Forecasts for cloudy skies cast shadow over North American solar eclipse

Cloudy skies forecast for Monday could spell disappointment for many of the millions of North Americans hoping to glimpse the continent's first total solar eclipse since 2017, potentially transforming this spellbinding celestial phenomenon into a dud.

Some regions that more typically experience clear skies in April within the "path of totality" – the narrow corridor where the moon can be seen obscuring the entire face of the sun – appear to have the gloomiest weather prospects for Monday.

Much of Texas, considered prime eclipse-viewing territory by many traveling there for the occasion, was predicted in forecast models on Friday to have cloud cover of 60 percent – 80 percent on eclipse day.

Parts of northern New England, by comparison, looked far more promising. The probability for clear skies was also improving across the middle Mississippi Valley and western Ohio Valley, including Indianapolis, according to the National Weather Service.

The reversal of fortune is attributed to a storm system moving through the U.S. upper Midwest and an associated cold front, according to Josh Weiss, a meteorologist with the Weather Prediction Center, a branch of the weather service.

Seasonal climate patterns "would suggest that New England and the Ohio Valley would be cloudiest in April, and the southern part of the eclipse path would be the most clear. It just so happens with this weather system it's almost the exact opposite," Weiss said.

Where clear skies prevail, skywatchers along the direct path of the eclipse will be treated to the rare spectacle of the moon appearing as a dark orb creeping in front of the sun, briefly blocking out all but a brilliant halo of light, or corona, around the sun's outer edge.

The period of up to four and a half minutes of totality in the sky will be ushered in by a number of other eerie eclipse effects.

Some stars will twinkle at midday as twilight abruptly descends, sending temperatures dipping and faint waves of "shadow bands" flickering over the landscape. Birds and other wildlife, reacting to the sudden darkness, may fall silent and still.

Eclipse enthusiasts were expected to flock to cities and towns along a slender zone averaging about 185 kilometers wide slicing through Mexico into Texas and across 14 other U.S. states, then into Quebec and four more provinces of Canada.

An estimated 31.6 million people live in the path of totality, compared with roughly 12 million in the last total solar eclipse that traversed the contiguous United States in August 2017, according to NASA.

But less-than-ideal weather forecasts have stirred anxiety for people who have made travel plans, some booking expensive airline and hotel reservations to get what they hoped would be the best possible view.

As of Friday, according to the Weather Prediction Center, clouds were most likely to impede U.S. viewing from Texas into Arkansas and possibly in Ohio, northwestern Pennsylvania and western New York. Overcast skies are likewise expected for much of Mexico.

The best chances of clear viewing in the U.S. are expected in the northern corners of Vermont, New Hampshire and Maine, as well as parts of Canada, and from southern Missouri to central Indiana, the center said.

Weiss also said the forecast would likely change by Monday, though current predictions leaning heavily one way or another will probably harden by then.