textproduct: Fairbanks

SYNOPSIS

Another low continues to progress eastward, north of the Aleutians which is helping to continue the broad area of low pressure across the state. A series of shortwave will progress into the state allowing for isolated showers to continue across the state. In addition, the southerly flow setting up with this pattern will allow for a brief period of gusty winds through the Alaska Range today. Wind Advisories are in effect for Isabel Pass through early Friday morning. Thunderstorm potential is expected to increase through the start of the weekend with the broad troughing expanding eastward, resulting in east/southeast flow across the Interior.

Another low is expected to move up the Aleutians by the start of the week. However models are in disagreement with the exact track with the latest runs. Some of these solutions have the potential to bring an increased chance for thunderstorms across the Interior next week.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Widespread showers will be confined to the northern Interior with the front's progression. Chances for thunderstorms increase to around 30% in the Central Interior by Saturday. - Isolated showers possible across the rest of the Interior Thursday night.

- Seasonably normal temperatures are expected to continue across the Interior through much of the week.

West Coast and Western Interior... - Showery conditions are expected along the Lower Yukon and Yukon Delta regions throughout the week. These showers will be mostly rain, especially nearer the Western Interior, but some periods of snow and light wintry mix are possible near St. Lawrence Island and the Bering Strait Coast.

- Increased thunderstorm potential around 15% on Friday, primarily for the Middle Yukon Valley and Upper Kuskokwim Valley, with chances increasing to 30% on Saturday.

North Slope and Brooks Range.. - Gusty northeasterly winds will gradually increase, to around 25 and 35 mph, along the Arctic Coast over the next couple of days. Gradient will begin to lighten by Friday night. - Strongest winds will be over the northwest and eastern Arctic Coast, peaking late Thursday night into Friday morning.

- Diurnal showers along the southern portion of the Brooks Range are expected to continue through the week. Little to no precipitation is expected for the North Slope

- Chilly temperatures persist with highs in the 20s and lows in the teens along the North Slope. A gradient of temperatures across the Brooks Range with highs in the 50s to near 60 along the southern slopes and low 40s for the northern slopes.

FORECAST ANALYSIS AND DISCUSSION

The remnants of a front from a shortwave moving across the eastern Interior will continue to shower portions of the Northern Interior throughout the day, today. A weakening, occluded low works its way east along the north side of the Aleutians. It is expected to stall once reaching Bristol Bay, later this afternoon. This will allow for the low to weaken quicker and also allow some other bits of energy to veer away from the prevailing flow. A disorganized front will swing across the state today, from this low over Bristol Bay, providing widespread showers across much of the Central Interior and West Coast. This influx of energy will help to enhance the upslope precipitation on the south side of the Brooks Range. This will allow persistent showers to continue through the end of the week.

The southerly flow associate with the week front moving across the State today will provide a decent set-up for moderate gap winds through the Alaska Range Passes. A Wind Advisory will be in effect today for potential gusts up to 55 mph through Isabel Pass. The gusty winds will taper off throughout the day, Friday, as the low over Bristol Bay quickly fills in.

In addition to the low weakening throughout the day, Friday, a shortwave will track eastward across the gulf of Alaska, reaching the southern portions of the Alaska Panhandle by Saturday morning. This track of the shortwave will be closely monitored as it has the potential to set up East to Southeast Flow, aloft, across the Central and Eastern portions of the Interior, favorable for scattered thunderstorms. Instability will begin to increase Friday, setting up a chance for isolated thunderstorms across the Central and Northern Interior during the afternoon. As the shortwave progresses further eastward in the Gulf and easterly flow set up across the Interior, this will increase the chances for thunderstorms Saturday afternoon. Latest guidance shows the greatest potential to be along a line from the Upper Kuskokwim to around Bettles, spreading across the White Mountains and into portions of the Fortmile Country. Broad troughing will continue across the southern portions of the state into the mid weekend. In addition, models are hinting at an upper-level ridge strengthening over the Yukon Valley. Both of these will continue to support the chances for isolated showers and thunderstorms across the Interior through the start of next week.

