Oddly Early Winter Storm Snarls California, And Additional Rough, Wet Weather Hits Other Parts Of U.S. Southwest

Workers try to clear storm drains in San Francisco
Monday as cars splash through the deep puddles.
An oddly early, strong storm is hitting
Californian. Photo from the San Fransisco 
Chronicle, via Facebook.

 California is being hit today by the kind of storm they usually have to wait until January or February to see. 

The storm features locally heavy rains, the threat of debris flows and mudslides, heavy snow in the mountains and even a low but still real chance of a brief tornado in the Los Angeles basin. 

This type of storm hits California fairly regularly in the dead of winter, but they almost never happen this early in the season. 

The biggest threat from this storm is for people who live near and below the sites of those giant, deadly wildfires that hit the L.A. area last January. 

The City of Los Angeles issued evacuation warnings for homes near the fire burn areas in Pacific Palisades and Malibu, KTLA tells us. 

People who live near the site of a big January fire in and around Altadena were also told to be on the alert to possible evacuations. Same was true near other burn scars in Orange County. 

Valleys in southern California can expect an inch of rain, give or take, which is wildly big for October. The mountains and foothills can expect two to four inches. 

Normal rainfall for the entire month of October in Los Angeles is about a half inch. 

The biggest problem is that the rain in southern California should come in a relatively brief time, with most of it falling within four to six hours. Such downpours can really move rocks and dirt in areas where vegetation was destroyed by wildfires. 

As of 5:30 a.m local time, a gusty thunderstorm with downpours and gusts to 55 mph was blustering through the Los Angeles basin. Very odd for what is normally a dry time of year. 

Further north, the first snows of the season have started falling in the notoriously snowy Sierra Nevada mountains. 

By midwinter standards, this storm isn't huge. But for October, it's impressive. Snow levels were forecast to fall to 5,000 feet above sea level today. Interstate 80 through Donner Pass should have slushy snow and traffic delays along it today. Higher up, some ski resorts, though not open yet, can expect maybe a foot of snow. So I imagine some renegade skiers and riders will be up there doing their thing.

In the San Francisco Bay Area, torrential rains flooded roads and drowned cars in many areas. Several days, mostly Ubers and Lyfts leaving the airport, got trapped in flash flooding Monday night, ABC7 News in San Francisco reported. 

San Francisco on average receives 0.79 inches of rain during the entire month of October. More than that fell in just one day Monday, as the city received 0.87 inches, at least as measured at the airport. 

The oddly early preview of the California rainy season might or might not be good news for the fall and early winter wildfire season.

Strong, dry Santa Ana winds propel the ferocious wildfires in southern California. The worst of them hit from about now through mid December. (Last year, the lack of rain and the Santa Anas kept going well into January, hence the deadly mega fires in the L.A area).

Initially, everything will be damp, so the wildfire risk will be low. But the rain will inspire new plant growth - grass, weeds, that kind of thing. 

By this time of year, northern California is close enough to the normal storm track so that wildfire season is probably over up there. 

But in southern California, that new growth could dry out and become tinder for fires later this fall and early winter.  Southern California is not out of the woods for wildfires just yet. 

That's true even though the weird October rains in California might not be over. Another storm, smaller and weaker than the one they're getting now, could come through next Monday with a little more rain. After that, it seems California will revert back to its normal dry, sunny late October weather.

SOUTHWEST STORMS 

An intense microburst caused a lot of damage in
Tempe, Arizona Monday. It was part of a stormy
pattern in the normally dry southwest U.s. 

It's been a strangely stormy autumn in the Southwest this year, thanks in part to the remnants of Hurricane Priscilla, which originated off the west coast of Mexico. The storm remnants became Priscilla, the (very wet) queen of the desert.   

In Tempe, Arizona, an intense thunderstorm microburst Monday packing winds of at least 70 mph tore roofs off apartment buildings, mobile homes and businesses, displacing at least 130 people. Parts of warehouses collapsed, semi-trucks overturned, and power lines collapsed in the storm. Luckily, there were no serious injuries. 

Another microburst Sunday in Tucson, Arizona damaged several properties, blew over trees and saguaro cactus and caused flooding. The city received 1.2 inches of rain, the biggest storm in almost a year. 

On Sunday, flash floods damaged several homes in Mesa, Arizona and closed roads. 

The bad weather extended into New Mexico and Colorado, causing damaging flash floods in both states. 

In normally arid southwest Colorado, flash floods wrecked about 100 homes, prompted nearly a dozen high water rescues and blocked roads. As much as five inches of rain fell in that part of Colorado. Flooding also hit around Salt Lake City, Utah.   

Perfect Vermont Summer Weather Ends, Looong Stretch Of Downpours, Humidity Coming

Deep blue skies Thursday over St. Albans, Vermont on a
perfect summer day.  We won't be seeing anything like
this again for quite awhile. 

 If there were a DoorDash type of business in which you could order in the kind of weather you want, and I ordered a perfect summer day, you'd end up with Thursday. 

