A new tropical storm is likely developing in the southeast Pacific not too far off the Mexican coastline. The National Hurricane Center will almost certainly begin advisories on the system later today (right now it is designated at invest area 97-E). The development of this soon-to-be-storm is important for a couple of reasons.
First and foremost, it will have a direct impact on the weather across portions of Pacific Mexico over the next few days. Heavy rain with the usual threat of mudslides and flash flooding will an issue due to the fairly close proximity to the coast.
Model plots for 97-E in the southeast Pacific
Computer models indicate that a track to the west with a gradual bend back to the northwest and eventually northeast is probable over the coming days. This means that there is the threat of a hurricane making landfall in Mexico as the system is forecast to intensify significantly over the very warm waters of the southeast Pacific. Interests along the coast of Mexico should pay close attention to this developing storm. It would not surprise me at all to see a hurricane watch posted for a portion of the Mexican coastline by sometime tomorrow.
The other interesting aspect of this system is where it developed. Right now it is situated just south of the Gulf of Tehuantepec which is itself not far from the Bay of Campeche in the extreme southern Gulf of Mexico. If you remember your geography, the strip of land that separates the two bodies of water is called an isthmus. The developing storm is on the Pacific side of the isthmus and likely precluded any development from taking place in the southern Gulf of Mexico. It is rare to have two tropical cyclones going at the same time so close together – and as such, the Pacific disturbance took over and is now on its way to becoming yet another hurricane for the region.
However, something very interesting may happen down the road. Tropical cyclones are incredible heat engines, driving their convective bursts with warm water. The transport of this energy in to the subtropics can often times lead to larger storms that have part hurricane, part mid-latitude cyclone characteristics. There is a chance that we see that happen with the Pacific system after it makes landfall in Mexico.
WPC precip forecast over the next 5 to 7 days indicating a lot of rain possible for parts of Texas and New Mexico
Some of the global models are indicating that at least some of the remnant energy will survive the trek across Mexico and combine with an upper level low coming out of the Southwest to produce a potentially heavy rain event for Texas and New Mexico. While the rain is needed, we could be faced with another instance of too much, too soon. The latest forecast from the WPC (Weather Prediction Center, formally known as the Hydrometeorological Prediction Center) suggests that a wide swath of Texas and part of eastern New Mexico could receive several inches of rain beginning later in the week. The timing of when and where is tough to call this far out but your local NWS office will have the best info concerning local impacts from this rain event.
Remember back in April and in to May, parts of Texas were inundated by very heavy rain as wave after wave of energy moved across the region dumping incredible amounts of water, resulting in widespread flooding issues. While this storm will not be nearly as prolonged, there is potential for more flooding so please pay close attention as the week wears on.
As I mentioned in the headline, the Atlantic Basin remains very quiet right now. I do not see any solid evidence of development happening anytime soon. It appears that a slow moving MJO pulse will eventually make its way in to the region as we get in to early November and it’s possible that we could see more activity flare up at that point, probably in the western Caribbean Sea. We’ll deal with that when and if the time comes.
I’ll have more in the developing storm in the southeast Pacific on my video discussion later today.
Ida has become stronger over the weekend with top winds of 50 mph as of this morning. The forecast keeps Ida on the maps for the next five days, eventually strengthening it in to a hurricane over the open Atlantic. Some of the long range models suggest that it could become quite a strong hurricane as the pattern changes and becomes more favorable for intensification. There are no indications that Ida will ever impact land, at least not directly. Perhaps, if it becomes strong, it could generate swells that would eventually impact the East Coast but that remains to be seen.
As we move through the week ahead, we will need to begin watching the western Caribbean and the Gulf of Mexico for possible development. Almost all of the global model guidance now suggests that something will form around the Yucatan peninsula and move in to the southern Gulf.
Climatology suggests that this is the area to watch as we begin to shift away from the Cape Verde storms (we have had several this season) and focus more on the western Atlantic and Caribbean Sea, Gulf of Mexico regions.
GFS day 6 map showing a broad area of low pressure in the western Caribbean Sea
So far, the long range guidance seems to want to develop a low somewhere in the vicinity of the western Caribbean with a track towards the north to north-northwest. This would bring the system in to the Gulf of Mexico where water temps are still very warm. From an ocean heat content perspective, there is plenty of potential for development.
