Discussion
Moisture remains in place over much of the forecast area today, allowing for another day of scattered showers and thunderstorms across central and southern Utah with more isolated coverage across northern Utah. As of 150PM, shower and thunderstorm activity is already well underway for central central Utah, as well as a portion of northern Utah. This activity is expected to continue through the remainder of the heating hours across the region. That said, it will be difficult for storms to sustain themselves as they drift off terrain features due to a lack of upper level support.
An area of drier air is expected to work its way into the forecast area tomorrow which will act to decrease the overall potential for convection during the heating hours. As such, coverage of showers and thunderstorms are expected to be much more isolated on Tuesday afternoon, particularly limited to the high terrain in northeastern and a portion of central Utah. Due to decreasing precipitable water values and lack of lower level moisture, the overall threat for heavy rainfall and flash flooding will be quite low, but not impossible, tomorrow afternoon. Moisture is anticipated to surge northward once again on Wednesday, bringing one more round of scattered showers and thunderstorms capable of producing heavy rainfall and flash flooding across the eastern half of Utah.
From Thursday forward, the area of high pressure (the center of which is currently just east of the Four Corners region) will shift south and west while an offshore trough remains parked over the PacNW region, helping to introduce a drier air mass into the region. As such, any chance for showers and thunderstorms will be greatly reduced as we finally rid the forecast area of monsoonal moisture. Contrarily, we'll begin to see some of the driest conditions since the monsoonal moisture arrived over the area in mid-July as afternoon humidity falls back into the single-digits for many low lying areas. Pairing with the very dry conditions, afternoon high temperatures are expected to rise back into the low- to mid-100s on the Wasatch Front, with lower Washington county potentially rising into the low-110s. Overnight low temperatures are also expected to remain elevated during this time which will limit the amount of relief from the daytime heat. Risk for heat related illness is likely to increase again through this period (Thursday through Sunday).