November 13, 2023 Outlook: Late season tropical system possible in the Caribbean, and we check in on — Alaska?

One-sentence summary

Today’s post talks about the potential for a late season tropical system in the Caribbean this week, as well as a detailed look at polar opposite weather that’s causing trouble in Alaska lately.

Tropical update: Caribbean mischief may present itself this week

We’ve got ourselves a late season system to possibly monitor in the southwest Caribbean later this week.

The Southwest Caribbean is highlighted with 60 percent odds of development this week by the National Hurricane Center. (Tomer Burg)

Model guidance is pretty persistent in developing low pressure off the coast of Nicaragua or Costa Rica around Wednesday or Thursday. It would quickly move northeast or north-northeast toward Jamaica, eastern Cuba, or Hispaniola from there, before accelerating out into the open Atlantic, perhaps impacting Bermuda on the way out this weekend. This will all occur quickly.

The GFS (left) and Euro (right) offer two differing outcomes but the same broad idea for the potential track of low pressure out of the Caribbean. (Tropical Tidbits)

As is often the case this time of year, the GFS model is much more aggressive with this system than the European model. The GFS has the equivalent of a strong tropical storm or low-end hurricane racing northeast of Jamaica on Saturday, whereas the Euro is a bit slower and notably weaker. The Euro has had a slightly better track record in the Caribbean, but it’s still a good idea for eastern Cuba, Jamaica, Haiti, and the Dominican Republic to monitor this potential system in the coming 2 to 3 days. From there, the Bahamas, Turks & Caicos, and Bermuda should also keep tabs on things. Whatever happens will happen fast, as this thing is going to be hauling north-northeast, tracking from the deep southwest Caribbean on Wednesday or Thursday to past Bermuda by Sunday or Monday.

U.S. Weather this week: Stormy Gulf, wet West Coast

A storm system on the Gulf Coast over the next couple days will bring some moderate to heavy precipitation between Texas and Florida, with anywhere from 2 to 5 inches likely. The highest totals are likely near Mobile, AL and Pensacola, FL. Flooding isn’t expected to be a huge concern, as the entire region is in pretty serious drought, and if anything, this will be a mostly beneficial rainfall.

This week’s rainfall will be mostly minor, except on the Gulf Coast and in coastal California and the Cascades. (Pivotal Weather)

The West will see a few surges of moisture this week thanks to a storm sitting offshore of California. This is expected to bring moderate to locally heavy rain to coastal California and some snow in the Sierra.

Rain totals have come off some versus a few days ago in California, but a wet period is expected this week. (NWS Monterey/SF Bay Area)

Overall, this should be more of a periodic ramp up/ramp down type precipitation event for California, but the rain (and snow) will add up over time. About 1 to 3 inches of rain is possible on the coast, including both San Francisco and LA, with locally higher amounts in the mountains and perhaps a little less in San Diego. Flooding isn’t a major concern at this point, particularly as the forecast has trended a little less excited about things.

Flaked Alaska: Heavy snow causes familiar problems in Anchorage

We don’t often talk about Alaska for weather unless it’s due to the pattern up there impacting the pattern for the weather across the U.S. But it’s worth talking about what’s happened in parts of Alaska to start November.

Precipitation to start the month in Alaska has been extremely heavy, with over 200% of normal for the period in southern Alaska, including the Anchorage area. (Brian Brettschneider)

Anchorage, the largest city in Alaska, with a population near 300,000 has received nearly 30 inches of snow this month so far, most of it courtesy of an atmospheric river event last week. This is the snowiest start to November on record in Anchorage. I reached out to the authority on all things Alaska weather, Brian Brettschneider, and I asked him to put into context how this sort of big time snow fits the typical climatology for Anchorage.

First, he tells me that the median snow depth for Anchorage around this time of year is about an inch or two. The snow depth there is around 2 feet, which only happens in maybe half of all winters at all there. “This snow will not fully melt out until April,” he says.

