Published today the 19th this is a must read for the event to come:
Here is a good forecast from MDA Weather Services in association with the upcoming wind event in California:
Day after day this week meteorological models have been painting the same picture for California and the Southwest for much of next week… There will be unprecedented record heat for late October. This is very bad news for those weary of fighting fires and dealing with stifling conditions this year. I’m pointing my fingers and blame on climate change for the upcoming event, which will start by Sunday.
Let’s break down the reasons for upcoming dangerous conditions and why they could be historical in nature. First a rarely strong if not record setting heat dome will build over the Southwest in the wake of a front, which will actually bring some relief to California this weekend:
I got this chart from Rob Ellington indicating that this forecast 594+ decameter ridge would happen about once every 10 years across the Southwest this time of the year. There is one reason why such a strong ridge will build over the area looking at water temperatures off the coast, which is a climate change signal:
This chart from NWS San Diego indicates that there are well above average sea surface temperatures off the coast, which will only aid, thermodynamically, in building of the heat dome.
Here is the latest Pivotal Weather GFS model valid for Monday the 23rd:
I certainly can’t recall seeing 500 mb heights this high in the month of October anywhere across the CONUS. The sad fact is that the building heat dome will be located over the worst possible area… burnt out California.
On top of the heat there will, at least initially next week, be a strong offshore flow in Southern California known as the dreaded Santa Ana wind. This happens when high pressure builds over the Great Basin area sometimes producing near hurricane force winds in canyons and passes of the Southern California area. In the fall this usually happens in the wake of a front, such as the one that will be moving through the West this weekend. Residents of Southern California are well aware of the phenomenon. Here is the GFS forecast pressure pattern over the area for Monday morning:
Note the pressure trough offshore of California with higher pressure over Nevada and Utah. This is a Santa Ana signature. Just how strong will this wildfire exacerbating wind be? At least above 40 mph in the canyons and passes east of the Los Angeles Basin, but I’ll be refining this forecast as we get close to the event on my fall heat diary posts.
Rob McGregor, a young up and coming meteorologist living in the area to be affected, thinks that daily maximum temperature records could be broken by 6-8 degrees on Monday the 23rd. I can’t disagree. Here is what we are initially seeing off the models about 132 hours out:
Notice that 90’s extend to the coast, even at San Diego, an indication of a very hot event to come. The combination of heat and wind may prove brutal spreading fires rapidly as was the case in northern California earlier this month. Even that area of the state may not be off the hook for more damaging fires given the offshore flow and extent of the heat dome.
Specifically, and for example, here is the temperature forecast for Long Beach CA:
Already by Sunday maxes are forecast to be near record levels at Long Beach. A 99F reading on Monday would tie the record for the 23rd.
Here are some conditions expected in Southern California for Tuesday the 24th:
An update: Here are some specific toasty forecasts for Southern California:
I’ll be adding more to this post as information crosses my radar the next few days.
The Climate Guy