Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
699 FXUS65 KPIH 110918 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 318 AM MDT Sat May 11 2024 .SHORT TERM...Today and Sunday. A ridge of high pressure will maintain dry conditions over the Pacific Northwest through much of the weekend. Models indicate only up to around a ten percent chance of a stray shower each afternoon and evening. High pressure will allow for ample sunshine and a continuation of the warming trend, with daytime temperatures reaching 5 to 10 degrees above climatological norms today. Winds will generally remain light today, outside of slightly breezy winds in the Shoshone area and along the ID-UT border, and again through much of the day Sunday. Sunday will likely be our warmest day before the pattern change, with temps reaching into the mid to upper 70s for our low elevations, 60s in the highlands, and 50s in the high terrain. Winds will noticeably increase Sunday evening as the ridge begins to break down and upper flow turns more zonal ahead of an approaching trough. Precipitation chances will also increase across the E and SE Highlands beginning late Sunday. Cropp .LONG TERM...Monday through next Saturday. Monday marks a change from a stable to unstable pattern as the ridge breaks down and shortwave troughs swing through Idaho both Monday and Tuesday. Along with widespread chances of precipitation and thunderstorms early to middle of next week, elevated 700mb westerly winds will lead to widespread breezy surface winds each afternoon. A Wind Advisory may be warranted for a couple of our forecast zones on Monday, although current forecast speeds are marginal. Deterministic models depict drastically different scenarios Wednesday through Friday, with the ECMWF suggesting that the pattern will remain unsettled through the remainder of next week and the GFS showing a ridge returning Wednesday. Interestingly though, the majority of 500mb ensemble cluster solutions now favor the return of a high pressure ridge mid to late week, although there are slight timing differences regarding the departing trough and building ridge. Only about 14% of total ensemble members favor a continuation of an unsettled pattern ahead of the next system that will descend from Canada next Saturday. In spite of the uncertainty amongst models, the National Blend maintains at least a 75% probability of widespread 70 degree or warmer max temperatures outside of the highlands and mountains through Friday. Cropp && .AVIATION...VFR conditions forecast with dry conditions and light winds throughout the period. FEW high clouds will develop early day, with mid-level clouds increasing during the afternoon to FEW to SCT. Winds will begin to increase Sunday evening ahead of the incoming system on Monday. Cropp && .HYDROLOGY...A ridge of high pressure will bring drier and warmer conditions to East Idaho for the weekend. High flows on area water ways are expected to continue, especially as warmer temperatures increase snow melt at upper reaches of the ranges. The Portneuf and Blackfoot rivers remain the water ways of concern, though there is some hope that conditions may slowly be improving. Have maintained the Flood Warnings for the Blackfoot as levels remain at or above Flood Stage. The Flood Warning remains intact for the Portneuf at Pocatello. Have rescinded the Flood Warning for the upper reaches of the Portneuf and issued a Flood Advisory instead. Current and forecast levels appear to remain just below Flood Stage, but the river remains elevated. With the pleasant weekend in store and the continued high levels, opted to maintain at least some kind of safety message, and wait to see how the temperatures impact the river going through the weekend. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$