Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
229 FXAK69 PAFG 051143 CCA AFDAFG Northern Alaska Forecast Discussion...CORRECTED National Weather Service Fairbanks AK 343 AM AKDT Wed Jun 5 2024 .SYNOPSIS... An impactful day is setting up over the Interior with scattered thunderstorms developing this afternoon. Some storms could be strong with frequent lightning, heavy downpours, gusty winds and hail. Some areas could see rainfall of around 1 inch or greater. The threat of thunderstorms will continue over the Interior through Friday. && .DISCUSSION... Upper Level Analysis... An upper low continues to sit in the Gulf of Alaska being the main driver of east/southeasterly flow, bringing multiple rounds of shortwaves and vorticity maxes across the Central and Eastern Interior. The Arctic low will continue to push south and slightly strengthen, becoming closed off and reaching the Central parts of the Aleutian Islands early Thursday morning. The low in the gulf will push westward and merge with the Arctic low, as it pushes south, switching the majority of the state to an easterly flow by early Thursday morning. By this point the southern part of the interior will have shifted to a southerly flow with a shortwave expected to impact the West Coast late Thursday night into Friday morning. Central and Eastern Interior... Wednesday looks like it could be one of the largest days for thunderstorms in the Interior so far, with models coming into better agreement. An easterly wave will move across the Interior enhancing some of the thunderstorms Wednesday afternoon. The area of thunderstorms expected to develop over the Middle Tanana Vally in the mid afternoon and continue through the early evening then push north and west in the evening. Some guidance is now showing Mixed Layer CAPE values near 1000-1500 J/kg with the strong shortwave which would promote scattered to numerous thunderstorms. Heavy downpours with some spots expected to receive 0.5 to 1.0" or greater of rainfall, especially in the most persistent areas of thunderstorms. Frequent lightning, gusty winds and hail are all possible with strong thunderstorms and also flash flooding of streets in urban areas. Thunderstorm potential continues over the Interior Thursday and Friday but looks slightly less impactful. Temps will remain the upper 60s to low 70s Wed through Friday. Gusty winds will pick up in the eastern Alaska Range north of Trims camp, southerly gusts around 50 to 60 mph this evening through early Friday morning. West Coast and Western Interior... Temperatures continue to warm with Isolated thunderstorms extending farther west from Ambler to McGrath. A few of these storms may come with small hail, gusty winds and briefly heavy rain. Late Wed evening into Thursday, the shortwave over the Central Interior will move over the West Coast and Western Interior, specifically from Galena south and west with areas of rain, potentially heavy at times. Then by Friday, it looks to dry out with the exception of a few showers and an isolated storm towards Ambler. North Slope and Brooks Range... Stratus and fog today along the coast with onshore flow continuing. Temperatures will be warming as well with highs in the 30s and 40s north of the Brooks Range, and highs in the 60s in the Brooks Range. Isolated thunderstorms will be possible in the Central and Eastern Brooks Range. Friday looks to be quieter, though a shower or storm is possible in the Western Brooks Range as the shortwave lifts north. Skies may try to clear along the North Slope with southerly flow increasing by Friday. Temperatures will also be warming significantly with highs in the 40s along the coast. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Still warm in the Yukon flats but min RH values slightly higher in that area, will say still near red flag conditions. Wednesday looks like it could be a big lightning day, potentially the largest one of the year so far, with an easterly wave producing scattered to numerous thunderstorms Wednesday afternoon. Models coming into better agreement with at 500-1000 J/kg of CAPE with areas along the Middle Tanana Valley showing up to 1500 J/kg producing scattered wet thunderstorms. Locally heavy downpours with some locations seeing 0.50 to 1 inch of rainfall or greater. Frequent lighting and gusty winds and hail are all possible. The area of thunderstorms expected to develop over the Middle Tanana Vally in the mid afternoon and continue through the early evening then push north and west in the evening. && .HYDROLOGY... Warming temperatures along the North Slope this week will promote snowmelt and the potential for high water for the Sag, Colville and Kuparuk Rivers and their tributaries. The Colville has a few ice jams on it already which may result in some flooding concerns. One ice jam of note is a known seven mile long ice jam downstream of Ocean Point (on the Colville) and a smaller ice jam a few miles long at Horseshoe Bend (roughly 9 river miles up from Nuiqsut). Snowmelt will likely push out these ice jams, but expect high water upstream before the release. Water levels are expected to crest by the end of this week into the weekend. The water level in Fort Yukon will continue receding very slowly. Satellites and ground observations continue to indicate abundant snow in the Porcupine Mountains. As temperatures warm this week, snowmelt could lead to continued high water along the Porcupine and the interrelated sloughs. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...Wind Advisory for AKZ849. PK...Gale Warning for PKZ806-807-854-856. Small Craft Advisory for PKZ810-816-817-851. Small Craft Advisory for PKZ811-857. Brisk Wind Advisory for PKZ861. && $$