textproduct: Fairbanks

SYNOPSIS

A stormy day is on tap for the Central and Eastern Interior as a weak front will bring increasing chances for thunderstorms this afternoon. These thunderstorms could be accompanied with small hail, gusty winds, and frequent lightning. Saturday fire weather concerns will begin to arise as temperatures will continue to rise and minimum RH values decrease to at or below critical threshold. A robust low will move into the northern Gulf of Alaska Sunday. This low will help to alleviate fire weather concerns due to the amount of moisture that will be brought into the Interior. Southerly gap winds in the Alaska Range are expected Saturday through Monday.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Temperatures will slightly cool across the Interior valleys compared to yesterday, but expect warmer temperatures to return Saturday. For the Tanana Valley and Yukon Flats, it could be our first 80 degree day of the year.

- With the temperatures approaching 80 for the valleys tomorrow, minimum RH values will be near critical threshold. A Fire Weather Watch has been issued for Delta Junction and Isabell Pass as southerly gap winds of 20 to 30 mph and gusts near 40 mph will exacerbate the fire concerns.

- Scattered to numerous thunderstorms are anticipated today from the Alaska Range to the Yukon Flats. The most thunderstorm activity is expected in the White Mountains to Chicken. - These thunderstorms could produce small hail, gusty and erratic winds, lightning, and heavy rain.

West Coast and Western Interior... - Isolated thunderstorms will be possible today in the Upper Kuskokwim Valley. Saturday these thunderstorm chances will spread north and west to the Yukon River.

- Temperatures will continue to rise for the next couple of days. Widespread 70s in the Western Interior are expected by Saturday, and 50s/60s along the coastline. Some parts of Norton Sound could even see 70s. Minimum RH values will drop in the upper 20s/low 30s in the Western Interior on Saturday, but will see improvement come Sunday afternoon.

- Gusty southwest winds across the Bering Strait will steadily decrease through today. North Slope and Brooks Range... - Temperatures will cool down a few degrees for the next couple of days, before warming up again on Sunday.

- Isolated showers will be possible today in the Eastern Brooks Range from Atigun Pass to the AlCan border. Some of these showers could become thunderstorms. Sunday another round of thunderstorms will be possible in the Brooks Range.

- Potentially moderate to heavy rainfall is possible in the Central/Eastern Brooks Range beginning Sunday night, and will last for 36 to 48 hours. Rain amounts could be 1/2" to 3/4", with a small chance to be an inch. Most of the precipitation will fall as rain, as snow levels will be 8000' to 9000'.

FORECAST ANALYSIS AND DISCUSSION

Friday through Sunday Night. High pressure aloft is continuing in the Southern Interior. This high pressure is bringing in warmer 850 mb temperatures from Western Canada. With 850 mb temperatures near 9C, we could see the Eastern Interior Valleys approach 80F with a dry adiabat layer. A shortwave trough is moving through the Central Interior this morning. This trough is not only faster than the models resolved in their previous runs, but also mid level clouds are blanketed ahead of the trough. The faster trough will force the higher thunderstorm chances east, as it will be moving over the Eastern Interior during peak heating instead of the Central Interior. With a weak frontal boundary associated with this trough, it may be able to overcome the reduced surface heating from the cloud, but it would be reduced compared to clear skies ahead of it.

Soundings are still showing favorable conditions for thunderstorm development along the front. Areas ahead of the front, will see ~500 J/kg of CAPE, a dry adiabat layer to 750-800 mbs, moisture in the Dendritic Growth Zone. These would all support thunderstorms that could produce 1/2" to 3/4" hail, gusty and erratic winds. With the flow being west to east, expect most of the storms to initiate along the western aspects of terrain due to upsloping mechanics. Something that model soundings are hinting at are higher DCAPE values. DCAPE represents the downward vertical motion of air when rain enters the dry layer near the surface, and begins to evaporatively cool. The highest values of DCAPE will be pre-frontal and they could be as high 600 J/kg. These values could translate to strong winds from a thunderstorm nearing 50 mph, but it is not a guarantee that they will occur, but the potential is there.