Thursday was a strong candidate for the best Vermont weather day or Summer '23. 

 It was warm enough to enjoy a dip in the lake, but the humidity was so low that you'd feel cool and refreshed after your dip. 

It was also mild and dry enough so that a hike up, say Camels Hump would be perfect. I imagine some of last week's mud would have dried up by now. 

There was enough of a slight breeze to power a sailboat, but not nearly enough wind to make Lake Champlain choppy y or dangerous. 

The sky was a brilliant blue, with just a hint of haze to remind you it's summer. High pressure blocked clouds from coming up from the south, and also blocked Canadian wildfire smoke from smothering out the azure sky. 

I hope you liked Thursday. You're not going to see anything like that for quite awhile. Expect a long stretch of humidity, clouds and rain. Some of that rain could down pretty hard. 

Let's get into the details:

HUMIDITY

Savor the last bit of dry air this Friday morning, we're in for what might be a week of oppressive weather. As our nice dry, clear high pressure system departs, south winds will gradually bring the  humidity in today.  By this evening,  you'll feel it.   

There won't really be any hot weather with our upcoming stretch of Louisiana style humidity. We'll have too many clouds, showers and thunderstorms for anything heat wave-ish. But the humidity will be very noticeable, especially at night. 

A good way to judge how humid it is to to look at the dew point. The dew point is the temperature to which the air must be cooled to become fully saturated with water vapor. 

If the dew point is under 60 degrees, like it was over the last few days, it feels pretty comfortable out there. Between 60 and 65 it feels kind of sticky.  Anything over 65 is just plain yuck. 

It's looking like most of the time tonight through the middle of next week will have dew points at or above 65 degrees. 

Usually by this time of year, we've already had a few spells of at least sort of humid weather, to get us acclimated to wet air. Not this year. It's been mostly dry, dry air. Except when it rained. But until now, the rain came with cool temperatures. 

With the lack of humidity so far, this muggy spell will definitely feel like a wet slap in the face. Especially since it will last so long. We can handle one or two days. But I'm sure a week of this will get tiring. 

With all the expected clouds, daytime highs will be in the 75 to 82 degree range for the next several days. That's about where they should be this time of year. But overnight lows will stay in the 60s to low 70s for most of us. That's warm compared to normal. 

LOTS OF RAIN

The next aspect of this upcoming stalled weather pattern is rain.  Since our friendly high pressure system is a little reluctant to depart today, I don't think you'll see any rain drops in Vermont today.

But you definitely will see that rain, starting late tonight. 

Yesterday, forecasters were telling us to expect rain every day Saturday through Wednesday. This morning, they're hinting that rain might go beyond next Wednesday and extend all the way to next weekend. 

It won't rain all the time during this stretch. But there will be lots of showers and thunderstorms, especially in the afternoons and evenings. 

Last weekend's rains dented but did not destroy what had been a developing drought in Vermont.  The rain a week ago cut in half the size of the area in northern Vermont considered in drought. Now it's just 10 percent of the state, mostly in Lamoille and eastern Franklin counties. Two-thirds of the state is considered to still be on the dry side. 

If the current forecast pans out, we'll see a lot more damage to the dry conditions, which of course is great news. 

Over the next seven days, it looks like we'll generally see two to as much as four inches of rain in Vermont. That would put June's total rainfall above normal, which is a surprise given how dry we started out this month. 

FLOODING?

With all this rain, there's actually some risk of flooding. It won't be anything widespread, and we're definitely not going to get anything like 2011's Hurricane Irene disaster.

However, if some unlucky towns have thunderstorms plowing through day after day, then have a train of them come through one after another during an afternoon and evening during the upcoming week, you can get a nasty local flash flood. 

Something to watch out for, definitely.  You won't know if or where there will be flash flooding until it's happening, or shortly beforehand. Just stay aware of warnings if you're in a flood prone spot over the course of the next week

SEVERE WEATHER?

Though we expect lots of thunderstorms - and you should always respect lightning - at least at this point, it doesn't look like there will be any widespread severe thunderstorms.

However, the weather pattern does make us prone to wet microbursts. The term sound like it refers to a small water balloon popping, but that isn't it. 

A microburst starts when a strong updraft suspends a lot of rain and some hail up in the cloud.  Then the  updraft abruptly fades, so all that rain and hail rushes to the ground in one great big whoosh. When it hits the ground, the wind spreads out.  Places near where the down rush hits the ground get strong, damaging winds. 

It's called a microburst because the damage area is usually quite small, almost always less than 2.5 miles diameter and often much smaller than that. 

The types of thunderstorms we're expecting in the coming days have the potential to contain microbursts.  But since the areas suffering damage from this phenomenon is small, the vast majority of us will be just fine.

WHEN WILL IT DRY OUT?

The short answer is, we don't know.  Some forecasts push a cold front into Vermont by next Thursday, which would help.  But other forecasts have strong high pressure off the East Coast, which would prevent that cold front from reaching us, or at least slow it down. 

The only thing I can say for sure is get used to the humidity and showers. You're going to have to.