textproduct: Fairbanks

SYNOPSIS

Seasonably cooler temperatures continues across the West Coast as an upper-level low moves south along the Western Interior. With this, scattered showers are expected to continue across the Interior over the next couple of days. A warm front is looking to move west across the Upper Tanana by early Saturday morning. The SE flow that will be set up aloft will increase the chances for isolated thunderstorms for the Upper Tanana on Saturday, spreading to the higher terrain areas north of FNSB on Sunday. Meanwhile, another shortwave will be moving south over the central Arctic Coast. This will allow for gusty winds to return to the NE and NW Arctic Coasts by the mid weekend. A few hazards for ice jams remain in effect as river breakup continues across the state.

KEY WEATHER MESSAGES

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

- Cooler temps expected through tomorrow morning, likely only reaching the mid/upper 40s Thursday. Similarly, low temperatures will cool into the low 30s, allowing for some patchy areas of frost to develop overnight.

- Winds through the Alaska Range and into the southeast Interior will be southerly today before weakening and turning easterly overnight. Light NE winds will continue across the Interior today, with gusty winds returning to the higher terrain on Friday.

- Gusty NE winds up to 35 mph. returns for the south slopes of the Brooks Range and Dalton Hwy Summits Saturday night in to Sunday.

West Coast and Western Interior... - A cool, dry air mass has settled over the western half of the state, resulting in cooler temperatures through the weekend. High temperatures will struggle to reach the 40s in the Western Interior through Thursday and will be colder along the coast. Lows will range from the upper teens across the Seward Pen and Kotzebue Sound to the low 20s in the Western Interior.

- Northerly winds slightly increase through the Bering Strait Thursday, dropping slightly overnight before restrengthening again Friday with gusts up to 30 mph through the Strait.

- 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.

North Slope and Brooks Range.. - Snow showers have ended north of the Brooks Range to the Coast. However, the Central and Eastern Brooks Range will continue to see chances for snow through the weekend. Daily snow accumulations look to be up to 3 inches in the heaviest places.

- North to northeast winds, at times gusty, will develop tonight across the North Slope and gradually increase through Friday night. There may be enhanced northerly gap winds trough Central Brooks Range Passes on Friday with gusts up to 30 mph.

- Northeasterly winds around Point Hope and Cape Lisburne will peak at over 40 mph Saturday into Sunday.

FORECAST ANALYSIS AND DISCUSSION

An upper-level low continues to dip south along the Western Interior. Satellites imagery from this morning shows the position of the closed, upper-level low just north of Galena. This will allow for isolated precipitation chances across the Interior throughout today. Precipitation type should remain mostly rain, especially for the lower elevation. A rain/snow mix is possible at higher elevations, which may transition to mostly snow overnight. The low will continue to move farther south to the upper/middle Kuskokwim Valley by late Friday night. It is getting blocked by another low moving into the central portions of the Gulf of Alaska from the northern Pacific Basin. An associated warm front will move across Interior, starting in the Upper Tanana, early Saturday morning and progress easterly across the Interior throughout the day. This will bring a slight chance for Thunderstorms for the higher terrain in the Upper Tanana Valley on Saturday. This will also bring a weak Tanana Valley Jet Saturday afternoon as the surface low in the gulf moves closer to the coast. With the progression of the front eventually reaching across the Interior, chances for storms will spread to the higher terrain north of FNSB Sunday afternoon. Models have continued to show the chances for this over the last several model runs. With the front moving easterly across the Interior, this will push the upper-level low farther west. There is a fair bit of agreement still in place with the positioning of the low, with the NAM solution farthest west.

Looking over the North Slope, a shortwave will begin to move south over the central Arctic Plains by late tonight. This will allow chances for additional snowfall to continue for the central and eastern portions of the Arctic Plains through the weekend. With an upper-level ridge already built up over the Bering and Siberia, the progression of the shortwave will tighten a N/NE gradient across the Arctic Plains through the early weekend. Wind are expected to gust between 30 and 40 mph with the strongest winds over the NW and NE Arctic Coast starting Saturday afternoon. Some of these stronger winds could stretch across the Bering Strait Friday and Saturday, but are not expected to be as strong.

Throughout the period, majority of the West Coast will continue to be cooler with the dry, northerly flow with the positioning of the low. However, the abundance of moisture that has been available may allow for some light showers across the Western Interior, spreading to the YK-Delta by late Saturday night as the upper-level low, that was previously mentioned, pushes farther west. The positioning of this low in the SW portion of the state is looking to set up SE flow, aloft, across the Interior which may also help with the convective potential through the end of the weekend. This will also set up the chance for another round of gap winds through the Alaska Range as some of the energy from this low works its way across the Alaska Range by the start of next week. More on this in the extended.

FIRE WEATHER

General troughing over the state is expected to support cool and moist conditions for most of the Interior. Chances for thunderstorms are likely this afternoon as uneven surface heating and instability could support convective potential. Higher thunderstorm and lightning potential is possible Monday afternoon, aligning with the brief drier period early next week. Chances of scattered precipitation are likely for Northern Alaska through the weekend and early next week, with a brief pause on Tuesday as the Interior enters a dry patch. Temperatures are expected to remain on the cooler side through the weekend, but an increase in high temperatures is likely for next week. In the Interior, some locations could see highs in the low to mid 60s.

As an upper level low moves from the northeast to the southwest, a tight pressure gradient forms in the Gulf of Alaska and is expected to support strong southerly gap winds through the Alaska Range passes Sunday night through Tuesday morning. Isabel Pass is likely to see stronger winds than Windy Pass with gusts up to 50 mph possible. Minimum relative humidity values are expected to stay in the upper 30s to lower 40s percent through the weekend, with a drop to the upper 20s percent likely early next week in the Eastern Interior. By mid-week next week, minimum relative humidities return to the upper 30s/lower 40s percent for most of the week.

HYDROLOGY

A Flood warning is in effect through early Friday morning for Chalkyitsik. Public reports of an ice jam along the Draanjik has resulted in a rapid river rise.

Breakup continues along the upper Yukon as Eagle broke up earlier this week. As of earlier this morning, a 25 mile run of ice is moving through Circle with the majority of it pass the jam spots. Upstream of Eagle the river continues to breakup. Additional delayed ice runs will happen there in the next few days.

Elsewhere rivers continued to rise with several locations remaining in action stage as of this afternoon. As such river flood watches have been issued for Circle.

EXTENDED FORECAST DAYS 4-7

As an upper level trough begins to move to the southwest, southerly gap winds are expected to pick up in the Alaska Range passes starting Sunday night going into Monday and tapering off by Tuesday morning. Scattered showers are still likely for most of Northern Alaska in the form of rain, as surface conditions are expected to warm into the low to mid 60s above for much of the Interior. However, snow is still likely at higher elevations. Once the low moves over the Bering Sea early next week, it will draw in moisture from lower latitudes and bring another round of scattered showers to start the week.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Flood Watch for AKZ833. PK...None.