Holiday travel has been worse before, but 2023 will bring its own set of headaches

One-sentence summary

While we’ve had worse travel outlooks for Christmases in the past, this year doesn’t look spectacular, with a few areas likely to experience weather impacts through next week.

Christmas weekend outlook: Rough in spots; not bad in others

After a rollicking couple of days on the Eastern Seaboard with record flooding in Charleston, nasty weather in Florida, and powerful winds knocking out electricity to hundreds of thousands in the Northeast, we will mercifully get a couple days of a break in the East. Meanwhile, the West is just getting started with another storm aiming to bring rain to California today and tomorrow.

Rainfall over the next few days will be significant in California with a flooding threat developing in portions of SoCal on Wednesday and Thursday. (Pivotal Weather)

As all of that mess starts to exit the West later this week, it promises to setup some impacts on travel days heading right through early next week. It doesn’t look horrific on any given day right now, but a series of systems will probably keep some travel headaches going into next week. Let’s walk you through what and where to watch as it stands right now across the country.

Wednesday: Focus on California

The main headaches on Wednesday are likely to be in California, with heavy rain expected as a cold front pushes down the West Coast tied to a storm system offshore. The highest risk for any flooding will probably be in the LA Basin and Ventura County into Santa Barbara in SoCal. About 1 to 3 inches of rain is expected from this storm on Wednesday which may be enough to cause some flooding and certainly impede travel a bit between LA and San Francisco.

Thursday: More rain, flooding in California

That storm system is expected to kind of slow down offshore of California, keeping a wet forecast going, especially in SoCal on Thursday. Another inch or two will be possible there, with flooding a definite concern. The Weather Prediction Center has placed the western portion of the LA Basin into Ventura and Santa Barbara under a level 3 of 4 moderate risk for excessive rainfall.

A moderate risk of flooding is in place in coastal SoCal from Santa Barbara through LA on Thursday. A slight risk is in place north of there and down the coast to San Diego. (NOAA)

Farther to the east, showers will begin to become a possibility in the Plains, but no real serious travel headaches are expected in the eastern half of the country.

Friday: Weather shifts east

I don’t foresee any real serious issues on Friday, but there will be a couple areas to watch. Rain in California will finally start to push east, more into Arizona, where heavy rain may fall in parts of the state, including Phoenix.

Forecast rainfall on Friday in Arizona is considerable, with some travel impacts and localized flooding possible in the Phoenix and/or Tucson areas. (Pivotal Weather)

Meanwhile, rain and/or thunderstorms may push across Texas into Louisiana Friday afternoon, perhaps causing a few modest delays in the Houston area.

Saturday: Calm before the storm

Nationally, Saturday may be the best travel day overall with only some minor issues in parts of the Rockies, Southern Plains, or Southeast. No major problems are currently foreseen.

Christmas Eve: Rockies, Plains, and Mississippi Valley see stormy weather

As everything slides east, we’ll get low pressure developing in the lee of the Rockies, probably between the Texas Panhandle and Kansas. This will lead to rain and thunderstorms in the Plains through Texas, expanding east to the Mississippi Valley as the day wears on. Some of these storms could be on the stronger side.

Snowfall/winter storm information that is known as of this morning for the Rockies. (NWS Boulder/Denver)

Meanwhile, snow should break out in the Rockies, with Colorado and Wyoming the most likely areas to see accumulation and potential travel headaches.

Christmas Day: Wet Southeast

The forecast confidence begins to fade rather aggressively here, as we end up with a storm system over the Midwest and a wet Southeast and perhaps Mid-Atlantic. Travel doesn’t look particularly awful here, but there will probably be some wet roads for the East in spots. Snow or a mix should continue on the backside of the storm from Wyoming into perhaps parts of Nebraska and South Dakota.

Beyond Christmas Day: East Coast Storm? Still wet in the West

Uncertainty plunges later next week. If you look at this map showing the forecast interquartile range for next Wednesday afternoon from the European ensemble, you can see ample uncertainty.

