textproduct: Pocatello

KEY MESSAGES

- Isolated showers and mainly dry thunderstorms, breezy winds, and near critical to critical fire weather conditions today.

- Another round of isolated to scattered mainly dry thunderstorms Tuesday and breezy winds Tuesday ahead of cold front late in the day.

- Cooler and drier Wednesday

- Warming trend to finish out the week.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 203 PM MDT Mon Jul 14 2025

Satellite imagery shows weak feature just north of the Nevada border allowing for shallow cumulus development and weak radar returns south of the border. Further north, isolated thunderstorms have developed from Copper Basin northeast toward the Divide. HREF probabilities continue to support 70+% chance of greater than 35 mph winds associated with the northern storms, including as they drift into the northern portions of the Snake Plain. Gusty winds still continuing to develop through the Arco Desert/Magic Valley/South Hills along with dry surface conditions. Overall combination of the above conditions contributing to critical fire conditions, so a Red Flag Warning remains in place through 9 pm tonight. Should see winds diminish and humidities rise above critical levels beyond that time. High-res models hint at weak convection possibly continuing after sunset, but confidence is low. Would not necessarily be surprised with weak nocturnal convection late tonight into early Tuesday morning across the south.

More organized system still forecast to work southeast across the panhandle and western Montana during the day Tuesday. Precipitable waters increase slightly into Tuesday, and coverage for thunderstorms increases, especially across the eastern half of the forecast area. Forecast soundings for Tuesday afternoon support stronger outflows, with potential increasing for 50+ mph gusts, especially across the south where SPC has included the region in a Marginal Risk for severe. Outside of the storms, gusts could still approach 25-35 mph, but humidities should be slightly higher tomorrow. Additional Red Flag Warnings may be needed for thunderstorm coverage, but not necessarily gusts and humidity.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 203 PM MDT Mon Jul 14 2025

The mid/upper-level shortwave trough responsible for tomorrow's anticipated weather will continue to pull east away from the area on Wednesday, leaving cooler, drier (in terms of showers/thunderstorms), and lighter winds in its wake. Can't rule out an isolated shower or storm (10-20% chance) along the MT Divide/Island Park area where a little moisture lingers beneath cooler temps aloft, but precipitation potential appears minimal as a whole. Will see a 5-8 degree cool down in the post-frontal airmass. Ensemble means and ensemble clusters remain in good agreement showing the upper flow backing to westerly by Thursday, allowing temperatures to quickly rebound. West/southwest flow aloft then persists into the weekend, leading to warm and predominantly dry conditions. A few weak ripples embedded in the flow will support an occasional isolated afternoon/evening thunderstorm chance (20% or less) in the mountains, but again expecting most locations to remain dry through this time. Seeing increased signals in ensemble clusters today of a stronger shortwave trough arriving by late weekend/early next week. This signal is showing up in roughly 60% of the cluster membership on Sunday and in over 80% by Monday. While this may briefly usher in slightly cooler air, unfortunately the bigger impact will likely be a period of enhanced winds and resultant fire weather concerns as moisture still appears lacking for any appreciable precipitation threat.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1148 AM MDT Mon Jul 14 2025

Another weak disturbance passing through westerly flow aloft will trigger isolated to scattered showers and thunderstorms this afternoon and evening. KDIJ and KIDA will see the highest probabilities of being impacted by any of these, and have maintained PROB30 groups at both sites for a thunderstorm mention and associated convective gusts around 30-35 kts. Otherwise, VFR conditions are forecast through the period. Will see west/southwest winds gust to around 20 kts this afternoon, before diminishing after sunset this evening. Can't rule out a few lingering light showers primarily near KBYI overnight, but not anticipating any real impacts from these. Another round of showers and storms will develop tomorrow afternoon, this time with greater areal coverage as a stronger shortwave and cold front approach, with strong wind gusts remaining the main concern with these storms.

FIRE WEATHER

Issued at 203 PM MDT Mon Jul 14 2025

Isolated thunderstorms beginning to fire across the central mountains from Copper Basin northeast to the Divide. High-resolution model runs still largely support erratic outflow gusts from these storms to exceed 35 mph from the western edge of Zone 476 across the northern portion of Zone 410 to Zone 411 as the storms mature and shift east through the afternoon and evening. The storms will be mostly dry, but a stronger storm or two may be able to produce amounts approaching one-tenth inch. Further south, wind gusts outside of thunderstorm influence still expected to range 25-35 mph across zones 425 and 427 this afternoon, encroaching into the Arco Desert/INL portion of Zone 410. This region also expected to continue to dry to afternoon humidity values below 15%. Thus Red Flag Warnings remain in effect until 9pm for these regions, mainly for gusty winds and low humidity, but also for the impact of the thunderstorm outflows across the northern half of zone 410.

A more organized system is still expected to drop through the Idaho panhandle and western Montana Tuesday. Moisture does look to increase across the region, and thunderstorms should become more scattered with the exception of 475, 422 and 425 where coverage drops off significantly further west. Storms tomorrow will have the potential to produce stronger wind gusts with potential for greater than 50 mph especially 427 and 413. There is better potential for wetting rains, but still not expected to be widespread with most thunderstorms remaining fairly dry. Another Red Flag Warning should be anticipated given the expected thunderstorm coverage and potential strong outflows.

Cold front drops south through the region late in the day, with temperatures slightly cooler Wednesday. A few thunderstorms remain possible Wednesday mainly along the Yellowstone region, otherwise dry conditions onset across the remainder of East Idaho. Westerly flow allows temperatures to warm through the remainder of the week, and weak passing shortwave features may produce isolated afternoon thunderstorms now and then through the weekend along or north of the Divide.

PIH WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM MDT this evening for IDZ410-425- 427.