Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
857 FXUS65 KPIH 291006 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 406 AM MDT Mon Apr 29 2024 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... A shortwave trough will swing across the region today, bringing scattered showers and t-storms this afternoon and evening. While some shear will be available, instability will remain quite marginal at generally less than 500 J/kg MUCAPE and soundings lack much thickness to the CAPE distribution along with little to no veering of the wind profile, all suggesting a garden-variety t-storm day with brief heavy downpours, some lightning, brief gusty winds, and perhaps small hail out of the strongest cells. The larger impact will be increased west winds this afternoon and evening regionwide as the pressure gradient tightens, with the ern Magic Valley/Snake Plain corridor along with the adjacent Wood River Valley and Raft River region reaching WIND ADVISORY criteria, which remains in place unchanged. After highs in the 50s to low 60s today, skies will clear and conditions will cool going into Tue with highs in the mid-40s to mid-50s. At least isolated rain/snow shower activity is still possible from the Central Mntns east across the Upper Snake Highlands and along the WY border corridor, however, as low pressure resides just to our north, while much of the Snake Plain southward remains dry. Low temps Tue AM will likely drop below freezing across the entire forecast area. 01 .LONG TERM...WEDNESDAY THROUGH NEXT MONDAY... Active progressive weather pattern continues in the extended period. It does seem certain that at least the first two mornings of May will be cold, likely leading a season-opening Frost and/or Freeze headline for the Snake Plain growing zones. Upper trough passage Wednesday will continue to produce showers, and given the cold temperatures, expect a mix of rain/snow to valley floors. Unsettled conditions continue Thursday, with similar conditions expected. QPF remains light throughout, so significant snow accumulations are not expected even at higher elevations. Heading into the weekend, we begin to lose the consensus in the clusters. Some version of shallow trough remaining over the northern/intermountain states Friday, and a weak ridge trying to build into the coast. By Saturday, a deeper trough approaches the coast, but the depth varies significantly between the GFS and ECMWF and ensembles, with varying downstream impacts over Idaho. Both deterministic GFS and ECMWF would remain dry over East Idaho through the weekend, but the varying ensembles lead the NBM into remaining weakly unsettled. DMH && .AVIATION... Fast moving shortwave trough impacts East Idaho today with a mix of wind and showers/tstorms. Winds begin increasing after sunrise, reaching sustained speeds of 25-30kts for KBYI/KPIH/KIDA and KDIJ. KSUN wont completely escape, with winds sustained around 20kts this afternoon. SHRA could begin filling in across higher elevation areas, mainly impacting KSUN and KDIJ by late morning, and all sites could see at least VCSH/VCTS after 21Z. Both winds and precip diminish after sunset, though winds will likely remain breezy at/around 15kts sustained for the Snake Plain terminals. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Wind Advisory from noon today to midnight MDT tonight for IDZ051>057-067-068-075. && $$