textproduct: Fairbanks

SYNOPSIS

As a Bering Sea system shifts eastward today, cooler conditions with widespread rain and cloud cover will likewise shift east across the Interior and Brooks Range and North Slope. In Western Alaska, minor rises in water levels and southerly wind gusts will also occur. Temperatures in the Central/Eastern Interior today will remain warm but will drop once the leading edge of the precipitation moves into the area beginning tonight. Southerly downsloping winds across the Alaska Range will yield strong gusts through the AK Range passes and at Delta Junction while also helping to keep the easternmost portions of the Interior drier (but not necessarily completely dry). While rain will continue in parts of Western Alaska from Wednesday onward, it will take a more showery form. High temperatures will be warm from Wednesday onward, with high temperatures south of the Brooks Range and in the southern North Slope broadly in the 60s and 70s.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Warm weather with highs in the 70s to low 80s continues this afternoon but will end tomorrow as rain and cloud cover moves across the area.

- As a low from the Bering Sea tracks east Sunday into Monday, widespread rain and gusty winds will shift east across the Interior and Alaska Range. The bulk of precipitation is expected west of Fairbanks and in the Alaska Range, with driest conditions along the Alcan Border and Upper Tanana Valley.

- Rainfall totals late Sunday through Tuesday are expected to be around 0.25-0.5" around FNSB, T-0.1" east of Fairbanks to the Alcan Border, 1.0-2.0" northwest of Fairbanks, and 0.5-1.5" in the Alaska Range west of the Tok Cutoff.

- High Wind Warnings and a Wind Advisory for southerly wind gusts have been issued for the Alaska Range passes and Delta Junction respectively. From Sunday night through Tuesday night, gusts could exceed 70 mph through the passes and 50 mph at Delta Junction. Wind gusts elsewhere across the Interior will peak on Monday around 20 to 30 mph.

West Coast and Western Interior... - A Bering Sea low near St. Lawrence Island will continue to shift eastward. The low will bring gusty winds and moderate to heavy rain across the region through Tuesday. - Rainfall totals Sunday through Tuesday of around 1.0" to 2.0" are expected along the Bering Sea coast and across the Western Interior, with locally higher totals up to around 2.50". Totals of around 0.5" to 1" are likely on the Chukchi Sea coast. - Winds gusts will peak around 30 to 50 mph regionwide as the low moves in, with minor coastal impacts expected for communities along the West Coast. A High Surf Advisory has been issued for the YK Delta coast for these conditions.

North Slope and Brooks Range.. - Highs will be in the 60s to low 70s with lows in the 40s/50s, locally cooler along the Arctic Coast. - While rainfall totals through the weekend are expected to remain light overall, steadier rain will move into the Brooks Range on Monday as moisture from a low in the Bering Sea tracks north.

- Rainfall totals Monday and Tuesday will be heaviest in central and eastern portions of the Brooks Range, where around 0.50-2.0" of rain is expected, focused on the southern slopes, as the North Slope gets downsloped and stays predominantly dry.

FORECAST ANALYSIS AND DISCUSSION

This morning, the leading warm front ahead of a Bering Sea low moved onshore over the West Coast of Alaska, driven by generally southwesterly flow across the Mainland north of a Gulf ridge. This Bering Sea low and southwest flow are collectively drawing moisture from well to the southwest, with tropical origins in the West Pacific east of Japan. As it moves inland, widespread rainfall will occur across Western Alaska, with most areas seeing rain start by later this afternoon and evening. Rainfall totals through Tuesday night will widely reach 1 to 2 inches across the West Coast south of the Bering Strait and in the Western Interior, with 0.5 to 1 inches likely from the Bering Strait north and on St. Lawrence Island. Heavy precipitation will be possible at times across the southern Seward Peninsula with southerly upslope flow. In spite of warm air aloft behind the warm front, the associated heavy rainfall and cloud cover will permit high temperatures this afternoon several degrees cooler than on Saturday. The Central and Eastern Interior will conversely see another warm summer day, with highs in the 70s and low 80s being common.

As rain and denser cloud cover spreads into these parts of the Interior by late Sunday morning, temperatures will cool by several degrees, with highs in many or most of these areas dropping into the 60s or low 70s. In the Central Interior, rain totals of around 0.5 to 1 inch will be possible, with gradually falling totals farther east where southerly downsloping flow across the Alaska Range will help to dry things out. This flow will permit winds through the Alaska Range passes to gust as high as around 70 mph, with winds up to 55 mph at Delta Junction. High Wind Warnings and a Wind Advisory remain in effect for these respective conditions. In the Fairbanks area, which is near the cusp of the heaviest precipitation and far enough east to not be completely insulated from the drying effects of downsloping, rainfall could range from as low as about 0.1 inches to as high as around 0.5 inches through Monday night. Thereafter, rain will diminish across the Eastern Interior with some lingering isolated showers. By Tuesday night into early Wednesday, the now-weak low will move ashore and the western edge of rain will mostly shift inland. This will coincide with residual rain in Western Alaska becoming more showery / less of a single large, cohesive area of continuous rain, although these showers could still be numerous as the low lingers over the area.