However, I am skeptical because the upper level winds look way too strong for anything purely tropical to get going. A large and expanding area of high pressure does seem to build in across the region but the low-shear environment appears to me to be to the south and east of where the low would be. None of this makes much difference right now since we have more than five days to monitor the situation. In any case, it is a region that becomes more favorable towards the end of September in most seasons. Whether or not that is the case this year remains to be seen. I’ll be watching the evolution of the pattern very closely over the next several days.
Satellite image showing deep thunderstorms moving across Mexico towards Arizona
Meanwhile, another possible significant flood event is taking shape out in the Desert Southwest as moisture from a tropical depression is moving north from the Pacific and in to Mexico and Arizona. The region from southeast California stretching across all of southern Arizona and in to New Mexico is under the threat of flooding from excessive rainfall. Anyone with travel plans to the region needs to keep a very close eye on the situation and be ready to avoid any and all areas of flooded roadways, etc. This event has the potential for widespread flooding across several major population centers across the Southwest. The worst of the weather is likely to take place over night tonight and in to tomorrow, mainly across southern Arizona.
I’ll have a video blog posted later this afternoon with more details on all of the goings on in the tropics.
The east Pacific hurricane season was extremely busy. Several intense hurricanes impacted Mexico, particularly portions of the Baja peninsula. The strongest of these impacts was hurricane Odile in mid-September with significant damage taking place in the Cabo San Lucas area.
Once these Pacific hurricanes turned north and eventually northeast, they spread deep tropical moisture across a region that is normally very dry and very hot: The Desert Southwest. The resulting influx of moisture often leads to a period of heavy rain for areas that are not used to such events on a regular basis. In fact, it had been quite a number of years since the last significant intrusion of tropical cyclone threats to the Southwest United States and this is what drove me to head out there not once, but twice, to document and study the impacts in person.
Norbert: September 5-10 Texas, New Mexico, Arizona, Nevada and Utah
Hurricane Norbert forecast track on Friday, September 5
Hurricane Norbert threatened to send copious amounts of moisture in to the Southwest United States during the first full week of September. The National Hurricane Center had warned in its advisories that a significant flood threat was shaping up for portions of the Desert Southwest.
Few people truly realize the far-reaching effects of tropical cyclones, even long after they make landfall and dissipate. For the Southwest U.S., there is a history of tropical cyclone impacts in places that we are simply not used to hearing about.
East Pacific hurricane season of 1976
Looking back, we can see that years such as 1976 stand out as big impact years for California, Arizona, Nevada and Utah. Several hurricanes turned northeast towards Mexico and brought with them substantial amounts of moisture which resulted in major flooding events for parts of the Southwest.
Flash-forward to 2014. Norbert was forecast to make landfall along the northern Baja peninsula as a weakening depression but its moisture was already being advected around a large high pressure area over parts of Texas and the western Gulf of Mexico.
Adding to the mess were the remnants of tropical storm Dolly in the Gulf of Mexico. The left-over moisture plume was also transported northward across Mexico and in to west Texas, New Mexico and parts of Arizona.
The complex pattern meant that there would be several days of flash flood threats across a large part of the Southwest. I thought that this set up would provide an excellent opportunity to observe and report on the impacts from a tropical cyclone’s effects in an unusual geographic location.
I hopped a plane in Wilmington on Friday, September 5 and joined my friend and HurricaneTrack.com supporter, Kerry Mallory, in Houston that afternoon. From there, we drove west-bound across the vast countryside of west Texas with Las Cruces, New Mexico our destination late that night.
Saturday, September 6 – photo showing deep moisture beginning to build as Norbert and remnants of Dolly combine for major flood threat across Desert Southwest
After a long drive from Houston to Las Cruces and some much needed rest, the plan was to head in to Arizona to be in position for any potential thunderstorm activity that could set off flash flooding. The moisture plume was steady with the flow coming north from Mexico, setting the stage for an active week ahead.
Saturday’s destination was Phoenix, Arizona and it wasn’t long after crossing the border in to Arizona from New Mexico that things got interesting.
