


Area Forecast Discussion
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
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857 FXUS65 KPIH 151817 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 1217 PM MDT Tue Jul 15 2025 .KEY MESSAGES... - Cold front later today will support isolated to scattered thunderstorms, breezy winds, and near critical to critical fire weather conditions. - Isolated strong to severe thunderstorms will be possible this afternoon and evening, capable of producing wind gusts up to around 50-60 mph, up to 1-1.5" diameter sized hail, moderate to heavy rain, and frequent lightning. - Cooler and drier conditions on Wednesday. - Warming trend to finish out the week with any shower and thunderstorm development remaining isolated. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 245 AM MDT Tue Jul 15 2025 Early morning satellite imagery shows a closed mid/upper-level low diving southeast out of British Columbia, tracking southeast into the Idaho Panhandle and Western Montana. As this trough works east through Montana throughout the day, a cold front this afternoon and evening will support another round of isolated to scattered shower and thunderstorm development along with breezy winds. Out ahead of this front, isolated showers will remain possible this morning ahead of convective initiation this afternoon and evening. For later today, we are looking at two main areas for stronger storms: one in the east-Central Mountains across the Upper Snake River Plain and Eastern Highlands starting first and a secondary area southeast of the Snake River Plain south into Utah starting second. These areas are where the HREF model probability of winds greater than 35 mph shows a 70-90%+ chance, including a 10-30% chance of winds greater than 58 mph southeast of the Snake River Plain. Given today`s ensemble convective environment supporting 500-1000 J/kg of MUCAPE, 25-40 kts of 0-6 km shear (pushing 40-50 kts further north), and 6-10 degree/km 700-500 mb lapse rates, isolated to scattered strong to severe thunderstorms are expected this afternoon and evening. As evident by stronger thunderstorms yesterday out across the Shoshone/Arco/Mud Lake Desert and South Hills/Raft River Valley regions producing wind gusts of 45-65 mph, strong to severe storms today will be capable of producing wind gusts up to 50-70 mph, up to 1-1.5" diameter sized hail, moderate to heavy rain, and frequent lightning. Given this increasing confidence, the Storm Prediction Center has expanded their Marginal Risk (5-14% chance) of severe thunderstorms today to include everywhere outside the west- Central Mountains and western Magic Valley. Stay tuned for additional forecast information, warnings, and alerts later today as we track this thunderstorm development. We will also see a mix of wet and dry thunderstorms today which coupled with scattered coverage, has prompted a Red Flag Warning for Idaho FWZ 410/411/413/427 from 12-9 PM MDT today. More on that in the Fire Weather Discussion below. Behind the cold frontal passage tonight, showers and storms will become increasingly isolated after midnight and shift east ahead of dry conditions back regionwide for Wednesday. Precipitation totals today will range from a T-0.25" for most, locally higher in that 0.25-1.00" range where stronger thunderstorms pass over. Highs today will be in the 80s/90s as synoptic winds outside of any convection will support gusts peaking around 25-45 mph this afternoon. Wednesday is shaping up to cooler and drier with lighter winds overall behind the cold front, as zonal flow fills in behind the exiting boundary. This will lead to highs in the 70s/80s (90s further south) with wind gusts peaking around 15-25 mph. The forecast for tomorrow has also trended drier, with less than a 10% chance of any shower and thunderstorm development during the daytime hours Wednesday into Wednesday night. | && .LONG TERM /THURSDAY THROUGH MONDAY/... Issued at 245 AM MDT Tue Jul 15 2025 Near normal to above normal temperatures and mostly dry conditions will prevail throughout the long term period as W/SW flow dominates the overall mid/upper-level flow pattern. A series of shortwave troughs later this week into early next week will help trigger a 5- 20% chance of afternoon showers and thunderstorms each day (primarily in the mountains), as conditions remain very dry overall outside of any of this isolated activity. As of the latest ensemble model guidance, coverage of these showers and storms will peak on Friday and Saturday, with very isolated coverage expected other days. Highs each day will be in the 80s/90s in the valleys with breezy winds expected each afternoon, supporting gusts up to around 20-40 mph. A combination of breezy winds and low relative humidity will need to be monitored later this week for any overlap for Red Flag Warning criteria. More on that in the Fire Weather Discussion below. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1209 PM MDT Tue Jul 15 2025 Hourly probability of thunderstorms in the NBM hourly output indicates a minor chance of TSRA that would rate for most airdromes a PROB30 group of varying intervals. Shortest is KSUN, then KBYI, with the longest for KDIJ. KDIJ has high enough probabilities during the afternoon for greater than 50 percent risk, so have for an interval at KDIJ a TEMPO group. TSRA ends from west to east, with KBYI ending prior to 16/00Z, and for KDIJ ending after 16/06Z. See no impact to VSBY or CIG, with the main issue being outflow wind and the TS hazards. There is the potential at all but KSUN for severe TSRA, which will mainly mean G50KT or more is possible. Conditions settle down in the late evening for light wind and unlimited CIG/VSBY. Not expecting a return of impactful weather for aviation interests on Wed. && .FIRE WEATHER... Issued at 245 AM MDT Tue Jul 15 2025 Today will be another critical fire weather day across eastern Idaho as a cold front passes overhead later in the day, supporting gusty winds, low RH, and isolated to scattered thunderstorms. Aside from isolated showers this morning, convective initiation will begin around 12-3 PM and continue through 9 PM to midnight, ahead of dry conditions back for Wednesday. As evident by stronger thunderstorms yesterday out across the Shoshone/Arco/Mud Lake Desert and South Hills/Raft River Valley regions producing wind gusts of 45-65 mph, strong to severe storms today will be capable of producing wind gusts up to 60-70 mph, 1-1.5" diameter sized hail, moderate to heavy rain, and frequent lightning. While most thunderstorms will remain wet, we will also see isolated dry thunderstorms at times as well. As a result, a Red Flag Warning remains in effect for Idaho FWZ 410/411/413/427 today with elevated to near critical fire weather conditions expected regionwide due to a combination of gusty winds and low RH in the teens/20s. Highs today will be in the 80s/90s as synoptic winds outside of any convection will support gusts peaking around 25-45 mph this afternoon. Wednesday is shaping up to cooler and drier with lighter winds overall behind the cold front, as zonal flow fills in behind the exiting boundary. This will lead to highs in the 70s/80s (90s further south) with wind gusts peaking around 15-25 mph. The forecast for tomorrow has also trended drier, with less than a 10% chance of any shower and thunderstorm development during the daytime hours Wednesday into Wednesday night. Looking ahead towards later this week into early next week, near normal to above normal temperatures and mostly dry conditions will prevail as W/SW flow dominates the overall mid/upper-level flow pattern. A series of shortwave troughs during this timeframe will help trigger a 5-20% chance of afternoon showers and thunderstorms (primarily in the mountains) each day, as conditions remain very dry overall outside of any of this isolated activity. As of the latest ensemble model guidance, coverage of these showers and storms will peak on Friday and Saturday, with very isolated coverage expected other days. Highs each day will be in the 80s/90s in the valleys with breezy winds expected each afternoon, supporting gusts up to around 20-40 mph. A combination of breezy winds and low relative humidity will need to be monitored later this week for any overlap for Red Flag Warning criteria. Stay tuned. && .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for IDZ410-411- 413-427. && $$ SHORT TERM...MacKay LONG TERM...MacKay AVIATION...Messick FIRE WEATHER...MacKay