textproduct: Fairbanks

SYNOPSIS

A swath of moisture will be brought up into the southeastern Interior on Tuesday leading to widespread rain especially in the Alaska Range where totals could reach between 1 to 2 inches through Thursday. Thunderstorms remain possible in areas to the north and west of the stratiform rain, primarily in the northeast and southwest Interior on Tuesday. Southerly winds through the Alaska Range strengthen Tuesday afternoon before weakening again Wednesday morning. Cooler conditions linger in the Interior on Wednesday before warming back up Thursday. Weather in the Western and Northern regions of our area should remain largely unimpressive through the short term.

KEY WEATHER MESSAGES

Central and Eastern Interior... - A cold front approaches from the southeast Tuesday. Temperatures are still warm ahead of the front, with widespread highs in the mid 70s to low 80s. Behind the front, temperatures will be cooler, with the Tanana Valley from Delta Junction to the AlCan Border only seeing high temperatures in the mid to low 60s.

- Scattered afternoon thunderstorms are expected for areas in the Interior that are north of the front through Tuesday afternoon. Highest chances on Tuesday are in an area from around Fairbanks to the Yukon Flats and Fortymile Country. Thunderstorms are not expected south of the front.

- The front tracking from southeast to northwest brings high rain chances from the White Mountains southward late tonight through Tuesday night with locally heavy rain and gusty winds possible, especially near the Alaska Range. Heaviest precipitation expected along the western portion of the Alaska Range.

- As the front passes through on Tuesday evening, southerly winds across the Alaska Range will briefly swell, with gusts up to 45 mph through Isabel Pass and up to around 35 mph through Windy Pass.

West Coast and Western Interior...

- Temperatures remain seasonably cool along the West Coast, with high temperatures in the 50s to 60s. In the Western Interior, highs in the mid to upper 70s are expected to continue through the latter half of the week.

- Isolated thunderstorms will remain possible in the Lower Yukon and Middle Kuskokwim Valleys through the week. - As winds in the Bering become southerly, we will likely see low stratus clouds and fog creep back towards St. Lawrence Island, the Norton Sound and Bering Strait.

North Slope and Brooks Range..

- Temperatures along the North Slope and in the Northern Brooks Range valleys will see highs in the 60s or low 70s today and Wednesday. Temperatures begin a cooling trend on Thursday. - Isolated thunderstorm chances increase in the Central and Eastern Brooks range on Wednesday as a cold front stalls over the area.

- A trough brings strong southwesterly winds into the Western Arctic Coast on Wednesday. Winds will turn from westerly to northerly on Thursday as the trough exits to the northeast.

FORECAST ANALYSIS AND DISCUSSION

A 554 decameter upper-level low in the Gulf is sending a front into the southeast Interior this morning. This front will bring good chances for widespread rain along with it as it travels north into the Eastern and Central Interior. In addition to the rain, winds will strengthen out of the south behind the front. Southerly winds through the Alaska range will be gusty, up to around 40 to 45 mph through Isabel Pass, with the peak looking like it will be Tuesday afternoon. Precipitation becomes more stratiform behind the front, and areas of heavy rain may develop with widespread totals greater than half an inch in the Southern Tanana and Upper Kuskokwim Valley by the end of the day on Wednesday. Rainfall totals are even higher in the Alaska Range, reaching up to an inch in the eastern half and around 2 inches on the Western half as the front pivots into the Interior. Isolated thunderstorms may still develop in areas ahead of the front as the ridge is broken down. As a result the area for potential thunder becomes angled from the Southwest Interior to the Yukon Flats. Areas outside of the Central and Eastern Interior will be largely unaffected by this system resulting in warm and dry weather in the Western and North Slope regions today and Wednesday.

Wednesday, the front begins to weaken and stall, oriented almost south to north over the middle of Alaska. The high pressure on the western side of the front will support more warm and dry conditions for the Western Interior, as well as afternoon thunderstorms from the Lower Yukon to the Central and Eastern Brooks Range. Meanwhile the rest of the Interior will have slightly cooler and cloudier conditions.

