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430 FXUS65 KBOU 222359 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 559 PM MDT Mon Jun 22 2026 .KEY MESSAGES... - Strong to severe storms expected for the plains this afternoon, producing large/very large hail, gusty winds, and possibly a weak landspout. - Additional rounds of severe storms expected Tue-Wed, with increasing potential for impacts to I-25 corridor and localized flash flooding. Temperatures to remain slightly below normal. - Elevated to locally critical fire weather conditions in the mountains most afternoons, increasing in severity this weekend under building heat and strengthening winds. - Drier and considerably hotter for the lower elevations starting Friday. && .DISCUSSION /Through Monday/... Issued at 230 PM MDT Mon Jun 22 2026 Current observations show thunderstorms starting to develop over the east Colorado plains. The Denver Convergence-Vorticity zone (DCVZ) is currently situated just east of the Denver metro, which is providing an area of enhanced surface vorticity. Bulk shear values over eastern Colorado are in currently in the 40-50KT range, although the better 0-3 km storm relative helicity (SRH) values are located over our northeastern CWA counties. Nevertheless, the aforementioned parameters, combined with precipitable water (PW) values around 0.70"-1.00", and steep lapse rates (~8 C/km), will support the development of supercells able to produce large hail, gusty winds, and weak landspouts. Localized flash flooding will also be a concern with any slow-moving storms this afternoon, as well as over the next few days, especially over areas with leftover soil moisture from the previous day`s storms. While the primary thunderstorm threat will likely be out of the area by 7pm, additional elevated thunderstorms cannot be ruled out later in the evening, as we have seen occur over the last few evenings where outflows from farther east have triggered convective initiation. A cold frontal passage is expected to bring northerly flow into the region Tuesday morning, as well as the potential for some patchy low clouds. Severe thunderstorms will be possible again tomorrow. However, the initial convective environment will face a few more challenges earlier in the day, given the slightly drier surface dewpoints behind the front, and northerly winds, as opposed to the moister southeasterly flow that is in place today. However, the shear profile tomorrow looks to be more favorable for rotating updrafts, with high-res model soundings showing curved hodographs, and a few isolated but longer-lived supercells. All hazards will be possible with any storms that develop tomorrow afternoon and evening, although the primary concern is very large hail (> 2.00"). Wednesday and Thursday will bring more rounds of severe weather potential (mainly hail), driven by zonal flow aloft and low-level moisture advection from the southern U.S. plains. The PW content in place over the Denver area through most of this week is at the 90th percentile of climatology for late July, which is when the annual peak of PW values occurs. However, the high terrain to the west is a different story, given that this surge in moisture will be confined to the low elevations of eastern Colorado and the foothills. As such, elevated to locally critical fire weather conditions will persist over the mountains and high valleys where relative humidities will drop into the teens and single digits each afternoon, with winds gusting to 20-35 mph. Widespread critical fire weather conditions are still on track to arrive on Saturday as an approaching upper level trough pushes the moist airmass in place eastwards while also causing winds to increase due to the tightening pressure gradient. && .AVIATION /00Z TAFS through 00Z Wednesday/... Issued at 555 PM MDT Mon Jun 22 2026 The DCVZ has been located east of KDEN for much of the afternoon sparking off showers and thunderstorms mainly to the east of KDEN and KAPA. TSRA development and strong gusty outflow winds remain possible at KAPA and KDEN until at least 02z this evening so have extended the prob30. Wildfire smoke is possible overnight, potentially impacting slantwise visibility at times, but currently looks to have minimal near surface impacts. Winds should stay elevated this evening with gusts as high as 25 kts given the continued outflow enhanced winds especially at KDEN and KAPA. A front will push through from north to south for all three terminals between 13z and 15z tomorrow morning with gusty winds from the north. This will also bring in low stratocu clouds as noted in Bufkit soundings and relative humidity cross sections. There is an increasing chance of IFR conditions or worse between about 13z and 17z on Tuesday morning. By tomorrow afternoon, winds should settle into a more NE direction. Showers and thunderstorms are possible especially at KDEN tomorrow afternoon with the threat for gusty outflow winds once again, but there is low confidence in exact placement and timing of thunderstorms at this time. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon to 8 PM MDT Tuesday for COZ212-213- 217. && $$ DISCUSSION...AA AVIATION...MV