Palm Springs Windstorm (21 Jan 2012)

[HurricaneJosh]

I'm back in SoCal and my Palm Springs friends mentioned a rather extreme wind event (by this region's standards) that occurred on 21 January. On that day, rough winds raked Palm Springs metro (a.k.a. the Coachella Valley), uprooting trees, snapping power poles, propelling large debris (lawn furniture and garbage cans), damaging roofs, and causing accidents. A dude I've been dating on and off said the wind tore off almost all the shingles on the W side of his roof. Locals say it was the worst windstorm in this region in decades.

I'm trying to get a handle on how high the winds were. My friends and also the local newspaper articles mention "hurricane-force winds" and values of 80-90 mph. However, I checked the local METAR reports and wasn't able to find any official readings that high. The best I could find:

• Palm Springs International Airport (KPSP): 35 kt gusting to 57 kt
  
• Thermal (KTRM): 36 kt gusting to 52 kt
  

Are there any other METAR (or official) stations in that area that I should be checking? I'm just trying to find the origins of these reports of hurricane winds.

[QVectorman]

I'm back in SoCal and my Palm Springs friends mentioned a rather extreme wind event (by this region's standards) that occurred on 21 January. On that day, rough winds raked Palm Springs metro (a.k.a. the Coachella Valley), uprooting trees, snapping power poles, propelling large debris (lawn furniture and garbage cans), damaging roofs, and causing accidents. A dude I've been dating on and off said the wind tore off almost all the shingles on the W side of his roof. Locals say it was the worst windstorm in this region in decades.

I'm trying to get a handle on how high the winds were. My friends and also the local newspaper articles mention "hurricane-force winds" and values of 80-90 mph. However, I checked the local METAR reports and wasn't able to find any official readings that high. The best I could find:

• Palm Springs International Airport (KPSP): 35 kt gusting to 57 kt
  
• Thermal (KTRM): 36 kt gusting to 52 kt
  

Are there any other METAR (or official) stations in that area that I should be checking? I'm just trying to find the origins of these reports of hurricane winds.

I used to work in tv there and the media is notoriously uneducated about weather and always exaggerates events. Especially down sloping wind storms. The wind gust to 66 mph is pretty close to the highest they have had in years. In 2007 or '08 they had one which I think gusted to 64 mph. But they like to think every mountain wave event is their worst ever. If you want to see some wicked winds check out Whitewater's OBS those are where the gusts are usually the worst. But sometimes in MW events Whitewater misses out on the rotors and waves. It's positioned poorly in respect to the base of the mtns. so the wavelength never matches up. I had the last wind storm in 2007/8 saved from the station skycam. It was pretty sweet watching the waves explode as they hit the ground you could see burst of dust expanding out for about a mile from each impact. I had a whole page describing the event and what caused it along with observations but I can't find it. I'll keep looking.

[HurricaneJosh]

I used to work in tv there and the media is notoriously uneducated about weather and always exaggerates events. Especially down sloping wind storms. The wind gust to 66 mph is pretty close to the highest they have had in years. In 2007 or '08 they had one which I think gusted to 64 mph. But they like to think every mountain wave event is their worst ever. If you want to see some wicked winds check out Whitewater's OBS those are where the gusts are usually the worst. But sometimes in MW events Whitewater misses out on the rotors and waves. It's positioned poorly in respect to the base of the mtns. so the wavelength never matches up. I had the last wind storm in 2007/8 saved from the station skycam. It was pretty sweet watching the waves explode as they hit the ground you could see burst of dust expanding out for about a mile from each impact. I had a whole page describing the event and what caused it along with observations but I can't find it. I'll keep looking.

You worked in TV in the Desert Cities? Wow-- that must have been interesting. How awesome to have your perspective in this thread-- thank you.

Yeah, as a hardcore data nerd, I never, ever take media wind reports at face value-- I always treat them with skepticism and immediately start investigating when I hear reports that are really out of the ordinary. I'm just wondering where the media got those values (80 to 90 mph). Were they based on an unofficial reading somewhere-- or perhaps a random estimate from an official?

I will say, the damage was extensive enough that it seems within the realm of possibility that they had some Cat-1 hurricane gusts (i.e., 64-82 kt).

