textproduct: Fairbanks

SYNOPSIS

Wet weather continues to highlight the forecast as the long holiday weekend ensues and we begin to say goodbye to summer. Widespread rain will continue to focus across much of the western and central Interior through Saturday before conditions start to dry out a bit. Spotty showers will remain in the forecast for most areas Sunday and Monday, but temperatures will get a bit of a boost after the recent chilly conditions of this past week. More unsettled weather is likely later next week as additional storms try and push in from the west.

KEY MESSAGES

Central and Eastern Interior...

- Widespread light to moderate rainfall will continue Friday night into the first part of the day Saturday as a combination of a lingering atmospheric river and approaching upper disturbance track north through much of the Interior.

- Additional rainfall of 1.00 to as much as 2.00 inches will be possible through Saturday, when overall rainfall begins to taper off.

- Main stem rivers are expected to see noticeable rises over the next few days, but flooding is not expected to be an issue. However feeder streams and rivers could see water levels nearing bankfull in a few locations.

- While the upper Tanana Valley has missed out on most of the rainfall over the past few days, shower activity will slowly pick up over this area in the days ahead.

- Warmer conditions are expected to return for the Sunday and Monday timeframe with highs back in the upper 50's and lower 60's, even a bit warmer in locations not impacted by rainfall.

Central and Eastern Interior...

- Occasional showers will continue to track across the region over the next few days, but total additional rainfall will remain rather light.

- Higher water levels are expected once again throughout the Norton Sound through high tide Saturday morning. Afterwards more normal tide cycles are expected through the region for a few days.

- Warmer than normal temperatures will continue across the region through the weekend with highs generally in the 50's to near 60 further inland.

North Slope and Brooks Range...

- Bands of precipitation will continue to push north over the Brooks Range through Sunday. Most precipitation will be light and predominantly in the form of rain.

- Snowfall through the weekend will be confined to elevations generally above 5500 feet with the possibility of mixed rain and snow at times near the Dalton through Atigun Pass.

- Low clouds and occasional showers will occur near the Arctic coastline through Saturday. However temperatures will be warming a bit above seasonal normals with readings in the 40's and 50's throughout much of the North Slope.

SHORT TERM /THROUGH MONDAY NIGHT/

The heavy rain threat for Interior portions of Alaska continues to be the primary forecast focus at the start of the short term. Friday morning precipitable water analysis showed normalized anomalies of up to +4 standard deviations across a large portion of the western and central Interior as deep northward moisture transport associated with an atmospheric river remained trapped in the southerly flow between an upper low in the Bering and an upper ridge over the Gulf of Alaska. This resulted in widespread moderate to heavy rainfall overnight and into early Friday with readings of .50 to 1.00 inches of rain.

Models and satellite imagery are also indicating a fairly strong shortwave currently over the Kuskokwim Delta ejecting northeastwards towards these same areas of the Interior this evening into early Saturday. The extra energy associated with the shortwave will combine with lingering atmospheric moisture to deliver a second round of steady and sometimes heavy rainfall. While main stem rivers appear to still have plenty of room to handle this extra volume of water, there will be noticeable rises and swift flows along these waterways. Smaller streams and rivers could even see minor flooding through Saturday, especially in areas where repeated heavy rainfall occurs.

In the wake of this ejecting shortwave, the atmospheric river connection should shift east and south of the central Interior, allowing for a slight drying trend for late in the weekend and into Labor Day. However with longwave troughing remaining over the Bering and southwest flow over much of the region, a few scattered showers can't be ruled out through the remainder of the holiday weekend.

Meanwhile additional energy will round the base of the Bering trough and set up a 996 surface low in the southern Bering by Monday. As of now, the general trend is to keep the primary impacts of this system south of the Alaska Range for Labor Day. However as flow becomes more southerly over the range, increased gap winds through the Alaska Range passes will be possible by Monday night and Tuesday with another round of precipitation as we head into the extended forecast period.

LONG TERM /TUESDAY THROUGH FRIDAY/

To start the extended time frame on Monday, general troughing will predominate across Western Alaska and adjacent marine areas, with ridging occupying the eastern Gulf of Alaska and extending into northwestern Canada. Model consensus supports a shortwave shifting from southwest to northeast along the eastern periphery of the trough across the Interior. As this occurs, scattered to numerous showers will develop from the Alaska Range to the Brooks Range, increasing in coverage Tuesday as the broader longwave shifts east across the area. There is significant uncertainty on exact rain totals and timing, but the highest totals (potentially over an inch) will be possible in portions of the Alaska Range and the Western Brooks Range and the southern Seward Peninsula. General model consensus supports at least a few tenths of an inch of rain across the southern Interior, although the Yukon Flats/northeastern Interior could potentially be a local drier spot. There is also uncertainty on exact precipitation amounts possible on the North Slope, although the heaviest precipitation will likely remain farther south.

