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Total Solar Eclipse Weather Forecast: Will Your View Be Blocked?
Published: August 14, 2017
We are about one week away from the first total solar eclipse in the Lower 48 states in over 38 years, and meteorologists are getting a look at the overall weather pattern that may be in place and could determine whether you'll get a clear view of this historic event.
A swath from Oregon to South Carolina will see the moon completely mask the sun Aug. 21. Nearly all other parts of North America – as well as parts of South America, Africa and Europe – will see at least a partial eclipse.
The eclipse will start mid-morning in the Pacific Northwest, around midday in the nation's heartland and early afternoon in the Southeast, ending in the Lower 48 states after 4 p.m. EDT.
First: Thunderstorms and the Eclipse
In summer, we don't typically have large-scale storm systems that can sock in dozens of states with clouds and precipitation as we do in colder months.
That leaves us with, for the most part, thunderstorms.
A single thunderstorm won't last long enough to affect the entire two- to three-hour viewing period of the eclipse in any given area.
However, one of these stray thunderstorms could be so poorly timed it occurs over part of the area seeing an eclipse for the roughly two- to three-minute period of totality.
(MORE: NASA's Eclipse Timing Maps)
Posing more of a threat to block out the eclipse, clusters of thunderstorms known as mesoscale convective systems – MCS, for short – are common in the summer. Their rain or cloud shield can linger over a given location for more than an hour.
However, these clusters are typically more active during the nighttime and early-morning hours – not necessarily during the early-afternoon hours, when the August eclipse will occur in the central and eastern U.S.
Forecast: What We Know Now
We are beginning to enter a timeframe where the forecast weather pattern for the eclipse is becoming a bit clearer.
That said, specific details are still uncertain regarding exactly where clusters of storms, or even sufficient cloud cover, could blanket the view in some locations roughly a week from now.
Here's a look at how things are shaping up by region at this moment.
Next Monday's Forecast
Without suppressing high pressure overhead, scattered thunderstorms seem a good bet from the central Appalachians to the northern Gulf Coast, including the Florida Peninsula, as is typical on a summer afternoon.
The eclipse will take place in the early to mid-afternoon hours along the East Coast, typically the time during which thunderstorms will flare up.
So, if this pattern holds, you may have to cross your fingers poorly-timed thunderstorms don't block your view.
A subtle dip in the jet stream will reside near New England, which could lead to a few showers, and therefore, cloud cover in some areas.
Right now, areas near the Canadian border may have the highest odds of having their view obscured.
Usually, thunderstorms in late August are most numerous in the northern tier of states, near the jet stream.
If this jet stream pattern holds, this could mean parts of the Midwest and Plains may have to deal with thunderstorm clusters.
Those clusters of storms could rumble through parts of the path of totality in Nebraska, northeast Kansas, Missouri and southern Illinois.
However, the timing of the eclipse in the nation's heartland, roughly midday into early afternoon, may allow any morning thunderstorm cluster(s) to die off by the time the eclipse happens.
It's currently too far out in time to determine the exact placement of any remnant thunderstorm clusters and/or the cloud cover associated with them.
Southern Plains/Lower Mississippi Valley
Farther south in the central states, the thunderstorm chances are typically less in late summer, and that may hold true on Aug. 21.
High pressure aloft is forecast to be in place across the south-central states, which may suppress cloud cover and thunderstorm chances in much of Oklahoma and Texas.
There may be slightly greater odds for showers and storms farther east into the lower Mississippi Valley.
The timing of the eclipse works to the West's advantage.
There should be plenty of afternoon thunderstorms from the Rockies to the Desert Southwest, as is par for the course in August.
However, a late-morning/midday eclipse should avoid most of those pop-up thundershowers.
The only hiccup may be some areas of low clouds near the West Coast in areas where winds blow onshore, if they remain stubborn enough to linger into the late-morning hours.
What About a Hurricane or Tropical Storm?
One wildcard is tropical cyclones.
Upper-level winds can spread a canopy of clouds over areas far from the center of a tropical storm or hurricane.
(NASA/Jeff Schmaltz, MODIS Rapid Response Team)
Just the remnant moisture of a former tropical storm or hurricane can either trigger more numerous thunderstorms or block the eclipse with clouds.
This can not only occur in the eastern and southern U.S., but also with remnant eastern Pacific tropical cyclones in the typically sunnier Desert Southwest.
But the chance of a hurricane or tropical storm affecting the U.S. on any particular day during the hurricane season is small.
In the satellite era, since 1966, there have been only four tropical cyclones active very near or over the U.S. on Aug. 21.
- Tropical Storm Fay (2008): Florida
- Hurricane Bret (1999): Cloud shield over Texas coast; made landfall the next day
- Tropical Storm Charley (1998): Again, cloud shield over Texas coast; landfall the next day
- Tropical Storm Dottie (1976): Had weakened to a tropical depression over South Carolina
For now, we don't see any obvious threats for the U.S. from a tropical storm or hurricane for Aug. 21, but, as with other weather, that scenario can change.
Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Facebook and Twitter.
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