Since you worked in this market, what other official stations are there in the Desert Cities besides KPSP and KTRM?

[QVectorman]

Those are the only NWS stations around. The only other one I can can think of is Big Bear, oh and 29 Palms the rest are private companies. Sometimes those values from the media are sent in by residents from their home weather stations or else the NWS normally puts them out in their LSR's and grabbed data recorded at an off time from the ASOS. But they normally document that in the daily climate report and I see they recorded the 66 mph. Like I said the media there is HORRENDOUS at data control and fact checking when it comes to weather events I wouldn't put it past them to have made it up You don't know how many times I had to correct them when they tried to call hail...snow when it would cover the ground from t'storms in the spring. I'm like seriously, listen it didn't snow when it's 57 degrees. And they would still go on air and say it was snow "because the viewer that called said it was snow". They are there and you are not we have to believe them.

The last one that had the 64 mph gust knocked over a gas station awning and tore the roof off a hotel. So it doesn't take true hurricane force winds to do much damage around there. Some of the stuff is poorly constructed.

[HurricaneJosh]

Those are the only NWS stations around. The only other one I can can think of is Big Bear, oh and 29 Palms the rest are private companies. Sometimes those values from the media are sent in by residents from their home weather stations or else the NWS normally puts them out in their LSR's and grabbed data recorded at an off time from the ASOS. But they normally document that in the daily climate report and I see they recorded the 66 mph. Like I said the media there is HORRENDOUS at data control and fact checking when it comes to weather events I wouldn't put it past them to have made it up You don't know how many times I had to correct them when they tried to call hail...snow when it would cover the ground from t'storms in the spring. I'm like seriously, listen it didn't snow when it's 57 degrees. And they would still go on air and say it was snow "because the viewer that called said it was snow". They are there and you are not we have to believe them.

That's so sleazy-- to exaggerate that way! Grrrr.

So KPSP's gust to 57 kt is the highest official reading you could find from the 21 Jan 2012 event?

The last one that had the 64 mph gust knocked over a gas station awning and tore the roof off a hotel. So it doesn't take true hurricane force winds to do much damage around there. Some of the stuff is poorly constructed.

Ah,that makes sense-- that SoCal buildings just aren't constructed to withstand wind. I'll bet this same even in Florida or Texas would have been no big deal.

[HurricaneJosh]

P.S. I see Twentynine Palms (KNXP) had 40 kt gusting to 55 kt, which fits nicely with the Palm Springs and Thermal readings.

[QVectorman]

Yup, 57 is the highest. KPSP is the usually the best spot to catch the highest wind gust. I think maybe the Cathedral City site might catch one every now and then. Like I said it's all relative to their distance from the foot of the San Jacinto mtns. The typical wave length of the waves favors the trough of the waves to be positioned near KPSP. All depends on the orientation of the 700 mb winds though. Some events KTRM can knock out a higher gust. You should look for satellite images from that day. I'm sure you will be able to see the mountain wave clouds on satellite propagating down wind...can probably see 29 Palms in a trough (no clouds).

[bluewave]

I'm back in SoCal and my Palm Springs friends mentioned a rather extreme wind event (by this region's standards) that occurred on 21 January. On that day, rough winds raked Palm Springs metro (a.k.a. the Coachella Valley), uprooting trees, snapping power poles, propelling large debris (lawn furniture and garbage cans), damaging roofs, and causing accidents. A dude I've been dating on and off said the wind tore off almost all the shingles on the W side of his roof. Locals say it was the worst windstorm in this region in decades.

I'm trying to get a handle on how high the winds were. My friends and also the local newspaper articles mention "hurricane-force winds" and values of 80-90 mph. However, I checked the local METAR reports and wasn't able to find any official readings that high. The best I could find:

• Palm Springs International Airport (KPSP): 35 kt gusting to 57 kt
  
• Thermal (KTRM): 36 kt gusting to 52 kt
  

Are there any other METAR (or official) stations in that area that I should be checking? I'm just trying to find the origins of these reports of hurricane winds.

Yeah, those 80-90+ gusts were reported at the higher elevation mountain stations.

