April 12, 2024

The latest weather forecast along the total solar eclipse path

This article is part of a special report about the total solar eclipse that will be visible from parts of the US, Mexico and Canada on April 8, 2024.

Millions of people living in the 115-mile-wide path of the April 8 total solar eclipse — and the millions more who will travel to witness the awe-inspiring astronomical event — are crossing their fingers that the weather will cooperate.

For those anxiously refreshing the weather forecast page, the hard news is that cloud cover and precipitation are much harder to predict than temperature. This is because the former involves so many small-scale processes in the atmosphere, and each of these factors can change rapidly, from hour to hour and even from minute to minute. These processes “are incredibly difficult to predict, even in real time,” says Greg Carbin, chief of forecast operations at the National Weather Service’s (NWS) Weather Prediction Center. So even on the day of the eclipse itself there will not be total certainty; When skies are mostly clear, stray clouds can still pass by during the few minutes of totality (as this writer frustratingly happened to while watching the 2017 solar eclipse in Nashville, Tennessee).

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To help avid eclipse observers prepare, Scientific American maintains the daily forecast for the U.S. path of totality – which begins at approximately 1:27 PM CDT in Eagle Pass, Texas, and ends at approximately 3:35 PM EDT in Houlton, Me. – and provides detailed information for a few major cities below. However, forecasts are likely to change, and when they do, we will update this article. So be sure to come back as the big day approaches.

Based on climatology (the long-term average weather conditions in a given place at a given time of year), the best bet for clear skies will be in Texas, with the likelihood of cloudy conditions increasing as one moves along the eclipse path toward moves northeast. But these expectations, as shown in the chart below, are just an average. The weather is inherently chaotic, especially in spring. But current forecasts suggest that the weather on the day of the upcoming solar eclipse could reverse the climatic pattern.

Credit: Katie Peek; Source: NASA (eclipse track data)

In general, dry areas like southern Texas are more likely to have clear skies this time of year because there is less moisture available to form clouds. But near the Great Lakes and in New England, soil soaked by spring rains and persistent snow can provide enough moisture for clouds, especially when relatively warm spring breezes blow through and promote evaporation.

April is part of “the transition season from the cool to the warm season,” says Carbin, noting that “the transition seasons are notoriously difficult times to predict weather.” In part, this is because the jet stream – the vast high-altitude river of air that guides storm systems across the continent – ​​covers much of the north-central US. Storm systems have a greater degree of forecast uncertainty than stable air. high-pressure masses, which generally bring clear skies. This year is particularly tricky, Carbin says, because the currently active El Niño climate pattern means that another jet stream, known as the subtropical jet, is relatively active over the southern part of the country.

The forecast right now shows a low-pressure system moving into the Mississippi Valley on Monday – and these systems often bring clouds and precipitation. There is also an associated front, which separates warm and cool air masses, and extends into the south-central US, where it is expected to linger. Clouds and rain will impact the area ahead of the front and could lead to severe weather in the path of the total solar eclipse in northern Texas.

Across the entire path of totality across the U.S., rain chances are currently highest in southeastern and south-central Texas, with lower chances between Arkansas and western New York State. The lowest odds are in New England. Likewise, cloudy conditions will be highest from south-central Texas to Arkansas and in the lower Great Lakes, according to NWS. The best chances for clear skies are between southeastern Missouri and central Indiana and northern New England.

But it’s still a few days away, and how quickly the storm system moves across the country will determine who gets clouds and rain and when. With each run of the weather models, the system has shifted a little further east, Carbin says. If this trend continues, conditions in the Midwest could improve.

Graphic solar eclipse

Key messages for the 2024 total solar eclipse.

Credit: NOAA’s Weather Prediction Center

Even as the broad patterns of the jet stream and air mass movement become clearer as Monday approaches, “the devil is in the details,” Carbin says. At best, forecasts on any given day may still only reflect expected hour-by-hour conditions – and the eclipse will occur on the scale of minutes. It is impossible to say exactly where a downpour or a puffy cloud will emerge. Carbin compares it to a pot of boiling water: you know bubbles will form, “but can you predict where that first bubble will emerge?”

For those who do expect cloudy skies on Monday, all is not necessarily lost: the NWS maps don’t say so what kind of clouds may be involved. Rainy, overcast skies will certainly hamper visibility, but “high cloud cover alone may not block the eclipse,” NWS meteorologist Cody Snell said during a briefing held by the agency on Wednesday. “So even if there is some cloud cover in the forecast, all hope is not lost on seeing this astronomical event.”

And the eclipse itself could even be a blessing if puffy white clouds prove to be the only potential eclipse: A recent study found that in a 2005 solar eclipse over Europe and Africa, low-level cumulus clouds actually disappeared during the event. Such clouds form when warm, moist air rises from the ground, cools and condenses into droplets. Blocking the sun’s rays by a solar eclipse can quickly drop the land’s surface temperature, disrupting the cloud formation process.

Below are the current forecasts for selected cities in the eclipse’s path.

San Antonio, Texas (Totality starts around 1:30 PM CDT)

Cloud cover in the area is currently expected to be around 60 to 80 percent, increasing as one moves from the northwest to the southeast, with a chance of rain and storms.

Dallas, Texas (1:40 PM CDT)

Low, dense clouds are expected in parts of the area, and at least some high clouds are likely. The lower cloud will spread northwards during the day, but the exact timing of this is uncertain.

Little Rock, Ark. (1:50 PM CDT)

Clouds and stormier weather will likely prevail in parts of southern Arkansas, with drier and clearer weather likely in the northern part of the state.

Indianapolis (3 p.m. EDT)

This forecast is quite uncertain, with some concerns about cloud cover during the eclipse, but the timing of the low pressure system’s passage over land will be a big factor.

Cleveland (3:15 PM EDT)

The chances are favorable for clouds and possibly some rain, but conditions will depend on the timing of the low pressure system.

Burlington, Virginia (3:25 PM EDT)

Clear, sunny skies and mild weather are expected.

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