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101 FXUS65 KBOU 181746 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1146 AM MDT Fri Sep 18 2026 .KEY MESSAGES... - Increasing coverage and intensity of afternoon/evening showers and t-storms for the lower elevations, peaking Saturday when locally heavy rainfall can be expected across the plains. - Warm temperatures through Saturday to give way to more seasonal conditions Sunday onwards. - Trending drier Sunday into Monday, although at least isolated to scattered showers will remain each day. && .DISCUSSION /Through Thursday/... Issued at 1144 PM MDT Thu Sep 17 2026 Though not as climatologically anomalous as the last couple of days, precipitable water values will remain plenty elevated today, combining with a hair higher instability to promote renewed scattered showers and a few generally weak thunderstorms this afternoon through the evening. As was the case over the past few days, steering level flow should remain above 20-25 kts, thus keeping storms on the move and limiting overall accumulations for most areas (with some locations, per usual, remaining dry). Temperatures will continue to hold 5-10 degrees above normal for the date. Saturday remains the day to watch in terms of both severe threats and localized flooding potential. Despite a small downtick in available moisture, PWs will remain elevated, with moderately deep warm cloud depths and increased instability as cool air advection returns aloft with the approaching upper-level low. Steering level flow will continue to be hefty, but improved shear and higher coverage of late day convection will lead to a greater potential for heavy downpours namely over the plains. The exception to the above trend will be the high country, where drier air will steadily gain influence through the weekend and reduce precipitation coverage and intensity. Scattered afternoon showers and thunderstorms look to continue into Sunday with the passage of the upper-level trough and sufficient shear and instability, however a more noteworthy decline in PWs and cooler surface conditions would suggest a slight reduction in activity compared to Saturday. Transient ridging emerges by Monday, providing for a drier day across most of the region with afternoon showers becoming much more isolated in nature, albeit not disappearing entirely. Temperatures will be fairly seasonal if not a touch below average, with highs in the mid 70`s Monday for the lower elevations. Southwest flow aloft will dominate past Monday, allowing for the intrusion of a few shortwaves through the week and keeping opportunities for additional precipitation in place most days, with the mountains being best positioned for the better coverage given the flow pattern. Beyond that, there`s still ample variance in model guidance, limiting how much detail we can extract. && .AVIATION /18Z TAFS through 18Z Saturday/... Issued at 1140 AM MDT Fri Sep 18 2026 Afternoon convection still appears likely today. Recent clearing evident on satellite has allowed temperatures to reach the upper 70s with dew points still hovering around 50F. ACARS profiles have also shown a gradual increase in instability over the last couple hours, with MLCAPE approaching 500 J/kg. Most guidance develops convection over the southwest metro before 20z, which then lifts northeastward through the terminals between roughly 21-23z. Some SHRA may linger beyond 00z but most impacts from TS or gusty outflow winds would be before that time. Winds are a bit uncertain today. There should be light upslope as a prevailing direction early this afternoon, before becoming more variable in the vicinity of convection. A return to drainage is expected this evening. Some guidance hints at some stratus or fog potential overnight though this would be almost certainly be dependent on getting meaningful precipitation across a large area near the terminals today. Tomorrow`s forecast is largely similar to today, with convection likely developing during the early afternoon hours, lingering into the evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...BRQ AVIATION...Hiris