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383 FXUS65 KBOU 180617 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1217 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 /06Z TAFS through 06Z Saturday/... Issued at 1217 AM MDT Fri Sep 18 2026 VFR conditions are expected to prevail for all terminals through the TAF period. The current light/VRB winds will steadily morph into a better defined (albeit still weak...< 7 kt) drainage flow pattern over the next couple of hours, with the latter holding through mid-morning before winds return to a more variable regime. Speeds will remain light and under 10 kts through early/mid- afternoon. Scattered SHRA/TSRA will redevelop mid-afternoon and carry potential for gusty outflows, mainly after 22-23Z. Coverage should dwindle mid-evening, but isolated SHRA may linger through most of the evening. Winds will favor a return to drainage flow in the evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...BRQ AVIATION...BRQ