- Temperatures will see a warming trend beginning Sunday with highs in the Plains and Brooks Range approaching 70, and the coastline in the upper 50s/60s.

FORECAST ANALYSIS AND DISCUSSION

A closed off 500 mb low will continue moving southeast through the Bering Sea today as it rotates through the longwave pattern. This low will be a primary weather maker for the next couple of days. Vorticity maximas will be lingering in the Western Interior today, and with a surface trough having developed we will see thunderstorm development across much of the Interior, with the highest thunderstorm chances in the southwest Interior. While temperatures will be marginal for convective initiation, there are plenty of synoptic scale features helping. A fairly weak arctic trough is moving east across the North Slope today, and as this feature digs into the Interior it will advect potential vorticity into the Western Interior. This potential vorticity (PV) is another upward vertical motion mechanic. With the PV, surface trough, and 500 mb vorticity maximas in the Western Interior, there is good confidence that scattered thunderstorms are possible today.

Saturday as the low in the Bering moves into Bristol Bay a very weak cold front will be ejected into the Interior. This front will bring a quick round of scattered showers and isolated thunderstorms tomorrow afternoon in the Central and Eastern Interior. These showers are not expecting to produce a lot of precipitation because PWAT values are low at around 0.5 inches. These storms will also have to contend with a dry layer near the surface.

As a Siberian high pressure begins to move into the region on Sunday, we will see widespread warming and drying. 850 mb temperatures will quickly rise to 10C to 15C across Northern Alaska, bringing temperatures 5 to 10 degrees above seasonable norm. This high will be discussed in more detail in the Extended Forecast Discussion on not only the impacts of temperatures, but also the enhanced thunderstorm potential early to middle of next week.

FIRE WEATHER

General troughing over Northern Alaska is expected to persist as a series of low pressure systems rotate around the state. This upper level pattern will continue to support cooler and more moist conditions through the weekend. The highest chances of scattered showers are expected for the YK Delta, Alaska Range, and high terrain in the Interior. In regards to thunderstorms, chances return by Friday afternoon into the evening. While isolated thunderstorms are likely to begin popping up by the early afternoon over a broad area including the Middle Yukon, South Slopes of Central Brooks Range, Dalton Highway Summits, and Interior, the highest chances are likely to be expected over the Central/Western Interior and Middle Yukon areas. By Saturday, the area of thunderstorm chances becomes narrower and only includes the Tanana Valley, most of the Interior, and portions of the Norton Sound Coast. North/northeast winds remain relatively light, but winds could become gusty and erratic near thunderstorms. Through the weekend, high temperatures are expected to remain in the upper 60s to mid 70s for the most part.

By early next week, upper level ridging will have gradually started pushing troughing out of the area and supporting a warm up beginning Monday. High temperatures could rise into the mid 80s by Tuesday, cooling off slightly by mid week. Hotter temperatures combined with a good indication for thunderstorms over the Western Interior and Norton Sound coast through the Central Brooks/Central North Slope on Tuesday suggests the potential for more fire starts. Intermittent showers are expected to linger over most of Northern Alaska throughout the week next week as well.

EXTENDED FORECAST DAYS 4-7

A ridge will be moving east over the North Slope on Monday bringing warm weather back to much of Northern Alaska as it does so. In the Gulf there will be a low which will help provide east-northeast flow over the Interior. Monday will likely be a warm and dry day with highs approaching the low 80s across much of the Interior and at least the 60s and 70s on the North Slope. As this ridge continues to push east into Canada, southeast flow does try to take shape over the Interior. This may allow for a couple of wet days by the middle of next week. We'll also be monitoring a low in the Bering next week which can bring some wet and cooler weather to Southwest Alaska. If the timing is correct, there is a chance for enhanced thunderstorm activity with the initial cold front on Tuesday. However, there is uncertainty in the pattern, mainly with how fast the ridge moves east. If it holds through mid week, it has a chance to strengthen and propagate west allowing for a prolonged period of warmer weather increased thunderstorm chances across Northern Alaska. If it remains transient, then we'll be looking at a cooler and wetter pattern with broad troughing once again. Nonetheless, expect a warmer start to next week with chances for thunderstorms across Northern Alaska.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ805. Small Craft Advisory for PKZ806. Small Craft Advisory for PKZ807-817-851-854-856. Small Craft Advisory for PKZ810. Small Craft Advisory for PKZ811-857. Small Craft Advisory for PKZ816. Small Craft Advisory for PKZ850. Small Craft Advisory for PKZ853.