Area Forecast Discussion

KEY MESSAGES

- Red Flag Warning in place for Prowers and Baca Counties for this afternoon and evening

- Very dangerous fire weather conditions forecast for Wednesday and possibly Thursday, with wind gusts 50 to 60 mph and humidity values under 10 percent for most of southern Colorado.

- Chances for precipitation go up Friday into next weekend, but details remain uncertain

SHORT TERM /THROUGH TUESDAY/

Issued at 1238 AM MDT Mon Apr 20 2026

Upper ridge over the area today, though a weak upper level wave and associated moisture will drift along the NM border late in the day. Still enough of a lee surface trough to generate some gusty winds over the far southeast, so kept the Red Flag Warning going for Baca/Prowers Counties, though it looks marginal, as lowest humidity may occur midday, while stronger winds late in the day are accompanied by slightly higher dewpoints. Elsewhere, could see a sprinkle/brief shower over the ern San Juans, though precip amounts will be very light. Max temps today well above average again under the ridge, with 70s/80s widespread at lower elevations.

Overnight into Tuesday, upper ridge migrates eastward through the area, with a subtle increase in mid-level moisture Tue afternoon as ridge axis passes and sly mid level flow strengthens. Suspect we'll see slightly better coverage of showers (maybe a weak thunderstorm) over the mountains, though again low levels stay dry, keeping activity mainly sprinkles/flurries/wind. Winds again increase along the KS border in the afternoon, though never quite get strong enough for any fire highlights. Max temps remain warm, with some 90s on the plains.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/

Issued at 1238 AM MDT Mon Apr 20 2026

Western U.S. upper trough/low deepens over the nrn Great Basin Wed, with upper jet wrapping around the south side and plowing into Colorado during the afternoon. 7h flow increases into the 35-45 kt range by Wed afternoon, with few 00z model solutions showing some 50 kt flags after 00z. 5h winds are even stronger, with 50-70 kts spreading over the area, strongest back toward the mountains. Dewpoints fall off into the single digits and teens, leading to RH below 10 percent in the afternoon. Overall, pattern looks very favorable for strong winds and extreme fire danger, with NBM even suggesting High Wind Warning potential over the San Luis Valley/Fremont County. Have upgraded the Fire Weather Watch to a Red Flag Warning for Wed, as by all appearances it looks like a very high end (potentially PDS) fire danger day. Winds continue well into Wed evening, and will keep the warning going until at least midnight, before RH slowly creeps back toward 15 percent by early Thu morning.

Upper jet continues over the area Thu, though mid/low level flow weaken slightly, and surface gradient on the plains slackens a bit in the morning. Cold front then drops quickly south through the plains in the afternoon/evening, with strong north winds behind it. Enough questions about winds on the plains, cold frontal timing and RH over the mountains Thu to hold off on a fire highlight at this point, though suspect we'll need something eventually, especially on the plains south of the Arkansas River, where wly winds will stay strong for much of the day. Could see a few showers Thu evening behind the front, though with upper energy pulling away, expect most activity to be scattered and light. Still appears cooler and unsettled from Fri through the weekend into early next week, as several hard to time upper waves rotate through upper trough over the Rockies. Again, went with the NBM broad-brush of pops across the area Fri-Mon, slightly higher Sun/Sun night as stronger wave and cold front may come through.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 522 AM MDT Mon Apr 20 2026

VFR conditions with generally light, diurnal wind regimes remain expected at COS, PUB and ALS over the next 24 hours, as upper level ridging continues to build across the Rockies.

PUB WATCHES / WARNINGS / ADVISORIES

Red Flag Warning from 10 AM Wednesday to midnight MDT Wednesday night for COZ220>222-224>237. Red Flag Warning from 11 AM this morning to 7 PM MDT this evening for COZ236-237.