Published: August 21,2017
The day of the historic, coast-to-coast total solar eclipse is finally here. Unfortunately, clouds could obstruct the view of Monday's for some locations to the east of the Rockies. The Northwest, however, will have optimal viewing conditions with mainly clear skies anticipated.
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A swath from Oregon to South Carolina will see the moon completely mask the sun on Monday. Nearly all other parts of North America – as well as parts of South America, Africa and Europe – will see at least a partial eclipse.
(MORE: See the Eclipse on Our Interactive Map)
Eclipse coverage percentage is shown.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.
(MORE: 10 Best States to See the Total Solar Eclipse)
Overall, the biggest trouble spots for viewing the eclipse may be in parts of the Midwest and northern and central Plains, as showers and thunderstorms rumble through parts of those regions. Portions of the Southeast may also have to contend with scattered patches of clouds.
Meanwhile, much of the Northwest should be free of cloud cover.
Cloud Cover Forecast 2 p.m. EDT Today
Without suppressing high pressure overhead, scattered thunderstorms are possible from the northern Gulf Coast to the coastal Carolinas, including parts of 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, you may have to cross your fingers poorly-timed showers or thunderstorms don't block your view.
Patches of cloud cover may affect other parts of the Southeast, as well. This may be a particular issue in the southern Appalachians, as clouds along with possible showers and storms develop with the heating of the day.
Conditions in the Tennessee Valley, however, are looking good at this time.
Selected Cities In Path of Totality: Nashville, Tennessee | Columbia, South Carolina | Charleston, South Carolina
A few showers or t-storms are possible in from parts of central and western New York into Pennsylvania and possibly as far south as Washington D.C. and the Delmarva Peninsula.
Most of New England should see sunny to partly cloudy skies.
Central OutlookPlains and Midwest
The Plains and Midwest have the diciest weather conditions for viewing the eclipse.
Disturbances in the upper atmosphere will contribute to patches of showers and thunderstorms in those regions on Monday.
(INTERACTIVE RADAR: Where the Storms Are Now)
Those clusters of storms could rumble through parts of the Dakotas, Minnesota, Iowa, Wisconsin, Illinois, Missouri and Kansas. The cloud cover associated with the scattered areas of stormy weather may obscure the view in some areas.
Selected Cities In Path of Totality: North Platte, Nebraska | Grand Island, Nebraska | Kansas City, Missouri | St. Louis, Missouri | Carbondale, Illinois | Paducah, Kentucky
An area of showers from West Texas into the Texas and Oklahoma panhandles may persist, obscuring the view.
Much of the rest of Oklahoma and central Texas are expected to have mainly clear skies.
Farther east, the chance of pop-up showers and storms increases all the way into the lower Mississippi Valley. Just like the Southeast, where showers and storms billow up with the heating of the day will dictate where the view could be obscured for a period of time.
West OutlookThe timing of the eclipse works to the West's advantage.
There will be some 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. In fact, the stripe of totality from Oregon to Wyoming looks virtually cloud-free.
One hiccup may be some areas of low clouds near the immediate West Coast in areas where winds blow onshore, particularly around San Francisco Bay, Monterey Bay and the Southern California coast. If they remain stubborn enough to linger into the late-morning hours, this could impact the view of the eclipse.
Selected Cities In Path of Totality: Corvallis, Oregon | Idaho Falls, Idaho | Casper, Wyoming
Thunderstorms and the EclipseIn 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.
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