National Weather Service Forecast Discussion |
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448 FXUS65 KBOU 241205 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 505 AM MST Tue Feb 24 2026 .KEY MESSAGES... - Well above-normal temperatures continue for the week. - Strong winds expected along the east slopes of the Front Range Mountains and foothills through this evening, with a few gusts of 80-90 mph possible. - Brief, but heavy round of mountain snow looking increasingly likely across the northern mountains this evening through Wednesday. - Elevated to critical fire weather conditions possible across the plains through the rest of the week. && .UPDATE... Issued at 435 AM MST Tue Feb 24 2026 A few notes from the overnight forecast desk tonight. First, lets talk wind. We`re starting to see winds gradually strengthen across the Front Range this morning, with a recent gust of 70KT at the Dakota Hill AWOS. Most high resolution models show a sharp ramp up by the mid morning hours, along with a steady push eastward into the foothills. A few gusts of 80-90 mph look likely given the consistent signal across the HRRR/RRFS/WRF-ARW, with a peak in winds sometime during the early afternoon. The last remaining question is if any winds manage to spread anywhere near the base of the foothills (Boulder/Highway 93 corridor). From a purely ingredients based approach, I`m not sure we have enough of a stable layer to bend the wave down. Not surprisingly, the deterministic output across HREF members echo that idea, with a majority of the winds occurring between roughly 6500-9500ft today. Across the plains, the general forecast has not changed significantly, with channels of gusty winds likely across most of the I-25 corridor, and steadier gusts across the Cheyenne ridge into far northeast Colorado. On the other side of the divide, snow is the main story going into Wednesday. As mentioned in the previous discussion, the plume of Pacific moisture is rather remarkable. In fact, ensemble plume data from CW3E classify this as a AR2 from this evening into roughly 18z Wednesday for the Park Range... with integrated vapor transport values near 250-350 kg/m/s (yes that`s a real unit of measurement). The anomalous moisture is also reflected by GEFS/ECMWF ensemble standardized anomalies... with specific humidity/PWAT/IVT values all near 4-6 sigma, which is either near the 99th percentile or exceeding the model climatology. However, a few factors will limit snow amounts across the northern mountains: (1) the deeper moisture is only available for around 18 hours, (2) temperatures are very warm for this time of year, and (3) lapse rates are rather poor. Snow levels hang around 8-8.5kft tonight, and as a result snow ratios are well below climatology for this time of year. The University of Utah`s snow ensemble keeps snow to liquid ratios near 7-10:1 even across the higher peaks tonight and only increases a bit tomorrow. That said, the amount of moisture and orographic lift will be enough for warning criteria snowfall across most of the northern mountains tonight into the first half of Wednesday. A HRRR/RRFS blend would favor 1-2" of QPF through Wednesday afternoon... translating to roughly 8-18" of snow. In addition to upgrading the northern Front Range mountains to a WSW, we also made various tweaks to the start times of all of the winter weather segments. && .DISCUSSION /Through Monday/... Issued at 1134 PM MST Mon Feb 23 2026 It will be windy and warm across much of the forecast area on Tuesday, with a High Wind Warning in place for the Front Range Mountains, elevations mainly above 7,000 feet, and a Red Flag Warning in place for the urban corridor and parts of the northeast plains. Winds are forecast to really ramp up early Tuesday morning as a mountain wave develops with increasing cross-barrier flow. Models have stayed fairly consistent in the strongest winds starting out at the ridgetops, then gradually migrating down the lee of the Front Range into areas down to around 7,000 feet (think our typical windy spots like Jamestown, Coal Creek Canyon, and Buckeye) by late morning. West winds ranging from 35 to 50 mph will be possible, with gusts as high as 80-85 mph in the aforementioned areas. While the strongest winds are expected to remain at elevations above 7,000 feet, there will likely be fingers of stronger winds (35-45 mph) that do make their way into the lower elevations that will coincide with low RH values (10-15%), leading to critical fire weather conditions developing from late morning through the afternoon. Winds are expected to retreat back up to the higher elevations Tuesday evening. High temperatures are forecast to come within reach of record values (current DIA record is 71F, current forecast temp is 69F), which gives us a fair shot at tying the current record if things warm slightly more than expected. Wednesday will be brought to you by the letter W, for windy, warm, and winter weather. A plume of Pacific moisture will stream into the mountains beginning Tuesday afternoon/evening ahead of our next