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531 FXUS65 KBOU 220656 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1256 AM MDT Sat Aug 22 2026 .KEY MESSAGES... - Heat eases, along with an increase in shower and storm coverage this weekend. - Highest coverage of showers and storms expected Saturday, along with a few severe storms on the plains Saturday and then again Sunday. - Gradual drying next week, but continued storm chances through at least Wednesday or Thursday. Slight cooling but temperatures still above normal. && .DISCUSSION /Through Friday/... Issued at 1258 PM MDT Fri Aug 21 2026 It`s a hot one today with temperatures early this afternoon already in mid to upper 90s along the I-25 Corridor, and approaching records in some spots (Denver`s record is 99F set in 2023). There was some slight relief over the northeast plains due to outflow from earlier Nebraska convection, so temperatures have been running a few degrees below expectations there. Given the strong surface heating and steep low/mid level lapse rates along the Front Range, we are seeing high based convection develop. These will be capable of producing strong microburst winds as DCAPE has grown into the 1400-1600 J/kg range. Meanwhile, farther east the low level moisture is holding steady with dewpoints in the lower to mid 60s in the easterly flow. While this easterly surge is expected to weaken during peak heating, it will provide for higher instability and a richer storm environment should storms be able to fire. Thus, a couple severe storms will be possible through this evening over the northeast plains given MLCAPE of 1200-2000 J/kg and bulk shear near 30 kts. For Saturday, monsoonal moisture will increase as the upper level ridge axis tilts ever so slowly eastward. Precipitable water values are forecast to reach near 150% of normal. However, the airmass is quite warm so we think most storms that originate over the mountains and then push onto the I-25 Corridor in the afternoon will still be relatively high based, and thus mostly outflow dominated. We think the majority of the storms with more widespread and beneficial rains will develop just east of the I-25 Corridor where outflows intersect with a richer low level environment. That`s where HREF ensembles show higher concentration of stronger storms. Locally heavy rain totals upwards of 1.5-2 inches will be possible there, and potentially the Palmer Divide, based on the environment and HREF Local Probability Matched Means (LPMM). Meanwhile, there will also be a threat of a few severe storms as MLCAPE once again grows to 1200-2000 J/kg and bulk shear of 25-35 kts is forecast. For Sunday, there is good agreement that the mid and upper levels will dry slightly as a more westerly component develops under a flattening ridge. Thus, storm coverage should decrease a little, in the absence of any forcing mechanisms. A few severe storms will once again be possible across the plains as we expect sufficient low level moisture and instability, with the greatest risk once again hovering just east of the I-25 Corridor. For much of next week, deterministic forecasts and ensembles are averaging toward flat ridging and weak westerly flow aloft. That likely keeps us too zonal for deep monsoonal moisture, but just enough for scattered storms most afternoons and evening. While individual model runs vary, there is still potential for a weak backdoor cool front or two. They will offer up very little in the way of cooling, but should keep us a few degrees "cooler" (mostly lower 90s for highs on the plains and I-25 Corridor) versus the full on summer heat experienced today. Ensembles are supportive of a decrease in precipitable water (PW) by the end of next week, which would support less, or only isolated, storm possibilities and a return of much above normal temperatures. && .AVIATION /00Z TAFS through 00Z Sunday/... Issued at 609 PM MDT Fri Aug 21 2026 Storms are starting to move out of the vicinity of the TAF sites, but we can`t rule out the possibility of more updrafts and gusty winds in the next few hours, especially with the current showers to the south and west sending out outflows. Because there`s been so many scattered storms across the metro area, confidence is low as to where the winds will be in a few hours. Models show varying wind directions, though observations would suggest an easterly component. Of course, any further convection or outflows could shift the wind in variable directions. After storms move out of the area to the east, winds should start turning towards drainage, getting there by around 02Z and staying generally S/SW overnight. Winds turn northward again in the morning, around 15/16Z, and staying north/northeast until storms start to move through in the afternoon. Current model guidance has more moisture in the environment tomorrow afternoon than we had today, and the CAMs remain in fairly good agreement on convection initiating around 22Z and lasting through 06Z on Sunday. DCAPE values in the most recent model runs also look to have increased from previous runs, so gusty outflows will most likely be a concern for tomorrow`s storms, as well. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 1221 AM MDT Sat Aug 22 2026 An outflow from severe storms over northeastern Colorado has pushed across KDEN/KBJC turning winds to the north. The boundary as slowed down as it passed over KDEN airfield that might keep it from reaching KAPA, but for now it has at least slowed it down from what is in the current TAF. With the upslope winds, weak showers are starting to develop around the TAF sites. Have introduced a PROB30 at KDEN/KAPA until 8Z to account for any gusty winds that may be produced if these can hold together before winds can make their way back to drainage in the next few hours. Expect some sort of southeast to south transition over the next few hours at KDEN while drainage tries to reestablish. Drainage winds are expected to turn around the clock and land to the northeast across all TAF sites by early this afternoon (17-18Z). Greater storm coverage is expected this afternoon compared to yesterday, with storms expected to move off the higher elevations between 20-22Z and continue through late tonight (5-6Z). Gusty winds are expected with passing storms, with gusts between 35-45 kts possible, but can`t rule out a severe storm passing over or near the TAF sites. Storms are expected to be high-based, with guidance showing CIG staying above 9,000 feet AGL. Like today, can`t rule out an outflow or two making their way across the TAF sites after storms have diminished that could disrupt or delay drainage winds from taking hold. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...20 AVIATION...9