With the the heating of the day and the surge of tropical moisture on the increase, isolated to scattered thunderstorms were popping up. Kerry and I could clearly see the towering thunderheads in the distance, matching nicely what we observed on radar.
One phenomenon that I really wanted to observe and study up close was a flash flood. Obviously you have to be in the right place at the right time, usually along a wash or dry riverbed that suddenly fills with rain water. Putting my geography and weather skills together helped me to better understand the conditions and locations that I would need to seek out in order to catch a flash flood as it happened.
The Desert Southwest is literally lined with dry washes or Arroyos, as they are also termed, that sit dormant for months at a time. When the rains come, these alley-ways for the run off to cascade through become instant raging rivers, filled with all kinds of debris and mud. When a road way crosses a wash or dry riverbed, and a flash flood occurs, the consequences can be deadly for those who are unaware.
Strong thunderstorm just north of I-10 in Arizona during the afternoon of September 6
The key for us was to be in the vicinity of a strong thunderstorm that dumped a lot of rain in a short amount of time. Safety was also an obvious element that we placed at the top of the list. We thought we had a shot, the first of many, near Bowie, Arizona, just north of I-10. A group of thunderstorm cells had developed over the mountains and we could clearly see a thick ,well developed rain shaft underneath. I have to admit, it is breathtaking to see something so beautiful take place in the desert. The juxtaposition of dry, desert landscape with a tropical downpour is a sight to behold. The rain literally makes the air come to life around the storm, with outflow wind blowing cool air like the best air conditioning you could ever imagine. We had our first storm of the mission and it was spectacular.
Kerry and I pulled off the Interstate and traveled north along Highway 191 for just a few miles until we had the perfect alignment with the approaching storm. I set up a GoPro on our tripod for a time lapse session. The slow moving storm came right at us but weakened as the heating of the day waned. However, the time lapse that I was able to process was wonderful. It clearly demonstrated the dynamic structure of the storm, the rain falling underneath and the outflow pushed ahead of it by the rain-cooled air. All of this in the desert, mind you, not over Florida or the Great Plains where such events are common place. It was a small but significant victory for us and once we had wrapped things up at that location, it was time to press on towards Phoenix.
As the afternoon wore on, more thunderstorms developed near Phoenix and produced a substantial Haboob or dust storm that was all the rage on Twitter. Kerry and I missed it by about three hours but arrived as the cluster of storms that created the dust storm was still ongoing.
I cannot begin to describe how strange it was to see Saguaro cactus back-lit by brilliant flashes of lightning – which is exactly what we saw as we approached Phoenix along I-10. We arrived an hour or so after dark and settled in for the night, ready for a busy and more active weather day on Sunday.
Sunday, September 7
Norbert was weakening as it turned northeast towards the Baja but the abundant moisture feed was already being pulled north in to the Southwest. The strong high over the western Gulf of Mexico continued to pump moisture from Dolly and the Gulf itself, setting the region up for a wild few days to come.
The plan for Kerry and me for Sunday was simple: literally go storm chasing! We wanted to try and get to a developing cluster of thunderstorms near peak heating in order to witness the elusive but dangerous effects of a flash flood. Keep in mind, most of southeast California, southern Nevada, western Arizona and almost all of New Mexico had been placed under a flash flood watch due to incredible PWAT or precipitable water values being very high considering the geographic location. Some areas were looking at 200% to 300% above the long term average for potential rain fall. This meant an increased risk of flash flooding where thunderstorms developed. Unlike a true hurricane or tropical storm making landfall with organized rain bands, this situation was different. The remnant moisture from dying hurricane Norbert was the culprit, not the tropical cyclone itself. We had to rely on radar via the iPad and of course, luck, to find what we were looking for.
We spent the morning surveying an area not far from Maricopa that had flash flooding during the night Saturday. Once again, I was stunned at the contrast between seeing dust devils dancing playfully across the open desert and standing water where torrential rain had fallen the previous night. It was a weather geek’s dream come true – seeing so many interesting elements all in the same place.
Thunderstorms over the mountains near Prescott, AZ during the afternoon of September 7
By early afternoon, the convection began to build over the mountains to the north of Phoenix, near Prescott. The distances from which you can see towering thunderheads out west is staggering. We were south and west of Phoenix watching clouds billow up nearly 100 miles away. We had to get moving if we wanted to get to the storms in time.