On top of that, this was a wet snow for Anchorage. What do we mean when we say “wet snow?” A number of factors play into what we call the “snow ratio,” or how much snow you would melt to get 1 inch of water. In general, colder and drier air masses produce higher snow ratios. It takes more snow to get that 1 inch of liquid. You see this a lot with lake effect snow. One inch of liquid may produce anywhere from 20 to 30 inches of dry, fluffy snow.

Warmer, more humid air masses tend to produce lower snow ratios, or situations where it does not take as much snow to produce an inch of liquid. A general rule of thumb, particularly on the East Coast, is that 10 inches of snow usually melts down to 1 inch of liquid. So the ratio is 10:1 (ten to one). In Anchorage, a colder and typically drier place, Brettschneider says that the average ratio is 17:1 typically. With this recent event, the snow ratio was 11:1. I wouldn’t call that “cement,” but that’s a very wet snow for Anchorage. Wet snow tends to be harder to move and clear, it can bring down trees and power lines, and it also causes significant issues on roadways as it will produce slush that can freeze into solid ice. This is one problem in Anchorage right now.

And it’s not a new problem either. Brettschneider said that it’s important to understand the current context of the situation in Anchorage. “Three rapid succession storms last December caused a month-long road-pocalypse around town. The state/city made it a priority to not let that happen again – yet here we are.”

Last December, Alaska Public Media asked “Should snow in Anchorage be this disruptive?” In a follow up article last month, APM reported that Anchorage said it was prepared should a storm like last December’s happen again. Anchorage mayor Dave Bronson said at his October news conference, “We are ready.”

The residents of Anchorage can decide if that’s the case. The second major multi-day snowstorm in Anchorage in less than a year is surely impressive. It’s also worth noting that despite the snow, it has not been cold in Anchorage, at least not compared to normal. “So far this month, the first 11 days are all warmer than normal in Anchorage – much warmer than normal,” per Brettschneider. It typically takes someone milder weather to produce this kind of snow in Alaska, as warmer air can hold more moisture.

On a serious note, the AP reports that four unhoused people died during the winter storm in Anchorage last week.

More snow is coming to Alaska today, including Anchorage.

The forecast through Tuesday afternoon in the Anchorage area calls for about another 6 inches of snow. (NWS)

As much as another half-foot or even a bit more of snow is possible in the Anchorage area today, with higher amounts in the Chugach Mountains east of the city. More snow is possible later this week.

Superfog is the current buzzword in the weather world, so why has it caused so many issues in Louisiana?

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Superfog, or near-zero visibility caused by the combination of fog and wildfire smoke has wreaked havoc on Louisiana recently, so we take a deep dive into how the term came about and why this is such a problem there this year.

Superfog: A super serious problem in Louisiana

If you’ve been paying attention to the news lately, particularly as it relates to weather, you’ve likely heard about “superfog” leading to a couple deadly traffic incidents in Louisiana. If you missed that news, here are a couple articles to catch you up.

The first incident was a major pile up on I-55 a couple weeks ago that killed at least 7 and injured over 60 people.

More recently, another superfog event led to an 11-car pileup on I-10 east of New Orleans that killed one and injured eight.

So what’s the difference between regular fog and superfog? And why is it so problematic?

What is superfog?

The technical definition of “superfog” is a combination of smoke and water vapor that produces zero visibility over roadways. What sets it apart from regular dense fog? The smoke. “Water vapor that produces zero visibility” is usually just plain old fog. When you combine fog and smoke and get zero visibility, you get “superfog.”

You may say to yourself, “Self, I thought smoke and fog was known as ‘smog?'” You are correct. The difference is that smog typically results from manmade pollutants, whereas superfog is produced from “smoldering organic material” and has extremely low visibility.

Is superfog some new clickbait term?

“Superfog” is not clickbait, a new term, nor is it a new problem. In fact, the South has been a notorious hot spot for superfog incidents for many, many years. This front page headline from the May 8, 2000 Biloxi Sun Herald reported on a similar incident on I-10 due to smoke from a prescribed burn mixing with fog.

