THEMARICOPAMOD.COM / WEATHER & ENVIRONMENT

Extreme heat and monsoon storms theaten tumultuous weather across Maricopa County

Starting Tuesday, a slight relief from the heat is anticipated.

PUBLISHED AUG 4, 2024

An Excessive Heat Warning remains in effect through Monday across much of the region.

Phoenix, Arizona: Phoenix and surrounding areas in Maricopa County are bracing for continued extreme heat over the next few days, with temperatures predicted to hover near record highs. Forecasts indicate that temperatures in the lower deserts will range between 110-116F through Monday. An Excessive Heat Warning remains in effect through Monday across much of the region.

Starting Tuesday, a slight relief from the heat is anticipated, not due to a weakening of the high-pressure ridge, but because of an influx of moisture. This moisture is expected to increase storm activity significantly, providing some respite from the scorching temperatures.

An Excessive Heat Warning is in effect today through Monday for southeastern CA and the lower desert & foothill communities of southcentral AZ and southwest AZ. Expect high temperatures to top out in the 105°-116° range. Make sure to limit time outdoors this weekend and drink plenty of water.

The subtropical high will continue to position itself favorably over the Four Corners area, ensuring daily chances of monsoon storms, particularly over Arizona's higher terrains. While moisture levels are currently sufficient for daily convection in these areas, the lower deserts face challenges with convective inhibition (CIN). Afternoon storms are anticipated over the mountains, with potential outflows reaching the south-central Arizona lower deserts.

From Monday, the monsoon pattern is set to shift due to an inverted trough moving from Oklahoma across west Texas into northern Mexico. This will enhance moisture levels in the area, increasing the chances of higher terrain convection extending into the south-central Arizona lower deserts. By Monday night into Tuesday, forecasted precipitable water (PWAT) levels are expected to rise to around 1.6 inches from Phoenix to Yuma, boosting convective available potential energy (MUCAPE) and setting the stage for potentially severe thunderstorms by Tuesday afternoon and evening.

The inverted trough is expected to persist through at least Wednesday, bringing chances of showers and thunderstorms across the lower deserts of Arizona, possibly extending to southeast California. While Tuesday is predicted to be particularly stormy, the best convection may shift to southwest Arizona on Wednesday. The forecast beyond Wednesday remains uncertain, dependent on the trough's duration and moisture retention.

As the week progresses, temperatures are likely to climb again, although they are expected to stay within the Moderate HeatRisk category, providing a slight relief from the extreme conditions experienced earlier in the week.