After a couple of hours driving towards Prescott, sure enough, the storms had dumped enough rain to warrant a flash flood warning for the area.
One interesting aspect of flash flooding in the Southwest is what are called “burn scars” or areas along mountains that suffered effects from wildfires in recent months or years. The left over barren landscape invites disaster as the ground is like concrete, not allowing rain water to soak in. Instead, you get these mud and ash flows, filled with burned out trees and other debris. In a severe flood situation, burn scars can help to lead to catastrophic flash flooding over quite a distance, even far from where the rains fell.
Kerry and I had studied up on nearby burn scars and there was one fairly close to where we were headed. After passing through Wickenburg, we turned northeast along Highway 89 and in to the mountains.
RadarScope screen shot showing the cluster of thunderstorms to the northwest of Prescott, AZ
The thunderstorm complex was nearly stationary and seemed to keep building over the area. Creeks were already filling up and the National Weather Service was busy dealing with flash flooding as a result. Our task was to try to get to where this was happening but do so with extreme caution.
We managed to get in to the region where the storm was but it had moved on just enough to lessen the impact of flooding in the Prescott area. We found an impressive dry wash out in the desert and I took the opportunity to fly the quad copter around it to get a better look at the structure and general look of these interesting geographic features. The one we had found was as dry as could be but the evidence of past flood events was frozen in time, preserved as if it had happened just days ago, yet it could have been months or even years. Seeing this just made me work harder to try and get to a location where one of these dry washes filled up with water. It is literally like trying to find a needle in a haystack, very tough to do unless you’re in the right place.
We pressed on and left Prescott behind us as more concentrated rain and thunderstorms had developed along I-40 between Flagstaff and points west, including Las Vegas, Nevada. In fact, an especially large cluster of storms was pounding the area around Kingman, just east of the Nevada border in Arizona.
Very heavy was falling over a burn scar area in the mountains near Kingman, AZ during the evening of September 7
Night was approaching quickly when we arrived in the Kingman area where very heavy rain had prompted flash flood warnings. A burn scar in the region was noted in the National Weather Service advisory which suggested debris flows could be moving down the mountain towards an RV park not far off the Interstate. Kerry and I did all we could to find it but the event was probably not too severe, great news for the people in the RV park for sure!
After taking a close look at the pattern setting up for Monday, it was clear to me that southwest Utah and southern Nevada should be the place to be for Monday when the tropical moisture from Norbert would get tapped and energized by an approaching upper level trough coming in from the Pacific.
Vast regions of the Southwest were now under flash flood watches. We are talking New Mexico, Arizona, southern California and Nevada, southern to central Utah and now extending in to parts of Colorado. The effects from Norbert’s moisture were going to impact a huge portion of the Southwest, putting lives at risk and disrupting travel at key locations throughout the region. Monday, it seemed, was the biggest day yet. We were going to be ready.
Our destination for Sunday night and through Monday was St. George, Utah. I would have never thought that anytime during my 20 year career tracking and studying hurricanes that I would be in Utah because of one. The situation was rather serious and local National Weather Service offices were doing an excellent job of posting information on their websites about the possible flood threat unfolding.
Kerry and I passed through Las Vegas and headed north via I-15. The night air was muggy – something you don’t experience very often out that way. Low clouds obscured a late-rising moon, foreboding as it tried to illuminate the barren desert landscape.
Map of St. George, Utah and Snow Canyon State Park
We arrived in St. George around midnight local time and immediately began scoping out a location along the Virgin River to place an unmanned camera unit – the same one that I had set up during hurricane Arthur along the Outer Banks earlier in the summer. This time, it would keep watch over the river which was likely to rise dramatically due to recent rain and the incoming flow of deep tropical moisture.
It did not take long and we settled on a spot right along the river not far from our hotel, just down from the bike and running trail that snakes around parts of St. George. Kerry had several flood gauges upstream bookmarked for monitoring and we knew that it was only a matter of time, and some added heavy rain Monday, and the Virgin River would spring to life.