Thursday, an arctic trough in combination with a low arriving in the Bering Sea from the North Pacific and the low still in the Gulf of Alaska keep the ridge from establishing any substantial foothold over us. The low in the Gulf looks to send at least one more wave of precipitation into the Eastern Interior on its way out of the Gulf. With the weak ridging over Alaska, thunderstorm coverage will become more widespread once again. Temperatures North of the Brooks Range will drop as the colder air mass moves south.

FIRE WEATHER

Following yesterdays active thunderstorm day across the Southern Interior, a front will continue to track east to west through the Alaska Range and Interior with rain and embedded thunderstorms today into Wednesday. This frontal system is expected to bring steadier rainfall rates and a swath of wetting rains across the Southern Interior. As the front passes, cloud cover and rainfall will work to limit high temperatures and raise RH values, leading to cooler temperatures where the bulk of precipitation is falling. This front is expected to stall roughly between McGrath and Bettles by Wednesday into Thursday. On the leading edge of the front is where we are expecting the best isolated to scattered thunderstorm coverage, some of which could be strong storms with gusts up to 30 mph, small hail, and heavy rain.

Widespread wetting rains are expected across the Southern Interior and Alaska Range Tuesday into Wednesday with preliminary totals around 0.25-0.75" south of the Upper Yukon Valley, locally higher in the Alaska Range closer to 0.75-1.50". Precipitation totals elsewhere just outside of this Southern Interior region will see totals closer to a T-0.25" up into the Eastern Brooks Range and Y-K Delta region. Widespread cloud building in out of the southeast Tuesday will push thunderstorm coverage farther north across the Interior towards the eastern Seward Peninsula and Y-K Delta. Thunderstorms will shift even more so come north and west on Wednesday, with more limited isolated thunderstorm potential across much of the Interior outside of a corridor from the Southwest Interior to NE Brooks Range.

Looking ahead, that front in the Central Interior south to Southcentral Alaska looks to begin to weaken later in the day Wednesday into Thursday. While steadier precipitation chances will begin to subside, increased sunshine will lead to an increase in areal coverage of thunderstorms starting Thursday with the return of isolated to scattered coverage back through the weekend across much of the Interior north to the Brooks Range and southwest to the Y-K Delta. Temperatures, while holding steady at near to above normal levels through midweek, will begin to slowly cool by the weekend as broad upper level ridging over much of our region is replaced by troughing building in out of the west.

HYDROLOGY

A front will move westward through the state this week. As this front progresses, it will produce widespread rain showers and isolated thunderstorms. Showers and thunderstorms are expected to begin Tuesday morning in the eastern Alaska Range and upper Tanana Valley and spread northwest through Tuesday night. The heaviest rainfall is expected to fall throughout the day Tuesday. Widespread rainfall totals of 0.5" to 1" and locally higher amounts > 2" possible will combine with glacial runoff to result in rising mainstream river levels around the Alaska Range for the middle to end of this week. Rapid rises of smaller rivers are possible with the heaviest rain on Tuesday into Wednesday.

By Wednesday, this front will be set up over the Western Interior and become relatively stationary, allowing for more precipitation to fall through Thursday afternoon. Upwards of 1" or more is expected in the Upper Kuskokwim area near McGrath and Lake Minchumina for this event.

Flooding remains unlikely for mainstream rivers in the affected areas.

EXTENDED FORECAST DAYS 4-7

At the start of the extended period, there are three distinct features influencing the overall pattern. The first is a closed low pressure system over Southeast Alaska, the second is a large Arctic trough hovering just over Utqiagvik, and the third being a weak upper level ridge over Northeastern Alaska in the Canadian Yukon. The most impactful of the three systems will be the low over Southeast Alaska as it advects multiple shortwaves into the region from the southeast. Isolated to scattered showers and thunderstorms are expected across much of the Interior and portions of the Brooks Range, with moderate to heavy rains possible. Exact rainfall amounts are uncertain for now, but the heaviest rains are expected over the Alaska Range and Central Interior through the weekend. A new pattern starts to take hold on Saturday as an upper level low in the Bering Sea tracks east into Bristol Bay by Sunday morning. This new system is expected to bring widespread cooler temperatures in the 60s from the Brooks Range south and continued showers to the much of the region into next week.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...None.