Jul 4, 2018

Searing but localized weekend heatwave across SoCal; heat slowly spreads north in coming days

Los Angeles, CA
USA
by
Daniel Swain
,
California Weather Blog
An unusual ridging configuration will keep this weekend’s extreme heat largely confined to SoCal. Credit: Tropicaltidbits
An unusual ridging configuration will keep this weekend’s extreme heat largely confined to SoCal. Credit: Tropicaltidbits

A lobe of the very strong upper-level ridge that has brought record heat to areas from Denver to Boston in recent days will retrograde slightly on Thursday and Friday. This regional enhancement of the ridge will lead to a pretty unusual atmospheric set-up across SoCal, with deep southeasterly flow aloft but easterly to even northerly winds closer to the surface.

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This will likely be a high-impact and memorable heat event, despite the fact that it will be largely localized to the SoCal coastal strip. NorCal will not be especially hot this weekend, and even the inland desert regions in SoCal will be hot, but not memorably so. But in Los Angeles and Santa Barbara counties, especially, the heat from Fri-Sun will be extreme due to the localized effects of the downsloping winds and associated compressional warming. Temperatures over 100 will be possible even close to the beach, and just 5-10 miles inland temperatures could approach 110.

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The National Weather Service expects widespread high temperature records to be set along the SoCal coastal plain this weekend, and an Excessive Heat Watch is in effect to account for this.