There is significant uncertainty on exactly how next week’s weather plays out. A major storm is possible in the Eastern U.S., but details are very much lacking at this time on timing and intensity. (Tomer Burg/Polar Wx)

The IQR shows the difference between the 75th minus the 25th percentile of ensemble sea level pressure. The higher the values, the greater the potential uncertainty with placement and intensity of low pressure (or high pressure). In this case, we see a strong signal for a storm in the Eastern U.S. What we do not see is any confidence within the ensemble members regarding location or intensity. So we know something is probably going to happen that could be a travel headache in the Eastern U.S. after Christmas, but we aren’t exactly sure what, when, or where.

Temperatures next week are likely to be warmer than normal in the Northeast, so this probably precludes snow risk for the major cities, but interior areas could be prone to some snow in the right (wrong?) scenario.

Temperatures are likely to be above to well above normal next week in the Northeast and Midwest, probably minimizing snow chances a bit with any storm system. (NOAA)

Meanwhile, the West looks mild too, with continued rain and mountain snow lashing the West Coast. This is pretty clearly an El Niño flavored pattern across the U.S. to close out 2023.

Let’s talk about the concept of blowing up a tornado

One-sentence summary

Today we assess some of the commentary around a viral tornado video from the weekend to discuss if it would be possible to “blow up” a tornado.

Can you actually blow up a tornado?

That’s a provocative subheading above, but it’s taken on a little more curiosity after video emerged from this past weekend’s tragic tornado outbreak in the Deep South and Tennessee Valley.

Click to enlarge severe weather reports from Saturday across Tennessee and Kentucky. Note the cluster of tornado reports north of Nashville. (NOAA)

The tornadoes killed six and injured over 80 in Middle Tennessee on Saturday. Clarksville was hit with an EF-3 tornado. This area has seen more than their fair share of significant weather in recent years.

A video from one of the tornadoes is what seems to have grabbed everyone’s attention, and justifiably so.

This one occurred between Madison and Goodlettsville, just north of Nashville, east of I-65. What you essentially see is the tornado striking a power substation, followed by an explosion. The power substation was Nashville Electric Service’s, which just released video from the site on Monday showing the strike and explosion.

But what’s notable about this whole thing: In the original video, it appears that, if only for a fleeting moment, the condensation funnel (what you are visually seeing as the tornado) disappears. Naturally, that started some interesting conversations on various social media platforms. The underlying question you would expect humans, especially on social media to ask was: Can you actually, like, blow up a tornado?

Before we go on: No. We cannot “blow up” tornadoes, just as we cannot “nuke” hurricanes. It’s too complex, not to mention the likelihood of collateral damage. So, let’s just get that out of the way.

But in a theoretical world without risk to lives or property, could you do it? I still don’t think so. Noted storm chaser Reed Timmer posted on X, formerly Twitter over the weekend that the “explosion changed the thermodynamic gradients dramatically within the vortex and blew up the Clausius-Clapeyron equation.” I’m not going to lose our audience here with a math lesson, but the C-C equation relates saturation vapor pressure to temperature. What is saturation vapor pressure? Vapor pressure is basically exactly that: What is the pressure of the water vapor in the air. But at a given temperature, there’s a maximum amount of moisture that the air can hold. That would give you the saturation vapor pressure. Using C-C, we can determine that as temperature increases, the saturation vapor pressure of the air increases exponentially. In other words: Warm air can hold a lot more moisture than cold air, and the relationship is exponential.

What does this all mean? Theoretically (very theoretically), the heat released from an explosion within the condensation funnel of a tornado would lead to a dramatic increase in saturation vapor pressure, thus decreasing the humidity in the vicinity of the funnel. You’re not adding more moisture to the equation, so all you’re doing is increasing temperature and increasing the air’s capacity to hold water — exponentially. All else equal, you’ve decreased humidity, and because the air is no longer saturated, the condensation funnel (which you see when the air is saturated) visually disappears.

