textproduct: Fairbanks

SYNOPSIS

Active weather continues for northern Alaska with the week coming to an end. Scattered showers are expected to continue across the Interior over the next couple of days with a front moving across the Interior. As it does, chances for thunderstorms will be possible for the Upper Tanana and Fortymile Country on Saturday, shifting to the Middle Tanana on Sunday. Southerly flow will be set up across the Interior with the positioning of an upper-level low over Bristol Bay. This will bring a gradual warming trend throughout the weekend. In addition, the southerly flow is expected to bring a brief round of strong gap winds through the Alaska Range starting late Sunday night.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Chances for precipitation become more widespread across the Interior through middle parts of the weekend. Precipitation type should be mostly rain, apart from higher elevations where snow or a rain/snow mix could occur.

- Cooler temps expected today with maximum temperatures in the mid to upper 40s. Similarly, minimum temperatures will cool into the low 30s, allowing for some patchy areas of frost to develop overnight. Gradual warmup is expected throughout the weekend.

- Gusty NE winds will continue across the Interior today, for the south slopes of the Brooks Range and Dalton Hwy Summits, winds could get up to 35 mph Saturday night into Sunday. Another round of Gap winds return to the Alaska Range Sunday night into Monday.

- There are chances for thunderstorms in the Southern Interior Saturday and Sunday. On Saturday, chances are best near the AlCan border in the Southeast Interior. Sunday, chances spread across the middle Tanana Valley.

West Coast and Western Interior... - Northerly winds will increase throughout today with gusts up to 30 mph through the Strait by the evening. Strong winds continue through Saturday night, peaking Saturday evening.

- Showers becomes more likely in the Western Interior Friday night/Saturday morning. Precipitation type will become snow or a rain snow mix overnight. Amounts will be light, less than a tenth of an inch liquid.

- A cool, dry air mass lingers over the western half of the state, resulting in cooler temperatures through the weekend. High temperatures will be in the mid 40s in the Western Interior and will be colder along the coast. Lows will range from the upper teens across the Seward Pen and Kotzebue Sound to the low 30s in the Western Interior.

- A front lifts north across Western Alaska Sunday night into Monday morning, producing a band of precipitation which should be primarily rain.

North Slope and Brooks Range.. - Northerly gap winds may be enhanced through the Central Brooks Range passes today with gusts up to 30 mph.

- Starting tonight, the Central and Eastern Brooks Range will see chances for snow through the weekend. Daily snow accumulations look to be up to 3 inches in the heaviest places.

- Northeasterly winds, at times gusty, will gradually increase across the North Slope through Saturday night. Winds will be strongest along the Western and Eastern Arctic Coast where winds peak upwards of 40 mph. Winds will remain elevated through the start of next week.

FORECAST ANALYSIS AND DISCUSSION

Not much change from the previous discussion as models have not shown much deviation with the overall forecast. The main driver for the period continues to be the upper-level low that continues to dig its way south into the Kuskokwim valley. Another shortwave has been moving south, from the central Arctic Coast, and become enveloped within the main low. This shortwave will continue to reinforce the general troughing pattern into the start of the weekend. Meanwhile, another low will continue to work its way into the northern gulf of Alaska. This is expected to swing a warm front, moving E to W, across the Interior. This will continue to provide the support for isolated showers along with slight chances for thunderstorms on Saturday and Sunday. Chances will be limited to the Upper Tanana and the eastern portions of Fortymile Country on Saturday, spreading to the middle Tanana on Sunday. The associated surface low moving NW to the Seward Peninsula will allow for a weak Tanana Valley Jet to form on Saturday with potential gusts up to 30 mph.

As the low in the Gulf moves farther north, the low over the Kuskokwim will shift slightly to the west and stall over Bristol Bay. This will help reinforce the thunderstorm chances on Saturday and Sunday with the SE flow that will set up over the Upper Tanana. Southerly flow will continue across much of the Interior through the back half of the weekend which will allow for gradual warming trend into the start of next week. A SE-NW oriented ridge will begin to build up over the AlCan boarder by the end of the weekend. This will take some of the energy, from the lows over Bristol Bay, and shoot it northward over the Alaska Range late Sunday night into early Monday morning. The orientation of this is favorable for another round of gap winds through the Alaska Range Passes during this time. This southerly flow coming over the Alaska Range will also result in some chinooking conditions which will allow for a quick warmup across portions of the Tanana Valley.

FIRE WEATHER

General troughing is expected to persist over most of Northern Alaska through the weekend. What is usually associated with hazardous fire weather conditions/fire starts, a strong and sturdy high pressure system, has not yet been picked up by weather models as we expect to stay in a general troughing pattern for at least the next week. Along with this troughing comes moisture, allowing for scattered showers and some mixed precipitation across most of the Interior. In terms of relative humidity, a dry patch is expected to begin early next week with low values in the 20 percent range. During this drier period, there are much fewer chances of precipitation. However, moisture is likely to return to the area late next week as low pressure over the Aleutians will move into the Gulf of Alaska. Thunderstorm chances are likely north of the Alaska Range Sunday afternoon. The ECMWF lightning flash density product is showing potential chances for lightning in portions of the Western Interior in the afternoons through mid-week next week. Temperature- wise, cooler conditions are expected to last throughout today. Warmer air will be brought into the area this weekend, allowing high temperatures to increase into the low to mid 60s for most areas in the Interior.

HYDROLOGY

A flood warning remains in effect, through Sunday, for Chalkyitsik. Latest reports say that 8 homes have flooded and some of them have now become unaccessible. Waters continue to slowly rise and are approaching the post office, clinic, and church within the village.

River Watch reports the Porcupine River at Old Crow is now breaking up. The ice appears to be very distorted and the water levels in town is currently low. However, flow remains high in the headwaters.

Over the Chatanika River, the advisory has been shifted west with the jam moving downstream. As a result, a new group of cabins have begun to flood just after the hard bend in the river. Water levels have dropped in the original location of the advisory. A mix of ice and high water continues for another 20 miles up river, followed by about 10 miles of open water to Elliot.

Water levels have begun to rise again along the Tanana River at Manley Hot Springs and another flood watch has been implemented. Reports from 13:05pm show the levels at 15.06 feet, an increase from this morning but the levels are starting to slowly drop. In addition, the landing in the Tanana River has large ice chunks that are moving quickly.

EXTENDED FORECAST DAYS 4-7

An upper level trough will push southeast towards the Gulf of Alaska Tuesday morning, allowing southerly gap winds in the Alaska Range passes to taper off through the day. Light, isolated rain showers remain possible for most of Northern Alaska, but precipitation is expected to become increasing limited for the Interior through the middle of the week. Surface conditions will remain seasonably mild with highs in the low to mid 60s and lows in the upper 30s and lower 40s for much of the Interior, though snow is possible at higher elevations. As a new low pressure system transits the Bering Sea early next week, it will draw moisture from lower latitudes, bringing another round of showers during the early part of the week. This precipitation is expected to be limited for the Interior into the middle of the week.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ846. PK...Brisk Wind Advisory for PKZ810-857-858. Brisk Wind Advisory for PKZ811. Heavy Freezing Spray Warning for PKZ812. Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ814-815-860. Brisk Wind Advisory for PKZ854-861. Brisk Wind Advisory for PKZ856.