textproduct: Salt Lake City

KEY MESSAGES, Issued 1005 PM MDT Sat Sep 12 2026

- An isolated flash flood threat will persist over southeast Utah to start the week as monsoon moisture lingers.

- Breezy winds will be in place today ahead of an approaching cold front, bringing wind gusts to 40 mph to portions of western Utah as well as Uinta county, Wyoming.

- The front will move through the northwestern half of the forecast area late today into Monday, bringing noticeably cooler and drier conditions behind it. Warmer temperatures and elevated moisture will persist over southeast Utah.

DISCUSSION

Morning water vapor and H5 analysis place Utah within a deep southwesterly flow as a deep upper low resides upstream over eastern Washington, and mean ridging remains centered near the New Mexico/Texas border. Coincident with the upper low, a surface cold front is draped from roughly EKO to PIH with leading edge just now pushing into extreme northwestern Utah. South of this front the S-N MSLP gradient is driving gusty southerly winds across much of the forecast area this morning which are only poised to increase further with continued slow encroachment of the front and heating of the day. Gusts to 40 mph remain likely across much of western Utah as such.

Deep layer moisture continues to advect SW-NE across the southeastern third of the state, with PW's between .8-1.0" extending from the UT/AZ border region on up through Castle Country. CAMs continue to advertise modest diurnal destabilization beginning early afternoon within this plume, and given surface dewpoints largely in the low-mid 50s and favorable H8.5-H7 mixing ratios existing across the southeast, will once again be watching for isolated flash flood threats from the convection that initiates within this zone this afternoon. Modest shear along the northern periphery of this zone will also aid the potential for isolated organized cells in east-central Utah.

The aforementioned cold front will sag through the northwestern third of the state later today/tonight as a largely dry feature, but solid CAA coincident with the baroclinic passage will significantly knock temps down for Monday in its wake. Highs across the north will drop to some 10 degrees below climo on Monday north of the boundary, but change only minimally across the remainder of the forecast area to the south and east. What is a bit more notable is that the this front will begin to pin moisture a skosh more to the south and east early in the week, but not completely out of the area maintaining a diurnal heavy rain threat with afternoon convection (namely far southern/eastern portions of the area).

Minimal change in the gross large scale pattern is evident through Tuesday, but details in the delineation of dry SW flow vs. deeper layer moisture associated within the return flow begin to wane midweek. Driving force behind this are subtle differences in amplitude/placement of the next upper level low which is expected to carve southeast into the western Great Basin region. Consensus attm shifts the return flow moisture gradient further west beginning Wednesday, increasing diurnal convective potential for the eastern half of the area (at least) during the latter half of the week.

AVIATION, Issued 1105 AM MDT Sun Sep 13 2026

KSLC...Gusty southerly winds will continue through the early afternoon, with gusts to 20-30kts. A frontal boundary will produce a transition to northwesterly between 21-22z. Winds may then lighten a bit between 00-04z before gusting again to around 20-25kts out of the northwest after 04-05z. VFR conditions will prevail with mostly clear skies.

REST OF UTAH AND SOUTHWEST WYOMING...Gusty southerly winds will persist across most areas with gusts to 20-35kts. Isolated to scattered thunderstorms will develop again after 18z mainly east of KBCE-KU69, though a shower or two may develop over higher terrain in the vicinity of KCDC. A frontal boundary will begin to push through northern Utah after 18z, with a secondary push of gusty northwesterlies late in the evening. VFR conditions will prevail with mostly clear skies.

FIRE WEATHER, Issued 241 AM MDT Sun Sep 13 2026

Drier conditions will persist over much of the area over the next few days, though monsoon moisture will continue to linger over southeast Utah, bringing isolated showers and thunderstorms each afternoon, with gusty outflow winds and brief heavy rain the primary threats. Southerly winds will continue to strengthen tomorrow ahead of an approaching cold front, with a decent chance of gusts to 40 mph for western Utah. The mostly dry front will pass through the northwestern half of the state late Sunday into Monday, bringing much cooler temperatures and further drying. The moisture will continue to persist over southeast Utah ahead of the front, however. Northern Utah temperatures are expected to rebound Tuesday, with maxes then expected to average around 5F below seasonal normals for much of the upcoming week.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.