textproduct: Fairbanks

SYNOPSIS

Cooler conditons are expected today across southern portions of the Interior. This will quickly switch back to a warming and drying trend as an upper-level ridge builds up over eastern Alaska through the start of the weekend. Southerly flow will return across the eastern Alaska which will enhance the warming and drying trend. In addition, this will allow for gap winds to return to the Alaska Range by Saturday. Recent rainfall seen over the Alaska Range have loosened soil and root systems, which could lead to downed trees with the stronger winds. Broad troughing will be setting up over western Alaska by the start of the weekend, which will allow for wetting rains throughout the weekend for the West Coast and Western Interior.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Highs in the 70s and 80s are expected in the northern Interior, with a heat advisory in effect for the Yukon Flats where temperatures will reach around 85F. Temperatures will be cooler in the southern Interior today before warming into the mid 70s on Friday.

- Rain is expected to continue along southeastern portions of the Interior through the late afternoon with additional rainfall between 0.15" and 0.50" with the heaviest in the Alaska Range.

- Isolated thunderstorms will be possible from the White Mountains to Tanana northward and northern Fortymile Country and along the AlCan Border on today and Friday.

- Southerly gap winds through the Alaska Range will strengthen Saturday afternoon, with potential gusts up to 60 mph through Isabel and Windy Pass.

- Warming/drying trend expected this weekend with Saturday potentially being the warmest day so far this season.

West Coast and Western Interior... - Temperatures cool slightly with highs in the lower 70s in Interior valleys today. Along the coast, highs will be in the 50s/60s.

- Stronger southwesterly/westerly winds with gusts up to 20 mph will be possible throughout the western Interior Valleys through tonight. Winds lull Friday before strengthening again Saturday with the next approaching low from the Bering.

- Fog and low stratus have moved in from the Bering along portions of the West Coast and will linger through the latter half of the week.

- Wetting rain expected across much of the area throughout the weekend.

North Slope and Brooks Range... - Warm temperatures persist through today. Highs warm into the 50s near Utqiagvik to around 80 in the Arctic Plains. A heat advisory is in effect for the Arctic Plains through tonight. Max temperatures on the North Slope will be closer to 70 on Friday and Saturday, and into the 60s on Sunday.

- Isolated thunderstorms will continue to be possible in the Central Brooks Range and Arctic Plains today. Thunderstorm chances move to the eastern Brooks Range by Friday.

- Widespread rain will reach the Western Brooks Range from the south on Saturday and may continue into the Western North Slope on Sunday.

FORECAST ANALYSIS AND DISCUSSION

Satellite imagery this afternoon shows a broad area of directional shear across the southern portion of the CWA, with values increasing west to east. The upper-level pattern continues to show a positively tilted ridge slowly building up through the end of the week from the Kuskokwim Valley to the Eastern Brooks Range. A weak shortwave will ride S-SW across the southeastern portions of the Interior today. This will continue to provide the area with persistent cloud cover through the early afternoon and another chance of wetting rains across the Upper Tanana. Amounts are not expected to be as much as what was seen Wednesday night into Thursday morning, however 0.25" to 0.50" is currently expected.

With the ridge strengthening, this will bring a quick warmup in temperatures across the Interior Friday and Saturday. Looking west, broad troughing over the Bering will continue to hold strong as a series of shortwaves moves down from Siberia. On Friday, a shortwave will be moving eastward, on the north side of the Aleutians, reaching Bristol Bay by the late evening. This will bring in a swath of moisture across Western Alaska, bringing back to back days of wetting rains over the weekend. Looking back east, the progression of this shortwave will turn the ridge over the Interior more meridional. This will set up southerly flow across much of the eastern half of the state by the mid to late weekend. This will help enforce the warming and drying pattern in areas under the ridge, especially over the Yukon Flats and areas just north of the Alaska Range with the help of downsloping. That said, Saturday has the potential to be one of the warmest days so far this season for some of these areas. One thing that could limit the warmer temperatures is some energy from a shortwave moving across the central portion of the state, that could bring patchy cloud cover at times. Southerly flow over the Alaska Range will allow for another round of gap winds through the passes on Saturday. Models do not have much agreement when it comes to the track of the previously mentioned shortwave, which will play a role into how much of a southerly influence there will be across the eastern portion of the state. In addition, history has shown models to do poorly with ridge breakdown. With both of these in mind, this will be closely monitored over the next several runs as the slightest of change can result in different weather conditions.

