textproduct: Fairbanks

SYNOPSIS

The front that triggered scattered thunderstorms across the Interior yesterday has stalled over the area from the the middle Kuskokwim Valley to the Eastern Brooks Range. On the northwest side of the front, showers and thunderstorms will develop with an emphasis on the area from the Central Brooks Range near Bettles, to near Tanana and southwest into the lower Yukon Valley. Behind the front, conditions will be cooler. Thursday, the Interior will begin to warm back up with another chance for wet thunderstorms in the southeast Interior.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Showers and scattered thunderstorms will develop across the North Central Interior as a front stalls across the Tanana Valley and Yukon Flats. These storms are capable of producing prolific lightning, moderate to heavy rain, small hail, and gusty winds.

- Moderate to heavy rain continues to impact the Western Alaska Range this morning, but will taper off through the day. Rivers will see rising water levels, but flooding is not expected.

- Thursday, thunderstorms will again develop in the Northern Interior during the afternoon. In the southeast Interior, showers and thunderstorms could bring 0.10 to 0.25 inches of rain to a wide area.

- Temperatures will have a gradual warming trend through Friday. Maximum daytime temperatures should be near 80 for most of the Interior by Friday although the Upper Tanana Valley remains slightly more moderate, closer to 70.

West Coast and Western Interior...

- Temperatures in the Western Interior will be warm, highs in the upper 70s and low 80s are expected to continue through the latter half of the week with cooler temps along the Coast.

- Isolated thunderstorms will remain possible in the Lower Yukon and Middle Kuskokwim Valleys through Friday. - Low stratus clouds and fog in the Bering have settled around St. Lawrence Island, and will continue to creep into the Norton Sound and Bering Strait through the day Wednesday.

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 Wednesday. Temperatures begin a cooling trend on Thursday, with max temperatures along the Coast staying below 40F on Friday. - Isolated thunderstorm will form in the Central and Eastern Brooks range on Wednesday and Thursday 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

The main weather maker for Wednesday will be a shortwave trough spanning across the Interior which is extending out from a 554 decameter low in the Gulf of Alaska. The band of vorticity associated with the shortwave is stretched from the western Alaska Range to the Eastern Brooks Range. A 565 dam upper-level high over the Western half of the state is keeping the Western and Northern regions of our area clear and dry. The band of vorticity will lose its steam and begin to stall over the Interior today as it becomes separated from the low in the Gulf. However, it will linger as it gets stretched between the low in the Gulf and a trough in the Arctic. As a result, we will see support for thunderstorms in a diagonal band across the Interior today on the western side of the feature, which should continue into Thursday. Surface high pressure in the Bering is pulling fog and low stratus into St Lawrence Island and toward the Seward Peninsula.

On Thursday, after the low in the Gulf deepens slightly, it will bring another round of moderate precipitation into the southeast Interior. Current totals look to be between 0.10 and 0.25 inches to the Upper Tanana and Fortymile. Two new features will arrive to keep things active as well: an arctic low begins to edge closer to the Arctic Coast and a low from the North Pacific moves into the Bering Sea. The arctic trough will send a shortwave across the North Slope on Thursday bringing chances for light rain along with it. Otherwise, its influence will be felt in cooler temperatures north of the Brooks Range and stronger winds along the Western Arctic Coast. The low in the Bering will have minimal impact until it starts to get closer to shore, but it will direct some energy and moisture into the southwest Interior on Friday.

FIRE WEATHER

Following widespread moderate to heavy rain and thunderstorms across the Southern Interior and Alaska Range yesterday with prolific lightning, that front is expected to stall over the Central Interior today as best shower and thunderstorm chances shift to being from the Lower/Middle Yukon northeast to the Eastern Seward Peninsula, Upper Kuskokwim, and Brooks Range. Farther east, drier air has already begun to take hold with drier conditions expected today. Another easterly wave over the Alaska Range will bring in another round of showers and thunderstorms Wednesday night into Thursday, with a focus east of Fairbanks as showers and storms continue to develop along that aforementioned active corridor on Wednesday. Outside of the Interior where daily showers and thunderstorms persist, warm and dry conditions will continue along the West Coast, NW Interior, and North Slope, with afternoon RHs driest in the NW Interior and Western Brooks Range around 20-30%.

Looking ahead towards Friday and the weekend, broad upper level troughing will continue to build in out of the Bering Sea which will support increasingly scattered to widespread daily precipitation chances, cooler temperatures, and improving humidity across Northern Alaska as we finish out the month of June. Details on this will come into focus over the coming days so stay tuned.

HYDROLOGY

Through Tuesday and Wednesday morning, thunderstorms have brought heavy rainfall to the Southern Interior, with northwesterly flow hitting the Alaska Range, helping to drive efficient rainfall. Over the past 36 hours, much of the Upper Tanana Valley has received 0.5 to 1 inches of rainfall. In the Alaska Range several stations report more than an inch, and some stations on the southern side of the Range have reported more than 2 inches in the last 36 hours. As this system stalls out in the Western Interior, another half inch or so of rain will fall through Thursday, mainly impacting the Upper Kuskokwim into McGrath.

Largest impact will be rapid rise in smaller rivers and creeks in prominent mountain drainages; however, the antecedent warm/dry conditions means that these rivers are starting low and will likely not exceed major flood stages. Expect an increase of trees/debris in rivers as well.

No major flooding of mainstream rivers is anticipated at this time.

EXTENDED FORECAST DAYS 4-7

Saturday through Tuesday. On Saturday a ridge will situate itself over the North Central Interior, blocking a series of vorticity maxima's beneath it. As the series of shortwaves moves into the Interior, chances of thunderstorms and showers increase Saturday morning into Sunday evening. Proceeding the shortwaves,on Monday, is a cold front brought on by a closed low in the Bering Sea, which will bring another round of precipitation focused on South Central Alaska clearing out by Tuesday afternoon. Higher chances of thunderstorms and will be focused to the Interior, with increasing intensity likely towards areas of high terrain. As precipitation occurs, and cooler air passes through temperature will likely trend downwards for the upcoming weekend. Wind speeds will remain calm outside of Point Hope, localized areas within the Central Interior, and Alaska Range.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...None. PK...Small Craft Advisory for PKZ811-857. Small Craft Advisory for PKZ812. Brisk Wind Advisory for PKZ813. Small Craft Advisory for PKZ858. Brisk Wind Advisory for PKZ859.