Monsoonal Moisture Continues

A bit grey outside this morning as stratocumulus clouds blanket much of the Salt Lake Valley. I will never complain to get some extra cloud cover during the summer months even if for part of the day. Stepping out the door, the air also feel moderately sticky by Utah standards. Both of these observations together allude to a change from the dry and hot pattern that we have been seeing . 

KSLC temperature, dew pt. and RH, timeseries 7/12-7/16/2026

Surface conditions have been gradually shifting over the past 3-4 days, with daytime temperatures cooling slightly and surface moisture increasing. As shown in the timeseries above from KSLC, the dew point has gradually inched up about 15-20 F over the past four days (black line) and now is in the low to mid 50s this morning. Dew point temperature is typically a good indicator for moisture availability during the monsoon season. 

GOES-18 West True Color imagery 7/16/2026

Taking a view from far above, GOES West satellite visible imagery reveals the clockwise swirl of clouds (and smoke) associated with the dome of upper level high pressure centered over the Intermountain West. The orientation of this upper level high has been facilitating moisture transport from the Gulf of California northward into Desert Southwest and interior western states. This is one factor contributing to the kickoff of the Southwest monsoon season. The other factor is surface thermal low that has developed across the Mojave Desert region.

WPC 12Z 7/16/2026 surface analysis (left) and SPC 500 mb height, winds, and temperature analysis 15Z 7/16/2026 (right). Surface low pressure and upper level high noted with rough moisture transport vectors.

We can discern to what degree the monsoon is facilitating moisture transport by taking a look at Precipitable water (PWAT) across the region. PWAT measures the amount of water if all water vapor in the column of air above a location was condensed out as precipitation. PWAT is a good indicator to deduce moisture transport associated with the Southwest monsoon, and over the course of the past week values have increased to near or above 1-1.5" for many locations across Utah. For reference, PWAT values above 0.75" are usually considered elevated for the Southwestern U.S. The abnormally high PWAT values are associated with the increased moisture transport from the Gulf of California northward into AZ, NV, and UT as seen in the figure below.

SPC PWAT 18Z analysis with rough moisture transport axis

PWAT values of 1-2" ( > 200% above normal) are forecasted the next five days and reveal continued  moisture transport into Utah from the monsoon. This will translate into shower/storm development across the state every afternoon, with most activity dying off at night. Storms will primarily initiate over the higher terrain of the state before drifting off the terrain depending on the mean steering flow (average winds between about 700-500 mb).  

ECMWF 12Z 7/16/2026 PWAT (in) (top) and PWAT % of Normal (%) (bottom)

Since Utah is currently stuck right under the upper level ridge, the steering flow is rather weak (5-10 kts or less), so storms will be moving slowly and likely develop along areas of lift associated with outflow boundaries. This setup has meant that the northern Utah valleys have not gotten much, if any, shower or storm activity. While PWATs are primed for precipitation development and there is modest instability (elevated CAPE), the lack of forcing mechanisms and weak steering flow has inhibited locations like SLC from seeing showers or storms thus far. A bit more energy is forecasted to move through the state late this workweek into next week, which may allow a greater potential for lift and ultimately shower and storm development over the northern valleys. However, the best chance for precipitation is in the higher terrain or central/southern Utah, where a flash flood risk will continue for the foreseeable future. 

ECMWF Ens 12Z 7/16/2026 7-day precipitation anomaly (in) (7/16-7/23/2026)

The ECMWF ensemble keeps above normal precipitation anomalies across the entire state of Utah for the next 7-days. Beyond 7-days, ensemble and deterministic models alike keep the waves of monsoonal moisture continuing to move through Utah through the end of July. That part is heavily TBD and uncertain, but it definitely seems to be the trend. We could have a good 2-week period of monsoonal precipitation across Utah...