697 FXUS65 KPIH 270925 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 325 AM MDT Sat Apr 27 2024 .SHORT TERM...Today through Sunday Night. Early morning satellite imagery shows a H5 low centered around the Four Corners region as radar imagery continues to show scattered rain and high elevation snow showers. Hi-res CAMS remain in good agreement throughout the day today showing showers this morning transitioning to a mix of showers and thunderstorms by this afternoon, aided by 200-500 J/kg of SBCAPE and 20-30 kts of 0-6km shear. Predominant dry conditions outside of isolated showers across ERN Idaho will then return tonight heading into Sunday as drier, zonal flow fills in behind this exiting system. Additional QPF/rainfall amounts today after 6 AM will range from around 0.10-0.30" in the valleys outside the WRN CNTRL Mountains/Magic Valley region where less than 0.10" is expected. Locally higher total are anticipated across the higher terrain with an emphasis along the Wyoming/Montana border region where around 0.25-0.60" with locally higher totals along the Continental Divide are expected. Accumulating snow has been observed at Willow Creek Summit and Lost Trail Pass over the past 24 hours which continues to support snow levels around that 6500-7000' mark. For Sunday, look for a return to mostly dry conditions as drier, zonal flow prevails which will keep temperatures consistent with highs in the upper 40s to low 60s and lows generally above freezing outside of some our colder mountain valleys. Best chances for isolated precipitation chances and a slight chance of thunderstorms Sunday will remain south and east of the Snake Plain into the higher terrain as any additional QPF amounts remain light. With respect to winds through the weekend, they will be strongest today around the Magic Valley with sustained winds around 20-30 mph and gusts up to 30-45 mph before increasing for Sunday, shifting NE up the Snake Plain with sustained winds around 15-25 mph and gusts up to 25-40 mph. These breezy winds will be ahead of a stronger wind event favored to move into our region on Monday as our next system moves in from the PacNW for early next week. MacKay .LONG TERM...Monday through next Saturday. Main impact in the long term period will be a very strong cold front moving through eastern Idaho on Monday. Will bring rain and snow showers but not expecting significant amounts. Winds will be extremely strong and at least advisory levels in most areas. Expect widespread 20 to 35 mph sustained speeds Monday afternoon into early evening with gusts 40 to 55 mph especially in northern parts of the Snake Plain. Is trending more toward advisory level than warning level but will play out of the next couple of days. It will be cool with highs in the 40s mountains with some 30s and 50s valleys. It will dry out Tuesday but blend still has some isolated to scattered showers with breezy conditions continuing under strong westerly flow aloft. Another system will increase the chance of showers once again. It will remain very cool through Wednesday with highs Tuesday and Wednesday remaining in the 30s and 40s mountains and lower 50s in the valleys. Model solutions diverge late next week and early weekend with the blend keeping some chances of precipitation in the grids with significant warming by Friday into Saturday with flow aloft becoming more southerly. Highs by Saturday expected to be in the 60s to near 70 in lower elevations and 50s and 60s in the mountains. GK && .AVIATION...For the 12Z TAFS through 12Z Sunday. Upper level low passing to south will keep showers going at TAF sites today with some isolated thunderstorms again this afternoon but will not go more than vicinity at TAF sites. Expect MVFR to IFR ceilings at all the sites with worst at DIJ where IFR conditions have persisted early this morning. Heavier showers will drop the other sites to MVFR conditions occasionally most of the morning and early afternoon. Strongest winds at BYI with 10 to 15 knots with gusts 20 to 25 knots. 10 to 15 knots likely at PIH and IDA. Main impact today will be the showers and low ceilings. GK && .HYDROLOGY... Water levels remain elevated on the Portneuf River from Pocatello to Chesterfield Reservoir where River Flood Warnings remain in effect until further notice. Minor to moderate flooding is ongoing in this area with both the Pocatello and Topaz river gauges forecast to crest this weekend before dropping slightly heading into early next week. Further north and west along the Snake River, water managers have increased releases from upstream reservoirs leading to high flows in excess of 10,000 cfs downstream from Palisades to Milner. The Snake River near Heise and Snake River at Lorenzo gauges have reached action stage as a result and are expected to be at that stage until further notice. Willow Creek below Tex Creek above Ririe Reservoir and the Blackfoot River above Blackfoot Reservoir both also continue to be in action stage since Monday with no major impacts seen elsewhere in our CWA as of Saturday morning. MacKay && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$