That would have been my kind of day to take a trip up there though.

http://palmdesert.pa...-damage-minimal

http://raws.wrh.noaa...r1=2012&hour1=0

[QVectorman]

That's burns canyon. It's on the windward or west face of the mountain range not palm springs area. Media may have pulled the numbers from there if it was issued on the san Diego lsr. But its always really strong winds at burns and it is never related to mountain waves that palm springs experiences. Burns gets really going during off shore wind events and easily tops over 100+ during those. But the tram observation is definitely what the media used. They do that a lot and twist the story to make it sound like those were the winds on the valley floor just for shock value and hype

[HurricaneJosh]

Yeah, those 80-90+ gusts were reported at the higher elevation mountain stations.

That would have been my kind of day to take a trip up there though.

http://palmdesert.pa...-damage-minimal

http://raws.wrh.noaa...r1=2012&hour1=0

Wow-- thanks for finding this, Chris! I appreciate it. I think this solves the mystery Re: where the media were getting the values they used. (Whether or not it was reasonable of them to use these values in the story is another matter...)

That's burns canyon. It's on the windward or west face of the mountain range not palm springs area. Media may have pulled the numbers from there if it was issued on the san Diego lsr. But its always really strong winds at burns and it is never related to mountain waves that palm springs experiences. Burns gets really going during off shore wind events and easily tops over 100+ during those. But the tram observation is definitely what the media used. They did that plenty of times and twisted the story to make it sound like those were the winds on the valley floor

I plotted the location (34.2083N 116.6217W) and it only seems to be ~20 mi or so NNW of Palm Springs. But I guess the elevation (6,284 ft) does kind of make the readings a moot point when assessing the event's impact on the Desert Cities.

[QVectorman]

Wow-- thanks for finding this, Chris! I appreciate it. I think this solves the mystery Re: where the media were getting the values they used. (Whether or not it was reasonable of them to use these values in the story is another matter...)

I plotted the location (34.2083N 116.6217W) and it only seems to be ~20 mi or so NNW of Palm Springs. But I guess the elevation (6,284 ft) does kind of make the readings a moot point when assessing the event's impact on the Desert Cities.

Well the only way the valley can see those strong of winds is from mountain waves. Plus the range isn't that wide so 20 miles puts it on the west side of the mountains. Mount san jacinto has one of the highest reliefs in north America so you get into high terrain quick. You can get up to 6k feet in ten minutes of driving from the valley floor. The tram is at like 8k feet.

[bluewave]

Wow-- thanks for finding this, Chris! I appreciate it. I think this solves the mystery Re: where the media were getting the values they used. (Whether or not it was reasonable of them to use these values in the story is another matter...)

No problem, Josh. I believe that those were the strongest winds in Palm Springs since 2009 so it was a memorable

wind storm for the people living there.

[QVectorman]

First, sorry, I confused Burns Canyon with Freemont Canyon near Laguna Beach. Burns is on the east side of the San Bernardino Mtns. and it also records strong gusts when PS does. The event I was referring to had a gust to 96 mph at Burns. Anyways, here is the article I wrote on it. Palm Springs recorded a gust to 55 mph and it was the strongest in 9 years back then...the highest gust recorded there before that was 58 mph in '99. So 66 mph is wicked. I was around there in 2009 so I'm not sure what the wind gusts were for that event.

http://www.kesq.com/weather/22432750/detail.html

Sunday February 3, brought with it a rare wind event to the Coachella Valley, creating a ton of damage including a roof being blown off a Travel Lodge hotel in Palm Springs. What the west end of the Coachella Valley, Twentynine Palms, and higher elevations experienced was is commonly referred to by meteorologists as a "Mountain Wave". For the public a "Down Slope Wind Event". Most pilots are aware of these because they are a very real risk to aircraft and create conditions that cause aircrafts to lose lift and crash.

The First Alert Weather team was the only weather team in the Valley to warn the area Saturday evening February 2, that conditions were prime for a major Down Slope Wind Event to occur on Sunday.

Saturday, February 2,"Pinpoint Microcast Winds" eluding to

extremely strong sustained winds on Sunday

The high resolution forecast model "Pinpoint Microcast Winds" on Friday eluded to the fact that such an event was possible Sunday. The reason "Pinpoint Microcast" was able to forecast this event so well is because the Pinpoint Microcast forecast model is exclusive to KESQ and housed right in the television station in Palm Desert, so we are able to personally adjust variables to continually increase its accuracy. No one else in the Valley, let alone Southern California has a forecast model with the capability to warn of Down Slope Wind Events, only KESQ with "Pinpoint Microcast Winds".

