860 FXUS65 KBOU 282017 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 217 PM MDT Sun Jun 28 2026 .KEY MESSAGES... - Widespread and prolonged critical fire weather conditions will be present in the high country through at least Monday due to warm, dry and windy conditions. - Little change in the forecast pattern through the middle part of next week. The only exception will be for a chance of thunderstorms over the plains on Tuesday. && .DISCUSSION /Through Sunday/... Issued at 140 PM MDT Sun Jun 28 2026 Much like yesterday, the main concern in the forecast remains a prolonged period of elevated to critical fire weather conditions, especially across the higher elevations. Southwesterly flow aloft remains in place as a positively tilted upper trough axis continues to edge closer to the forecast area. Unsurprisingly, deep mixing has already developed across the high country, with Kremmling recently reporting a T/Td of 79/19, with an 11% relative humidity and a 34 mph gust. The Red Flag Warning will remain in effect across most of the high country until later this evening. Meanwhile, a pronounced Denver Cyclone has developed across the southern Denver metro, which has left most of the I-25 corridor in an easterly flow that's limited the amount of surface heating so far. That cyclone should lift a bit further north, but it will likely mean temperatures along/north of I-70 will be a bit cooler than originally forecast this afternoon due to the weaker mixing. By tonight, a mid-level cold front is expected to push across the northern high country into the northeastern plains late this evening into the overnight hours, though the accompanying surface front is rather weak. Meanwhile, smoke from ongoing wildfires across Utah and western Colorado is likely to make it to the region sometime this evening and continue through tomorrow morning. Most HRRR/RAP cycles develop a fairly substantial plume across the northwestern half of the CWA this evening which slowly disperses and pushes southeastward overnight into Monday morning... and we'll likely see a pretty hazy sunset/sunrise tonight/tomorrow. The forecast this week has remained almost unchanged. A few shortwaves will pivot around the longwave trough over the northwestern US, while ridging builds across the Ohio Valley/Mid Atlantic this week. In general, that leaves dry southwesterly flow aloft in place across our forecast area. Temperatures across the plains look to reach the upper 80s to mid 90s each day. With 700-500mb flow still around 25-40kt, that should translate to gusty winds (especially across the high country) each afternoon, meaning that critical fire weather conditions are likely to continue through the week. While the pattern will remain generally dry, there are a couple of chances for some precipitation across the plains. The most likely period is late Tuesday afternoon or Tuesday night, with isolated/scattered showers and a few storms also possible as we get closer to next weekend. && .AVIATION /18Z TAFS through 18Z Monday/... Issued at 1220 PM MDT Sun Jun 28 2026 Wind direction will be tricky this afternoon due to the expected development of a cyclone. Winds at this time are easterly over the region with a hint of southeast winds starting arrive to the southeast Denver metro area, closest to KAPA. At the same time, winds over this area are starting to curve to the northeast as they interact with the terrain. There are two possible scenarios this afternoon given recent model trends and current observations. The first one would involve a cyclone forming N/NE of Denver, and this is the scenario that most models have trended towards. With a cyclone to the north, KDEN would experience a shift to SSW winds around 21Z and then a shift to west winds around 00Z as the cyclone migrates eastwards. Under this scenario, winds at KBJC would shift NE to NW as the afternoon progresses. The second scenario would occur if a cyclone continues to form over or just east of KAPA. If this occurs, winds at KDEN would stay easterly through the afternoon before turning counterclockwise as the cyclone migrates to the east. KAPA would shift to the NE and then turn counterclockwise as well, while KBJC experiences a light to NE to N wind. Otherwise, the other point of concern for this TAF period is the transport of smoke from the wildfires in western Colorado. Although plumes will continue to evolve over the next couple of hours, it looks like smoke could cause slant-range visibility impacts as early as 00Z this evening with the highest smoke concentrations arriving near 06Z. A weak cold front may help push some of the smoke southwards around sunrise, but smoke aloft is expected to continue and worsen as the day progresses on Monday. && .FIRE WEATHER... Issued at 140 PM MDT Sun Jun 28 2026 Critical fire weather conditions have been observed across a large portion of the high country so far this afternoon. In fact, it's drier across many of the high mountain valleys than this time yesterday, with a couple of sites starting to fall to around 10% RH, with several RAWS also reporting 40-45 mph wind gusts. These conditions are likely to persist through the rest of the afternoon and evening, and no changes were made to today's Red Flag Warning. While a cold front is expected to bring some very modest relief to the region overnight tonight, a continued southwesterly flow aloft will lead to elevated/critical fire weather conditions yet again on Monday. Given recent models underestimating the amount of mixing/drying during the day, we lowered Td/RH a bit again... and have a large swath of critical fire weather conditions forecast across the higher elevations, especially along/south of I-70. The previous Fire Weather Watch has been upgraded to a Red Flag Warning across the same zones. As we look towards the upcoming week, unfortunately there is very little change in the large scale pattern. Elevated to critical fire weather conditions look likely to continue across most of the higher elevations each day, with the potential for some of the warmest/driest air to reach the area by late in the week. There is also some concern about fuels status along the northern Foothills and most of the I-25 corridor/Palmer Divide... and if fuels status changes over the next few days, some fire weather highlights may need to be expanded into those regions going forward. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for COZ211>214-216- 218. Red Flag Warning from noon to 9 PM MDT Monday for COZ212>214-216. && $$ DISCUSSION...Hiris AVIATION...AA FIRE WEATHER...Hiris