Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
766 FXUS65 KPIH 110837 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 237 AM MDT Tue Jun 11 2024 .SHORT TERM...Today through Wednesday night. Expect clear skies through Wednesday with minimal weather impacts in the short term period. Will get a bit breezy on Wednesday as strong zonal flow aloft sets up and expect some 15 to 25 mph sustained winds in the Snake River Plain with gusts up to 30 mph. Mountain high temperatures will be in the 70s today with low elevations in the mid to upper 80s. Lows tonight will be in the 40s to 50s and highs Wednesday again 70s to lower 80s mountains and mid to upper 80s in valleys. GK .LONG TERM...Thu through Mon night. Upper level high pressure remain in control through at least Fri, then a low begins the breakdown of the ridge, possibly as early as Sat afternoon. The breakdown on Sat has 30 to 35 percent chance of occurring, so it is more likely that Sat will be dry in eastern Idaho, slightly higher for central Idaho. The low is expected to cross through Idaho on Sun and Mon, with only a 10 to 15 percent chance of staying farther north and keeping things dry. 500mb heights are falling by Sat afternoon, and thus a cool-down should start by then. Guidance is indicating an 8 to 11 degree cool-down to the high, which will bring afternoon highs to around seasonal normals. By Sun, temperatures could be below normal, or at least bottom out. Then warm-up returns Monday. The Sat-Sun front looks like it packs considerable wind with limited precipitation. Best thunderstorm days appear to be the Fri afternoon/evening prior to passage and then Sat afternoon/evening. Positive tilt trough would tend to favor non-severe level convection. Messick && .AVIATION...High pressure will dominate, and the only clouds expected are with a shortwave embedded in the moderate to strong westerly flow that slides through during the late night hours Tuesday night. And even with that, no CIG is expected, anywhere. No precipitation or TSRA with the very dry air and only weak instability in the WY-ID border region. With the upper level support, expect gusty afternoon and evening wind for the valley airports. Messick && .FIRE WEATHER...Warm up and drying out continues through Thu afternoon. Lower elevation humidity in the central Idaho mountains and eastern Magic Valley should drop below 15 percent on at least two of the three days. Expect afternoon/evening gusty wind each day, with an increase in the wind on Fri. Humidity will start to rise with the approach of a front on Fri, then what looks like a fairly dry cold front will push through on Sat, amping up the wind and producing dry thunderstorms. Messick && .HYDROLOGY... A FLOOD WARNING remains in effect for the Teton River near Driggs as small streams/creeks and the main stem river continue to run high. Minor flooding is being observed on the Teton River and is expected to remain at that level through this afternoon, aided by additional snowmelt from the Tetons and Big Holes. With the latest NWRFC forecast showing this gage dropping below minor stage on Tuesday, have gone ahead and added an expiration time for the warning to be 3 PM this afternoon. This may need to be adjusted dependent on future flows and trends going forward, with warmer temperatures certainly still leading to additional snowmelt. This additional snowmelt is expected to keep the river in action stage through much of this upcoming week. Further downstream along the Teton River near St. Anthony, that gage remains at action stage and is only a couple inches away from minor flood stage. That gage is expected to crest today and come down below action stage by Wednesday. Several other rivers across the CNTRL Mountains are also seeing diurnal increases with the Big Lost River at Howell Ranch currently hovering around action stage. Along the Snake River, increased flows out of Palisades Reservoir have also led to the Snake River near Heise gage climbing up to action stage and it is expected to stay there until further notice. MacKay && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$