Buresh Blog: Can you say Derecho?! .... August skies

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The “Buresh Blog” will take a week off returning the week of Aug. 24th.

An intense band/cluster of severe t’storms - known as a derecho - rolled across parts of the Midwest Monday (08/10) from Nebraska & Iowa to Indiana, Michigan & Ohio. There were numerous wind gusts of more than 70 mph & a few gusts of 90 - 110 mph! Damage was serious & widespread but there have no confirmed fatalities & only a “handful” of injuries. Damage to property & crops will be in the billions of dollars. While not necessarily common, derecho events are by no means rare either (2nd image below). Definition by NOAA:

  • A derecho produces a swath of particularly damaging thunderstorm winds (specifically, wind gusts of at least 58 mph along most of its length with several well-separated 75 mph or greater gusts) over an area at least 250 miles long.
    • These are primarily classified as straight-line winds rather than tornadic.
    • Even so, wind speeds in a derecho can exceed 100 mph which is equivalent to that of an EF1 tornado but over a vastly larger area than a tornado would impact.
    • Tornadoes can also be embedded within derechos and produce concentrated areas of even more intense damage.
    • Derechos develop in an environment with very warm and moist air at the surface, colder air aloft, and moderate to strong winds at upper levels of the atmosphere.

See more info, radar imagery, pics & maps at the following N.W.S. web sites:

Des Moines, Iowa

Quad Cities, Illinois

Chicago

Milwaukee

Fantastic weather info. from Cedar Rapids t.v. station KGAN as the derecho moved through Benton Co. showing a sharp pressure drop as an embedded meso-low moved overhead. The red line is air temp., the green line dew point. They also measured a wind gust to 99 mph before a window was blown out & the anemometer had to be turned off.

My 81-year old dad helping clean up a friend’s damaged tree in Tama, Iowa:

The photo below is from Toledo, Iowa & is the Middle School I attended “back home”. The second photo is the local car wash.

August/early September skies:

(From skyandtelescope.com)

Aug. 11–12 (all night): Perseid meteor shower peaks. Last-quarter Moon rises around midnight, but meteors will start appearing soon after nightfall. Factoring in moonlight, expect 30-50 meteors per hour from a dark location. Some Perseids can be seen on the nights before/after the peak.

Aug. 13 (morning): The waning lunar crescent rises less than 4° from bright star Aldebaran, the Eye of the Bull (Taurus).

Aug. 15 (dawn): A thin waning crescent Moon and Venus are about 3° apart. Castor and Pollux are to their lower left.

Aug. 22 (dusk): The waxing crescent Moon is 5° from Spica, Virgo’s brightest star.

Aug. 25 (dusk): The first-quarter Moon is about 5° from the red supergiant star Antares, the heart of the Scorpion.

Aug. 27 (dusk): The Moon, Jupiter, and Saturn form a line above the southern horizon.

Aug. 28 (dusk): The waxing gibbous Moon hangs some 2° below Jupiter, with Saturn to the pair’s left.

Aug. 29 (dusk): The fattening Moon has leapfrogged over Saturn, and the Moon, Saturn, and Jupiter form a graceful arc.

During August, Jupiter and Saturn dominate the southeastern sky after sunset. The Moon is near them on the evenings of August 28th and 29th. Credit: Sky & Telescope

Sept. 5 (evening): The waning gibbous Moon and Mars rise together as a close pair, getting closer as they climb higher. The Moon glides under the planet as seen in North America, but some parts of the world will see it occult (cover) Mars.

Sept. 9 (dawn): The Moon lingers just outside the Hyades star cluster with the Pleiades cluster to its upper right.

Moon Phases

Last Quarter - August 11, 2:45 p.m. EDT

New Moon - August 18, 10:42 p.m. EDT

First Quarter - August 25, 1:58 p.m. EDT