textproduct: Grand Junction

KEY MESSAGES

- Thunderstorm activity will continue across northern portions of the area through early evening with gusty outflow winds and locally moderate to heavy rainfall rates possible.

- Localized critical fire weather conditions favor mainly far southeast UT and southwest CO again tomorrow afternoon.

- A prolonged and significant heat wave will be impacting much of eastern Utah and western Colorado through the weekend and lingering across the northern area through early next week.

- Afternoon highs of 100 to 110 could produce near/record temperatures Sunday into Monday and with warm night time lows the threat of heat-related illnesses are possible.

DISCUSSION

Issued at 128 PM MDT Thu Jul 9 2026

The bottom line up front is a significant heat wave is coming to portions of western Colorado and eastern Utah this weekend into early next week. With this multi-day event...peaking Sunday and Monday...we upgraded to warnings across portions of eastern Utah into northern Colorado where the hottest temperatures are expected...with heat advisories on the periphery to the East. The southeast areas will still be very warm but less impactful and prolonged and were 17cancelled. Going forecasts have temperatures near or exceeding all time records across northern portions of the forecast area along with warmer night time temperatures giving minimal relief overnight. This heat is following the the dome of high pressure aloft as it ejects northward from the Desert Southwest and settles over the eastern Great Basin and northern High Plains from Sunday into the middle of next week. Ensemble clusters suggest mid level temperatures and return intervals will be the highest across the 4 Corners into northern portions of Utah and Colorado and where we are highlighting the biggest impacts. Daytime readings in the 100 to 110 range are forecast with the hottest temperatures over the lower Utah desert valleys including the National Park region. However all time record high temperatures are in jeopardy in places like Vernal (104) and Craig (101) if this heat pans out as trends over the past several days have suggested. All this heat is only being exacerbated by the persistent drought conditions and there is a probability some headlines may need to be extended into Tuesday up North. This heat is not good news for the ongoing wildfires and those on the ground fighting them. There continues to be localized area of critical fire weather conditions this afternoon into Friday across the South. Under these hot conditions and deeper mixing there are also likely to be some afternoon gusts through the weekend as well. Overall however winds should be decreasing under the as the ridge migrates through. Temperatures moderate slightly in the south by Monday as deeper moisture is drawn northward across the 4 Corners region. This is likely to mean more cloud cover and lead to a better chance of afternoon convection. The high slides farther into the Plains through mid week and sets on on the edge of the ring of fire. The better moisture looks to be rotating upstream through the western Great Basin but there appears to be enough moisture trapped in the easterly flow aloft lead to a daily thunderstorm threat. With the moisture saturating and recirculating the SubTrop high aloft this trend is likely to continue through week and hopefully bring some relief to the heat.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1157 AM MDT Thu Jul 9 2026

Orographic westerly flow will produce terrain based showers and thunderstorms across most mountain groups this afternoon. A few of these will drift over valleys and contribute gusty outflow winds to airfields. Gusts of 45-55 mph can be expected adjacent to decaying showers. Rainfall will be minimal and thus breakpoint ceilings and/or visibility are not expected to impact terminals. Skies will clear back out this evening and lighter down valley drainage winds will resume after dark.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Extreme Heat Warning from noon Saturday to midnight MDT Monday night for COZ001-002-006-007. Heat Advisory from noon Saturday to midnight MDT Monday night for COZ008-011. Heat Advisory from noon Saturday to midnight MDT Sunday night for COZ020-021. UT...Extreme Heat Warning from noon Saturday to midnight MDT Monday night for UTZ024-027. Extreme Heat Warning from noon Saturday to midnight MDT Sunday night for UTZ022-029.