I spent another hour or so researching local canyons for possible flash flood potential on Monday. The advisories from the National Weather Service mentioned slot canyons and area washes and dry river beds as being prime targets for fast moving, deadly flash floods. Obviously, there was no way to pinpoint which of the many canyons and dry washes would be impacted. We would have to get lucky but this time, the heavy rain was poised to cover a much wider area and with greater intensity.
I suggested to Kerry that we check out Snow Canyon during the early part of Monday. There was a substantial dry wash that ran through the canyon area which is itself a state park. Of particular interest to me was a point where the road and the wash intersected. I had a feeling that this would be the best spot for us to capture a flash flood, even if it were not especially dangerous or damaging, I just wanted to document the event without having to put Kerry or myself in harm’s way.
Monday, September 8
After rounding up some hardware needed to set out the unmanned camera along the banks of the Virgin River during the mid-morning hours, it was time to get to work.
Our unmanned camera location along the left bank of the Virgin River in St. George, Utah
We set up the camera system in less than 15 minutes and it was streaming live video not far from the river bed itself. The view was great and it allowed us to continuously monitor the river throughout the day. Nothing much was happening just yet but the unit was functioning as designed, now we just had to wait.
I set up the GoPro along the bike bath just up from where we had the live cam feed along the river. Deep moisture was gathering from the south and it wouldn’t take much to set off large clusters of very heavy showers and thunderstorms.
By mid to late afternoon, the storms initiated in Nevada and began to track north. They were slow moving, probably less than 10 miles per hour. It did not take long for the first flash flood warnings to go up. One of them was near Moapa, along I-15 just southwest of Mesquite and the Arizona border. We could see the tops of the thunderstorms, resembling a large cluster that you might see over the Everglades in Florida on a steamy August day.
Within the same hour that the storms fired off in Nevada, more took shape in southwest Utah, including around the St. George area. The intensity of the rain was just like what I would expect in a tropical storm. Storm water run off was a big problem from the get go and people had to slow down or face perilous driving conditions for the rest of the day.
We learned via Twitter that Moapa Valley and vicinity were facing a flash flood emergency. A wall of water was apparently cascading down I-15, sweeping away vehicles and people. This news was chilling, knowing that we drove that exact stretch of Interstate just the night before. There was no way to get to the location safely and it was, in fact, very dangerous in and around the Moapa area. Kerry and I kept a close watch on Twitter for any reports coming from the highway patrol or local news media. The deluge had begun and the first significant impact to people and commerce was unfolding less than an hour from our location.
As the day wore on towards dusk, the rain kept falling. We drove out to Snow Canyon to see if flash flooding had taken place yet along that intersection that I was suspect of. Nothing yet. There were, however, spectacular waterfalls pouring out of the sides of the canyon walls. So far, there was nothing noteworthy happening in and around the St. George area.
By evening time, we learned that I-15 was literally torn up and washed out in places near Moapa. People were stuck and some had to be rescued during the flash flood. Fortunately, despite the ferocity of the flood waters, no one was killed. However, the major north-south Interstate that connects Las Vegas with Arizona and Utah was, for the time being, closed.
Hundreds of people were stranded along I-15 between Mesquite and Las Vegas. This casino was the only facility that had power, a literal beacon of light for those trapped by the flooded out highway
Kerry and I made our way south to Mesquite by going around via secondary roads and through the mountains. Most of the town was without power and in fact, several hundred people were stranded in the dark, many along the Interstate. It was quite an eerie scene. I wonder how many people really knew what the cause was and that it had everything to do with a Pacific hurricane? Even Las Vegas had to deal with some flash flooding, filling up my Twitter feed with incredible, dramatic photos of water rushing through casino garages.
After a long day, it was time to head back to St. George and keep an eye on the river gauges along the Virgin River. There was a noticeable rise but nothing dramatic just yet. The skies had all but cleared but the moisture remained in place, ushering in yet another very humid night in southwest Utah.
We returned to St. George and I used the last hour or so of my waking moments to check the forecast for Tuesday. Our time was running out as I had a plane to catch back in Houston, some 1,800 miles away, in less than 36 hours.
