textproduct: Grand Junction

KEY MESSAGES

- Temperatures will begin to surge well above normal Monday, approaching record values through Wednesday.

- Localized critical fire weather conditions continue, becoming more widespread Wednesday ahead of an approaching front. Fire Weather Watches are in place Wednesday.

- Dry thunderstorms could impact the region Wednesday, favoring the terrain of southwest CO.

- A pattern shift is expected mid-week which will prompt stronger winds and a few showers along the higher terrain.

DISCUSSION

Issued at 1005 PM MDT Sun May 10 2026

Hot, Dry, Windy

High pressure is still forecast to amplify across the Southwest early this week. This will push temperatures nearly 20 degrees over mid-May climatology, including some record highs. Monday's record of 90 degrees at Grand Junction has stood since 1934. Tuesday looks like the best bet for records though, as 500mb heights reach their peak then. Well mixed conditions should bring surface winds up each afternoon on the terrain. Hot, dry, windy conditions with relative humidities in the teens will produce localized critical fire weather Monday and Tuesday. Held off on any headlines for Monday, as it looks like winds will be too spotty across northwest CO to necessitate a warning. However, I did issue a Fire Weather Watch for Wednesday(explained below). Low pressure will push across the Great Basin Wednesday night, this is expected to tighten surface gradients and drive up winds Wednesday afternoon. Some weak moisture works beneath the departing ridge and afternoon instability/orographics will likely produce some terrain-based showers. Dry boundary layer conditions could lead to dry lightning and gusty outflow winds.

Cooler?

Deterministic models begin to diverge from one another quickly on Wednesday following our mini heatwave. The GFS is taking a deeper, colder low southward, while the Canadian/EC both prefer an open wave that modifies the existing airmass very little. There are bigger fish in the pond to worry about for now, but temperatures Thursday and Friday are expected to modify downward some, but I wouldn't expect a seismic shift. Non zero chances for showers west of the Divide could help cool things down too. Winds remain gusty late week and relative humidities hover around critical value for fire weather. I do believe June has plans for a visit sooner than later.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1114 PM MDT Sun May 10 2026

Winds will follow typical terrain driven patterns, with some afternoon gusts of 15 to 20 knots after 18z tomorrow. Skies will be mostly clear and VFR conditions will prevail.

FIRE WEATHER

Issued at 1005 PM MDT Sun May 10 2026

High pressure will break down Wednesday ahead of a low working from NORCAL westward across the Great Basin. This promises to ratchet up surface winds across the region following a period of anomalously high temperatures and low relative humidities. A Fire Weather Watch has been issued for northwest CO, where relative humidities will be in the upper single digits to low teens, with winds gusting to around 35 mph. Given, non-critical fuels across the remainder of the region, COZ200 and COZ202 were the only fire zones included for the time being. Should fuels in other zones respond to the hot and dry conditions early this week, we will have to include others in the likely critical fire weather headlines, as much of the region will be within critical fire weather wind speed/relative humidity values. SPC has also highlighted a 10 percent chance for dry thunderstorms thanks to some moisture sneaking beneath the ridge on Wednesday afternoon.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Fire Weather Watch from Wednesday afternoon through Wednesday evening for COZ200-202. UT...None.