Meteorologist Peter Cannella continued to review atmospheric data Saturday afternoon and confirmed conditions were quite favorable for a Down Slope Wind Event. He went on-air Saturday evening showing the "Pinpoint Microcast Wind" forecast and warning everyone that winds and damage could exceed that of the January 28 wind event with wind gusts of 50 mph possible locally in Palm Springs and gusts to 65 mph in higher elevations on Sunday.

Down Slope Wind Events are not like the normal windy conditions. They can generate a lot stronger wind gusts than a typical wind event and result in a lot more damage. The real difference though is in how the stong wind gusts are actually created, resulting in the Down Slope Wind actually being able to produce stronger gusts than the typical wind.

Your typical strong wind is created by a pressure difference, a high pressure system and low pressure system being to close to one another. In a minute we will explain how the Down Slope Wind Event forms.

Down Slope Wind Events occur a couple times a year here in Southern California. They are more common on the leeward (east side in the Northern Hemisphere) side of the Rockies where winds have been recorded to gust to near 120 mph before. What makes the February 3 event stand out is its strength. The difference in the atmosphere Sunday was that there were a lot stronger winds in the middle part of the atmosphere at about 8,000 feet and they approached the mountains at the most favorable angle for the strongest wind gusts to occur, the perfect combination. Figure 2.

Figure 1: Coachella Valley wind gusts Sunday, February 3

Wind gusts in Palm Springs gusted up to 55 mph at approximately 4 p.m.. The last time we recorded wind gusts that strong was back in June of 1999 with a gust to 58 mph. In Burns Canyon winds gusted to 96 mph which is a rare event there, but not as rare as the 55 mph wind gusts in Palm Springs. Sustained winds of over 45 mph were common in Twentynine Palms. In the west end of the Valley winds remained steady between 30-35 mph from 3 and 5 p.m., toppling trees, power poles, ripping shingles off roofs, and destroying fences.

How this "Down Slope Wind Event" developed

There is one distinct aspect of the atmosphere Sunday that had to be present for this event to evolve. That was the presence of a "stable" layer of air at approximately 15,000-20,000 feet above the ground. We will use several analogies to simplify this, the "stable" layer acts as a brick wall. It is simply a layer of air that is not buoyant (doesn't rise).

Figure 2: Birth of a Mountain Wave-strong winds from the come in from the Pacific

As strong winds of 40 mph at 8,000 ft. (blue arrows) come in off the Pacific Ocean perpendicular (90 degree angle) to the San Jacinto Mountains they hit the mountains as Figure 2 shows. This air acts like a rubber ball and bounces off the west face of the mountain and up into the higher parts of the atmosphere.

On its journey up it ran into the "stable" air (brick wall) at approximately 15,000 to 20,000 feet and is bounced back to the Earth below. At 15,000 to 20,000 feet winds were blowing at approximately 90 mph, that bouncing ball of air will get sped up if you will while at that altitude and then bring its new acquired speed down to the Earth below. Now it won't totally inherit all of the 90 mph wind speed. A rough estimate would be to average the starting speed of the air, 40 mph, with the 90 mph wind speed in the "stable" layer, and you come up with a gust possible of 65 mph. Which is approximately what was recorded in Pinyon. Burns Canyon's speeds are amplified by the constricting space of the Canyon so we don't want to use that as a example of max wind gusts.

Then as the air or "rubber ball" as we call it, crashes into the ground it creates strong wind gusts at random times and locations west of the base of the mountains as Figure 3 shows in the areas in red. This isn't the end of the story for this rubber ball though. It's acting like a rubber ball after all!!! We all know that rubber balls can't bounce just once. After hitting the ground the air bounces off the ground and heads back towards our "stable" air or brick wall.

Figure 3: A trapped pocket of air (blue arrows) bounces east creating clouds and damage (this is not actual locations of damage, just an illustration)

It again is on a crash course with the "stable" layer of air. It hits it again!! Figure 3 shows this, as the air (blue arrows) rises, like all pockets of rising air that have enough moisture in them, the rising air creates a cloud. Like before though it bounces back towards the Earth and this air is sinking, so cloud do not form.

