textproduct: Fairbanks

SYNOPSIS

More summer like weather will continue across the Eastern Interior for the next couple of days as temperatures rise, skies clear, isolated thunderstorm chances return, and the potential for elevated fire weather concerns. On the West Coast, however a different story will play out as rain showers and cooler weather will continue for the next couple of days. By Thursday night these rain showers will be shifting north and east to the Northern Interior and North Slope. As we turn towards early next week, high pressure is looking likely to build across the North Slope and the Central and Eastern Interior. This will bring warmer than normal temperatures and drier conditions. Meanwhile, on the west coast a broad area of low pressure is possible keeping it cooler and wetter.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Warm and drier weather will continue as daytime highs will be in the mid to upper 70s with the Upper Tanana Valley potentially reaching 80.

- Gusty southerly gap winds in the Alaska Range passes will continue through Thursday with wind gusts of 30 to 45 mph. The strongest winds will be in Windy Pass.

- Outside of isolated showers through Wednesday farther west, those chances will expand east on Thursday with accompanying isolated thunderstorms. Best thunderstorm chances will be Thursday afternoon and evening along the Alcan Border north of the Tanana Valley northwest to the Brooks Range. Very isolated dry thunderstorms could also be possible.

- Temperatures will cool slightly for most on Friday and Saturday with highs in the 60s to mid 70s as isolated showers persist.

West Coast and Western Interior... - A stalling front is bringing more rain showers to the region through Thursday night. An additional 0.5" to 1.0" of rainfall will be possible with the highest amounts on the Southern Seward Peninsula and the Nulato Hills.

- Gusty winds southerly to southeasterly winds of 25 to 35 mph will continue today before weakening overnight Wednesday.

- The stalling front will begin to be pushed northeast out of the region on Thursday bringing a brief period of warmer and drier weather to the region Thursday and Friday. - Another low will potentially move into the Bering Sea this weekend bringing more rain showers and cooler temperatures across the region.

North Slope and Brooks Range.. - Above seasonable normal temperatures will continue across the North Slope as the Arctic Plains will be in the mid 70s and even near 80 on Thursday. The Arctic Coastline will be in the upper 50s to low 60s. These warmer temperatures will continue through Friday.

- Steady rain will continue for the western Brooks Range north of the Kobuk Valley today. Showers and isolated thunderstorms will lift northeast on Thursday across the Brooks Range and North Slope as a Bering Sea low tracks towards the Arctic Coast.

- As the Bering Sea low works over the North Slope Friday into Saturday, expect cooler and wetter conditions to finish out the week as winds remain light overall.

FORECAST ANALYSIS AND DISCUSSION

The 545 decameter closed off upper-level low is continuing to meander over Norton Sound. There is a stalling front stretching from the Northwest Interior south towards the Kuskokwim Delta. This front is allowing for continued rain showers to continue across the region, even with the surface low beginning to weaken completely. Along the front rain showers will be lighter, but as you get closer to the upper-level low we will see higher rain rates from upslope flow. An additional 0.5" to 1.0" of rain is expected over the next 24 to 36 hours in the Southern Seward Peninsula and Nulato Hills due to this upslope flow. With the showery nature these rain totals will not be widespread, and will be heavily dependent on rain bands.

With the closed off low stuck between a ridge to it's west and east it will continue to meander in Norton Sound until Thursday afternoon. The aforementioned ridge over the eastern half of the state is keeping 850 mb temperatures of 9C to 12C. These temperatures will help to support the widespread mid to upper 70s and even 80 in the Eastern Interior valleys. As we see a low pressure moving east off of Eastern Siberia on Thursday, it will begin to push the closed off low from the West Coast northeast towards the North Slope. As this low moves northeast it will create some instability across the Interior bringing chances for isolated thunderstorms Thursday and Friday.

