Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
539 FXUS65 KPIH 100825 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 225 AM MDT Fri May 10 2024 .SHORT TERM...Today and Saturday. High pressure will continue building in from the west and ultimately dominate the synoptic pattern into the weekend. That said, upper level flow associated with the low pressure system to our south will continue to filter remnant moisture into the southern extent of Idaho. Furthermore, CAMs suggest chances for very isolated showers across the southeast portion of Idaho and therefore we have increased PoPs slightly from the Blend to around 15% to 20% across the aforementioned area. Come Saturday, CAMs show a similar scenario but with most activity further south into Utah as the low to our south shifts eastward. High pressure will mean light winds over the next couple of days, as well as ample sunshine and a warming trend, with high temperatures reaching 5 to 10 degrees above climatological norms on Saturday. However, widespread low temperatures this morning will still run in the 30s and cooler, prompting another FROST ADVISORY for the Lower and Upper Snake River Plain zones from 3 AM to 9 AM. Portions of the Arco/Mud Lake region could just barely reach frost criteria but the zone as a whole is borderline and therefore will remain free of any headlines. Our agricultural zones will not have to worry about frost or freeze for at least the next week or so beginning Friday night/Saturday morning, as low temperatures will generally span the 40s for these zones. Cropp .LONG TERM...Sunday through next Friday. Sunday continues to look like our warmest day under mostly clear skies as temperatures warm by several more degrees into the upper 70s across the Snake Plain, eastern Magic Valley, and valleys further south, with 40s and 50s in the mountains and highlands. As early as Sunday afternoon though, models show weak moisture signatures reaching the eastern highlands with the ridge breaking down on Monday as a shortwave swings through the Pacific Northwest. Along with widespread chances of precipitation early to middle of next week, increased westerly 700mb winds will lead to widespread breezy surface winds each afternoon. Deterministic models depict drastically different scenarios Wednesday onward, with the possibility that the pattern could remain unsettled through the remainder of next week. 500mb ensemble clusters highlight this well, showing varying degrees of both ridging and troughing over SE Idaho during the latter half of next week. That said, the National Blend maintains fairly stable and slightly above normal temperatures throughout this timeframe. Cropp && .AVIATION...VFR conditions forecast with light winds throughout the period. FEW to SCT low and mid-level clouds will increase this afternoon. There are slight chances of isolated rain showers across extreme southeastern Idaho, but high resolution models show them remaining south of KBYI and KPIH. Cropp && .HYDROLOGY...Warming temps over the next several days are expected to result in slight rises on several area rivers. Whatever snowfall was realized recently at mid-slope is likely to melt off, and temp profiles support some snowmelt at higher elevations as well. So far, main flooding impacts still appear confined to the Portneuf and Blackfoot rivers where FLOOD WARNINGS remain in place, although the Big Lost River at Howell Ranch could approach bankful early next week. Remember that flows are high, fast, and cold on waterways across the region this time of year, as melting mountain snow is still a significant contributor to these waterways. People recreating on/near East Idaho rivers and streams are urged to remain cautious, and keep children and pets away from the water. 01 && .PIH WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 9 AM MDT this morning for IDZ053-054. && $$