Moving into Thursday afternoon and Friday, another low, possibly moving out of Siberia, will bring renewed potential for heavy precipitation across the area, with the heaviest rain likely in the Western Brooks Range and southern Seward Peninsula. This rain could spread east and affect the Eastern Interior/North Slope by Friday. There is little confidence on exact strength of this low, but high waters could be possible in some coastal areas with onshore flow.

COASTAL HAZARD POTENTIAL

High Surf Advisories will remain in effect for portions of the Norton Sound through Saturday morning for elevated water levels of 2 to 4 feet around the time of high tide. In general winds across much of the west coast have diminished, but there remain a large fetch of water being transported towards the Norton Sound. Highest levels will likely be near Golovin and Elim. A return to more normal tide levels is expected later in the weekend.

FIRE WEATHER

An active and increasingly wet pattern will continue across Northern Alaska through the weekend. An atmospheric river will continue to bring periods of rain to much of the Interior today into Saturday, followed by continued troughing across the Western portion of the state, bringing additional opportunities for precipitation through the week. Fairbanks NSB and west are expected to be the primary recipients of the most consistent precipitation, however areas East are expected to see some scattered showers as continued shortwave disturbances wrap around the ridge axis that remains over the southeast.

Across the Eastern Interior, the Upper Tanana Valley will remain the area of greatest concern. Warmer temperatures and relatively lower humidities keep areas east of Tanacross with RHs in the upper 30s. However, a shortwave disturbance is expected to make its way up and over the ridge axis Saturday morning bringing chances for isolated showers through the first half of the day. Thunderstorms may develop in the afternoon as another shortwave reaches the area during peak heating. Thunderstorms are expected to remain mostly confined to the higher elevations of Fortymile Country, and will bring localized heavy rainfall and gusty outflow winds.

Winds are generally expected to remain light across most of the state, with the strongest winds expected along the West Coast and through the Alaska Range passes. Strong gusts through the passes bring potential for Delta Junction to see gusts up to 30 mph on Monday night into Tuesday morning, however continued rounds of precipitation are expected to raise minimum RHs to the upper 50s to low 60s helping mitigate potential wind driven fire risk.

Temperatures remain moderate, with the highest temperatures expected to be near 70 in the Upper Tanana on Saturday before cooling back into the 60s through the week. Cloud cover is expected to continue across the state, keeping temperatures moderated into the week.

HYDROLOGY

A strong push of moisture from the West Coast to the Central Interior is expected to continue through tomorrow. Rainfall totals through Saturday of 1 to 1.5 inches expected between the Yukon Flats, Bettles, and McGrath will be possible with locally higher amounts in the Upper Kuskokwim Valley especially. Expect fairly decent rises in local streams and rivers with sandbars potentially covered, but there are no immediate concerns for the main stem rivers in the area. Average return intervals of 2 to 5 years is possible throughout much of the Central and Western Interior through the weekend. If the heavier totals shift east towards the Chena Basin, there may be concerns for FNSB.

AFG WATCHES/WARNINGS/ADVISORIES

AK...High Surf Advisory until 11 AM AKDT Saturday for AKZ822-824. MARINE...Small Craft Advisory until 10 PM AKDT this evening for PKZ811. Small Craft Advisory until 1 PM AKDT Saturday for PKZ812-858. Small Craft Advisory from 1 AM to 1 PM AKDT Saturday for PKZ813. Small Craft Advisory until 6 PM AKDT Saturday for PKZ814. Brisk Wind Advisory from 7 PM this evening to 6 PM AKDT Saturday for PKZ814. Brisk Wind Advisory from 4 AM to 6 PM AKDT Saturday for PKZ815. Small Craft Advisory from 4 AM to 6 PM AKDT Saturday for PKZ815. Small Craft Advisory until 7 AM AKDT Saturday for PKZ857. Small Craft Advisory from 1 AM to 6 PM AKDT Saturday for PKZ860. Brisk Wind Advisory from 10 AM to 4 PM AKDT Saturday for PKZ860. Brisk Wind Advisory from 7 AM to 6 PM AKDT Saturday for PKZ861. Small Craft Advisory from 7 AM to 6 PM AKDT Saturday for PKZ861.