Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
636 FXUS65 KPIH 080958 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 358 AM MDT Wed May 8 2024 .SHORT TERM...Today and Thursday. There is an upper level low over the western Dakotas, which is continuing to bring moisture mainly across our eastern areas in northerly flow. To the west, there continues to be strong high pressure ridging currently over the west coast. For this morning, expect temperatures in the mid to low thirties for all lower elevations across the Snake Plain/Arco Desert/Eastern Magic valley. Thus, have continued the frost advisory for these areas. Breezy northerly flow is coming down the Snake Plain and Arco Desert, expect northerly gusts of 25 to 35 mph today. Some gusts will be in the mid 40 mph, especially coming over the Montana Divide into the Arco desert. There is a convergence line setting up over the Upper Snake plain and Driggs area now. Models show this line moving very slowly south this morning making it to the Lower Snake Plain and Southeast Highlands by late morning/early evening. Models don`t show northerly winds taking over the westerly winds in our western areas (Eastern Magic Valley) by late afternoon/early evening. There is light snow around 1 inch with up to 2 inches possible in the Upper Snake plain. Snow levels look to rise and bring rain to the Lower Snake plain by late this morning. However, if this convergence line drops down more quickly, some light snow would be possible for the Lower Snake plain. Most of the snow will be in the Big Hole mountains and the Southeast Highlands with 2 to 5 inches of additional snow likely this morning into this afternoon mainly above 5500 to 6000 feet. By Thursday, high pressure starts to build into our northern and western areas. Expect breezy northerly winds to continue mainly for the Arco Desert and the Snake plain. The Southeast Highlands will still have lingering light snow and chances of fog in the morning. Additionally, temperatures in the low to mid thirties are expected again Thursday morning across our frost/freeze zones. Another frost advisory will likely be needed for the same areas Thursday morning as Wednesday morning. In the afternoon Thursday, scattered showers and isolated thunderstorms, again mainly for the Southeast Highlands, are likely with heating. Mostly dry conditions are expected for our entire area by Thursday evening. Today expect temperatures 10 to 15 degrees below normal and then moderating some but still 3 to 6 degrees below normal by Thursday. Wyatt .LONG TERM...Friday through next Wednesday. All models are showing high pressure build in across the area and remain through the period bringing dry and warmer conditions. Look for temperatures slightly above normal by Friday becoming 8 to 12 degrees above normal for the weekend into early next week. Temperatures will be the warmest Sunday and Monday, upper 70s across lower elevations and our southern areas. Both the ECMWF and GFS model show weaker high pressure by late Tuesday and Wednesday with a weak system dropping down Montana and Wyoming and grazing our eastern areas. However, currently both models have slightly different timing and intensity on this system. Wyatt && .AVIATION...A low pressure system to our east will continue to bring rain and snow to our area, mainly our eastern areas today. Expect breezy northerly winds for KDIJ and KIDA with gusts up to around 25 kts. Breezy westerly winds are expected for KPIH and KBYI before turning northerly by the afternoon. Expect snow showers for KDIJ and KIDA bring MVFR and possibly IFR conditions (especially KDIJ) this morning. By late morning into the early afternoon light snow showers are possible for KPIH but will likely be rain. MVFR conditions are possible for KPIH as well. KBYI has a chance of MVFR conditions by late afternoon into the early afternoon but will likely stay VFR all day. KSUN will see some lower CIGS but will very likely remain VFR all day as well. Wyatt && .HYDROLOGY...Portneuf and Blackfoot remain the rivers of concern in East Idaho, though high flows also continue on the Snake River. Showers continue through today mainly impacting the eastern half of the forecast area with generally light precipitation. Very cool temperatures today begin to moderate some by later today, then begin to warm significantly into the weekend. For now, weekend high temperatures look to generally be in the 70s at lower elevations, so expect snowmelt to restart. Forecast flows remain high for the Portneuf: Minor Flood for the gage at Pocatello, and fluctuating right at Minor Flood for the gage at Topaz. Given the fluctuation, simplified the wording and continued the flood warning until further notice for that gage. Similar conditions exist for the Blackfoot, with the river expected to remain at or fluctuating right around Minor Flood Stage. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 9 AM MDT this morning for IDZ051>055. && $$