The National Weather Service in Las Vegas has forecasted a mix of monsoonal moisture and thunderstorms for the region which will persist through the weekend before drier conditions and cooler temperatures return next week. According to the area forecast discussion, monsoonal moisture is expected to linger today and begin receding eastward, with storm chances shifting further east each day through Saturday.
As the high pressure system over the Southwest interacts with Hurricane Lorena's inflow, humidity in Arizona, California, and Nevada remains high. Thunderstorms, driven by this moist environment and supported by orographic lift, are likely across the high terrain this afternoon. The National Weather Service warns that with PWATs between 1 and 1.5 inches and saturated forecast soundings, flash flooding will once again be a primary hazard. Drier air is expected to take hold by Sunday as the trough off the Pacific Coast moves east across the western United States.
For the aviation sector, erratic gusty winds, lightning, and the potential for brief MVFR/IFR conditions in heavy rain are the primary concerns through the period. The forecast for Harry Reid airport includes the possibility of thunderstorms developing nearby, with a 15-25% chance of them directly impacting the terminal. After sunset, additional showers and storms could travel southward out of the Great Basin, possibly resulting in a northeasterly wind shift at the terminal.
Beyond Las Vegas, showers and thunderstorms are expected to develop this afternoon across southern Nevada and portions of southeastern California and northwestern Arizona. These conditions are also set to persist into the early evening with erratic gusty winds, lightning, and brief MVFR/IFR conditions in heavy rain, as stated by the forecast. Post 06Z, there is moderate confidence in storms bringing gusty northerly to northeasterly winds across southern Nevada and northwestern Arizona. Flight conditions outside of these weather events will predominantly remain at 10KT or less and variable, with VFR conditions prevailing. Local spotters have been advised by the National Weather Service to report any significant weather or impacts following standard procedures.
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