The Biloxi Sun Herald after a May 2000 superfog event in southern Mississippi. (

In that article a Mississippi Highway Patrol officer was even quoted as saying “We’ve had two or three multi-car accidents because of smoke and fog mix.” A 1989 study by Hugh Mobley found that from 1979 through 1988, visibility reduction caused by smoke or a combination of smoke and fog caused 28 fatalities, over 60 serious injuries, numerous minor injuries, and litigation expenses into the millions. That study, as cited in a more recent 2003 USDA Forest Service paper by Gary L. Achtemeier started to quantify the impacts of what had (presumably) yet to be coined as “superfog.”

The origin of the term “superfog” itself seems to come from Achtemeier. As best as I can tell, he first formally coined the term in a 2001 abstract that I believe was intended for an American Meteorological Society meeting. So, I think Achtemeier is the Father of the term Superfog, and Hugh Mobley may be the originator of understanding its impact. Whatever the case, in this 2003 USDA Forest Service paper by Achtemeier, he does a good job explaining why the South is a hotbed for superfog events. And it appears that recent issues in Louisiana broadly fit the mold.

In his paper, Achtemeier notes a high number of prescribed burns that are done in the South. To my knowledge, the recent fires in Louisiana were not prescribed burns. But his other points stand. It’s a relatively humid period in the cool season right now, making fog more likely on the Gulf Coast. And this most recent marsh fire occurred very much at the wildland/urban interface in New Orleans East. So you have a number of people traveling in a smokey area, with conditions ripe for fog. From the paper, you can see imagery that shows the difference and uniqueness of superfog. Unlike regular dense fog with, say, visibility under a quarter-mile, superfog is literally zero visibility, often 10 to 20 feet or less. It’s easy to understand why that would lead to such severe outcomes on roadways. Anyway, if you want to better understand some of the initial hypothesis behind specific superfog development, that paper makes for an interesting read.

Why all of a sudden in Louisiana?

Louisiana is currently experiencing one of their worst droughts in recent memory.

While a new drought monitor update will be released later this morning, Louisiana is in just an exceptional and widespread drought. (US Drought Monitor)

Almost 70 percent of the state is covered in level 4 of 4 (exceptional) drought. It’s bad. And marsh fires have been happening for weeks from Cameron Parish in the southwest corner of the state east into the New Orleans area. Now, as fog season begins to ramp up on the Gulf Coast, we are seeing additional consequences of these fires.

If you want to look more specifically at Tuesday’s incident, you can at least pick out the fog easily on modeling. A forecast sounding, or vertical profile of the atmosphere from the NAM model averaged for the area just east of New Orleans at 7 AM on Tuesday shows what we call an inversion in the atmosphere about 500 to 1,000 feet off the ground.

A model forecast atmospheric sounding (vertical profile) from Tuesday morning east of New Orleans showed conditions ripe for the development of fog. (Tropical Tidbits)

What is an inversion? Normally, as you go up in altitude temperatures decrease. Inversions are places in the atmosphere where temperatures actually rise as you go up in altitude. In other words, you see warming in a slice of the atmosphere before temperatures begin to cool again. Inversions tend to suppress thunderstorms. During the storm season, we refer to these as “caps” or “capping” in the atmosphere. That inversion acts as a barrier to cloud-top growth, or vertical development. It also tends to act as a “lid” on the atmosphere, trapping any gunk underneath it near the surface. This can cause smog in cities and fog in cities and rural locations as well. In most cases, inversions tend to break as surface temperatures warm up during the day. But long-duration inversion events over days or worse with fog and severe smog problems will sometimes occur in Utah’s Wasatch Front in the winter months. There is also Tule fog in California’s Central Valley, which is common in the cool season.

In this case, a sharp, shallow inversion in a humid environment was able to lead to fog development outside New Orleans on Tuesday. The fog in the area of the fire was able to transition to a localized superfog event just east of New Orleans.

A cool front should push through most of Louisiana by early next week hopefully providing a respite from fog. But it does appear that another substantial period of humidity and fog risk may be possible later next week. The NWS in New Orleans has been all over this for awhile now and remains the best source for local information in that area.

Checking in on where our El Niño event stands as we descend toward winter

One-sentence summary

Today’s post primarily dives into where we stand with El Niño currently and what sort of impacts that could have heading into winter.

Tropics: Quiet!

