Area Forecast Discussion

KEY MESSAGES

- Quiet and warm today, a few sprinkles/light showers possible along the Continental Divide this afternoon

- Very dangerous fire weather conditions arrive on Wednesday with very strong winds and very low humidity values. These conditions will prevail well into the overnight hours

- Critical fire weather conditions possible across the region on Thursday with gusty winds and low humidity values

- Active weather pattern from late Friday into early next week with increased chances for precipitation across the region, wettest time frame appears to be Sunday into Sunday night

SHORT TERM /THROUGH TONIGHT/

Issued at 1240 AM MDT Tue Apr 21 2026

Upper ridge migrates eastward across Colorado today, with very minor increase in mid-level moisture along the Continental Divide this afternoon as southerly flow begins to strengthen behind the departing ridge. Will likely see a few light showers/sprinkles over the higher peaks along the Divide by early evening, though any precip amounts will be light. Unseasonably warm today at most locations, with some low 90s on the plains. Air mass remains very dry, though winds stay relatively light through the day, keeping fire danger limited. Overnight, increasingly breezy as south winds ramp up, keeping min temps rather mild at many locations.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 1240 AM MDT Tue Apr 21 2026

Warm, dry and windy on Wednesday with very high fire danger, as upper low moves from the nrn Great Basin in wrn Wy by evening. Strong upper jet wrapping around the south side of the low noses into wrn Colorado by Wed evening, while at the surface lee trough/dryline sharpens up near the KS border by mid-afternoon, then moves quickly eastward into KS Wed evening. A few CAMs suggest a high-based tsra possible along the dryline across ern Prowers/Kiowa Counties mid/late afternoon, so will keep a narrow sliver of pops along the border to account for this. If storms develop, main threat would be wind, and at at least a low risk of a fire start or two due to lightning. Remainder of the area will be windy and very dry, with w-sw winds gusting 45-55 mph, windiest San Luis Valley and in/near the Sangres. Current Red Flag Warning covers the situation nicely for now, though will continue to monitor for PDS warning potential in the San Luis Valley/Fremont County/Sangres, where winds will be strongest.

Upper jet remains overhead Thu, though forecast soundings show a pronounced weakening of mid level flow during the day, with strongest winds well above mountain top level until late afternoon. Surface low pressure spins up on the plains 18z-00z, though gradient remains rather slack east of I-25 until evening. Overall, confidence is rather low (30-40 percent) in critical fire weather conditions, given we'll have to mix 15k-20k feet AGL to reach stronger winds, especially on the plains. Will keep Fire Weather Watch in place for now, as air mass will remain very dry, and it won't take much wind for areas of critical conditions to develop, with the greatest risk over the mountains and along the NM border. Max temps cool 5-15 degf Thu as mid level thermal ridge is knocked down by passing upper trough. Weak cold front then passes Thu night, though moisture increase behind the boundary is rather meager, keeping any shower chances limited to mainly the central mountains and Pikes Peak region. Breezy and continued cooler Fri, with at least some pockets of near critical fire weather over the area once again, as we await secondary cold front and at least a weak surge of moister air Fri night.

Still cool and unsettled over the weekend into early next week as series of upper waves rotates through the region, with still a good deal of model/ensemble spread on where/when heaviest precip will fall, Rough consensus is Sun/Sun night will have the highest pops, though will note 00z ECMWF deterministic solution and many of the EC ensemble members continue to keep the heavier precip to the north, while 00z GFS leans a little more south. Air mass will be cold enough for snow in the mountains, with even a rain/snow mix possible across most interior valleys and the Palmer Divide.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 526 AM MDT Tue Apr 21 2026

Upper level ridging in place across the Rockies will keep VFR conditions and diurnal winds at COS, PUB and ALS over the next 24 hours.

PUB WATCHES / WARNINGS / ADVISORIES

Red Flag Warning from 10 AM Wednesday to midnight MDT Wednesday night for COZ220>222-224>237. Fire Weather Watch from Thursday morning through Thursday evening for COZ221-222-224>237.