textproduct: Fairbanks

SYNOPSIS

Warm weather and chances of thunderstorms are the big weather stories as we approach and then head through the weekend. A building ridge over the interior has brought with it building temperatures across much of the state, with the warmest weather expected over the weekend. A strong shortwave moving over the ridge will bring with it periods of showers and some thunderstorms. Between these showers and thunderstorms, drier weather will prevail, with minimum relative humidities dropping down as low as 25-35 percent over the eastern interior by late in the weekend. A cooldown and a return of more widespread rain are expected beginning early next week as a low in the Aleutian Islands steers northward and into the Kuskokwim Delta.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- A warm and largely dry pattern persists into the weekend, with high temperatures reaching into the 70s and mid 80s. As clouds and chances of scattered showers increase north of Fairbanks on Friday, temperatures will cool by a few degrees.

- A weak upper-level disturbance moving through on Friday will bring chances of showers and isolated thunderstorms, mainly from Fairbanks northward and across higher terrain. Any rainfall will be light, with drier weather returning Saturday as high pressure builds over the region.

West Coast and Western Interior...

- Warm conditions will continue through the weekends. Daytime highs will reach the 60s to near 70 along the coast, while inland areas warm into the mid to upper 70s. The warmest temperatures will be on Saturday.

- Showers and isolated thunderstorms will taper off after Thursday, leading to a warmer and drier trend Friday through the weekend.

North Slope and Brooks Range...

- Warm weather will continue across the Western and Central North Slope and Brooks Range, with highs reaching the 60s and 70s. Highs will approach 80 across the Arctic Plains near Umiat. Temperatures will remain cooler from Deadhorse east along the Arctic Coast, with highs in the 40s and 50s.

- Scattered showers and thunderstorms are anticipated along the Western Brooks Range and North Slope through Thursday before shifting into the Eastern North Slope on Friday.

- Thursday morning, onshore flow will usher in fog along the Arctic Coast.

FORECAST ANALYSIS AND DISCUSSION

Warm summertime conditions-with some chances for showers and thunderstorms, look set to be the big story for the weekend, while early next week will feature a sharp change in the pattern, as a low moves into SW AK and brings cooler temperatures and more widespread areas of rain back northern Alaska.

Aloft, a strengthening ridge over the interior is responsible for the rising temperatures across much of the region. The 576 decameter ridge will contribute to 850 mb temperature anomalies reaching 5-8 C above normal. Closer to the surface, expect this to lead to temperatures warming into the mid to upper 70s for much of the area, and even into the lower 80s for areas further in the central and eastern interior. The warmest temperatures are expected Saturday into Sunday. Two separate organized shortwaves moving up and over the ridge axis will be the main flies in the ointment through the weekend, bringing chances of thunderstorms to the central and eastern interior and North Slops on Friday, and then in a band ranging from the Alaska Range west across SW AK (south of the Seward Peninsula) on Saturday as another shortwave begins sweeping up from the South, ahead of a broad area of low pressure which looks set to move into SW AK (the Kuskokwim Delta Area), by late Sunday into Monday. Ensemble guidance has not yet finalized on an exact track for this low low, but confidence is good in a return to more widespread rain for much of the area, Potential rainfall totals from Monday into Tuesday reaching anywhere from 0.5 to 1.5 inches for valleys and areas near sea level along the Western Interior, with 2-3 inches possible for areas at elevation. Tentatively expect amounts to trend towards the higher ends of these totals given the inclusion of some moisture from the subtropics with this system, though actual system isobaric strength will be limited by a lack of any deep cold air advection along its NW flank. For additional information, see the long term discussion.

FIRE WEATHER

Warming temperatures through the weekend, along with drier weather across much of the area will bring temperatures until the mid to upper 70s across the western Interior, and into the low 80s for the central and eastern Interior. The warmest temperatures are expected through the weekend. Relative humidities will reach as low as 25-35 percent across the eastern interior on Sunday, although winds will generally be on the light side during this time frame for that portion of Northern Alaska. Isolated chances of thunderstorms are expected for the central and eastern interior on Friday, and for the Alaska range and immediately north of it on westward, including the Kuskokwim Delta Area, for Saturday. By late Sunday into Monday, a low moving up from the Aleutians will bring with it widespread wetting rain and cooler temperatures, especially between the western coast and central interior.

HYDROLOGY

River levels remain normal. No hydrology concerns are expected.

EXTENDED FORECAST DAYS 4-7...SUNDAY THROUGH WEDNESDAY

At the start of the extended, a high pressure ridge will still be the dominant feature over northern Alaska. However, troughing in the north Pacific will join with a low in the Bering, dragging the center of low pressure east toward Bristol Bay on Sunday. As this happens, the gradient between the low and the ridge becomes situated over the Alaska Range, supporting southerly gap winds through Isabel and Windy Pass. It will also pull a moderate amount of tropical moisture into western Alaska. Run-to- run, models have been trending upward with respect to the strength of the winds and amount of rain associated with this low. Probabilities of getting an inch of rain have gone from ~25% in the lower Yukon to more than 50% with the latest NBM guidance. Similarly, the probability of wind gusts greater than 45 mph in the Alaska Range passes has jumped from 30 to 50% to between 75 and 100%. The timing of strongest winds in the AK Range and heaviest rain in the southwest are both Sunday evening/Monday morning at this time. Sunday, while the low is bringing cooler and wetter weather to the southwest, the ridge will still have considerable influence over the Interior and North Slope regions continuing the trend of warm and dry weather. That ridge's influence should gradually wane through the start of next week as the low carves into it, leading to gradually cooler temperatures through the rest of the forecast period. Southerly winds and wetter weather in Western Alaska will diminish beyond Monday, but not cease, as the low meanders over Alaska through Wednesday.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Heat Advisory for AKZ806-808. PK...None.