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. Scattered thunderstorms will be possible across the Southern Interior today and Sunday, with isolated thunderstorms across most of the remainder of the Interior and parts of the Brooks Range. Cooler temperatures are expected on the North Slope from this evening into Sunday behind an Arctic front but will recover by early next week. Additional chances for isolated to scattered thunderstorms will return on Monday. Rain chances will improve across the Southern Interior early and especially mid next week.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Highs continue to increase across the area over the weekend with widespread upper 70s to upper 80s. The warmest temperatures continue to be across the Yukon Flats with a Heat Advisory in effect for today and Sunday.

- Scattered thunderstorms are forecasted to impact much of the Tanana Valley and Alaska Range. Further north we will see isolated thunderstorm activity, with an uptick in the Yukon Flats Sunday.

- Increasing rain chances are favored moving into early to mid next week, although there is still uncertainty on any exact rainfall totals.

West Coast and Western Interior...

- Temperatures remain seasonably cool along the West Coast, with temperatures in the 50s to 60s. In the Western Interior, highs will likely rise into the upper 70s.

- Isolated thunderstorms are likely to continue across the western portion of the state, with scattered thunderstorms possible in the Upper Kuskokwim and Lower Yukon Valleys today and Sunday.

North Slope and Brooks Range..

- An Arctic front edging its way southeastward along the Western Arctic Coast will spread across the North Slope today, bringing cooler conditions and northwesterly winds in its wake.

- Northern Brooks Range valleys are expected to warm into the 70s to near 80 today before falling into the 50s Sunday behind the front. - Isolated thunderstorms will be possible today across the Eastern North Slope and will be more predominant in the southern Brooks Range on Sunday and into next week.

FORECAST ANALYSIS AND DISCUSSION

A 554 dm upper-low at 500 mb is in place over the southeastern Bering Sea and is helping to bring some sparse showers to the area. A warm air mass dominates most of Interior Alaska, with extensive ridging aloft extending across the area from over northwestern Canada. Temperatures at 850 mb this morning are around 10 to 12 C over the Eastern/Central Interior and 8 to 10 C over the Western Interior and could rise by 2 to 3 C this afternoon. This warm air aloft will correspond to surface temperatures in the 70s and 80s, with the Yukon Flats, where a Heat Advisory is in effect, potentially seeing highs rise into the upper 80s this afternoon and evening.

The Eastern North Slope will likely see highs in the 60s and 70s, but the Western North Slope will be much cooler in the 40s and 50s with an Arctic trough/cold front moving through. By Sunday, even the warmer valleys of the North Slope will likely see highs fall into the 50s, with lows ranging from the low 30s into the 40s. Along the front, brisk southwesterly winds and a chance for rain and snow are expected. The precipitation band is likely to be fairly narrow, limiting the maximum precipitation chances to a period around 6 hours long. In the wake of the front, winds will generally shift to the north to northwest, with low clouds and areas of fog. These effects will remain limited to the north side of the Brooks Range, with the trough/front exiting the area by early next week.

Convective indices across the Southern Interior are expected to be supportive of thunderstorm activity today and Sunday, with several hundred joules of surface-based CAPE and minimum LIs widely in the 1 to 3 C range. Multiple shortwave troughs moving across the Alaska Range and into the Interior will provide additional dynamic support for ascent. Scattered thunderstorms will resultantly be possible over across the Southern Interior today and Sunday, with isolated thunderstorms possible across the rest of the Interior and the southern North Slope. The best chances for thunderstorms on the North Slope will be east of the Dalton Highway and in the eastern Brooks Range. Individual storms will likely be slow-moving with fairly weak steering flow. They could produce brief heavy rainfall, frequent lightning, and gusty/erratic winds, even at some distance with spreading outflows. Storms tonight could continue until as late as the early morning hours of Sunday before ending completely. Moving into early next week, there will be slightly cooler temperatures and continuing chances for thunderstorms in the Interior, including scattered thunderstorms near the eastern border on Monday. There will also be much better chances for rain in the Southern Interior with moist flow being brought into the area on the north side of a Gulf low.

FIRE WEATHER

A continuation of active thunderstorm days is expected this weekend as upper level ridging persists over the state. Isolated to scattered thunderstorms are likely to develop across the Interior and southern North Slope this afternoon, with increasing confidence for slow moving storms that linger overnight. Tomorrow follows a similar trend with isolated storms expected from the Eastern Brooks Range southwest towards the YK Delta, and scattered thunderstorms over the Central/Eastern Interior and Alaska Range. Given the high amount of lightning activity observed yesterday over the Kuskokwim Valley and a highly favorable atmospheric environment, Red Flag Warnings were issued for the Central/Eastern Interior through Sunday night. It is imperative to stay weather aware this weekend as everyone enjoys the summer solstice activities. Those who plan to be outdoors should prepare for periods of gusty winds, strong outflow boundaries, localized heavy rain, and frequent lightning. Fairly active thunderstorm activity continues early into next week with models hinting at elevated activity possible over the AlCan border. However, with increased southeasterly flow expected at the upper levels, storms that develop next week will likely see consistent wetting rains and scattered showers, helping to limit critical fire weather conditions.

Across the Central/Eastern Interior, high temperatures in the low to mid 80s are expected this afternoon before slightly cooling into the mid to upper 70s by early next week. Highs in the Western Interior will remain fairly consistent in the low to mid 70s through the weekend, with temperatures reaching their peak this afternoon. Relative humidities will remain fairly dry this afternoon between 30 to 40%, with the exception of the Yukon Flats and Upper Koyukuk Valley seeing values near 25%. As scattered showers move in from the southeast early next week, relative humidities in the Central/Eastern Interior will gradually increase while the western half of the state sees relative humidities on a slight downward trend. Winds will continue to remain fairly light and out of the west/northwest with the strongest winds expected near the Norton Sound coast, Kotzebue Sound, and Western Brooks Range.

HYDROLOGY

Water levels in rivers continue to recede. 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.

EXTENDED FORECAST DAYS 4-7

The long term forecast remains in reasonable agreement come midweek, with ensemble models continuing to show broad upper level ridging over Northern Alaska with a H5 low in the Gulf of Alaska. Increasing confidence surrounds higher PWATs around that 120-150% of normal range lifting north over the Alaska Range into the Southeast Interior Tuesday into Wednesday, which will bring with it steadier precipitation chances for this region. This corridor of steadier precipitation will then extend north along the Alcan Border to finish out the work week through the Eastern Brooks Range as the a plume of moisture from the Gulf lifts north. This upper-level setup will remain conducive for widespread light precipitation in this area Tuesday to Wednesday/Thursday with highest totals in the Alaska Range, Fortymile Country, and Upper Tanana with drier conditions elsewhere. Daily thunderstorms will also be possible, particularly during the afternoon and evening hours where coverage peaks diurnally where a mix of sun and clouds exist. While temperatures see a cooling trend in these region given the increased cloud cover, warmer and drier conditions will prevail elsewhere across the state and leading to temperatures see a warming trend. While the H5 low continues to shift east Thursday into Friday, precipitation chances will continue daily into the weekend with increased uncertainty on the exact track of our next H5 low building in out of the southwest.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Red Flag Warning for AKZ934>947-951>953. Heat Advisory for AKZ833. PK...Small Craft Advisory for PKZ801. Small Craft Advisory for PKZ850.