Watch out For Those Damn Clouds!
By Jack Williams April 26....
On Aug. 21, the moon will totally block out the sun along a 60-mile-wide
path from Oregon to South Carolina. The last time a total solar eclipse
swept across the entire continental United States was 1979, and the next
time it happens isn’t until 2045. Given the rarity of the event, people
have been making travel plans and booking hotels since last year. But
before you buy the plane ticket, you might want to consider which
destination has the best odds of clear skies in August. The eclipse
begins at 10:15 a.m. Pacific Time near Lincoln Beach, Ore., and races
across the United States until 2:49 p.m. Eastern Time when it crosses
the tip of Cape Romain, just east of McClellanville, S.C., as it heads
out to the Atlantic Ocean. Places north and south of the path of totality
— including all of Alaska and Hawaii, Mexico, Central America and northern
South America — will see a partial eclipse. In the Washington, D.C., area,
for example, the moon will cover roughly 81 percent of the sun.
- Clouds-Be-Gone!
- cloudy.jpg (3.63 KiB) Viewed 4916 times
Unfortunately, while astronomers have been predicting the paths and timing
of eclipses decades into the future, meteorologists can’t say more than a
day or two in advance whether it will be cloudy enough to ruin the show.
Weather events operate on tiny scales from the molecular (latent heat
released when water vapor condenses) to the global (jet stream patterns).
This means small changes in conditions can lead to large differences in
outcomes. Chaos plays a large role in weather forecasts — but not in
eclipse predictions. To decide where to go for the best chance of clouds
not hiding the eclipse, we have to turn to the past. That is, look for
places along its path with the best odds of clear — or at least partly
sunny — skies in August. “The big challenge with a summer eclipse is the
risk of showers and thunderstorms, which are by nature short-lived and
impossible to predict in a pinpoint fashion,” Weather Underground’s Bob
Henson wrote. “Fortunately, the midday timing of the eclipse in the western
and central U.S. should be just ahead of the typical formation time of the
next day’s showers and thunderstorms.” But Henson also notes that mid-August
is also near the peak of hurricane season, which means there’s increased
risk of cloudiness, especially for the Southeast.
Along the South Carolina coast, you could encounter afternoon “sea breeze”
clouds. As the land heats up, warm air begins rising and air from over the
cooler ocean flows inland, feeding humidity into the rising air to form
cumulus clouds. Since the clouds form over warm land, you are more likely
to see the eclipse from the ocean beach than a few miles inland. Coastal
Oregon is the first place the eclipse will be seen, but the most likely to
be clouded over. Nevertheless, if you head inland to the eastern slopes of
the state’s north-south mountain ranges, you find good odds for clear weather.
Humid air flowing in from the Pacific feeds clouds and maybe precipitation
on the mountains’ western slopes, which usually removes much of the humidity
from the air by the time it crosses the mountains. Most of the time this
makes places on the eastern sides of the West’s mountain ranges prime viewing
locations. This isn’t true of the southern Appalachians where it’s much
more humid. In this region, moist air flows in from the Atlantic Ocean or
Gulf of Mexico. If you want to get really specific, Jay Anderson and Jennifer
West developed eclipsophile.org, which is a state-by-state guide to typical
weather along the path of totality.
Arcturus24 on 4/26/2017 2:43 PM EDT posted...
Well, I've already made my travel and lodging plans along the coast of South
Carolina for this eclipse. I guess I could make a slight adjustment and instead
drive to the Snake River Valley of Oregon. Also, I'm surprised there wasn't
the usual obligatory warning in this posting, namely, "DON'T LOOK AT A SOLAR
ECLIPSE FOR ONE NANO-SECOND OR INSTANT BLINDNESS WILL FOLLOW!!!"
Having watched -- even stared at -- the Feb. 1998 eclipse on Guadeloupe, I
haven't lost my vision yet. I never have understood how looking at an eclipse
is intrinsically any worse than looking at the Sun any other time including
at, say, sunset. Sure, staring directly at the Sun for an extended period isn't
perhaps the best idea, but the idea of instant blindness is just silly --
basically, a sort of throwback to Medieval superstitions about eclipses dressed
up to the present era. I would like to see the one on Tristan da Cunha on
Dec. 5, 2048 but I'll probably be dead by then.