textproduct: Fairbanks

SYNOPSIS

While there will be some day-by-day change, warm weather will continue across much of the Interior and North Slope the next few days, with daily thunderstorm chances. Today, scattered to numerous thunderstorms will be possible across the Western Interior, interior Seward Peninsula, and western North Slope. Isolated thunderstorms will be possible across most of the remainder of the Interior and North Slope. Tomorrow, the risk for thunderstorms shifts northward, with scattered storms again possible in the west-central/northwestern Interior and North Slope. While thunderstorm chances will be a bit lower in the southwestern Interior, numerous to widespread showers and isolated storms will be possible.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Warm and dry daytime temperatures in the 70s and 80s are expected again today. A heat advisory is in effect for the Yukon Flats for highs near 85F Tuesday and Wednesday. Temperatures cool late Wednesday into Thursday.

- Isolated thunderstorms will be possible today across much of the Central and Eastern Interior with the exception of the Yukon Flats.

- Tuesday night into Wednesday, southerly flow through Isabel Pass will support gap winds gusting between 40 to 45 mph.

- Heavier rain is expected in the south-central Interior Wednesday evening into Thursday. Up to a few quarters of an inch could occur from near Minchumina and to the southwest.

West Coast and Western Interior... - Temperatures will continue to be warm with daytime highs in the 70s and low 80s in Interior valleys. Along the coast, highs will be in the 50s/60s. Temperatures will cool across the region on Wednesday.

- Scattered thunderstorms are expected Tuesday afternoon across the Western Interior with numerous thunderstorms in the southern half. The thunderstorm threat will shift northward again Wednesday, with coverage becoming isolated to scattered.

- Heavy rainfall along the northern slopes of the Western AK Range and in the Upper Kuskokwim Valley could support rain totals ranging from around a quarter inch to over an inch.

- Stronger southwesterly/westerly winds will develop Wednesday afternoon and gusts up to 20 mph will be possible throughout the western Interior Valleys through Thursday night.

North Slope and Brooks Range.. - Warm temperatures expected. Daytime temperatures warm into the 50s near Utqiagvik to the low 80s on the Arctic Plains. A heat advisory is in effect for the Arctic Plains for through Thursday.

- Scattered thunderstorms will be possible in the Brooks Range and Western Arctic Plains Tuesday and Wednesday.

FORECAST ANALYSIS AND DISCUSSION

The strong, persistent ridge (around 570 dm at 500 mb) over northeastern Alaska has shifted eastward since yesterday, but warm-to-hot temperatures will continue across the Interior today. Temperatures with the ridge at 850 mb are forecast to reach around 8 to 15 C across most of the Interior and North Slope, with 14 to 16 C possible in the Yukon Flats and Eastern Brooks Range today. This will support widespread surface highs in the 70s and 80s this afternoon, with the Yukon Flats potentially reaching the mid to high 80s. Vertically-stacked lows in the southeastern Bering Sea and eastern Gulf of Alaska will also have impacts on the weather in the area; the former of these two will push moisture into southwestern Alaska while the latter draws moisture into the southern/southeastern Interior. As a subtle shortwave trough moves northwestward across the Alaska Range and Western Interior where LIs will widely range from 1 to 3 C with a few hundred J/kg of surface-based CAPE, plentiful showers and scattered to numerous thunderstorms will be possible. Isolated storms will also be possible in much of the eastern Interior.

From tonight into tomorrow, the ridge will shift eastward, allowing for temperatures to cool by a few degrees across the area, but temperatures will still remain warmer than normal. Southerly flow through the Alaska Range will support gap winds through Isabel Pass which could gust upwards of 40 mph. The eastward movement of the ridge will also allow for showers and storm chances to extend eastward across the North Slope and Brooks Range, with scattered thunderstorms possible in the northwestern Interior, Brooks Range, and inland portions of the North Slope. These storms will have similarly low LIs and SBCAPE to today to work with. Isolated storms will remain possible elsewhere in the northern Interior but especially in the higher terrain. Farther south into the southwestern Interior, while thunderstorm chances will be much more limited than they have been recently, an isolated storm could still occur, and widespread showers are likely. From the northern slopes of the Western Alaska Range into the Upper Kuskokwim Valley, anywhere from a quarter inch to over an inch of rain will be possible through Thursday morning, contingent on where individual rain showers/storms track. Lower totals of around a quarter to a half inch of rain will be possible in eastern portions of the Lower and Middle Yukon Valleys during this same time frame.

By Thursday, ridging will begin to shift westward again, but it will not be quite as strong as earlier this week, and with abundant moisture/cloud cover, it could be a 'dirty ridge' with showers and storms underneath it, with temperatures generally still being a few degrees cooler. Any thunderstorms will generally be focused in the Brooks Range and in the higher terrain of the Eastern Interior (especially along the Canadian border). Increasing westerly to southwesterly wind gusts will be possible, especially in the higher terrain and in Western Alaska, with gusts up to around 20 mph possible in the valleys.

FIRE WEATHER

Tuesday, the prominent ridge that has taken hold over the western portion of the state will break down, allowing ample moisture and energy to advance north. This will serve as the catalyst for numerous thunderstorms, with storms continuing to expand into the Brooks and Arctic Plains. Expect big lightning days over the next 48 hours for the west, with storms bringing increased chances for heavy rain. Anticipate the focus of storms to rotate clockwise from the western Interior today, northwest Wednesday, and to the east by the weekend. Another hot/dry day is in place for the Arctic Plains persisting into Wednesday before beginning to see some relief. Furthermore Wednesday, cooler temperatures and higher min RH penetrate into the southwest near lower Yukon, working north into the western Interior through the weekend. Focus for hot/dry will likely remain over the Yukon Flats.

EXTENDED FORECAST DAYS 4-7

Friday through Monday.

A broad upper level ridge will keep much of Alaska warm and relatively dry through Friday before an upper level low moves east from the Bering Strait on Saturday. This pattern shift will bring cooler temperatures, increased cloud cover, and expanded chances for showers. Rain will spread into the YK Delta through Saturday with scattered showers becoming more common through the weekend across the state. Isolated afternoon thunderstorms remain possible, mainly across portions of the Eastern Interior and areas of higher terrain in the Eastern Brooks Range where daytime heating provides enough instability, though coverage should become more limited as the cooler, wetter pattern settles in.

By Monday, forecast guidance suggests ridging may begin rebuilding, spreading from the northeast to the southwest across the state into the Bering Sea while low pressure lingers over the Gulf of Alaska. Showers may develop across the eastern Alaska Range and Upper Tanana Valley, but forecast confidence decreases early next week. There remains uncertainty regarding precipitation amounts and whether the ridge becomes strong enough to bring drier weather or if another low pressure system moves into the state from the Bering Sea, resulting in a more unsettled pattern.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Fire Weather Watch for AKZ916-918-919-928. Red Flag Warning for AKZ918-919-923-928-929. Heat Advisory for AKZ833. Heat Advisory for AKZ806-808. PK...None.