Moving into Saturday we will finally warm weather continue across Northern Alaska, but in the evening will finally see the first influence of the approaching low in the gulf. The first band of isolated to scattered rain showers will move into the Interior. With southerly flow, much of the Southern Interior will be downsloped, and will most likely not see any precipitation. Sunday the main precipitation band will begin to move into the Interior. This band is expected to produce light to moderate rain in the Western Interior, Brooks Range, and potentially the North Slope. This feature will talked about a bit more in the Extended Forecast Discussion, as this feature will be a 36 to 48 hour event.

FIRE WEATHER

High pressure continues to build over the Bering Sea and Western Canada allowing for a continuation of warm and dry weather going into the weekend. Isolated to scattered wet thunderstorms are expected today across much of the Interior, with numerous wet thunderstorms possible across the White Mountains and east towards Eagle/Chicken. These storms may produce periods of frequent lightning, small hail, and erratic winds at times through the evening. Isolated thunderstorms will linger through the afternoon Saturday across the Southern Interior and Alaska Range, with very isolated pockets of thunderstorms possible across the Brooks Range and Western Interior Sunday afternoon. High temperatures are expected to rise into the mid to upper 70s across much of the Interior through Sunday, with a few spots seeing afternoons highs reaching near 80F. Winds are expected to remain fairly light across the Central/Eastern Interior today with periods of gusty southwest winds possible over the Seward Peninsula and Western Brooks Range this afternoon. Going into the weekend, winds will shift towards the east/southeast with gusty southerly winds possible through Isabel Pass and Delta Junction Saturday afternoon. Current model guidance suggests winds could gust as high as 40 mph at times creating the potential for critical fire weather conditions at Delta Junction. A Fire Weather Watch is out through Sunday evening. Min RH values will continue to remain dry between 20% to 30% through Saturday, with the driest spots being in the Yukon Flats and Interior Valleys. Min RH values are expected to be on a steady increasing trend going into next week as a low in the Gulf of Alaska advects anomalously high amounts of moisture into Northern Alaska. As upper level southeast flow sets up over the state, increased chances for isolated to scattered showers are expected for much of Northern Alaska with the exception of the Southern Interior as strong downsloping effects keep the area mostly dry. Despite this, areas that do see persistent showers may experience heavy wetting rains at times, especially across portions of the Eastern Interior, Western Interior, and Brooks Range.

HYDROLOGY

No updates since the previous discussion. Unless there is a significant change, the next update for the rivers will come on Friday 6/12/26.

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/weekend, 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 with the Brooks Range only dropping into the 40s while the North Slope remains in the 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. On top of this, we are also monitoring the potential for heavy rain in the Brooks Range from Sunday night through Tuesday. There is a potential for over 1 inch of rain across a wide area.

EXTENDED FORECAST DAYS 4-7

Monday through Thursday. High confidence continues early next week with ensemble models favoring a broad upper level trough over Northern Alaska, anchored by two H5 lows with one in the Gulf of Alaska/Aleutians and another over the Chukchi Sea. This setup will remain conducive for scattered to widespread light precipitation chances regionwide, with a focus on locally heavier totals in the Brooks Range. Here is where we will see a plume of moisture stall between these two lows over the higher elevations and as a result, see steadier rainfall rates. The NBM probability of 0.50" of rain or more from Bettles and Coldfoot through the Central/Eastern Brooks Range sits at a 50-75% chance with deterministic totals closer broadly speaking to 0.25-0.75". Elsewhere, precipitation totals are expected to remain light around a T-0.25" as snow levels remain confined well into the highest terrain of the Alaska Range. Following above normal temperatures regionwide over the weekend, temperatures will turn cooler overall for Monday before slowly rebounding throughout the week. This is due to the broad upper level troughing gradually weakening and a ridge of high pressure moving in to take its place. As a result, conditions will trend drier Wednesday onwards as precipitation becomes increasingly isolated.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Fire Weather Watch for AKZ937. PK...Small Craft Advisory for PKZ801. Small Craft Advisory for PKZ806-811. Brisk Wind Advisory for PKZ807. Small Craft Advisory for PKZ812. Small Craft Advisory for PKZ850. Small Craft Advisory for PKZ856. Small Craft Advisory for PKZ858.