textproduct: Fairbanks

SYNOPSIS

Warm weather with isolated to scattered thunderstorms expected Sunday through much of the week. Temperatures cool Wednesday and Thursday. The forecast becomes less certain later in the week, but likely remains seasonably warm with additional isolated to scattered storms.

KEY WEATHER MESSAGES

Central and Eastern Interior... - A warming and drying trend will occur across the Interior through Tuesday with daytime temperatures rising into the 70s and lower 80s. A heat advisory is in effect for the Yukon Flats for highs near 85 Tuesday and Wednesday. Temperatures cool late Wednesday into Thursday.

- Isolated to Scattered thunderstorms will be possible in the White Mountains and Fortymile Country Sunday PM. These storms will develop and then may southwest into the valleys. Longer lived storms could produce heavy rainfall up to 3/4", frequent lightning, and pea size hail. West Coast and Western Interior... - A warming and drying trend will occur across the region through Tuesday with daytime temperatures rising into the 60s/70s. Tuesday is expected to be the warmest day of the week.

- Isolated to scattered thunderstorms will be possible across the southern half of the Western Interior today. Monday those chances expand to cover the rest of the Western Interior. Thunderstorm chances continue through much of the week.

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

- Isolated thunderstorms will be possible in the Brooks Range and Central Arctic Plains Monday. These chances will continue on Tuesday, but will extend in coverage to the coastline.

FORECAST ANALYSIS AND DISCUSSION

For Sunday through Wednesday. At the start of the forecast period, Sunday, the overall pattern consists of an upper level high over the North Slope and Chukchi Sea and 4 upper levels lows surrounding it; two to the north, one in the Gulf of Alaska, and on in the western Bering Sea. The high is keeping temperatures warmer than normal across Northern Alaska and far warmer than normal across the Arctic Plains. The lows to the south push back against the high creating the instability and energy needed for afternoon thunderstorms each day. The high moves east through the week reaching the eastern North Slope/Beaufort Sea Coast Monday and then connecting with a building ridge over northwestern Canada. This allows thunderstorm chances to push further north and west to cover the entire Western Interior and most of the Central and Eastern Interior Monday, Tuesday, and Wednesday afternoons. Temperatures remain warm through Wednesday.

Model agreement weakens substantially after Wednesday as the ridge (former high) over northwestern Canada attempts to push farther west back into the Alaskan Interior. Some models are favoring keeping the ridge further east allowing for cooler temperatures and more room for showery conditions. Others are favoring the ridge building back in over Northern Alaska with lows to the south and west pushing against it. This would lead to warmer conditions with some showers and isolated to scattered thunderstorms in the Southern Interior and Western Interior.

FIRE WEATHER

Sunday, a broad ridge of high pressure continues to transit east across the North Slope, with a closed low undercutting the state. An area of upper-level divergence is bringing a stalled frontal boundary to the Central Interior, serving as the catalyst for continued thunderstorm development through the late afternoon Sunday. As the Interior warms and dries, this wave will lift to the northwest Monday, expanding the footprint of thunderstorm activity from the YK Delta into the Upper Kobuk/Western Brooks Range. Expect continued scattered storms for the much of the higher terrain across the Interior.

Touching on temp/RH, temperatures will continue to trend upwards into Wednesday, reaching 75F to 85F and min RH down to 20 to 30 percent. The focus of hottest and driest continues to be from Bettles north into the Arctic Plains and east through the Yukon Flats. Middle Yukon will likely hold on to 30 to 40 percent min RH.

Park

EXTENDED FORECAST DAYS 4-7

Wednesday through Sunday After the Bering Sea low moves east across the Gulf of Alaska on Thursday, forecast solutions start to diverge. Confidence is high that ridging will build back in after the low moves through, but lower in the location, strength, and extent of the ridge. If the ridge axis stays farther to the west, temperatures will stay warmer. In this case, more instability will be present in the Central and Eastern Interior, increasing thunderstorm chances, especially thunderstorms with higher rain totals. The pressure gradient is also weaker in this solution, making stronger winds less likely. On the other hand, if one of the solutions favoring ridging building more in the Yukon/NW Territories, troughing is able to extend more into the state. Flow will be more southerly, cutting off the Central an Eastern Interior from moisture and instability, making widespread rain and thunderstorms less likely. In this case, gap winds are also possible in the Brooks Range with a tighter pressure gradient in the northern portion of the state. The strength of the ridge and troughing off the coast are both variable in current model guidance, so either solution, as well as other solutions, are viable at this point.

Schlezinger

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Heat Advisory for AKZ833. Heat Advisory for AKZ806-808. PK...None.