FIRE WEATHER

For the next few days, the most favorable fire weather conditions will be in the southeast Interior. That area will remain mostly sheltered from a significant amount of rain coming in from the southwest. Temperatures in the upper Tanana Valley and Fortymile Country will peak near 80F Sunday afternoon and relative humidity will fall in the 20 to 30 percent range. Temperatures dip into the mid to low 70s on Monday with more moderate RHs, before warming and drying again on Tuesday. South to southwest winds across the Alaska Range will strengthen Sunday evening, downsloping locations in the Tanana Valley. Winds through the Alaska Range Passes will blow 30 to 50 mph with gusts up to 70 mph. Winds farther away from the passes will also be gusty, 15 to 25 mph, in the afternoon until the pattern weakens Tuesday night. Isolated thunderstorms are possible in the Yukon Flats, White Mountains, and Upper Tanana Valley to the AlCan border on Sunday afternoon.

Meanwhile, a band of moisture containing around 1 to 2 inches of precipitable water has arrived in southwest Alaska. Between Sunday and Wednesday, much of the West Coast and Western Interior will receive 1 to 2 inches of rain, with the wettest spots getting more than 2 inches. This moderate to heavy rain will reach as far as the Central Interior, with totals higher than an inch remaining mostly west of the Richardson and Parks Highways. The Fairbanks area will be on the southeastern edge of the rain, which in combination with the aforementioned downsloping is resulting in a large amount of uncertainty when it comes to rain totals in the central Tanana Valley. Along with the rain, there will be strong southerly winds in the southwest Interior to the Coast. Winds in the Middle/Lower Yukon Valley, Innoko Valley, and Upper Kuskokwim will see gusts up to 45 mph through Monday. There may be a few isolated thunderstorms in the Western Interior on Tuesday, but fuels should be sufficiently wetted as to reduce ignition potential to near-zero.

HYDROLOGY

A coastal low moving into Western Alaska early this week will continue to bring widespread rainfall to the area as it moves east. Nearly an inch of rain has already fallen at Gambell on St. Lawrence Island. 1-2 inches of rain are likely south of the Bering Strait and across the Western Interior, with 0.5-1 inch likely in coastal areas north of the Bering Strait.

EXTENDED FORECAST DAYS 4-7

At the start of the extended forecast, a few light to moderate rain showers are expected to linger mainly over the Western Alaska Range and Upper Kuskokwim Valley on Wednesday before becoming more isolated and spotty by Thursday. The main driver for these lingering showers will be a weakening Bering Sea low hovering over Western Alaska. This low will progressively move south through the latter half of the week, working to keep the western half of the state cool and wet. Out east, a building upper level ridge over the Canadian Yukon keeps the Central/Eastern Interior fairly warm and dry going into Friday. Forecast uncertainty starts to come into play looking towards the weekend as an Arctic trough dips farther down over the North Slope. In addition to this trough, a low pressure system over Siberia starts to push its way southward into the Chukchi Sea towards the West Coast. Models diverge on how far south this Arctic trough and Siberia low move, but guidance is currently leaning towards a continuation of cool and wet weather over Western Alaska, with cooler and wetter conditions across the North Slope as well. These systems may work in tandem to push the upper level ridge over Eastern Alaska farther east into Canada, cooling temperatures down across the state. However, if the upper level ridge holds strong, southerly flow will continue over the eastern half of the state and keep conditions warm and dry this weekend.

Coastal Hazard Potential... As a Bering Sea low moves inland today, water levels in coastal areas will rise by 1 to 3 feet in unsheltered coastal areas. The highest water levels will occur during high tide between Sunday afternoon and Tuesday evening. For these water rises, a High Surf Advisory is in effect for the YK Delta. Minor coastal erosion will be possible.

AFG WATCHES/WARNINGS/ADVISORIES

AK...High Wind Warning for AKZ849. Wind Advisory for AKZ829-830-852. Wind Advisory for AKZ837. High Surf Advisory for AKZ825. High Wind Warning for AKZ847. PK...Gale Warning for PKZ801. Gale Warning for PKZ802-850. Small Craft Advisory for PKZ803. Small Craft Advisory for PKZ804. Small Craft Advisory for PKZ805-851>853. Small Craft Advisory for PKZ806-854. Small Craft Advisory for PKZ812-858. Small Craft Advisory for PKZ816-817. Small Craft Advisory for PKZ856.