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Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
182 FXAK69 PAFG 112211 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 211 PM AKDT Tue Jun 11 2024 .SYNOPSIS... Continued regime with isolated thunderstorms over the S Interior, with heavier rainfall over the Alaska Range. Some thunderstorms North winds over the Bering Strait will switch to south on Thu, and this will also bring in much cooler temps out west. Slow warming trend begins over the Interior Friday as a ridge builds in. && .DISCUSSION... Upper Levels and Analysis... There is a strong 570 dam closed blocking high over the Chukchi Sea. There are a pair of undercutting shortwave troughs moving west at the base of this trough, with one over the Chukotsk, and the other over the Noatak Valley. A remnant thermal trough persists over the S Interior, with the main low center over the Tanana Valley. There is a weak shortwave trough over the Fortymile, slowly moving southwest. Model Discussion... Models are in good agreement with the larger scale pattern. They are overall in better agreement with the convective pattern as well, the next few days. The GFS and ECMWF were favored with the NAM nest for winds, and the hi-res models for precip. Central and Eastern Interior... Heavy rain showers with some strong thunderstorms will develop late this afternoon and continue into the overnight over the E and SE Interior into the Alaska Range. It`ll be dry north of the White Mtns, so this will mainly be a S Interior threat. Storms may produce small hail with heavy downpours, as the amount of instability is moderate. There is a concern for fairly heavy rainfall over the Alaska Range, which may cause issues on smaller streams. We will be issuing a Special Weather Statement with this forecast package with more details with that. Showers with more thunderstorms are likely on Wed, although instability will be a bit less on Wednesday. Slowly, ridging builds in Thu with general drying weather. Friday will be warmer with chances for thunderstorms, especially over the E Interior, where instability parameters look best, with the possibility of a shortwave trough dropping south over the E periphery of the ridge axis. West Coast and Western Interior... Isolated thunderstorms this afternoon and evening will be possible across the Interior and into the Seward Peninsula today. By Wed isolated thunder chances will be over the Interior and into the W Brooks Range. A low with cooler air will be moving into the West Coast with winds switching around to west-southwest Thu and Fri, which will quickly reduce temps back to more seasonal normal levels. North Slope and Brooks Range... Northeast winds and high pressure over the Arctic continues, with more stratus for the Arctic E of Point Lay and up to the slopes of the Brooks Range. There is very little change in weather the next few days, with persistent 15 to 30 mph northeast winds, strongest over the W Arctic. Extended Forecast Days 4-7... A moderate strength ridge will be building into the E Interior this weekend and into the next week, which will promote warmer temps and more chances for thunderstorms over most of the Interior. Meanwhile, a strong arctic low will be meandering over the NW Arctic, which will bring in west winds to the West Coast and cooler temps to the western half of the Mainland. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... The thermal trough remains over the S Interior and into the Western Interior to Seward Peninsula this evening. This will promote areas of widely scattered thunderstorms, and given the instability, some storms will be strong and may produce a fair amount of lightning activity. However, these will continue to be very wet, with a high likelihood of heavy wetting rains from about Salcha east to the headwaters of the Tanana Valley, with heavy rains possible through Wed night. Storms will be more isolated after today as the thermal trough weakens. It will remain drier north of the thermal trough across the Yukon Flats. Wed and Thu will be near red flag criteria, with min RH in the low 20s and highs near the mid 70s, but winds look to be around 6 to 11 mph and just below criteria. We are monitoring the chance for very high based thunderstorms over the E Interior on Friday, as a ridge aloft builds in and a disturbance passes over the E side of this ridge. Overall though, a warming trend is expected over the eastern half of the Interior this weekend, while it cools out west. && .HYDROLOGY... High water from snowmelt will make its way down rivers on the Central North Slope over the next several days, and minor flooding remains possible. Water levels will remain high through at least Thursday, then fall slowly through the weekend. The high water caused by warm temperatures and snow melt in the Brooks Range. It is expected that high water will remain through at least Thursday, and that water levels will fall slowly through the weekend. Water levels will fall more significantly next week as temperatures cool in the Brooks Range. The Sagavanirktok River near Pump Station 3 crested on Saturday, but remains high today. That high water is expected to reach the coast today and to remain high for several days. Water will be near bankfull, with minor flooding possible in low lying areas downstream of Pump Station 3 over the next several days. Water levels are expected fall slowly late this, then fall more next week. The Colville River at Umiat crested Monday and remains high on Tuesday. That high water will reach the coast Today and Wednesday and remain high for several days. Minor flooding of low lying areas along the Colville River downstream of Nuiqsut is possible. On the Kuparuk River at the Bridge, flooding is occuring. The low-water crossings approaching the bridges are inundated with water, with up to 8 inches of water over the road. Water will remain high through Thursday, and then is expected to fall slowly through the weekend. Heavy showers over the next two days will result in the potential for 1 to 3 inches of rainfall across parts of the Alaska Range, which will likely result in fast stream rises and overall rises along all rivers draining the Alaska Range. Some storms will be strong and will drop copious rainfall in a short period of time. Residents should be aware of the possibility of rapid stream rises with heavy rainfalls generally lasting into Wednesday evening. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...None. PK...Small Craft Advisory for PKZ811. Small Craft Advisory for PKZ812-858. Brisk Wind Advisory for PKZ814-815. Small Craft Advisory for PKZ857. Brisk Wind Advisory for PKZ859. && $$ Ahsenmacher Hydro: Brader