If the condensation funnel is our visual cue of a tornado and it disappears, then to the human mind the tornado itself has disappeared. So you can actually blow up a tornado, right? Not quite. Other videos from other angles that I’ve seen seem to show the condensation funnel picking back up a little after the viral video ends. Meaning the tornado was only briefly visually disrupted, not destroyed. Were the winds disrupted or just our visual cues? I’m not sure. Thunderstorms are big, and the forces producing tornadoes are also significant. To truly destroy a tornado, you’d likely have to go after the supercell thunderstorm itself, which is producing the tornado, in theory perhaps something that could be done but in practice probably next to impossible.

While it’s certainly a fun thought exercise, also keep in mind that we’re all taking some liberties here to make assumptions about this using the science that we know. There could be another explanation for what’s happening here, but the one suggested by Reed and others seems to be the most reasonable that I’ve seen. But the bigger point still stands: Blowing up a tornado is not a practical alternative to preparedness, structure hardening, shelter availability, and awareness on severe weather days.

A look back at the 2023 Atlantic hurricane season as we bid it adieu today

One-sentence summary

It’s November 30th, so today’s post will take stock of what was a very interesting hurricane season.

By the numbers

The 2023 Atlantic Hurricane Season was a busy one. It wasn’t so much that there were a lot of large storms; the season itself had “only” 7 hurricanes and 3 major hurricanes, which is spot on normal for a typical hurricane season. But we had a lot of storms that lingered for awhile, traversing the open Atlantic for a long time.

The 2023 Atlantic hurricane season featured an extremely active Atlantic, an extremely quiet Caribbean, and a mostly quiet Gulf. (NOAA)

Recall that ACE, or accumulated cyclone energy is calculated using just the wind intensity and duration of a storm. It’s an inherently imperfect calculation, but it serves us well in terms of putting a season into context. Examples of recent seasons with ACE values in the “hyperactive” category include 2020, 2017, 2010, 2005, and 2004. Not many would argue that those seasons were anything but busy. 2023 falls into the next bucket of seasons, which are considered above normal. Our ACE will finish the season around 145.5 units, falling short of the 159.6 needed to be a hyperactive season.

You can see how seasonal ACE behaved relative to climatology (normal) for 2023. Other than some differences in amplitude and slope, the season behaved normally but was a bit busier than usual. (Colorado State University)

Because of the duration of some of the stronger storms, the 2023 season certainly felt above normal. As noted, ACE is not perfect, but it tends to do better from a seasonal standpoint than number of storms. As our capability to name a greater number of storms increases, the actual storm count means a bit less than it used to perhaps. But ACE manages it better.

Speaking of, we will finish with 20 named storms this year. We managed to get to Tammy, leaving Vince and Whitney unused.

Why was the Atlantic so busy? Why were the Gulf and Caribbean not very busy?

Let’s talk for a quick moment about what happened this season. From the map at the top of this post, you can see that the amount of traffic in the open Atlantic was excessive. Other than Arlene, Idalia, and Harold in the Gulf and Franklin and Bret in the Caribbean, all of the action was in the open Atlantic. So why was that?

If you look at the upper air pattern for August and September, when 13 of the 20 storms occurred, you can sort of understand what happened. We’re looking 20,000 feet up here at what we call the 500 millibar (mb) level of the atmosphere. This is a good proxy for steering currents, or what will move tropical systems from point A to point B.

An annotated map of the 500 mb level (20,000 feet up) showing average August & September steering currents across the Atlantic Basin (NOAA)

What can we make of that map? A couple things. Let’s work left to right on the map above. First, over Texas, high pressure was stagnant. It was arguably the worst modern summer in Texas history in terms of heat, but it did keep storms out of the western Gulf. So that kept that part of the basin quiet. For the eastern Gulf, we managed Idalia in there, the one bad storm that found its way northward into the U.S. But overall, most storms would have been directed northward off the East Coast based on this map due to pretty persistent low pressure in the upper atmosphere off the New England coast. This is also to blame for the extremely wet summer in that part of the world.

