textproduct: Fairbanks

SYNOPSIS

Low pressure in Bristol Bay is expected to bring some showers and thunderstorms into the Interior today. These showers will be isolated in the morning hours, becoming more scattered as the afternoon progresses. This afternoon there is the potential to see an isolated thunderstorm. Most of these storms will be relegated to the higher terrain in the Interior. After today, high pressure will be building in across Northern Alaska. Expect warming temperatures and daily afternoon showers and thunderstorms through at least the middle of next week. By Monday afternoon expect the Interior valleys and North Slope to be in the upper 70s to low 80s. These temperatures could potentially last all the way till Friday.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Isolated to scattered showers will be possible today beginning as early as 10 am for the Tanana Valley. Later this afternoon these showers could be accompanied with a handful of thunderstorms.

- Temperatures will steadily rise Sunday as high pressure builds. By Monday these temperatures will approach 80 with the Yukon Flats around 85. These temperatures could continue through the end of the week.

West Coast and Western Interior... - Temperatures will rise across the region with the Western Interior Valleys approaching 80 by Monday, and the coastline in the 50s/60s. Temperatures could begin to cool down Thurs/Fri.

- Isolated showers and thunderstorms will be possible today across the Middle Yukon and the Kuskokwim Mountains.

- Northerly winds will continue to drop from St. Lawrence Island to Point Hope today. These winds will shift southwesterly Sunday night and will see wind gusts up to 30 mph.

North Slope and Brooks Range... - Dense fog and low stratus continues for much of the Arctic Coastline. This fog should slowly mix out west to east starting in Utqiagvik this morning by 10 AM. As high pressure builds low stratus will continue to be an overnight concern for the next couple of mornings.

- Temperatures will quickly rise across the region Sunday and Monday. By Monday daytime highs will be in the 80s across the Plains, and 60s/70s along the coastline. These should be shortlived, with temperatures cooling by Thursday.

- Isolated thunderstorms will be possible across the Central Brooks Range to the Arctic Coastline on Tuesday/Wednesday.

FORECAST ANALYSIS AND DISCUSSION

A 540 decameter low is moving southeast from Bristol Bay and into the Gulf this morning. As this low moves southeast it will continue to rotate a very weak cold front and additional moisture into the Interior. As this front moves further north into the Interior it will meet a trailing arctic trough. This will provide an area of convergence to help initiate showers and thunderstorms today. We could see two chances for showers/thunderstorms today. It will be with the initial cold front passage this morning, and then later this afternoon when the trough moves deeper into the Interior. The best chance to see a storm will be in the afternoon when there are two boundaries as well as daytime heating to help provide instability. Models are showing a similar profile as yesterday, so if we can initiate storms in the afternoon, then we could see pea size to half inch hail.

Sunday afternoon we will see high pressure move east into Northern Alaska from Siberia. This high will be around 1018 mbs, so not exceptionally strong for this time of year. It will still however bring warmer 850 mb temperatures with them peaking at 10C to 15C Monday/Tuesday. These 850 mb temperatures will help to support widespread 80s in the Interior Valleys as well along the Arctic Plains. As this high settles into Northern Alaska Monday we will see vorticity maximas move through the base of the high. This could create enhanced thunderstorm concerns, and with the warming and drying trend we will be experiencing could create fire weather concerns for a large swath of the Interior.

Models begin to quickly diverge in the solutions starting on Tuesday. While warm temperatures will continue, there are differing impacts to the different model solutions for the remainder of the week. This will be talked about more in the Extended Forecast Discussion.

FIRE WEATHER

Models still depict three low pressure systems moving around the state, supporting general troughing over much of Northern Alaska and is expected to last through the weekend. This pattern will continue to influence scattered showers over most of the Interior, Alaska Range, and YK Delta. Very spotty and brief showers are also likely to be associated with isolated thunderstorms, with a band stretching from the high terrain over the Eastern Interior and Yukon Flats to the Norton Sound Coast including Kotlik and Emmonak Saturday afternoon and evening. By Sunday afternoon, chances for storms shift slightly eastward but are expected to cover a similar area. High temperatures are expected to stay on the relatively cooler side in the low to mid 70s in the Interior and the low to mid 60s on the West Coast.

Early next week, models show brief ridging building over Northern Alaska which is likely to heat up high temperatures into the upper 70s to low 80s over most of the Interior and North Slope. The North Slope especially will see a relatively dramatic increase in high temperatures between Saturday and Tuesday. By Monday, afternoon thunderstorm chances will begin expanding northward to include the Central Brooks Range. By Tuesday afternoon, model guidance indicates thunderstorm coverage as far north as Atqasuk through Kaktovik, along with the Central/Western Interior and YK Delta. Scattered showers are expected to accompany these storms and lightning may induce new fire starts. Throughout the forecast period, winds are expected to remain relatively calm but may become gusty and erratic resulting from thunderstorm-produced outflow boundaries. However, models are pointing to northeast winds strengthening over the Upper Tanana Valley by Monday morning. Gusts in this area could reach up to 40 mph and weaken throughout the day on Tuesday. Elevated fire weather concern is likely early in the week for the Interior and North Slope.

EXTENDED FORECAST DAYS 4-7

Tuesday through Friday A very stout ridge will be extending from a strong high pressure in the Western US. This ridge axis is what is creating our diverging solutions for Alaska weather. The GFS solution including its Ensemble wants to begin to break down the ridge axis over Alaska as a low pressure moves into the Bering Sea Tuesday/Wednesday. If this solution pans out we will be able to cool down to a more seasonable normal, as widespread showers move into Northern Alaska. The ECMWF solution however keep the ridge axis stronger, and diverts the low in the Bering towards the Gulf. If we see this solution we could still see some cooler temperatures in the Southern Interior, but for the most part the warmer temperatures aloft will remain, keeping us warm through the end of the week. The ECMWF solution also keeps us much drier compared to the GFS solution.

I would tend to believe the ECMWF solution at least until a potentially strong arctic low moves into the Northern Bering Saturday. Models tend to move ridges or break down high pressure much quicker than what would happen in reality. There is a lot of moving parts in this pattern leading to large model spreads even within the ECMWF ensemble and GFS ensemble.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ806-807-816-817-850-851-853-854-856.