Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
876 FXUS65 KPIH 172036 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 236 PM MDT Fri May 17 2024 .SHORT TERM...Today and Saturday. There is a strong trough moving through southeast Idaho currently with weak high pressure ridging just off the Oregon and Washington coasts. There is an upper level low just off the southern British Columbia coast. Winds are strong across the area currently, with widespread gusts of 40 to 50 mph with isolated gusts near 60 mph. There is blowing dust across the area, especially near the Blackfoot rest area and, to a lesser, degree Arbon valley. Current wind advisories and high wind warnings are in effect until early this evening. Temperatures are near normal to slightly below normal across the area, mid 60s to lower 70s for valley areas. Saturday high pressure ridging develops over northern Idaho and weak high pressure looks to build in slightly across southeast Idaho. However, winds aloft look to remain mostly zonal. Expect slightly breezy winds tomorrow afternoon with gusts near 20 mph for most locations. The Arco desert will see gusts near 35 mph, possibly around 40 mph. Will hold off on a wind advisory for the Arco desert. Winds for the American Falls reservoir look to be around 5 mph below the criteria for a lake wind advisory. Again, have held off on a lake wind advisory for American Falls reservoir for Saturday afternoon. Temperatures will be near normal for tomorrow`s high temperatures, 60s and low 70s. Wyatt .LONG TERM...Sunday through next Friday. The long term period begins with a shallow upper trough situated over the northwest and shortwave passing through northern Idaho. Enhanced 700mb westerly winds will lend to breezy surface conditions, with sustained winds ranging 25 to 35 mph and gusts 35 to 45 mph. We will likely need a Wind Advisory for the Upper and Lower Snake River Plain and Arco Desert/Mud Lake zones. Considering the location of the shortwave, precipitation chances will likely be limited to the northern extent of our CWA on Sunday, with National Blend PoPs generally 35 percent and lower. Models show a closed low forming over southern Idaho late Monday into early Tuesday as the trough progresses eastward, which will support more widespread precipitation chances. Late Tuesday into early Wednesday will be a brief break behind the departing low and ahead of the next system. A well-organized low will drop south into the Pacific Northwest on Wednesday. The deterministic ECMWF continues to show the low passing directly over Idaho on Thursday while the GFS shows the low tracking south into Oregon before shifting eastward and over Idaho on Friday. Chances for precipitation will become widespread again on Thursday, however, 500 mb ensemble clusters still show differences predominately in the depth of the low. Daytime highs will run 5 to 10 degrees below normal throughout much of the week. The National Blend features the warmest temps of the entire extended period on Friday, which favors the faster progression of the low and brief zonal or weak ridging on Friday featured in the ECMWF. Cropp && .AVIATION... Impacts today will continue to be the strong winds and resultant reductions in VIS due to BLDU. The period of strongest winds today will continue through around 23z before tapering off after that. Expect sustained winds over 30 kts at KPIH and KIDA with gusts generally 40 to 50 kts with relatively lighter winds at KBYI and KDIJ, where sustained winds are forecast to reach up to 30 kts and gusts up to 40 kts. KSUN will observe the lightest winds of all terminals with typical diurnal wind patterns returning by late tonight. Cropp && .HYDROLOGY...A flood warning continues for the Portneuf river in Pocatello. A flood advisory continues along the Portneuf river at Topaz. Water levels are slowly receding for the Portneuf river due to the snowpack diminishing. Water levels for other rivers, including the Big Wood, Big Lost, Henrys Fork, Teton, and Snake, are continuing to slowly climb due to snowmelt, but all rivers look to remain below action stage with current forecasts. Wyatt && .PIH WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 8 PM MDT this evening for IDZ051-055>058-062- 065-067-068-070. High Wind Warning until 8 PM MDT this evening for IDZ052>054. && $$