approaching shortwave. Moderate amounts of new snowfall is expected across the Front Range Mountains and Mountains of Summit County, where a Winter Weather Advisory is in place for new snowfall totals between 5-12 inches will be possible. With a slightly more favorable flow regime for the Park Range, a winter storm warning has been issued for where heavier accumulations between 8 and 18 inches are expected through early Thursday morning. With strong winds around 55 to 65 mph possible, blowing snow will lead to significantly reduced visibilities, making for very difficult travel despite snowfall rates generally remaining light. Be prepared for winter driving conditions if heading into the mountains from Tuesday evening through early Thursday. Across the lower elevations, well above-normal temperatures are expected once again, with gusty winds expanding over much of the plains, as a 75-80 kt, 500 mb jet drops south over the Wyoming border. Winds will be strongest along the Wyoming border where 40 to 55 mph gusts will be possible, with lighter gusts (35-45 mph) from the Palmer Divide to just north of DIA. It`s looking like there will be enough moisture to make it off the mountains that relative humidities should stay above 20% (20- 25%) where winds strongest, however, if RH were to drop even a little under what is forecast, conditions would quickly reach critical thresholds, so will still keep on eye on this to see how hi-res models handle tomorrow`s conditions to see if any fire weather highlights are needed. A few light showers will be possible Wednesday evening as QG fields show some weak upwards motion and a cold front slides south across the forecast area, though anything that falls will be light, with the highest PoPs over the Palmer Divide, where northerly winds behind the front could bring some upslope conditions. Warm, windy, and dry conditions will continue on Thursday and Friday. Despite wind speeds being lighter than Wednesday, RH looks to drop to 15% or lower across the majority of the plains both afternoons, which will bring potential for widespread elevated to critical fire weather conditions both days. Less wind and slightly cooler temperatures are expected for next weekend that should ease any fire weather conditions for at least a few days! && .AVIATION /12Z TAFS through 12Z Wednesday/... Issued at 435 AM MST Tue Feb 24 2026 VFR through the TAF period, with winds the main concern through early Wednesday. Drainage flow this morning should turn to the west-northwest close to 18z. Most likely scenario for this afternoon looks to be a few channels of stronger (G25-30KT) winds near the terminals, with light - and perhaps briefly south/southeast - winds outside those channels. Guidance is surprisingly consistent in bringing one of those channels through BJC-DEN through most of the afternoon hours with a little less confidence for APA. Winds should turn slowly turn towards southeasterly or drainage flow by the evening hours with drainage likely continuing overnight. Sustained/stronger WNW/NW flow is expected to develop near 18z Wednesday. && .FIRE WEATHER... Issued at 1134 PM MST Mon Feb 23 2026 Another extended period with elevated to critical fire weather conditions will persist through Friday. Strong winds are expected to develop early Tuesday morning along the Front Range Mountains, with gusts to around 80 mph possible down to elevations around 7,000 feet. RH values will range between 15-25% in areas where winds are strongest (7,500-8,500 feet in elevation), while lower RH values, as low as 10% are expected across portions of the plains, where channels of winds gusting between 35-45 mph will be possible throughout the afternoon. The RFW has been expanded to now include Logan County where the latest guidance indicates critical fire weather conditions are likely to develop. Gusty winds will continue on Wednesday, but with RH values improving over Tuesday`s with increasing Pacific moisture entering the region, RH will range between 20-25% where the strongest winds are expected to gust between 40-55 mph (generally along and north of US-34 across the plains), though fire weather conditions will be elevated across much of the plains due to the strong winds, no fire highlights are planned at this time. With continued warm, windy, and dry conditions expected again Thursday and Friday, critical fire weather concerns will remain elevated to critical for much of the plains as RH values are expected to be at or below 15% both days, coinciding with gusty winds. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 6 PM this evening to midnight MST Wednesday night for COZ031. High Wind Warning from 8 AM this morning to 6 PM MST this evening for COZ033>035. Winter Storm Warning from 8 PM this evening to midnight MST Wednesday night for COZ033. Winter Weather Advisory from midnight tonight to midnight MST Wednesday night for COZ034. Red Flag Warning from 10 AM this morning to 5 PM MST this afternoon for COZ215-216-238>240-242-243-248. && $$ UPDATE...Hiris DISCUSSION...9 AVIATION...Hiris FIRE WEATHER...9