Posts tagged weather
Posts tagged weather
Derechos are widespread, long-lived windstorms associated with a band of rapidly moving showers or thunderstorms. Coined by Dr. Gustavus Hinrichs in 1888, “derechos”, a Spanish word which means “direct” or “straight ahead”.
Although a derecho’s strength can produce destruction similar to tornadoes, the damage pattern produced by these events will occur along relatively straight lines. Thus the term, straight-line wind damage.
Derechos are produced by long-lived thunderstorm complexes that produce bow echoes, another word for radar signature.
Derechos are produced by a family of downbursts clusters. Downburst clusters have overall lengths of 50 to 60 miles (80 to 100 kilometers).
A downburst cluster itself is made up of several downbursts. A downburst is an area of strong, often damaging wind produced by a convective downdraft with the overall size of the downburst varying from 4 to 6 miles (8 to 10 kilometers).
Within the downbursts are microbursts; smaller pockets of more intense wind.
While not shown in the illustration at right, within the microbursts are even smaller pockets of extreme wind called burst swaths. Burst swaths can range from 50 to 150 yards (45 to 140 meters) long. The damage pattern from burst swaths can often resemble a path of a tornado.
Due to this nature of the derecho, damage produced by these wind storms is highly variable along its path. Damage surveys following derecho events have shown that within large areas of overall damage are much smaller pockets of intense damage.
It is not uncommon for one house to be nearly destroyed while adjacent houses have relatively minor damage.
It is official: This year’s spring was the warmest on record and this May was the second warmest, according to data from the National Oceanic and Atmospheric Administration’s National Climatic Data Center. NOAA scientists found that the average temperature — 64.3 degrees F – for the contiguous US during May was 3.3 degrees higher than the long-term average. All told, the data reveal that, so far, 2012 has been the warmest year-to-date since recordkeeping began in 1895.
In addition, while rainfall totals varied across the nation in May, the US was drier than average as a whole. The nationally averaged precipitation total was 2.51 inches, which is 0.36 inches below average and 37.4 percent of the contiguous US is experiencing drought conditions. The Southwest in particular has been stricken by drought, alleviated somewhat by Storm Beryl, which made landfall near Jacksonville, Fla., on May 28.
A few more facts about how much hotter it is getting:
Overall, 26 states had May temperatures ranking among their ten warmest. Only the Northwest did not see warmer-than-average temperatures; only Oregon and Washington had temperatures that were normal.
31 states experienced record warmth for the season.
The drought and windy created ideal wildfire conditions in the Southwest. Over 210,000 acres of the Gila National Forest in western New Mexico are already charred.
However, some states experienced wetter-than-average temperatures: Oregon experienced record wet and Minnesota and Washington had the third wettest seasons on record.
The June 2011-May 2012 period has been the warmest twelve-month period for any twelve-month period in the contiguous US. In that period, the second warmest summer has occurred as well as the fourth warmest winter and, yes, the warmest spring on record.
It’s official: Gardeners and farmers can count on warmer weather. If that’s you, it might be a good time to rethink those flower and vegetable beds for this year’s growing season.
That’s the word from the U.S. Department of Agriculture, which released a new version of its “Plant Hardiness Zone Map” this week, the first update since 1990. The color-coded zones on this map of the United States are widely used as a guide for what perennial flowers will survive in a particular area, or when to plant your vegetables.
Now the zones have shifted northward. The new map shows that in much of the country, winters aren’t as cold as they used to be, and spring planting comes earlier.
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during daylight hours caused by the stable atmosphere found near its location.