986 FXUS65 KBOU 281642 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1042 AM MDT Wed Jul 28 2021 .UPDATE... Issued at 1037 AM MDT Wed Jul 28 2021 Mid-level water vapor imagery shows an upper level ridge oriented over Colorado and the US Central Plains. Dry air in the mid-levels is quite evident over eastern Colorado with the more favorable moisture to our north and west. Observational soundings this morning reflect these conditions with dry air and warming in the upper levels indicating a dry day for most areas. Seeing some cumulus development over the mountains/foothills from the heating this morning. HREF members show weak instability and moisture over the higher terrain in the afternoon, so kept in chances for scattered showers and weak storms for the mountains/foothills. Current temps are around a few degrees warmer than this time yesterday over the plains keeping the forecast on track for slightly warmer highs for today. Given the current trend, Denver has a good shot at meeting or breaking the previous record of 98 degrees. && .SHORT TERM...(Today and tonight) Issued at 406 AM MDT Wed Jul 28 2021 The upper ridge over the CONUS will continue to build today and heights continue to rise across northeast Colorado. High temperatures will climb into the upper 90s to low 100s across the plains under mostly clear skies. The daily record high for Denver of 98 F, set in 1876, will definitely be in jeopardy. Recent runs of the HRRR Smoke model suggest a continued relative break in smoke concentrations as flow around the high keeps most of it north of Colorado. Subsidence and warm, dry air aloft will continue to suppress convection but moisture will start to increase over the mountains as the ridge slowly shifts east, which should allow for some isolated to scattered storms over the high terrain. Storm intensity will be limited by a lack of instability but expect some light precipitation and gusty outflow winds. Skies will clear overnight but lows will still be a bit warmer than normal, in the mid 60s across the plains and 40s and 50s in the high country. .LONG TERM...(Thursday through Tuesday) Issued at 426 AM MDT Wed Jul 28 2021 High pressure will remain centered east of the forecast area Thursday into mid day Friday. The flow aloft is very weak. By Friday afternoon and night, the upper ridge center is stretched across Colorado northwestward out of the state. The flow aloft remains extremely weak through the weekend. The QG-Omega fields show very weak upward vertical velocity in place over the CWA Thursday through Friday night. With the upper ridge center moving into Colorado on Friday and through the weekend, moisture is progged to increase over the CWA. Precipitable water values are expected to come up into the 0.8 to 1.4 inches range Friday night through at least Sunday night. With the light flow aloft and all the increased moisture, heavy rainfall and flash flooding is certainly possible, and more so over the burned areas in the foothills and mountains from Friday afternoon into early next week. Temperatures look to stay above normals Thursday and Friday. Thickness fields indicate a cool down later Friday afternoon and evening. It looks like high temperatures will get below seasonal normals from Saturday through Tuesday, with Sunday looking like the coolest day. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1037 AM MDT Wed Jul 28 2021 Expect VFR conditions through the period. Winds will become more northerly through the afternoon then turn clockwise back to drainage by the evening. Showers and weak storms are possible over the higher terrain, but should stay confined to the higher elevation. && .HYDROLOGY... Issued at 426 AM MDT Wed Jul 28 2021 Wednesday will see isolated to scattered thunderstorms over the mountains. Storms will be slow moving but the moisture supply remains limited, so the threat of burn scar flooding will still be very low. There will be a limited threat of flash flooding over the burn areas late day on Friday moisture increases. The threat of flooding will increase on Saturday and Sunday for all the forecast area, not just for the burn areas. This is because of the increased moisture and slow movement of the showers and thunderstorms. Two inch per hour rain fall rates will be possible during the afternoon and evening periods of Saturday and Sunday. There will be a slight decrease in moisture Monday and Tuesday, but there will still be a threat of heavy rainfall. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Mensch SHORT TERM...EJD LONG TERM....RJK AVIATION...Mensch HYDROLOGY....EJD/RJK