It seemed that one more piece of upper level energy was forecast to move through California, across Nevada and in to Utah overnight. This would likely set off one more round of thunderstorms over the same areas that were pounded during the day Monday. I turned in for the night and figured we would just wait and see how things were Tuesday morning.
Tuesday, September 9
The sun had barely risen when Kerry woke me up, urging me to check the live camera that we had set up along the banks of the Virgin River. He had stayed up all night monitoring river gauges upstream from St. George.
As forecast, more heavy rain was falling across the region and once again, flash flood warnings were plentiful.
The rain from Monday had finally done its work, forcing a substantial and dramatic rise in the Virgin River. The flow had increased significantly as well with the live camera feed showing all sorts of debris moving swiftly along in the muddy water.
As more thunderstorms lined up like box cars on a long track to the northwest of our location, practically over Snow Canyon, I made the call to head out there immediately. We jumped in to Kerry’s truck and took off for Snow Canyon.
The park ranger we met at the gate alerted us that flash flooding was taking place along the wash and for us to be careful. I told her that hew news was music to my ears and that I was there to document just such an event. To my surprise, she was very understanding and encouraged us to go for it, wishing us to be careful of course.
Within a mile or so in to the park, we found it. Water was streaming across the two land road like a small stream. The flow was not very substantial at the moment but the rain all around us was coming down heavy with more lined up back behind us.
I contacted The Weather Channel and set up a live video feed right from our location. All of a sudden, the flow increased and within seconds, the small stream became a full-own flash flood. I grabbed the GoPro and began recording from as many angles as I could. It was the moment I had been hoping for and the good news was that the flood was not affecting anyone directly since it was contained within the state park of Snow Canyon.
Kerry positioned his truck so as to alert anyone else venturing in to turn around or just park and take in the awesome spectacle. Several people stopped and witnessed it along with us, thunder rolling against the canyon walls.
I was utterly fascinated and intrigued by the rapid changes in flow as the minutes ticked by. I could hear more water coming down the wash as the roar would increase. Seconds later, the intersection of the road and wash would swell, rocks banging in to each other underneath the swift current. I was like a kid on Christmas Day because to me, this was what it was all about. Seeing the effects of a hurricane in an environment that was alien to me made it all worth the effort. The fact that no one was harmed by the flooding was even better. I could just observe and record via GoPro what was happening. The Weather Channel took the stream live during their evening broadcast, amazing considering the fact that I was in a canyon out in the middle of desert countryside in Utah. Technology sure has come a long way!
Meanwhile, our Virgin River cam was doing its thing, recording and streaming live as the river sent tons of upstream debris towards the south and east. The Weather Channel also took this feed live, showing the audience a unique perspective of the effects from Norbert. I was very proud of our success even though the bulk of it came on the last day that we were out there.
Photo of rain-swollen Virgin River as seen from our quad copter
The rain let up as the afternoon progressed and it was time to pull up the live cam from the river and begin the long trip back to Texas. I captured my moment and had satisfied my urge to witness the impacts from a Pacific hurricane on an area that rarely has to deal with such events.
Norbert faded in to a remnant low pressure area over the cool waters of the east Pacific, not too far off the Baja peninsula. Its reach was far and wide, affecting millions of people from southern California to west Texas. Even as Kerry and I made our way back to Texas for me to fly home, the left over, nearly depleted moisture continued to produce scattered thunderstorms along our route. If I hadn’t documented the incredible journey, I might not have believed it happened. While the Norbert field mission was not in the same category as something like Ivan or Katrina, it was very much worth the time, expense and effort it took to hang in there for five days as the event took place.
I am a geographer at heart and with that comes a deep passion for weather. Hurricanes are such an important part of shaping the landscape, both natural and man-made. Norbert was an opportunity for me to learn about something that I had always wanted to experience. I was glad to have made the trip and felt that I had contributed to the story, even if only a little bit. After all, every little bit helps, right? Turns out, I would be back sooner rather than later. Another powerful east Pacific hurricane was brewing and already it looked like a track very similar to Norbert’s was possible. It was 1976 all over again for the Southwest United States.
Next up in my recap blog series: a very challenging hurricane Odile threatened to surpass Norbert’s flood threat, putting Arizona, New Mexico and west Texas in the cross hairs.
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