Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
009 FXUS65 KPIH 150843 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 243 AM MDT Sat Jun 15 2024 .SHORT TERM...Today through Sunday night. Satellite and radar imagery shows multiple regions of weak convection over East Idaho early this morning. First is over the central mountains along shortwave axis. Second lies slightly further east over the eastern Upper Snake/Island Park region, and lastly another over the southeast corner/Bear Lake region with both of these better aligned with the surface cold front. The nested NAM appears to have the best handle on the current convection, thus relied heavily on forecast for the remainder of tonight. Shortwave axis should shift through the state by/around Noon, so the threat of convection associated with this feature should be short-lived. That leaves the wind as the next impact of concern. Surface gradient ramps up significantly through the day, with good mixing potential for stronger mid level winds. NAM shows peak 700mb winds approaching 50kts late this afternoon. Models favor the Mud Lake/Arco Desert/INL zone for the strongest winds, which is where the High Wind Warning remains painted. Surrounding zones north and east in line for Wind Advisory level winds. Confidence is high as even the lower 25th percentile (3 in 4 chance of exceedance supports these headlines). Pushing up toward the 90th percentile (1 in 10 chance of exceedance) supports holding off on upgrading these headlines, though the best chance would be for the Idaho Falls/Rexburg zone mainly WEST and NORTH of Idaho Falls, and north into Clark county. Winds should subside with sunset at least out of headline territory, but should remain breezy for a chunk of the night, rebounding again during the day Sunday, remaining below headline thresholds. Temperatures should be some 10-15 degrees cooler today, and another 5 degrees or so cooler for Sunday. DMH .LONG TERM...Mon through Fri night. Mon through Tue night continue to forecast wet and cold conditions with an upper level low nearly stationary overhead. Weak troughing continues on Wed as a transition day. Positive height anomalies develop for Thu and Fri, but the clusters have a wide disparity in solutions. It appears as though this should be a dry period with temperatures warming to above normal for highs. Meanwhile, lows on Mon night and Tue night will likely need frost advisories as temperatures bottom out in the middle 30s across much of the low elevations in the Snake River plain. Wind increases to windy to possibly very windy and requiring Wind Advisories again on Mon. This looks to be the last day of windy conditions as the upper level gradients turn much weaker. Messick && .AVIATION...A cold front passing through in the late night hours last night will bring very strong wind, but fortunately it is west and southwest and should not be a cross-wind hazard. Clouds will return tonight as another wave from an upper low anchored over Puget Sound moves through tonight and Sun morning. May see some light showers over the northeast corner by late afternoon, then spreading southward during the overnight hours. Do not expect any impact on CIG, VSBY, or any TS hazard. Messick && .FIRE WEATHER...A cold front will trigger some showers this morning, and partial clearing during the afternoon will end most of the shower activity. Very strong winds behind the front will start in the morning and last all day today. Breezy to windy conditions continue on Sunday. The air mass settling in is cold and temperatures will drop to below normal today, then well below normal for highs on Mon. This should keep humidity from getting very low. Showers will be limited on Sun as well. Messick && .HYDROLOGY... A flood warning remains in effect for the Teton River at Driggs through Saturday and the Snake River at Heise until further notice. The latter has seen a slight drop in river levels due to reduced releases upstream so it`s possible that river levels drop a bit more over the days ahead. Given the uncertainty though, will continue the flood warning for now and will consult with local emergency managers over the days ahead. McKaughan && .PIH WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 11 AM this morning to 9 PM MDT this evening for IDZ052. Wind Advisory from 11 AM this morning to 9 PM MDT this evening for IDZ053-054-067-068. && $$