Matt Lanza

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.

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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. (Weathernerds.org)

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.

November 1, 2023 Outlook: Tropical rains head for Central America while atmospheric river rains head for the Northwest

One-sentence summary

We continue to watch the rain potential from Invest 97L as it tracks toward Central America, while in the U.S., an atmospheric river event will bring locally heavy rain to the Northwest.

Invest 97L: Still watching development chances, but focused more on rainfall

I think we’ve got a bit of a good news/bad news update this morning. The good news is that Invest 97L looks as if it will not be following earlier GFS operational runs, which had this exploding in the southwest Caribbean. Rather, it will be sort of slow getting its act together. The hope is that this will lower the ceiling on 97L’s potential intensity.

Invest 97L on satellite this morning remains very disorganized and void of a lot of thunderstorms near its center. (Weathernerds.org)

In fact, odds of development from the National Hurricane Center have dropped to 50 percent today.

The bad news is that we are still looking at a pretty substantial rain event for portions of Central America, particularly along the coast along the Gulf of Honduras. How much rain? Well, if you believe most model guidance, it should be double digit totals spread out over a few days.

Forecast rain totals through Sunday from the European model suggest 10 inches or more of rain ranging from the extreme southern Yucatan into Belize & Guatemala and along the coast of Honduras. (Weathernerds.org)

This will be capable of causing flooding, mudslides, and general problems. So regardless of what Invest 97L does, at the very least, it should be a significant rainstorm for portions of coastal Honduras, Guatemala, and Belize, as well as perhaps the southern coastal Yucatan and portions of Nicaragua.

In general, 97L will track west or west-southwest over the next few days on a beeline toward Honduras or Nicaragua. We’ll keep tabs on this over the coming days just in case anything changes and obviously to monitor the flooding risks in Central America.

Elsewhere: Moderate to strong atmospheric river event for the Pac Northwest

Pilar is now on its way out to sea in the Pacific and should no longer be an issue for land.

Tropical Storm Pilar is now on its way out to sea. (Tomer Burg)

Some residual rain or localized flooding is possible on the Pacific side of Central America between El Salvador and Costa Rica before things clear out. At this point, impacts from 97L should stay on the Caribbean side of the coast.

Atmospheric river for the Northwest

An atmospheric river (AR) that looks like it should reach level 3 out of 5 on the AR scale will come ashore in Washington or Oregon later this week. ARs of that magnitude are considered strong but offer a general balance of positive and hazardous impacts. Not quite Goldilocks.

The maximum intensity of this atmospheric river based on research is about a level 3 of 5 into Oregon, making it a “strong” AR. (UCSD Center for Western Weather & Water Extremes)

Widespread flooding is not expected, but some localized urban or small stream flooding is possible. The NWS in Seattle has identified the Skokomish River near Potlatch as a possible flooding candidate as well. Rainfall totals are expected to be on the order of 2 to 5 inches with round one that comes ashore tonight into tomorrow.

Snow levels will be high with this event, so you will be mainly talking rain below 8,000 to 10,000 feet. A second atmospheric river (a weaker one) will arrive Saturday and perhaps a third round follows Monday. But the more potent one will be tonight into tomorrow. When all is said and done next week, look for about 2 to 5 inches of rain in the Seattle and Vancouver, BC areas, 3 to 5 inches in the Portland area, and higher amounts at the coast and in the Cascades.

Significant rain will fall from extreme northern California into British Columbia from this atmospheric river event tonight and subsequent weaker ones this weekend. (Pivotal Weather)

Early season chill

Elsewhere, record cold continues in parts of the Appalachians and Deep South tomorrow morning before things begin settling. One impressive record of note may occur in Caribou, Maine which is forecast to hit 12 degrees tonight and Thursday morning. This would be the second earliest date they’ve been this cold. The only time better was when they hit 12 degrees back on November 1, 1972.

A map of Thursday morning’s forecast lows that are near records. The most impressive would probably be in Caribou, ME which may record their second earliest coldest temperature since 1939. (NOAA WPC)

Brrr! More tomorrow.

October 31, 2023 Outlook: Caribbean’s Invest 97L is likely to bring some sort of impacts to portions of Central America

One-sentence summary

Invest 97L in the Caribbean is likely to deliver impacts to portions of Central America in several days, but the exact issues beyond heavy rain and flooding potential remain unclear at this time.

Invest 97L: A troublemaker for the southwest Caribbean

We finally got the Caribbean disturbance a classification yesterday. It is Invest 97L. As we noted yesterday, this one will bear close watching for folks in Central America in particular.

Invest 97L saw a big flare up in storms overnight that is already weakening. (Weathernerds.org)

Thunderstorms really popped with 97L overnight, but in the last few hours those storms have begun to steadily weaken. In order for 97L to develop, it will need to be able to sustain thunderstorm activity.

In general, 97L is going to be steered west or just south of west around the periphery of high pressure over the open Atlantic. This will take it on a beeline toward Central America. Unfortunately once it gets there, it looks like it may slow down. This could lead to a considerable rainfall event for portions of the region. In fact both the GFS and European operational models, despite vastly different intensity outcomes each produce nearly double digit rainfall totals through early next week in portions of Central America, particularly near the coasts of Honduras, Guatemala, and Belize.

Rain totals of at least 5 to 10 inches seem like a good bet somewhere near the coasts of Honduras, Guatemala, or Belize as 97L (or whatever it is then) approaches. (Weathernerds.org)

So we have two aspects of this system that will give us heartburn in the coming days. The rainfall is one, but the intensity of the storm is another. As I noted above, the GFS and European models have been on different planets in terms of what they do with 97L. The GFS continues to be very aggressive, while the European model is far slower to develop the system.

We often get asked “Well, which one do you believe?” The answer is not so simple. The GFS suite tends to develop more persistent thunderstorm activity with 97L, giving it more time to feed on the extremely warm Caribbean waters. The Euro is less excited about persistent thunderstorms at the core, so it remains a rainmaker but not so much a wind-maker. We’ll get a better sense in the next day or so based on the actual speed in organization of the system.

Again, however, the rainfall forecast is already somewhat concerning, so whether or not this becomes a stronger storm will probably not exempt portions of Central America from some noteworthy impacts. We’ll have more on this tomorrow.

Other news: Pilar, record cold, and a wet Northwest

Tropical Storm Pilar will make its 180 degree turn today on approach to El Salvador, shifting back west out into the open Pacific. Conditions should improve in that portion of Central America.

Pilar will be making a J-turn over the next 24 to 36 hours heading back out into the open Pacific. (Tomer Burg)

Meanwhile, early season cold continues across much of the country. Quite a few spots will threaten record lows tomorrow morning, ranging from the Ohio Valley into Texas. Places like Oklahoma City and St. Louis are forecast to just eke out new records, while about 35 other locations are within a degree or two of records. Temperatures should moderate for the end of the week.

A map of Wednesday morning’s forecast low temperatures that will be near records, featuring just over 35 locations that will be close. (NOAA WPC)

Otherwise, the only real U.S. weather of note for the rest of the week will be a series of storms into the Pacific Northwest that we discussed a bit yesterday.