We’re all quiet out there at the moment in terms of anything meaningfully developing in either the Atlantic or Eastern Pacific basins. It should be a quiet week overall.

U.S. Weather: Warmth taking hold

Overall, it should be a relatively calm week across the country. We are not expecting too much in the way of severe weather or excessive rainfall this week. One could argue that there’s at least some interesting weather happening though. A storm today and tomorrow will bring more rain and mountain snow to the Pacific Northwest. Another may follow toward the weekend. Overall, these systems look relatively minor on the atmospheric river scale this week.

The beefiest moisture this week off the Pacific will be aimed at British Columbia, with overall minor atmospheric river impacts. (UCSD C3E)

A pair of systems will bring rain and snow to the Great Lakes and southern Canada through the week. And a relatively strong system will bring showers and thunderstorms to portions of Texas later this week. There should also be a rather significant winter storm in southern Alaska later this week as well.

Temperature-wise, it looks like a very warm week nationally. Multiple record highs will be threatened from the Southern Rockies to the Carolinas this week, including close to 20 tomorrow.

Temperatures this week are expected to be above to much above normal across the Ohio Valley and Mid-South into Texas. Cool temperatures prevail primarily in Ontario, Quebec, and the Maritime Provinces. (Tropical Tidbits)

Not terribly cold in most of the country.

Updating El Niño: It’s here and still strengthening

To this point, I don’t think I would describe the behavior of the current burgeoning El Niño as “classic” in many ways. It’s basically already a “strong” El Niño event, and while its influence is there it is not complete just yet. For example, if you look at just sea-surface temperatures in what we call the El Niño box in the tropical Pacific, the current event ranks about 7th strongest since 1950 (based on the Oceanic Niño Index, or ONI).

If you focus on the 2nd and 4th charts, which date back to last December, you’ll see that the Niño 3.4 region has been slowly strengthening, while the 1+2 region (bottom) has been strong for months. (NOAA)

However, if you look at another dataset called the Multivariate ENSO (El Niño) Index, or MEI, this event is only the 9th strongest since 1979 (which is probably around the 14th or 15th highest since 1950). Why am I sharing these data points with you? Well, the ONI is looking purely at ocean temperature. The MEI is typically a better index in that it factors in other variables, which we would liken to how the atmosphere is responding. So the ONI can be a proxy for ocean response, whereas the MEI can be a proxy for atmospheric response. To this point, the atmosphere has not yet responded to the same extent as the ocean has.

But that may finally be changing. I shared the chart above showing the sea-surface temperature anomalies in the various different El Niño regions of the Pacific to highlight the differences between the 1+2 region (bottom panel, which is the eastern Pacific) and the 3.4 region (2nd panel from top, which is closer to the International Dateline.). The eastern Pacific has been revved up since spring. The central Pacific took a bit longer, but it finally appears to have hit a level where it should allow for El Niño to become the more dominant feature for global weather.

And if anything, this event is likely to intensify further in the next couple weeks. So if you’ve been wondering if this El Niño was going to show up like a typical strong El Niño, there may be reason to assume it will.

What does that mean? No relationship is perfect, but in general, El Niño has a decent correlation to a couple key elements here in North America.

El Niño relationships typically yield a cool, damp Southern U.S. and a warm North. (NOAA)

Generally, we see a cooler, wetter Southern U.S. and northern Mexico, as well as a milder Canada and northern tier of the U.S. into Alaska. Usually more storms will crash into California during El Niño winters. Sometimes, like in 2015-16 that isn’t the case. But on average, it is. Seasonal climate models are fairly confident in a warm North/cooler South but a bit split right now in terms of how they view precipitation. An American climate model, the CFS, shows a rather classic wet California and wet Texas through Southeast. The European model has the second part but shows near-normal to just slightly above average precipitation in California.

The bottom line at this point is with El Niño strengthening, one should expect the atmospheric response to also strengthen over the next couple months. And with a rather strong El Niño in place, that response would probably look similar to what is typical in El Niño as shown above. Of course, there are risks as noted, as well. I also think there are wild cards.