FIRE WEATHER

The greatest area of concern this week is from Delta Junction south, where winds will be gusting to 55 mph at times on Thursday and around 45 mph on Friday. Min RHs will be in the low 30s on Thursday but around 20 to 30% on Friday. Red Flag conditions are possible, especially on Friday. Otherwise, rain showers and areas of light rain move into the northern Interior Thursday afternoon leaving most spots south of the White Mountains dry. Wetting rains are likely north of the White Mountains and towards the southern slopes of the Brooks Range with rainfall amounts around 0.10 to 0.20". The Western Interior will have widespread rain showers, especially in the afternoon and evening with rainfall amounts generally around 0.05 to 0.10". Friday is a drier day overall across the Interior with isolated rain showers and thunderstorms, though the coverage will be far less than Thursday. Saturday and Sunday continues the dry trend in terms of low min RHs (20 to 30% in the valleys), but thunderstorms will be isolated to scattered across the Interior and there is a chance that Saturday is the most active thunderstorm day in the Interior so far this year. Sunday looks to be another active thunderstorm day, but the threat does shift northeast from Fairbanks to the Kobuk Valley eastward to the Al-Can Border. Any thunderstorm can come with lightning, brief heavy rain, small hail and erratic wind gusts. To wrap it up, expect wetting rain north of the White Mountains today, a drier day on Friday, then active thunderstorm days this weekend with temperatures remaining relatively cool and RHs near critical values in the valleys.

HYDROLOGY

Yukon River: The breakup front on the Yukon has passed Russian Mission. As of 4pm AKDT Wednesday, an ice jam 10 miles downstream of Russian Mission remains in place. It is made up of about 3 miles of large intact ice sheets extending from Roosevelt Island to Seven Mile. River Watch overflew the ice jam at noon Tuesday and again at 5pm and saw no change. About 60 miles of chunk and pan ice extend from the head of the jam upriver past Holy Cross. The most extensive flooding is occurring at Holy Cross and in the lowlands between Holy Cross and Anvik. Most large Yukon River ice jams during recent years decay, erode and fail within a few days. The current jam at Russian Mission is going on day 3.

Flood warnings remain in effect for Russian Mission, Holy Cross, and Grayling. A Flood Advisory is in effect for Anvik. Extensive flooding of the lower portion of Holy Cross community was occurring Tuesday, including the Holy Cross runway. Water remains high on the Yukon upriver from the breakup front due to snowmelt and the Yuki Ice Jam release. As of noon Wednesday the River Watch Team reported that the river slows down around Anvik and that the backwater from the jam seems to have extended to Anvik. In addition, immediately downriver from the ice jam river level remained low indicating the ice jam is not weakening and may prolong ongoing impacts at Holy Cross.

When the ice jam releases there will likely be a period of water level rises and dense ice runs at Russian Mission for at least 24 hours as the backwater flows past there. Downriver of the ice jam towards Marshall the ice is rotten and river levels are low.

Chena: The Chena River continues to respond to warmer temperatures with higher elevation snowmelt leading to rivers running higher than normal, but likely remaining below action stage.

Additional Information: Visit www.weather.gov/aprfc for the latest hydro information.

Please report observed flooding to local emergency services, law enforcement, or to the National Weather Service when you can do so safely.

EXTENDED FORECAST DAYS 4-7

This upcoming weekend concludes with another low moving up the Aleutians. All of the global models are in agreement with the low moving up the Aleutians, but they are all showing a different placement in where the low sets up by the mid-week. The GFS is the most aggressive with the easterly progression having the low set up in the central Gulf of Alaska by Tuesday afternoon. A solution like this would support better chances for thunderstorms through the back half of the week. The CMC and EC keep the low around Bristol Bay by Tuesday, yet they are also showing some potential for thunderstorm potential. However, both the EC and CMC have been showing fairly similar solutions over the last several runs, while the GFS recently started showing the farther eastern with the latest run. Not only would the thunderstorm potential be higher with the GFS solution, it would also result in slightly warmer and drier conditions across the Interior. This will be closely monitored over the next several days with the start of summer just around the corner.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ849. Flood Watch for AKZ826-830. PK...Small Craft Advisory for PKZ801-850. Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ814-815. Small Craft Advisory for PKZ858. Brisk Wind Advisory for PKZ860. Brisk Wind Advisory for PKZ861.