Ken Clark

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California Heat Wave Coming

September 27, 2012; 12:19 PM ET

Much of the talk this week has been about Miriam and its possible impacts on the weather in California. I have been a proponent of wait and see and not go overboard with too much talk of rainfall. There certainly was a chance, but there were also a lot of ways it would not rain. The writing is now on the wall. Miriam is devoid of convection anywhere near the low-level center which will continue to spin down. Much of the rich moisture is gone off to the east and northeast. Some high-level moisture in the form of clouds can move north through parts of southern and maybe central California the next two days, but no rain is expected.

The big story now is going to be a heat wave building for the weekend with excessive heat likely Sunday and Monday and lingering Tuesday in some areas. An upper-level low will develop off the coast of southern California later tomorrow then sit out there through the weekend and perhaps drifts a little more west and north into early next week. At the same time, an upper-level ridge builds north and east of the low promoting offshore pressure gradients and even midlevel offshore winds. Then the 500 mb high parks itself over southern California Monday and Tuesday. Both the European and GFS are very similar, frightening so, right through the middle of next week. Here is the charts for Sunday and Monday showing the overall pattern.



This pattern will allow the heat to build Saturday through Monday with Tuesday being as hot as Monday in all but perhaps the central and northern coastal areas of California.

In Southern California:

High temperatures will rise to well into the 80s to near 90 for Saturday for metro coastal cities and will be well into the 90s for the valleys. Sunday will be even hotter with highs 90s for most of the coastal cities and 100 or a little better in many of the valleys. Monday and Tuesday, expect middle to upper 90s for much of the coastal plain and 100 to 107 in the valleys. Some record temperatures may be set, and it is possible that coastal cities could be even a little hotter than I have.

Central Valley:

Highs on Saturday are going to be generally in middle 90s then upper 90s to low 100s Sunday through Tuesday which will challenge record highs.

Central Coast and Bay Area:

Coastal areas warm to the 70s by Sunday with mid-80s to mid-90s for coastal plain cities to the East and North Bay regions. Coastal valleys are likely to heat into the low 100s by Sunday. Similar temperatures are likely on Monday if not a couple hotter then it drops some on Tuesday especially along the immediate coast.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or


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Ken Clark
Ken Clark's Western U.S. weather blog tackles daily weather events with commentary from one of the most experienced and trusted Western U.S. weather experts.