Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
195 FXUS65 KPIH 020956 CCA AFDPIH Area Forecast Discussion...CORRECTED National Weather Service Pocatello ID 356 AM MDT Sun Jun 2 2024 .SHORT TERM...Sunday and Monday. Currently there is zonal flow aloft over southeast Idaho and a very moist, atmospheric river, system just off the coast of Washington and Oregon. For today, the NBM model shows isolated showers and thunderstorms in upslope flow mainly over the Eastern Highlands along the Wyoming border. However, other models, like the ECMWF and HREF models, show very little, if any, chance of showers and thunderstorms due to the lack of moisture. If any thunderstorms and showers do occur, very little, if any, moisture is expected. Today, especially this afternoon and for our northern areas, winds will be breezy with gusts of 20 to 30 mph. The Arco desert will see gusts of 30 to 40 mph with slightly higher gusts for a few hours this afternoon. Temperatures will run near normal today, 60s for mountains and 70s for lower elevations. For Monday, look for an atmospheric river system to hit our area in zonal flow hitting mainly the western Central mountains (mainly the Sawtooths) where 1 to 2 inches (with isolated areas up to 2.5 inches) of rainfall in a 24 to 30 hour timeframe. Galena Summit will get around 1 inch of rainfall with Ketchum receiving around 0.5 inch. The Pioneer mountains will get around 0.75 inch of rainfall. Currently the western Central mountains are in a slight risk in the Excessive Rainfall outlook by the Weather Prediction Center. This area is also highlighted by the ECMWF model Extreme Forecast Index product. Snow levels will start around 11k feet dropping to around 10k feet Monday evening. Currently, the Salmon river and Big Wood river only look to rise around 1 foot. For the Eastern Highlands along the Wyoming border, including the Wasatch mountains and the Big Hole mountains, expect around 0.50 to 1 inch of rainfall. It will be breezy to windy on Monday. Currently look at gusts of 25 to 40 mph across the area. Will likely need a wind advisory for the Arco desert and the Upper Snake plain. Blowing dust is possible but is not expected to be widespread. A lake wind advisory will likely be needed for the American Falls reservoir with moderate to large waves expected. Temperatures Monday will be cooler than normal, around 8 to 12 degrees below normal. Expect 50s in the mountains and 60s in lower elevations for daytime highs on Monday. Wyatt .LONG TERM...Tuesday through next Sunday. Tuesday will mark a change from a wet and seasonably cool pattern to a dry and seasonably warm pattern. A warming trend will continue through late week courtesy of high pressure building over the Southwest. Widespread daytime highs will reach 15 degrees above climatological norms by Friday, with portions of the eastern Magic Valley and Snake River Plain potentially reaching 90 degrees for the first time this year. Winds will be breezy Tuesday afternoon, and to a lesser degree Wednesday afternoon, before becoming light through the remainder of the extended period. Widespread sustained winds will range 15 to 25 mph with gusts of 25 to 35 mph. The National Blend introduces slight chances for precipitation beginning Thursday and continuing into the weekend, as models show weak signals for moisture filtering northward into Idaho in the upper level flow. Cropp && .AVIATION... Clouds will scatter/clear from NW to SE during the early to late morning before cloud cover increases again this afternoon and evening. Upper flow will turn zonal this afternoon with enhanced 700 mb winds creating breezy conditions at the surface. Sustained SW to W winds will range 15 to 20 kts with gusts 25 to 35 kts. Expect each afternoon for the next several days to be breezy as the trough works through. Slight chances for showers and thunderstorms exist this afternoon, mainly near KDIJ, with widespread precipitation and isolated thunderstorms on Monday. VFR conditions are forecast through around 12z Monday, with MVFR CIGs and VIS likely at times in the afternoon during the heaviest rain. Cropp && .FIRE WEATHER... The next system arrives this evening with precipitation reaching the central mountains tonight. Widespread wetting rains will overspread the region early Monday with chances for isolated thunderstorms during the afternoon and evening. The Weather Prediction Center has included portions of Fire Weather Zones 475, 476, and 422 in their Excessive Rain Outlook. The most accumulated rainfall will be over the Sawtooths and Stanley region, where 1 inch to 2.5 inches of QPF is forecast to fall between this evening and Monday night. During this 24-hour or so timeframe, 1.25" to 1.75" is forecast over the eastern half of the Ross Fork burn scar, with 1.75" to 2.25" over the western half. Elsewhere, generally 0.50" or less is forecast with higher totals of 0.75" to 1" in the high terrain of the eastern mountains. Min RH will continue to increase through Monday, ranging 20 to 35 percent for much of the region today before rising to 50 percent and higher. Elevated winds aloft will support breezy conditions at the surface each afternoon and evening beginning today and continuing through Tuesday or Wednesday. The strongest SW to W winds are expected across Fire Weather Zone 410, where SW winds will range 25 to 35 mph with gusts 35 to 45 mph. The pattern turns dry and warmer beginning Tuesday as a ridge of high pressure builds in from the Southwest. Temperatures may even reach into the 90s for some portions of the Magic Valley and Snake River Plain beginning Thursday into the weekend. Widespread minimum humidities will begin to drop below 25 percent during this timeframe, but winds should remain light. Cropp && .HYDROLOGY...A special weather statement is in place for the Sawtooths where 1 to 2 inches of rainfall is expected Sunday evening through Monday evening. Up to 2.5 inches of rain could fall for some western slopes of the Sawtooths. High mountain snowmelt of around 2 inches, if not higher, is expected as well. The Salmon river is expected to rise around 1 foot currently and could go higher on Monday into Tuesday. Valley creek in Stanley could reach bankful, if not higher. Aerial flooding, especially creeks, in higher elevations of the Sawtooths is likely. The western Central mountains will get around 1 inch of rainfall and the Pioneer mountains are expecting around 0.75 inch. The Big Wood river is expected to rise at least 1 foot on Monday into Tuesday, if not higher, especially with high mountain snowmelt of around 2 inches. Currently action stage on the Big Wood at Hailey is not forecasted, but action stage for the Big Wood at Hailey is possible depending on actual snowmelt and rainfall. Currently small rises area are expected with main stem rivers along the Wyoming border for Monday and Tuesday. Some streams in the mountains could reach around bankful. Wyatt && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$