National Weather Service Forecast Discussion |
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129 FXUS65 KBOU 260950 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 350 AM MDT Thu Mar 26 2026 .KEY MESSAGES... - Another unseasonably warm day Thursday with locally critical fire weather conditions in South Park, but cooling quickly with gusty northeast winds behind a mid afternoon cold front. - Light to moderate rain/snow showers expected late Thursday evening through Friday morning. - Temperatures warm well above normal again for the weekend into early next week. - Signs of a pattern change by the mid to latter portions of next week, but highest chances of meaningful precipitation confined to the mountains. && .UPDATE... Issued at 337 AM MDT Thu Mar 26 2026 A few adjustments have been made to the near-term forecast based on the latest guidance and the upcoming cold front. To start, the Red Flag Warning has been trimmed with Lincoln County now excluded, as there`s growing confidence in a lack of overlap between the low humidity (through early afternoon) and the stronger frontal and post-frontal winds (mid-afternoon onwards). Second, cross-sections are relatively consistent in depicting several hours of easterly upslope flow tonight, aiding in precipitation development for much of the I-25 corridor and foothills. There`s still some uncertainty as to the placement of the highest totals with convective showers possible in and around the Denver metro, but generally the central/southern foothills should be favored given the flow pattern. Have increased PoPs for all areas to above 60% (higher for the foothills), as well as projected precipitation amounts (several tenths of an inch appear increasingly feasible for wherever we see convective and upslope enhancements). A dusting to a couple inches of snow is within reach for portions of our foothills, but no accumulations are expected below 7,000 ft (though some flakes may certainly mix in). The forecast remains otherwise on track, and no other changes of note were made. && .DISCUSSION /Through Wednesday/... Issued at 1155 PM MDT Wed Mar 25 2026 The persistent ridge that has been responsible for the record- breaking high temperatures across the West will flatten out and begin to move eastward on Thursday. Lee troughing is expected to develop over southeastern Colorado by Thursday morning ahead of an approaching shortwave and associated cold front. Guidance shows 700 mb temperatures gradually cooling throughout the day, and by about 6 PM, we are looking at a 12-16C decrease compared to today (Wednesday). There are still some uncertainties with Thursday`s temperature forecast, as a fairly wide spread of scenarios is portrayed in the latest guidance, and are highly dependent on cold front timing. After the cold front that oozed into northeastern Colorado back in early March (3/10/26 to be exact) that never retreated back northward through the day as models portrayed, this forecaster is skeptical of the warmer solutions playing out, at least across the northern portion of the forecast area. Therefore, temperatures were blended with some of the cooler guidance along the Wyoming/Colorado border. This does make for a fairly large temperature gradient from the northern border (highs in the upper 60s) to our southern border (highs in the upper 80s in southern Lincoln County), where a 22 degree temperature difference is forecast. If the front speeds up at all, this will impact temperatures across the lower elevations, but for now, the current forecast does still keep some locations climbing towards another day of record highs before the front slides south by the afternoon. This will also allow for critical fire weather conditions to develop over portions of our southern forecast area where a Red Flag Warning is in place from 11 AM to 6 PM (more in fire discussion below). Gusty winds and increased moisture will accompany the front, with gusts between 35-45 mph possible as it passes. Light precipitation will be possible as there will be enough moisture and northeasterly winds will provide upslope conditions to the Front Range Foothills and Palmer Divide. Can`t rule out the possibility for some lightning or even some dry lightning where instability is greatest (SBCAPE ranges from 150-300 J/kg) generally along the foothills, adjacent plains, and Palmer Divide. Will have to watch for potential fire starts if we do see any lightning strikes as fuels remain dry and available after the recent stretch of record breaking temps and dry conditions (see more in fire weather discussion below). Temperatures will drop low enough to even allow for a dusting of snow overnight for the higher foothills and Front Range Mountains, with some flurries possible for the lower elevations late Thursday night/early Friday morning. Temperatures will cool significantly on Friday, with high temperatures finally expected to be a few degrees below normal for the lower elevations, while the mountains and mountain valleys stay about 5 to 20 degrees above normal. Cross sections show low level moisture sticking around through the day Friday, with precipitation shutting off by the afternoon. While the cooler temperatures and precip are a welcomed change, nothing significant is expected with this system that would make any dent in our lacking snowpack or worsening drought. Expecting total QPF between .05" for the plains, and up to .2" for the higher elevations. The perpetual warming and drying cycle will start over again on Saturday as the upper-level ridge rebuilds over the West. This will start to bring temperatures back up to well-above normal values through next week, leading to elevated to critical fire weather concerns returning to portions of the forecast area. Signs are pointing to a significant pattern change by early next week as the upper-level ridge finally shifts into the eastern CONUS. The exiting high pressure looks to wrap some Gulf moisture around itself and into Colorado by Monday, and by midweek a trough looks on track to bring Pacific moisture into the Rockies. && .AVIATION /06Z TAFS through 06Z Friday/... Issued at 1155 PM MDT Wed Mar 25 2026 VFR conditions will prevail for all terminals through at least 21Z Thu. Expect current drainage winds to persist through early morning, before gradually transitioning to light NW/N flow for a brief period early afternoon. Cold front is set to arrive 20-22Z, bringing a sharp increase in NE winds with gust 25-35 kts likely for all terminals. Some BLDU is possible with and shortly behind the front, with brief and localized vis restrictions to ~6SM. There is a slight (~20%) chance of weak, elevated convection late afternoon/early evening over the Denver area. Confidence is not quite there for a PROB30 group at this time, but one may be needed if forecast trends continue. By 03-04Z, an increase in low-level cloud cover is expected, with CIG development increasingly favored for all terminals with bases 008-018. -SHRA will be possible as well, but most likely between ~06- 10Z Fri. && .FIRE WEATHER... Issued at 1155 PM MDT Wed Mar 25 2026 Temperatures will warm into the upper 80s across the southern portion of our lower elevations on Thursday that will coincide with relative humidity values in the 10-15% range and increasing northwesterly winds. Additionally, South Park will see gusty west winds throughout the day with relative humidities dropping into the low to mid teens. A cold front is expected to bring a wind shift to the northeast and wind gusts between 35-45 mph during the afternoon/evening hours. Therefore, a Red Flag Warning is in place for South Park and far eastern Elbert and southern Lincoln Counties from 11 AM to 6 PM Thursday. Moisture is expected to increase behind the front that will see vast improvements to relative humidity recoveries, though winds will take a little longer to see the improvements, diminishing from north to south. There is potential for a few lightning strikes with the frontal passage, mainly for the foothills and adjacent plains. With only light precipitation expected, dry lightning can`t be ruled out that could spark new fires as fuels remain very dry and available after the recent period of record breaking heat and dry conditions. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM this morning to 6 PM MDT this evening for COZ214. && $$ UPDATE...BRQ DISCUSSION...9 AVIATION...BRQ FIRE WEATHER...9