textproduct: Fairbanks

SYNOPSIS

Warm temperatures with relatively dry conditions continue across the area through this weekend, with highs widely in the 60s and 70s in the Interior and southern North Slope and the 50s (upper 40s in colder spots) in coastal areas. Moving into the weekend, the warmest spots (especially the Yukon Flats) could reach into the mid 80s. Isolated showers and thunderstorms will be possible today in inland areas but will increase in coverage from Friday into the weekend. Saturday evening into Sunday, a colder air mass will brush along the Arctic Coast and cool temperatures down a bit while bringing some light precipitation, but it will not impact temperatures south of the Brooks Range. There will be better chances for more numerous showers in the southern Interior to occur during this same time frame.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Warmer temperatures in the mid to upper 70s today. Expect highs in the upper 70s and low 80s in the Central Interior by Friday with mid to upper 80s expected in the Yukon Flats and portions of the Eastern Interior this weekend.

- Showers and thunderstorms will be possible today but will become more prevalent Friday into the weekend.

- Highest probability for thunderstorms in the Interior is Friday and Saturday.

West Coast and Western Interior... - Temperatures remain seasonably cool along the Coast with highs in the 50s to low 60s through the weekend. Highs in the Interior in the 60s to near 70 today will rise into the mid to upper 70s by the weekend. - Showers and thunderstorms today will gradually move east by the weekend. Isolated thunderstorms will be possible today in the Western Interior.

- Thunderstorms persist on Friday in the Western Interior, mostly from McGrath to Huslia east. A farther east progression persists on Saturday with most storms south and east of Ruby.

North Slope and Brooks Range... - A warming trend continues in the area. Expect high temperatures to increase through Friday, reaching into the 50s to near 60 for portions of the coast, 60s to mid 70s in the Plains, and 70s to near 80 for the valleys of the Brooks Range.

- A cold front arrives Saturday afternoon with cooling temperatures and chances for rain from west to east through Sunday.

- Thunderstorms will be around the Brooks Range and Arctic Plain each day through the weekend with the most abundant coverage being Saturday and Sunday afternoons.

FORECAST ANALYSIS AND DISCUSSION

A 557 dam upper-level low over the Chukchi Sea is gradually shifting southward (and is merging with a low to its west) as ridging in Northwest Canada expands westward. With that being the case, surface temperatures in the Interior on Wednesday were able to reach into the 60s and 70s across most of the area, with somewhat cooler temperatures in near-coastal portions of Western Alaska. As the ridge expands westward, 850 mb temperatures will rise into the upper single digits to low double digits, and surface highs will reach into the upper 70s to low 80s. In some of the warmest Interior valleys (especially the Yukon Flats), mid 80s will be possible, with 850 mb temperatures rising to near 14 C. A series of shortwave troughs will cross over the Alaska Range from the south and will offer multiple opportunities for convective showers and thunderstorms in the Interior and on the North Slope, especially moving into late week and the weekend, when model prognosis supports the presence of several hundred J/kg of surface-based CAPE and LIs of around 1 to 3 C. From Saturday evening into Sunday, showers in the southern Interior could become more numerous as a shortwave trough crosses the Alaska Range.

FIRE WEATHER

Fairly active thunderstorm days continue this week across Northern Alaska as upper level ridging settles over the state. Isolated thunderstorms are expected to mainly impact much of the Western Interior and Brooks Range this afternoon, with very isolated thunderstorms possible in portions of the North Slope and White Mountains. Going into Friday, thunderstorm coverage shifts eastward towards the Central/Eastern Interior with scattered thunderstorms expected through the weekend. Thunderstorms may still develop across the Western Interior and Brooks Range this weekend, but will be more isolated in nature. Given the uptick in expected thunderstorm activity this weekend, it will be especially important to stay weather aware as Midnight Sun/Summer Solstice festivities are held outdoors. As with all thunderstorms, gusty winds, heavy rain, and frequent lightning are possible with the strongest storms.

Besides thunderstorms, there is high confidence in warm summer-like temperatures through the rest of the week. Across the Central/Eastern Interior, highs will be mid to upper 70s today with widespread upper 70s and low 80s expected Friday through Sunday. The Western Interior will remain slightly cooler with highs in the low to mid 70s through Friday, then potentially seeing a few spots reach the upper 70s by the weekend. Min RHs will largely remain above critical thresholds through the rest of the week with the exception of the Yukon Flats and Tanana Valley as values bottom out around 20% to 25% by Friday. Winds are expected to remain fairly light through the weekend, outside of some gusty outflow winds.

EXTENDED FORECAST DAYS 4-7

The extended forecast period begins with a seasonably weak closed low over the Alaskan Peninsula and an unseasonably strong Arctic low centered near the North Pole. The Arctic low sends a weak trough across the North Slope this weekend, which also helps shift the weak cold front across the interior during the extended period. This front is shifting under a weak ridge axis extending west across interior Alaska from western Canada that doesn't move much through the middle of next week. More importantly, this front focuses shower and thunderstorm potential along and east of the boundary. There is good model agreement that this frontal boundary will be oriented roughly north-south between McGrath and Bettles Saturday afternoon before shifting to be more west-east oriented from McGrath to Eagle by Monday afternoon. The summer solstice provides plenty of insolation to fuel thunderstorm activity so frequent lightning and gusty winds are expected with the strongest storms, despite rather weak synoptic scale forcing. The latest 00z guidance continues to suggests a more robust easterly wave by the middle of next week, but confidence in that feature is low at this time.

Coastal Hazard Potential Days 3 and 4...None

HYDROLOGY

Most of the concern from the recent heavy rain in the Brooks Range has diminished. We'll notice some higher water in Allakaket tomorrow as well as on the Colville River. But observed values have been near bankfull. We still have a Flood Advisory for the Colville River and Umiat will be seeing cresting water over the next 36 hours. This water will continue to move downriver towards Nuiqsut with minor flooding of low-lying areas possible.

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...None.