textproduct: Fairbanks

SYNOPSIS

Ridging is building over the Interior with warming temperatures likely today. Over the weekend, temperatures will begin to decrease over Western Alaska due to increased cloud cover, but they remain warm in the Central/Eastern Interior and North Slope. Temperatures will continue to fluctuate on Sunday, but they should be cooler for most spots besides the Eastern Interior. More uncertainty arises early next week as our attention turns to a developing weak low in the Bering Sea. This low has the potential to bring heavy rain and gusty west-southwest winds to Western Alaska from Sunday night through at least Monday. The placement of this low will help determine if the heaviest rain reaches as far north as the Brooks Range, or stays south towards the Yukon River. High Wind Watches have also been issued for the AK Range Passes and Delta Junction from Sunday night through Tuesday evening. This evolving pattern will be elaborated on in the Short Term Forecast Discussion below.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Saturday is the pick of the weekend with mix sun and clouds and highs in the 70s to near 80. Temperatures remain warm on Sunday, but the Central Interior drops a few degrees. 60s to low 70s are expected from west to east on Monday with Fairbanks around 70.

- Showers become possible Sunday afternoon from FNSB north and west with the highest probabilities expected from Minchumina to Bettles.

- The Southern AK Range, including Cantwell, likely sees steadier rain Sunday night into Monday.

- High Wind Watches have been issued for the AK Range Passes and Delta Junction from Sunday night through Tuesday night for southerly wind gusts up to 70 mph. There is some uncertainty and winds may end up being weaker.

West Coast and Western Interior... - For those with outdoor activities planned, today and tomorrow are your days to do them as temperatures sit in in the 50s/60s along the coast and 70s in the Interior.

- Sunday features cooler temperatures and heavy rain moving in from the west as early as Sunday morning in St. Lawrence Island, and Sunday evening in the Interior. Moderate rain is likely north of the Seward Pen./Yukon River Sunday night as well.

- Periods of rain, heavy at times persist into Monday with widespread rainfall amounts around 0.50" to 1.50" possible.

- Winds gusts up to 45 mph along the West Coast and 35 mph in the Interior Valleys are possible on Monday.

North Slope and Brooks Range.. - Warm weather is expected with highs in the 50s/60s along the coast and 60s/70s in the Brooks Range and Flats through Monday. The coast will have periods of dense fog through Saturday.

- Mostly dry weather is expected today but rain showers exist in the Western Brooks Range and Chukchi Sea Coast today. Scattered showers are likely for most of the area Saturday afternoon, then the eastern half of the Slope into Sunday.

- Steadier rain moves into the Brooks Range from the south on Monday. Rainfall totals Friday-Sunday will be around 0.05" to 0.15", heavier in the Western Brooks Range. Around 0.15" to 0.35" possible on Monday in the Brooks Range.

SHORT TERM

Satellite imagery from this morning shows the remnants of a frontal system moving SE from the Upper Tanana. This is providing a shallow cloud layer across the White Mountains and portions of the Eastern Interior. These are not expected to last long as higher pressure builds in from ridging expected to continue shifting east across the state. This will allow for seasonal temperatures to return across the Interior during the weekend with highs in the mid 70s to low 80s. Meanwhile, a series of shortwaves will continue to move NE across the NW Arctic Coastline; providing ongoing isolated showers across the West Coast through the start of the weekend. These shortwaves are a part of a sub-arctic jet energy over Siberia that is expected to shift south a play a larger role in the second half of the forecast period.

Up to this point in the forecast, models are in fairly good agreement. However this does not last much longer. The sub-tropical jet is expected to move across the Kamchatka Peninsula by the mid weekend and phase with the energy from the south moving sub-polar jet. The timing and positioning of the phasing is the disagreement that begins to be seen amongst the models. The GFS shows a more aggressive solution, phasing just east of the Kamchatka Peninsula. This would allow the trough to develop into a more organized upper- level low as it moves into the Bering. Associated with this system is a 990mb low and a series of fronts moving NE across the state from the YK Delta. Widespread, heavy rainfall and gusty winds are expected across much of the West Coast and Western Interior Sunday and Monday. The earlier phasing would allow higher potential for the system to tap into tropical moisture from systems in the Western Pacific and allow for more rainfall across the area. The ECMWF shows the phasing occuring about 12 hours later and slightly farther east. This solution would not allow the organized low to form until the trough reaches the Central Bering and the warm front begins to move across the YK-Delta. While this would still allow for widespread rain, the heavier rainfall would be kept farther south over the Kuskokwim Valley and South-Central Alaska. In addition, wind gusts would be slightly weaker as the associated 925mb low-level jet will not be as strong.

More uncertainty continues through the end of the forecast period. The different solutions yield different impacts regarding the strength and the positioning of the ridging that is expected to form over Eastern Alaska out ahead of the trough. This will continue to be monitored closely as southerly flow is expected to set up across the central portion of the state; bringing gap winds across the Alaska Range and chinooking conditions across the Interior. More on this in the extended portion of the discussion.

FIRE WEATHER

Drier weather has settled across much of northern Alaska as a ridge build across the interior of the state. High Temperatures through the weekend will be on a warming trend as the ridge traverses east across Alaska, reaching into the 70s and -for some locations-the lower 80s. Relative humidity will reach down to 25 to 35 percent over the weekend across the Eastern Interior and Yukon Flats, and 30-50% across the central and Western Interior. By late Sunday, widespread wetting rains will be spreading across the Western Interior, and into the central interior by Monday, though drier weather may linger further east between the Yukon Flats and Fortymile country. Cooler temperatures in the 50s and 60s will arrive with this precipitation, with wet weather expected to continue south of the Brooks Range through the first half of the week.

HYDROLOGY

An atmospheric river arriving across the western interior late Sunday into Monday will bring river rises across smaller rivers in the west and along the Alaska Range through the first half of next week. No flooding concerns are expected. Precipitation totals of 1-3 inches are looking increasingly likely from Sunday to Tuesday for these areas, with isolated higher amounts possible in areas of terrain.

EXTENDED FORECAST DAYS 4-7

The big story for the middle and latter half of next week will be the decaying low along the west Alaska Coast. By Tuesday, the low will have largely occluded. While the GEFS and EMCWF ensembles do show some differences in final placement - dependent on how the low phases with shortwaves moving in from the West and how strong a ridge that builds to the east is - the broad brush strokes remain the same. The low will remain centered over the West Coast until late in the week when it is dislodged into the interior of the state. By Tuesday, the heaviest precipitation over northern Alaska will be winding down as the atmospheric river wraps around further south, instead focusing on the Alaska Peninsula and areas further east (Anchorage). The previously moderate to heavy rainfall over the western interior will revert back to more standard periods of light rain. In the east, drier weather (or at least a significantly lower chance of showers) will prevail north of the eastern AK range as southerly flow brings general downsloping across the area. The southerly flow will also bring chinook conditions at times to some of the mountain passes, with the strongest Chinook winds likely to be Tuesday into early Wednesday.

Coastal Hazard Potential Days 3 and 4... Some minor beach erosion and high surf are possible for Norton Sound and the Kuskokwim Delta Monday and Tuesday as a 985-995 mb low over St Lawrence Island sends SW winds up across much of the west coast. More updates will be made available as forecast confidence in a final track and strength of the low develops.

AFG WATCHES/WARNINGS/ADVISORIES

AK...High Wind Watch for AKZ837-847-849. PK...Small Craft Advisory for PKZ811. Small Craft Advisory for PKZ812. Small Craft Advisory for PKZ856. Small Craft Advisory for PKZ857-858.