By the end of the weekend, broad troughing is looking to set up, once again, over the western half of the state as more shortwaves moves SE from Siberia. With this, a colder airmass has the potential to move across portions of the West coast. This could bring a chance for a rain/snow mix by the start of next week.

FIRE WEATHER

Certainly, a complex fire weather season. Three primary synoptic features will drive our fire weather concerns over the next 48 hours: the first being a broad longwave trough digging into the Bering, and the second, a ridge of high pressure shifting into Canada. Lastly, general troughing in the Gulf of Alaska will likely serve as a source of moisture, with southeasterly waves moving across the Yukon bringing continued chances for thunderstorms.

Touching on the trough first, this system will be largely responsible for bringing wetter and cooler conditions into lower/middle Yukon and west, particularly over the weekend where we will likely see widespread rain. The heaviest rainfall will be over the southwest and Seward Pen, shutting down fire weather. As the west soaks, southerly winds increase across much of the AK Range over the weekend, bringing warm temps to the Central Interior and concerns for gap winds for Windy/Isabel; however, amble wetting rains Thursday have moderated fire weather concerns for the Tanana Flats. We may be a bit too optimistic on RH for Delta Junction, we will watch how Friday pans out and work with our fire partners at AFS as we assess fuels and moisture. Gusts 50 to 60 mph likely in Isabel Saturday into Sunday.

Also, focus continues to be on the ridge, with model guidance starting to shift the ridge axis further into the eastern portion of the state. This will bring continued concern for hot/dry across the Yukon Flats, where isolated thunderstorm activity over the next 48 hours could lay down some new ignitions or holdovers. Saturday, thunderstorm outflow boundaries look particularly strong over the Yukon Flats/Eastern Brooks. Stay tuned.

Troughing continues over the west next week. Extent/magnitude of an area of high pressure over the eastern interior and how this system brings inverted troughs and thunderstorms into the southeastern interior, continues to serve as the main subject of interest.

HYDROLOGY

0.50" to 2.5" of rain fell overnight and this morning across much of the southeast Interior and Eastern Alaska Range. This will cause some slight rises in water levels across the Tanana River and its tributaries. Levels are expected to remain below Minor Flood Stage, but will peak in action stage this weekend. The main concern is water over gravel bars as of now.

EXTENDED FORECAST DAYS 4-7

A Bering Sea low is expected to continue transporting moisture over Northern Alaska. By Monday afternoon, thunderstorm chances will have almost entirely moved over the border into Canada. Models are showing a slight indication of some instability over the high terrain near Eagle as well as the Eastern Brooks Range. Storm chances are expected to decrease over the next couple of days as well. The highest accumulations are expected for the Brooks Range and the Western Alaska Range through Tuesday, with the West Coast, specifically near the Norton Sound, joining the mix by Wednesday. Southerly gap winds are expected to pick up through the Alaska Range passes by Tuesday morning with gusts up to 35 mph possible.

A cooling trend is likely to start by the end of the weekend and continue throughout the week. The Interior is likely to see highs in the low 70s with mid 50s to mid to upper 60s expected for the West Coast and North Slope.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Heat Advisory for AKZ833. Heat Advisory for AKZ806-808. PK...Small Craft Advisory for PKZ804-805. Small Craft Advisory for PKZ807. Small Craft Advisory for PKZ856.