If you look at sea surface temperatures around the world right now, virtually all Northern Hemisphere oceans are warmer than normal.

Sea-surface temperature anomalies show almost the entirely Northern Hemispheric ocean system warmer than normal, and in some cases record warm for this time of year. (Weather Bell)

Why does this matter? We are in a bit of uncharted territory. One of the big reasons El Niño is such a big deal is not just because where it occurs is so important to global weather but also because it’s often so anomalous relative to other global sea surface temperatures. It becomes a dominant feature. Well, what happens when you trigger an El Niño on a planet with a lot of oceanic temperatures that are also extremely warm, relative to average? We’re going to find out this winter. While the smart money is probably still on El Niño leading to El Niño things, there is at least some chance the typical impact could be perhaps a bit muted because the majority of the planet is so much warmer than normal. Would I bet on that? No. Am I watching it as a forecaster? Yes.

Suffice to say, we live in interesting times.

November 2, 2023 Outlook: Invest 97L running out of time and a site update!

With the Atlantic tropics (and Pacific to a lesser extent) quieting down now, our schedule at The Eyewall will take on more of a “less regular” pattern. We will update on significant US or late season tropical weather events, and we’ll work to incorporate some suggestions for other content we can offer. For now, expect at least a post on Mondays to table set the week ahead.

Our ultimate goal is to be a daily one-stop shop for weather news and notes, with a focus on hurricanes. Sort of like “The Morning” or whatever other favorite morning newsletter you use — but for weather. So look for coverage of major storms, cold outbreaks, blizzards, etc. irregularly (for now) in the coming months.

And please, continue to spread the word to your friends and family. We’ve had a great first few months building up a base thanks to our coverage of storms like Lee in Canada, Idalia in Florida, and Hilary in the West. Our top cities for viewers come from Houston obviously but also Dallas, New York, Halifax, Chicago, Atlanta, Miami, and Boston.

My two favorite posts so far have been our in depth look at what has fueled an increased frequency of major Gulf hurricanes, as well as our post explaining why Hurricane Otis did what it did recently to Acapulco. We will recap the Atlantic season next month when the final tally is in.

Feel free to offer any suggestions for things you want from us in the comments. Or things you don’t want! We can’t promise anything, but we’ll do our best to work in suggestions.

Continue to give us a follow on our social media platforms, as we’ll update those periodically through the next few months as well.


Thanks for your support in our first 5 months, and here’s to our future growth!

One-sentence summary

Invest 97L now seems unlikely to develop, but it will bring a healthy amount of rain and flooding risk to Central America in the coming days.

Invest 97L: Probably out of time to develop, but will still bring big rains to Central America

In the words of the legendary Hall & Oates, “I’m out of time.” Or at least that’s what Invest 97L is saying at this point.

Invest 97L is struggling mightily this afternoon. Development chances have dropped to a paltry 20 percent with this system as it approaches Central America.

There is an invest somewhere in here, but it seems highly unlikely to organize. (Tropical Tidbits)

And judging by the satellite picture I pinned above, even 20 percent might be generous. Whatever the case, an area of disorganized showers and thunderstorms will approach Central America over the next few days. Two things: First, credit to the European model for being very lukewarm on organization with this, whereas the GFS was quite bullish on intensity. Second, this remains a heavy rain and flooding threat for Central America and places ringing the Gulf of Honduras. Rain totals as forecast by various models continue to show anywhere from 5 to 15 inches or even more in spots. I am most concerned about the coast of Honduras, Guatemala, and Belize, as well as far northern Nicaragua.

Rain totals will be significant in Central America, even if 97L never organizes. Flash flooding, mudslides, and problems are likely in this region. (

Rain of this magnitude will likely lead to flash flooding, as well as the potential for mudslides in these areas. And this assumes little to no organization of 97L, so as we have been highlighting, we can view this as a big time rainmaker.

Elsewhere, both the Atlantic and Pacific look quiet over the next week, with no real land issues expected.

The rest of the U.S. looks pretty quiet with no significant extremes in temperature expected over the next 5 days or so. Rain will continue but should be manageable in the Northwest. Mountain snow, not atypical for November will continue in the interior West at times.