Area Forecast Discussion

KEY MESSAGES

- Dry and unseasonably warm weather continues through Wednesday. Highs will be nearly 20 degrees above normal Tuesday and Wednesday.

- Critical fire weather conditions likely on Wednesday due to increasing winds and very low humidity, with elevated to critical conditions continuing on Thursday.

- Pattern change to cooler and unsettled weather Friday through the upcoming weekend.

SHORT TERM /Through Wednesday/

Issued at 152 PM MDT Mon Apr 20 2026

Upper level ridging will be in place across the region for the first half of this week. For the plains, expect high temperatures in the upper 70s and 80s today, tomorrow, and Wednesday with the mountain valleys reaching the 60s. On Tuesday night into Wednesday morning, a trough will move across the western US bringing southwest (downslope) flow to our area.

Wednesday will bring elevated to critical fire weather conditions, especially for the southern and eastern portions of our CWA. A mid- level jet will move through the area with the main axis generally located over the four corners region and SW CO on Wednesday afternoon. Models still differ on the exact placement and strength of this jet at this time affecting wind speed and gust forecasts. A lee surface trough is also expected to develop bringing tightening surface pressure gradients and enhancing the winds. Relative humidity will be in the upper single digits to teens across the Southern Foothills and all of the NE Colorado plains for Wednesday afternoon into the evening. Some models even have RH in the mid single digits on Wednesday afternoon across the Urban Corridor and plains. These conditions have warranted us to issue a Fire Weather Watch for Wednesday morning through Wednesday evening. Gusts are expected to be around 30 to 40 mph with some gusts as high as 45 mph expected, especially across Lincoln, Elbert, and Washington counties. See the fire weather discussion for more information.

LONG TERM /Wednesday night through Monday/

Issued at 152 PM MDT Mon Apr 20 2026

A longwave upper level troughsets up over the western half of Canada andextends into the Pacific Northwest and Northern Rockies. Colorado will be under the base of the trough most of the time through the weekend. Shortwave troughs pass through the longwave trough, the first one will move across Colorado sometime Wednesday night or Thursday. Gusty southwest winds ahead of this system will decrease Wednesday evening as the airmass decouples. Winds turn west and increase as the shortwave trough and associated cold front sweep east across Colorado. This could happen as early as Wednesday evening, according to the GFS or Thursday morning according to the ECMWF. Either way, cooler temperatures and gusty west winds are expected by Thursday afternoon. This system could also bring rain and snow showers to the high country.

The forecast for Friday through Monday looks cool and unsettled as Colorado generally remains at the bottom of the trough. The timing of the rain/snow will depend on when the shortwave troughs pass over Colorado. Temperatures will fall below normal Friday with highs in the upper 50s to lower 60s over northeast Colorado. The cooling trend continues through the weekend. Sunday is expected to be the coolest day as a shortwave trough from the Pacific travels across Colorado. This storm system is expected to have more moisture than the others. Both the GFS and ECMWF models show this, so there is a little more confidence Sunday will be cooler and possibly wet.

AVIATION /00Z TAFS through 00Z Wednesday/

Issued at 533 PM MDT Mon Apr 20 2026

VFR will persist through the period. Winds will follow fairly normal diurnal patterns at KDEN and KAPA turning from ENE-SE-SSW through 06Z tonight, and then holding S-SW through about 15Z. Then expect a period of VRB winds 15Z-18Z Tuesday before an E-SE component develops 18Z-20Z, and slowly increases to ~12kts on average after 22Z. The main differences for KBJC will be that winds start this period northerly, before a return to SW flow by 03Z-05Z tonight.

FIRE WEATHER

Issued at 158 PM MDT Mon Apr 20 2026

Hot and dry conditions are expected for the first half of the week. A trough moving over the Western US will bring gusty southwest to west winds (30 to 45 mph) on Wednesday persisting well into the evening hours. Single digit RH values are expected. This has led us to issue a Fire Weather Watch for Wednesday morning through Wednesday evening due to elevated to critical fire weather conditions. The highest danger will be in the southeast portions of the CWA, where winds will be the strongest.

Elevated to critical fire weather conditions will likely persist into Thursday, but RH will be slightly higher- mainly in the low to mid teens across the plains. Wind gusts around 30 to 35 mph are expected on Thursday. Highlights could be needed for Thursday as confidence increases, especially given the timing of the cold front.

The cooling trend continues Friday and into the weekend as additional systems reinforce the cooler air and possibly bring rain/snow showers.

BOU WATCHES / WARNINGS / ADVISORIES

Fire Weather Watch from Wednesday morning through Wednesday evening for COZ214-216-238>251.