We also had low pressure northeast of the Azores. When you have low pressure systems like that one and the one off New England, you are often going to induce a poleward motion to the tropical system. In other words, they feel the “pull” north. All tropical systems generally track west, then north, then northeast in Atlantic (with plenty of notable exceptions). But on the long-term average, that’s what we see. In this case, they had help this season, and that’s why so many “fish” storms occurred and so many impacts to Bermuda occurred out in the open Atlantic.

Did the much hyped warm oceans play a role?

When the season began, one thing we honed in on right here in The Eyewall’s early days were sea-surface temperatures. The Atlantic, the Caribbean, and the Gulf were all record warm at times this hurricane season. The August and September mean of sea surface temperatures (SSTs) was above normal virtually everywhere. Why is there that pocket of so much cool water off New England and southward? Hurricanes Idalia, Franklin, and Lee all worked to basically devour all the warm water there.

Sea-surface temperatures at the heart of hurricane season showed warm water everywhere — except the northwestern Atlantic, which was drastically cooled by Hurricanes Franklin, Idalia, and Lee. (NOAA)

When the season began, we noted that the extremely, if not record warm SSTs were enough reason to justify an active hurricane season forecast. Many articles were written across the media about this. And indeed, that is what allowed most seasonal hurricane forecasts to come close to verifying this year. Instead of the 16/7/3 consensus forecast for the season, we got 20/7/3 for our storm/hurricane/major hurricane slash line this year. I will say this: It takes courage to call for an active hurricane season in the face of one of the strongest developing El Niño events in recent memory. So kudos to those that stuck to that logic, despite what history has told us about El Niño.

What about El Niño? Did it matter at all? What else?

The answer to whether El Niño mattered or not this year is “sort of.” Wind shear is usually enhanced during El Niño summers, especially over the Caribbean. That did not actually happen, but we did see very strong shear near the Gulf Coast this season.

Wind shear was strong near the East Coast and generally weaker out over the open Atlantic. (NOAA)

While I think that was notable, the dry air in the western part of the basin didn’t hurt. With high pressure dominant and so much drought development on the Gulf Coast this summer, it definitely worked to help mitigate any storms.

Above normal relative humidity about 10,000 feet up dominated the open Atlantic, while dry air dominated most of the northern Gulf Coast. (NOAA)

So it was an interesting season. It’s worth noting that the average of the strongest El Niño hurricane seasons (taking the July-September ONI from NOAA) was 9 storms, 4 hurricanes, and 1 major hurricane. Suffice to say, 2023 will go down as one of the most active El Niño hurricane seasons ever recorded. That’s a little concerning given that an El Niño of this magnitude is usually enough to mitigate things. That only partially happened this year, in part due to the extreme warmth in the Atlantic. So does that mean that if we live in a world of more permanently warmer SSTs, El Niño might not matter as much when it comes to hurricane season? It’s a tantalizing and unsettling question, but it’s one we should be asking.

Thanks to those of you that joined us on this journey for the hurricane season and put your trust in our commentary. We are appreciative of your support. The Eyewall’s parent site, Space City Weather is holding a fundraiser for a couple more days. Any contributions you make will go toward both sites. If you feel compelled, click here to donate or purchase some Houston-focused swag. Thanks for considering! We will be back from time to time through winter with an update on big weather when we can. Stay with us, and enjoy the non-hurricane season!

Thanksgiving week weather outlook features mostly minor headaches in spots

One-sentence summary

Thanksgiving week travel looks a little sloppy in spots at times, but we can hopefully avoid any massive travel disruptions this year, at least due to weather.

Thanksgiving week outlook

It’s never easy, right? Travel anytime of year is a crapshoot to be sure, but of course during probably the busiest travel week of the year, we punctuate our mostly benign autumn with a fairly big storm. Different days this week will have different hazards in different parts of the country. As of now, it doesn’t look like we’ll see anything severely disruptive, but there are a couple things to point out.

Today: Severe weather risk in the Deep South

The main story for the Monday phase of this storm will be severe weather risk for the Southern US. Louisiana and Mississippi seem to be the prime spots at risk today for strong winds, hail, and possible tornadoes.

