Area Forecast Discussion

KEY MESSAGES

- Saturday will see isolated to scattered showers and storms with moisture on the downward trend for the rest of the weekend.

- A few storms may strong to severe this afternoon. Also localized heavy rainfall could result in flash flooding.

- Another push of moisture on Tuesday and Wednesday brings precipitation chances back into the forecast for the region.

- Daytime highs this weekend and into next week will be relatively seasonable, if not below at times.

DISCUSSION

Issued at 1123 AM MDT Sat Sep 19 2026

TAIL END OF THE MOISTURE:

A low pressure will track just north of the area area today and tonight. This low is providing several rounds of forcing, which with moisture in place has resulted in showers and storms. Those chances continue through tonight as the low clips the northern CWA. During the afternoon shower coverage will be highest in the eastern tow thirds of the area and tonight the highest chances will be along and north of I-70. Marginal shear will be present once again this afternoon so that along with cape around 500-1000 j/kg a few storms may be strong to severe. The main threats would be large hail and damaging winds. Given PWAT values are still 150 percent of normal and saturated soil there is a potential for heavy rainfall and therefore flash flooding.

DRYING OUT:

The low pressure tracks to our east tomorrow and dry air moves in from the northwest. There may still be enough lingering moisture for showers mainly over the higher terrain, but those chances are low. The same can be said for Monday as well.

PRECIPITATION CHANCES RETURN:

The next system of interest will be a low pressure that makes landfall in California. It will progress eastward and tap into the moisture that will be shunted to our south tomorrow. The low is expected to become an open wave and move through the area relatively fast. The result from the wave will be scattered showers and storms across the area on Tuesday and Wednesday at the least. The wave will provide shear so some of the storms could be strong to severe. Also, freezing levels may come down enough to coat the highest peaks with snow. The uncertainty is will the wave push the moisture to our south or will it linger in portions of the area. If it does get pushed southward how quick will it return. Confidence in the forecast mid to late week is low attm.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 508 PM MDT Sat Sep 19 2026

Lingering shower and storm activity is expected for the next few hours at terminals along and north of I-70. KHDN has the best chance to see overnight showers, so included PROB30 groups to account for that. Overnight winds should be generally light and terrain driven. Sunday will see drier conditions with less cloud coverage. Breezy conditions could be around Sunday afternoon at some terminals. VFR conditions are likely to prevail, but cannot rule out MVFR at terminals with reduced visibilities due to heavy rainfall.

GJT WATCHES / WARNINGS / ADVISORIES

CO...None. UT...None.