068 FXUS65 KBOU 020232 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 832 PM MDT Fri Sep 1 2023 .UPDATE... Issued at 827 PM MDT Fri Sep 1 2023 Adjusted PoPs upwards slightly over the northern Front Range mountains and foothills with ongoing, albeit dissipating, showers moving north into Wyoming. Convective activity has remained almost exclusively over the higher terrain today as expected, and any lingering showers this evening will continue to do the same. Denver did register a record daily high temperature of 99F today, exceeding the previous Sep 1st record of 98F set in 2019. Other than the aforementioned PoP changes, minimal forecast adjustments made this evening. && .SHORT TERM...(This afternoon through Saturday) Issued at 230 PM MDT Fri Sep 1 2023 The strong low over the Pacific Northwest will slowly shift south down the west coast while the broad ridge over the Midwest and Southeast will stay about in place. Flow aloft looks to turn more southerly and increase a bit before weakening again. This evening and tonight, elevated fire weather conditions on the eastern plains should subside by early evening with cooling and moderating winds. Skies will gradually clear from mostly to partly cloudy, while any isolated showers lingering in high country diminish before midnight. Overnight low temperatures are forecast generally 5 to 10 F warmer than normal across most of the area. Tomorrow, looks quite similar again to today, partly to mostly cloudy but with less coverage of showers, and even lighter precipitation. Temperatures will also be similar, but the daily record high is 100 (set in 2019), a bit higher of a bar. Afternoon minimum humidity will also be similarly low across the plains, near or just below 15 percent again in many areas, but winds should be yet more moderate which will mitigate fire weather conditions. Expect more isolated showers and storms across the high country in the afternoon and evening, precipitation should be light, and there may be some modest outflow gusts. .LONG TERM...(Saturday night through Thursday) Issued at 230 PM MDT Fri Sep 1 2023 Summer heat continues into Sunday, then gradual cooling is expected Monday into Tuesday. We'll have a chance of storms spreading onto the plains during this transition, but then drier weather returns much of next week. On Sunday, the deep upper trough over the western U.S. will begin to shift eastward into the Great Basin, while the ridge begins to break down. This will allow a plume of monsoonal moisture on the leading edge of the trough to push slowly north/northeast across the area in the afternoon and evening. Most of this moisture is in the mid/upper levels, but still some brief heavy rain will be possible from a few storms due to the increase in precipitable water. Otherwise look for gusty outflow winds with DCAPE of 1300-1500 J/kg on the plains. MLCAPE will top out at just a few hundred J/kg, so updraft and storm strength will be limited. For Monday, it appears the best moisture is already shifting north and east of the area. However, models had been trending slower with the shortwave so a little better chance of storms could linger along the northern border area. For Tuesday, there's uncertainty about another potential shortwave so we'll have some chance of storms in the forecast. That day should also feature the coolest temperatures of the week ahead, with lower to mid 80s for highs across the plains. For the latter half of next week, there's good agreement with regard to flat ridging over the Central Rockies. That would result in warmer temperatures and dry weather. Temperatures should return to above normal levels with highs averaging in the upper 80s to near 90 in the lower elevations. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 513 PM MDT Fri Sep 1 2023 VFR conditions will prevail for all terminals through the period. Mid to high level clouds will persist into tomorrow, with bases AOA 080. High-based showers will remain largely confined to the higher mountain terrain, with a generally low threat of impacts for the lower elevations. Southeasterly flow this afternoon will become southerly later this evening with light drainage flow persisting overnight. SE winds expected to return tomorrow afternoon. && .HYDROLOGY... Issued at 230 PM MDT Fri Sep 1 2023 This evening, isolated to scattered showers/storms are not expected to pose a threat of flash flooding in the burn areas as the rainfall is expected to be light. After a dry Saturday, moisture will increase for Sunday. Some thunderstorms will be slow moving and could produce heavy rain Sunday afternoon and evening, so there will be a limited threat of flooding for the burn areas. For Monday and Tuesday, there will be a decreasing threat as drier air should return. That drier air will then hold through much of the upcoming week. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Rodriguez SHORT TERM...EJD LONG TERM...Barjenbruch AVIATION...Rodriguez HYDROLOGY...Barjenbruch