Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
498 FXUS65 KPIH 250938 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 338 AM MDT Sat May 25 2024 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT... A shortwave low pressure system crossing the region today will bring light morning showers, and then isolated to scattered afternoon t- storms, with potential t-storm coverage greatest across the far ern Central Mntns, Upper Snake Highlands, ern Highlands, and east of I- 15 to Bear Lake across the south (although an isolated storm cannot be ruled out just about anywhere). 1 PM to 9 PM will be the favored period for storms, and while severe wx is generally not expected, enough instability may be present along with steep low-level lapse rates to allow a cell or two to produce gusty winds or small hail. Breezy conditions are also expected...models have had a really hard time pinpointing exactly where the winds may be strongest (generally the ern Magic Valley and Snake Plain corridor) and have fluctuated on speeds over the last two days of runs, but overall conditions still look close to but perhaps just shy of WIND ADVISORY criteria. We have issued a LAKE WIND ADVISORY for American Falls Reservoir from 1 PM to 9 PM as criteria are slightly lower there for creating hazardous waves. Conditions clear out for Sun as the shortwave moves east and high temps gain about 5 degrees, topping out in the upper 50s to upper 60s. Modestly breezy conditions are likely again Sun. 01 .LONG TERM...MEMORIAL DAY MONDAY THROUGH NEXT SATURDAY... Ridge of high pressure remains in place for Memorial Day, with highs in the 70s for most lower elevation locations and dry sunny conditions. Confidence is increasing on leading shortwave bringing moisture and the chance for showers and thunderstorms mainly higher elevations Tuesday, ahead of main trough passage for Wednesday and Thursday. Ensemble clusters are still showing some variation on depth of the trough, which has some implications on how much and where precipitation should occur, as well as high temperatures. As expected, model agreement continues to devolve moving into the remainder of the week. By Saturday, clusters are almost evenly split with half showing another deep trough and half showing development of another ridge. NBM carries light precipitation chances into the weekend, mainly north, which would favor an average solution of weak trough passage to the north. DMH && .AVIATION... Well defined shortwave feature shifting through Oregon very early this morning slides through East Idaho today. Have already seen VERY weak showers shift across the region ahead of main activity per radar returns over western Idaho. Precipitation chances favor KSUN/KDIJ today, but can`t rule out VCSH/VCTS at any of the sites this afternoon. Winds do not appear to be as strong as previously thought, but 20kts sustained is still possible KBYI/KPIH/KIDA. SHRA/TSRA end west to east late afternoon through about 03Z, exiting even KDIJ by 06Z. VFR CIGS expected throughout, though stronger showers could drop to MVFR. DMH && .FIRE WEATHER... Upper trough shifts through East Idaho today. Showers and isolated or scattered thunderstorms are possible, along with gusty winds throughout the Snake Plain, and gusty thunderstorm outflow. Dry conditions spread west to east late afternoon through the evening, with upper ridge developing over the region for Sunday into Memorial Day Monday. Moisture creeps into the ridge Tuesday for the next potential round of showers and thunderstorms, with breakdown of the upper ridge for Wednesday. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$