Thursday afternoon there are some concerns in the far eastern Interior that some of the isolated thunderstorms could be dry. Model soundings at Northway and Eagle are showing a decent dry layer at the bottom 5000' to 7000' of the atmosphere. This could be a big enough dry layer to have all of the falling precipitation be virga, but with PWATs of 0.75" to 1.25" in the region, there should be enough moisture to overcome this dry layer. The chances for dry thunder remains extremely low as of now, but with current fuel statuses across the Upper Tanana Valley and Fortymile country it is worth to mention.

Friday afternoon ridging will begin to build back in across the Interior with troughing from the Siberian low along the West Coast. This pattern looks to be what holds for the weekend and even through early next week, but model confidence is low and will be discussed in more detail in the Extended Forecast section.

FIRE WEATHER

A large, quite wet, low over the Bering Strait region keeps steady rain falling and gusty winds blowing over the West Coast and westernmost portions of the Interior. Less consistent, more showery, rain continues over the Central Interior and Chukchi Sea Coast. The heaviest rain is expected from the Lower Yukon north to the southern half of the Seward Peninsula. Total accumulations through Thursday lie in the 0.5 to around 2 inches with greater totals possible along south facing slopes in the Nulato Hills, Seward Peninsula, and the Western Brooks Range. Wind gusts will be strongest along the Norton Sound Coast with gusts up to 35 mph. Weaker winds up to 25 mph are possible through the Western Interior.

A ridge of high pressure over the Yukon Territory keeps the low stalled in place over the West Coast and keeps warmer, drier, conditions over the Eastern Interior through Thursday. Highs in the mid 70s to near 80 are expected for areas from Fairbanks east with minimum RHs in the 30s to 40s for most areas. The Upper Tanana Valley and the Fortymile Country could see slightly lower values in the 20s to 30s.

On Thursday another low near the North Pole pushes front into Siberia which then causes the stalled low to begin moving northeast. This pulls much of the remaining moisture into the south side of the Central Brooks Range and suppresses the ridge over the Eastern Interior. Temperatures decrease over the Eastern Interior Friday and Saturday with the suppressed ridge, but chances of wetting rain remain low despite the low moving closer. As the low approaches isolated thunderstorms are possible in the Eastern Interior amongst the isolated to scattered showers Thursday and Friday. The greatest thunderstorm potential lies in the Northeastern Interior Thursday and along the Canadian border Friday. Minimum RH values look to recover slightly faster than anticipated yesterday slightly limiting the potential for dry lightning over the Southeastern Interior, but there still remains a non-zero chance of isolated thunderstorms dropping a few dry lightning strikes as the remaining dry air limits precipitation. This chance remains highest Thursday with Friday seeing slightly greater thunderstorm potential, but less chance for dry lightning due to recovering RHs.

HYDROLOGY

A very wet past couple of days along the West Coast and Western Interior. In the past 72 hours 1" to 3" of rain has fallen, and more rain is expected over the next 48 hours across the region. No flooding is occuring or expected, but smaller creaks and streams could still become bankfull.

EXTENDED FORECAST DAYS 4-7

SATURDAY THROUGH TUESDAY Moving into the weekend the forecast is in decent agreement, but the models have large spreads for qpf and temperatures, as the models struggle to resolve what will happen to the current low meandering in Norton Sound. Cluster analysis of the ensembles for Saturday and Sunday shows ridging building throughout the Interior keeping the region warmer and drier, and broadscale troughing along the West Coast keeping it cooler and wetter. This analysis is in alignment with the deterministic models, so there is fairly decent confidence looking through at least Sunday night.

As we look to Monday, however, Cluster analysis is split on what will happen to the ridge axis that builds over the Interior. THe GFS is very aggressive with an arctic trough dipping down into the Northeast portion of the state. This kind of solution would weaken the ridge axis over the Interior bringing the temperatures to a bit more seasonable. The ECMWF on the other hand keeps that feature further north allowing temperatures to continue to rise, as warmer 850 mb temperatures could be advected into the region. As of now we are leaning towards the ridge remaining fairly strong therefor it being warmer across Northern Alaska.

Coastal Hazard Potential...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ803. Small Craft Advisory for PKZ804-805-852. Small Craft Advisory for PKZ807-808-856. Small Craft Advisory for PKZ809-810-855.