What is taking place is that our air is maintaining its momentum and has become trapped between the ground and the "stable" layer (brick wall). As a bouncing ball does, this air bounces up and down between the ground and the "stable" layer. It's what we call a trapped wave. Figure 3 shows this pocket of air or "bouncing ball" bouncing eastward from the base of the San Jacinto Mountains. The strongest wind gusts will always occur with in the first or second crash with the ground. In Figure 4 you can see the cloud that formed at the "highest" point of the trapped air's "bounce". This image is looking northwest towards the Banning Pass. The cloud extended south down in to Mexico as the satellite image in Figure 5 shows.

Figure 4: First Alert Sky Cam Sunday, February 3, 12:45 p.m.

These pockets of air can be trapped and travel for several thousand miles from the bases of mountains before they run out of energy like the rubber ball and basically disappear. Creating nice uniform rows of clouds (rising air-"ball bouncing up")and empty gaps (descending air-"falling ball") traveling east, like waves on the ocean. How far these rows of clouds can travel away from the base of the mountain is partly dependant on the speed of the winds hitting the west side (Northern Hemisphere) or windward side of the mountain.

Sunday's event was a text book example with the wave or "row of clouds" traveling several hundred miles away into central Arizona. As you can see in Figure 5 a visible satellite image from the early afternoon on Sunday February 3, rows of clouds spread east from the base of the San Jacinto Mountains across Riverside and Imperial counties and into Arizona. Yellow arrows have been placed to show the equal distances between the rows of clouds. The cloud rows wiggle from north to south and are not in a straight line because they form with the contours of the mountains.

Figure 5: Visible Satellite image from February 3 at 12:45 p.m.

This is not coincidence!!

The equal space between the rows of clouds are not by accident. The atmosphere can be explained by complexed calculus and physics and there is actually a formula to predict the distances between the clouds-the crest (top) of a wave. It is a trigonometric function like Sine or Cosine and the distances between the crests of the wave (where the clouds form) are dependant on the initial speed of the winds coming off the ocean.

Why is it not this strong every time?

Earlier we said that the wind hit the San Jacinto Mountains at a 90 degree angle along with our "stable" layer being in place. Those are the two major ingredients that do not come together to often around here.

Most of the time the winds don't hit the mountains at the correct angle-90 degrees, or a "stable" layer isn't in place, or the winds at 15,000-20,000 feet are not as strong, or the winds at 8,000 feet are not as strong. On February 3, all of those ingredients were in place to create the strongest wind gusts we have experienced in nine years here in the West Valley. This is a once in10-20 year event, making it extremely rare!!!

Other mountain waves or down slope wind events that occur in the Coachella Valley several times a year usually do not have as strong of winds at 15,000-20,000 feet and they don't hit the San Jacinto Mountains directly perpendicular to the mountain face. Both of those factors greatly reduce the resulting wind gusts.

Figure 6: Wind at 8,000 feet hit the mountains at a 90 degree angle (dotted line indicated the orientation of the mountain ridge)

The wind hitting the mountain square at a 90 degree angle is like a car (wind) running directly into a wall (mountain), it comes to a stop and then bounces backwards, but the car wanted to continue traveling forward but the wall got in the way. Figure 6 shows the air does almost the same, but it can't not go backwards so its forced up and over the mountain with most of its momentum (wind speed) in tack (while gaining extra speed from the "stable layer" winds)still traveling forward.

Figure 7: Wind at 8,000 feet hit the mountains at a 45 degree angle (dotted line indicated the orientation of the mountain ridge)

Where as if the wind hits at a smaller angle, say 45 degrees, or from the northwest, the wind speed (momentum) is distributed to the north and south along the west face of the mountain, so the winds that actually make it up and over the mountain moving southeast are not as strong. Figure 7 helps visualize this effect, with winds on the west side of the mountains moving at slower speeds. Making the car analogy, the car (wind) having a glancing blow to a wall (mountain), will continue in the general direction it was traveling but at a slightly different angle and it keeps going.....in wind terms, the wind gets stuck on the west side of the San Jacinto Mountains.