As of Monday morning, an enhanced (level 3/5) risk for severe storms was in place between extreme east Texas, across northern Louisiana and into parts of southwest Mississippi (NOAA SPC)

The tornado threat is not a guarantee, but if storms can maintain themselves individually in Louisiana or extreme eastern Texas (before “lining out” into bands of t’storms), a strong tornado or two will be possible. Either way, reports of hail and strong, damaging winds are possible, if not likely with storms today that should get going through the afternoon hours. The severe risk will push into Mississippi later this afternoon and evening and into Alabama and parts of the Florida Panhandle perhaps by the overnight hours, with a continued severe risk. Some adjustment of the above risk is possible before the end of the day today. If you’re traveling in this region today or tonight, please ensure you have the ability to receive weather warnings.

Tomorrow: Rain & wind in the Northeast and Midwest

The storm itself will track from about the Red River Valley into southern Michigan or near Lake Erie between today and tomorrow. This means that on Tuesday, we’ll begin to see widespread rain, thunderstorms, and gusty winds in the Eastern U.S. Gusty winds will likely delay some flights to and from places like Chicago, Detroit, Cleveland, or Pittsburgh.

Gusty winds will be strongest in Appalachia, as well as into parts of the Midwest, where gusts of 30 to 40 mph will be possible through Tuesday. (Weather Bell)

Rain may begin as a wintry mix for parts of the interior Northeast as well. Overall, this won’t be a massive storm up that way, but it will be enough to cause disruption.

The primary severe weather risk tomorrow will be with the continuation of storms overnight into the morning hours moving across Alabama and the Florida Panhandle.

Wednesday: Improving, except in the Northeast

Boston and New York may still see some gusty winds on the backside of the storm Wednesday as it exits in the morning.

Some fairly strong wind gusts on Wednesday may impact flights into Boston, southern New England, or the NYC metro airports. (Weather Bell)

Gradually improving weather is expected during the PM hours, but some of those wind gusts in the front half of the day may cause some travel headaches.

Elsewhere, there’s at least a subtle severe risk in eastern North Carolina before the front exits, but that’s not expected to be a big deal.

Thanksgiving Day: Showery Gulf Coast, snowy Wyoming?

Travel overall looks fine on Thanksgiving Day if you’ll be hitting the road. The two exceptions to this are on the Texas Gulf Coast and in Wyoming.

For Texas, showers are possible between about Laredo and Matagorda Bay south through Corpus Christi and the Valley. This won’t disrupt travel much, but it could put a slight damper on any outdoor Thanksgiving plans.

Potential snow from the National Blend of Models, most of which falls Thursday in Wyoming. This is subject to change, but some travel disruption is possible in this region into southern Montana. (Pivotal Weather)

The situation in Wyoming and southern Montana is a little trickier, as is always the case with snow forecasting more than a day or two out. A storm seems likely to deliver some wintry weather to the region on Thanksgiving Day, but exact amounts are TBD. Whatever specifically happens, if your travels take you to Yellowstone or portions of northern Wyoming and southern Montana, you will want to be prepared for some travel difficulties.

Friday: Storms in the Southeast, snow into Colorado?

The aforementioned winter storm in Wyoming on Thursday will probably slide into Colorado on Friday bringing a chance of winter weather there that could cause some travel issues.

A moderate risk for travel issues across Colorado exists on Friday as a winter storm slides in. Details and specifics will be sorted out in a few days. (NWS Boulder)

Travel impacts are currently expected to be on the moderate side across Colorado, so if you are traveling from Denver to go skiing or visit the mountains on Black Friday, you will want to be ready to deal with some weather.

Elsewhere, the showery system in Texas on Thursday will move across the Gulf Friday, bringing a chance of showers and storms to the Southeast, particularly Florida. The rest of the country looks pretty good.

This weekend: Some uncertainty

The weekend looks ok at this point, with the Colorado system diving into the southern Plains bringing a chance of showers. Additional showers are possible on the East Coast later Saturday and Sunday, but as of now nothing looks too serious. We’ll keep tabs on things.