textproduct: Fairbanks

SYNOPSIS

Warm weather will continue across Northern Alaska today, with widespread highs in the 70s and 80s in the Interior and southern North Slope, with 50s and 60s in coastal areas. Isolated thunderstorms will be possible across the Interior and parts of the Brooks Range every day through early next week, with scattered thunderstorms in the southwestern Interior today spreading into the Central/Eastern Interior Saturday through Monday. Cooler temperatures are expected on the North Slope from Saturday evening into Sunday behind an Arctic front but will recover by early next week. Rain chances will improve across the southern Interior early and especially mid next week.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Highs across the Central and Eastern Interior will widely be in the upper 70s to mid 80s today and Saturday, with the warmest temperatures in the Yukon Flats where highs could reach the upper 80s on Saturday.

- Showers and storms are expected each day through the weekend and into next week. Scattered thunderstorms are expected, mainly across the southern Interior from Friday through Sunday, with isolated storms farther north.

West Coast and Western Interior... - Temperatures remain seasonably cool along the Coast with highs in the 50s to low 60s, warming this weekend with most spots in the low 60s from the Seward Peninsula south.

- Highs in the Interior in the upper 60s/low 70s today will rise into the mid to upper 70s over the weekend.

- Isolated thunderstorms are possible for most of the Western Interior today, with scattered thunderstorms from near Galena/Ruby south. Thunderstorms may persist through the night, then continue on Saturday/Sunday but return to being isolated.

- Light to moderate rain in the YK Delta and Lower Yukon Valley will gradually decrease through early Friday morning. Totals will be 0.10 to 0.25".

North Slope and Brooks Range... - Warm temperatures are expected, with highs in the 50s/60s along the coast and 60s/70s in the Plains through Friday. Gradually cooling temperatures are expected on Saturday from west to east during the afternoon/evening with a cold front.

- Expect northern Brooks Range valleys to warm into the 70s and near 80 through Saturday, then drop on Sunday.

- Isolated thunderstorms will be possible each day through Saturday in the Plains and Brooks Range and will be more predominant in the southern Brooks Range on Sunday and into next week.

FORECAST ANALYSIS AND DISCUSSION

A broad, south-moving 561 dm upper low at 500 mb occupies the northern Bering Sea, with ridging in northwest Canada edging its way westward into eastern Alaska. At 850 mb, temperatures are already around 8 C in the Central/Eastern Interior this morning and will further rise to around 10 to 12 C by this afternoon. Surface high temperatures will likewise rise into the upper 70s to mid 80s across much of the area with light winds and mostly clear and sunny conditions save some isolated showers or thunderstorms. The exception is the southwestern Interior, where showers/thunderstorms could be more scattered in coverage. The Western Interior and southern North Slope will be somewhat cooler but still in the low to mid 70s. Most of Northern Alaska will correspondingly be around 5 to 10 F above normal, but a cold Arctic trough/front northwest of Alaska will move in by late tonight. As it moves across the North Slope, it will bring with it a narrow band of precipitation, brisk southwest winds, and drop highs on the Arctic into the 30s and 40s, with the more inland areas falling into the 50s by Sunday. These effects will remain limited to the north side of the Brooks Range, with the trough/front exiting the area by early next week. South of the Brooks Range, save coastal areas which will remain in the 50s and 60s, most of the lower elevations will remain in the 70s and 80s for highs during this time frame, with lows in the 50s. Fort Yukon and the Yukon Flats could see highs in the upper 80s on Friday, with 850 mb temperatures around 14C. Scattered thunderstorms will be possible from Saturday through early next week in the south- central and southeastern Interior where several J/kg of surface- based CAPE and LIs in the 1 to 3 C range each day. Shortwaves moving across the Interior from the south will provide additional dynamic support for ascent for thunderstorms each day. Storms Saturday in particular could last well into the night, with potential for instability lasting to near or just after midnight.

FIRE WEATHER

Active thunderstorm days continue today as upper level ridging persists over the state. Expect isolated thunderstorms over much of the Interior this afternoon with scattered thunderstorms possible over the Upper Kuskokwim Valley and portions of the Western Interior. As we approach the weekend, there is increasing confidence for scattered, slow moving thunderstorms, especially from the White Mountains south towards the Alaska Range. Some of these storms may linger into the overnight hours. It will be especially important to stay weather aware this weekend as people plan to go outside and enjoy the summer solstice activities. As with all thunderstorms, gusty winds, strong outflow boundaries, localized heavy rain, and frequent lightning are all possible. A Fire Weather Watch is in effect from Saturday morning through Sunday evening due to lightning, warm temperatures, low relative humidities, and gusty winds.

Accompanying these storms will be some of the warmest temperatures of the summer so far. Across the Central/Eastern Interior, high temperatures in the upper 70s and low 80s are expected today through the weekend. Along the Western Interior, highs will remain slightly cooler in the mid 70s today, then potentially seeing a few spots reach the upper 70s by the weekend. While relative humidity is generally expected to remain between 30% to 40%, there will be a few pockets of 20% to 25% in the Tanana Valley and Yukon Flats through Saturday.

By early next week, the well established area of high pressure over the state will gradually weaken as a low moves into the Gulf of Alaska and a trough dips south over the Arctic Coast. Despite weakening high pressure, thunderstorm activity is expected to continue into next week, in addition to cooler temperatures and higher relative humidities.

EXTENDED FORECAST DAYS 4-7

Starting on Monday, the 500 mb pattern consists of a closed low near Kodiak Island with weak troughing over the North Slope and modest ridging across the interior. A weak frontal boundary connects the Arctic trough and Kodiak Island low, which is expected to focus repeated diurnal shower/thunderstorm chances. On Monday, chances for convection are greatest across the southern interior from the White Mountains southward and especially along the Alaska Range. Model differences grow on Tuesday and Wednesday, which are related to how models handle the closed low that is currently dropping south along the West Coast. This low phases with a subtropical closed low lifting north into the Gulf of Alaska. EPS guidance has consistently advertised a Fujiwara effect with the current West Coast circling around the Gulf of Alaska low and pivoting over the southern interior as a potent easterly wave on Wednesday. Other model guidance appears to lose definition of what were initially two distinct closed lows, which seems less likely to me. Either way, the ridge axis initially across the interior shifts further north, displacing Arctic troughing across the North Slope bringing a trend toward above normal temperatures with it as cloudiness and rain chances brings cooler temperatures across the southern interior.

Coastal Hazard Potential Days 3 and 4...None

HYDROLOGY

After a wet week on the North Slope and Brooks Range, water levels in the rivers are receding. We have cancelled or expired all flood hazards and flooding is no longer expected. Rivers will return to near normal levels through the week and into the weekend.

AFG WATCHES/WARNINGS/ADVISORIES

AK...Fire Weather Watch for AKZ934>945-947-953. Heat Advisory for AKZ833. PK...Small Craft Advisory for PKZ811. Small Craft Advisory for PKZ812. Small Craft Advisory for PKZ857. Small Craft Advisory for PKZ858.