textproduct: Fairbanks

SYNOPSIS

It was a bit chilly over Northern Alaska this morning! There is another chance for frost tonight, though it is mostly possible in the Northern Interior and typical cold valleys like Goldstream. Otherwise, a warming trend is expected from Wednesday through the weekend across Northern Alaska, including the North Slope. Tranquil weather is expected from the Brooks Range northward as well as the West Coast through Thursday with showers returning Thursday night and Friday. In the Interior, isolated thunderstorms will develop Thursday afternoon with temperatures in the 70s. More robust thunderstorms are expected on Friday with the potential for the most thunderstorms so far this year.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Drying and warming trend through the end of the week with highs in the 60s/70s and RHs dropping to around 20-25%. Warmest and driest in the valleys.

- Isolated showers and thunderstorms develop Thursday afternoon over the AK Range and from Minchumina to Bettles, with a couple of showers east of there.

- More robust thunderstorms expected on Friday with a chance across the entire Interior Friday afternoon/evening.

West Coast and Western Interior... - Tranquil and cool weather today, a warming trend begins tomorrow in the Interior with highs in the 60s/70s. A warming trend lags until Friday on the coast with highs in the 40s/low 50s through Thursday, then 50s/60s on Friday.

- Mostly dry weather through the week, but isolated showers and thunderstorms develop Thursday afternoon mostly east of the Yukon River.

- Another round of thunderstorms expected again on Friday, mostly east of the Yukon River again.

North Slope and Brooks Range... - Chilly weather today with a warming trend beginning tomorrow. Highs near 40 along the coast and 50s/60s in the Brooks Range through the weekend.

- Mostly dry conditions, but isolated rain/snow showers return to the NW Arctic Coast by Thursday night then spread east on Friday. Many locations remain dry.

FORECAST ANALYSIS AND DISCUSSION

A potent 505 decameter Arctic low is loosening its grip on Northern Alaska as it drifts northeast through Wednesday. This allows a weak ridge to take hold beginning on Wednesday. This ridge will allow warmer 850mb temperatures to intrude in the Interior and North Slope, promoting warmer and drier conditions overall. Current 850mb temps are currently about 0C to -4C in the Interior and -5C to -10C on the North Slope. These will rise nearly 10C to 15C across Northern Alaska allowing for surface temperatures to rise by 15F to 25F by Thursday and Friday. With heat comes thunderstorms and we do expect an uptick in storms Thursday and Friday afternoons. The latest 12Z ECMWF brought a very different outcome, however. Models have been generally consistent on bringing a shortwave trough over the Central and Eastern Interior during peak heating on Friday, bringing an active thunderstorm day. However, the latest 12Z ECMWF brought the trough through the Interior much quicker, which puts a cap on any afternoon convection. The 12Z CMC, GFS and UKMET still bring this trough to the Interior during peak heating which results in quite a bit of thunderstorm activity. We are still holding steady and expecting thunderstorms on Friday, but it is an interesting development from the ECMWF that cannot be ignored because it would lower our temperatures and limit convection. Nonetheless, temperatures in the Interior after this trough on Friday should return to near normal values this weekend. It will also be much drier given the lack of instability after the trough moves through.

FIRE WEATHER

A drying trend begins today with the warming trend following tomorrow. RHs across the Interior will be around 25 to 35% with the lowest expected in the Yukon Flats and Western Interior. RHs remain low tomorrow through Friday, as low as 20% in the valleys across the Interior. Temperatures enter a warming trend on Wednesday with highs across the area reaching the 60s and 70s with mostly 70s by Thursday and Friday. Thunderstorm chances return on Thursday, especially in the Western Interior towards the Western Alaska Range. By Friday, there is a chance this is the largest thunderstorm day of the year so far but there is still some uncertainty with a trough moving through the Interior, acting as the forcing mechanism. If this trough moves quicker, there will be less thunderstorms, if it is slower there will be more. Right now we will err on the side of caution with a slower trough, meaning more thunderstorms. This will be monitored closely.

Otherwise, dry and warm weather returns this weekend with a strong chinook possible allowing for near Red Flag conditions in Isabel Pass/Delta Junction.

HYDROLOGY

Satellite imagery indicates the Sag River has broken up close to the mouth with no updates on the Kuparuk given the lack of clear satellite imagery. The Colville has broken up near Nuiqsut and potentially farther downstream but there are 2 ice jams at Horseshoe Bend and Ocean Point. Even with the ice jams, water has remained relatively low.

Heading into the end of the week, we'll see temperatures rise into the 50s/60s in the Brooks Range and 40s/50s on the North Slope. Low temperatures will be above freezing later this week with the Brooks Range only dropping into the 40s while the North Slope remains in the mid 30s. The increase in temperatures along with the recent snowfall may result in rapid river rises by this weekend but there is high uncertainty in any potential flooding impacts.

EXTENDED FORECAST DAYS 4-7

For Saturday through Tuesday

This Saturday high pressure system will situate itself over Alaska with two low pressure systems to the north and south. As we move forward into Sunday the southern low will dig into the ridge weakening it through the end of the weekend, resulting in the eastern portion of the state remaining under a stationary ridge, bringing warm and dry weather to the area. A low resting near SW Alaska allows for more wet, cloudy and marginally cooler weather. This pattern should remain consistent for a short while as it swiftly moves starting on Monday, with the high pressure moving towards the North Slope and the low pressure settling near southern Alaska. This pattern should result in dry and warm weather throughout northern and eastern Alaska with cooler and wetter weather in western Alaska.

On Saturday we expect the ridge to drive warmer high temperatures, reaching between 70-80 degrees. From Sunday to Monday it is likely to see temperatures in the Eastern Interior remain in the 70-80s and the Western Interior dip to the 60s-70s. By Tuesday the low pressure system will have a larger influence resulting in cooler temperatures across most of Northern Alaska.

Winds will be most impactful Sunday evening. As a low pressure system drives wind gusts up to about 50 mph through the Alaska Range which begins to drop off Monday morning. Around the same time, wind gusts are likely to increase along the eastern Arctic Coast to about 30 mph. Just north of the Alaska Range, the minimum relative humidity ranges between 20-40% on Saturday with a steady increase into Tuesday. With the wind gusts reaching 50 mph at the Alaska Range, and the trend of the lower relative humidity values, fire weather is a concern during the beginning portion of this weekend.

As for precipitation, we are expecting a drier start to the weekend, with signals for heavier precipitation possible next week as a low moves into the Gulf of Alaska. As the low approaches the vicinity of the Alaska Peninsula, moisture may wrap around the east side bringing higher chances for more widespread rain for portions of Northern Alaska.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ813. Brisk Wind Advisory for PKZ814-860. Brisk Wind Advisory for PKZ815.