Another Round of Severe Weather Threatens Eastern U.S.

Predicted thunderstorms could spawn tornadoes from astern Iowa to western Pennsylvania

The Storm Prediction Center has forecast possibility of severe thunderstorms Tuesday afternoon and evening from the northern Plains across the Upper Midwest and Ohio Valley and into the Northeast and New England. The primary threats will be large hail and damaging winds, especially from eastern Iowa to western Pennsylvania. Some of the storms could produce isolated tornadoes: NWS

Significant Tornado Probabilities

Any Severe Probabilities

Excessive Heat Watch

Meantime, NWS has issued Excessive Heat Watch for southern Nevada, SE California and large portions of Arizona, as drought maintains intensity across the region.

Expected High Temperatures (degrees F)

LAS VEGAS (MCCARRAN INTERNATIONAL AIRPORT)  ~ 113 to 115
MESQUITE AND THE COLORADO RIVER VALLEY ~ 115 to 123
PAHRUMP  ~  110 to 112
BARSTOW   ~ 112 to 115
MORONGO BASIN   ~ 108 to 115
DEATH VALLEY  ~  125 to 127
KINGMAN  ~  107 to 110

[Source: NWS]

Mega Tornadoes to Bombard U-S Tornado Alley

2011 Tornadoes Ever Deadlier: FEWW

Start of Meteorological Spring Signals Hyper Tornado Season

Based on several climatic indicators and recent weather trends, FIRE-EARTH forecasts a deadly peak tornado season in 2011.

“Tornado reports are already coming in,” says the National Weather Service forecast offices.

“Tornado Alley should be geared up. Typical peak tornado season runs from late winter through mid summer. The peak period for tornadoes in the southern plains runs from May to early June. On the Gulf coast, it is earlier during the spring. In the northern plains and upper Midwest, it is June or July. Remember, tornadoes can happen any time of year if the conditions are right.”

The Maximum Threat

The following map shows the time for maximum probability of significant tornadoes.

Time for maximum probability of significant tornadoes (F2 or greater). Source: Severe Thunderstorms Climatology

Time for maximum probability of tornadoes. Source: Severe Thunderstorms Climatology

1. Tornado
2. F2 or greater (significant) tornadoes
3. Wind
4. Hail

Monthly Probabilities

Any Tornado	Signif. Tornado (F2-F5)	Violent Tornado (F4-F5)
Java animation	Java animation	Java animation
Monthly frames	Monthly frames	Monthly frames
January	January	January
February	February	February
March	March	March
April	April	April
May	May	May
June	June	June
July	July	July
August	August	August
September	September	September
October	October	October
November	November	November
December	December	December

The probability of having one or more days with a tornado within 25 miles of a point sometime during a month. The base data for all tornadoes are the reports from 1980-1994 and for significant and violent tornadoes are the reports from 1921-1995. The values are probabilities in percent. Source: Severe Thunderstorms Climatology

F5 and EF5 Tornadoes of the United States: 1950-present

[Storm Prediction Center]

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• Tornado FAQs

Tornado Stats:

• Deadliest U.S. tornadoes: The “Tri-state” tornado of 18 March 1925 killed 695 people along a 219 mile track across Missouri, Illinois and Indiana, causing F5 damage. The 25 deadliest tornadoes on record are listed here.
• The deadliest U.S. tornado days: On 3 April 1974, a “Super Outbreak” of tornadoes killed 308 people. Two lists of the top 15 deadliest tornado days since 1950 are posted here.
  • First, from midnight to midnight CST (by calendar day, Central Standard Time),
  • Then from 12 UTC to 12 UTC (the “convective day” for SPC outlooks)

• Biggest outbreak of tornadoes: Some 147 tornadoes touched down in 13 U.S. states on 3 and 4 April, 1974. See map here.
• The biggest known tornado: “The Hallam, Nebraska F4 tornado of 22 May 2004 is the newest record-holder for peak width, at nearly two and a half miles, as surveyed by Brian Smith of NWS Omaha. This is probably close to the maximum size for tornadoes; but it is possible that larger, unrecorded ones have occurred. “
• Single month with the most tornadoes: Tornado record was set in May 2003, with 543 tornadoes touchdowns confirmed . Previous record was 399, set in June 1992 (modern tornado records began in 1950).
• The strongest tornado/ the highest wind speed in a tornado: Not Known! “Tornado wind speeds have only been directly recorded in the weaker ones, because strong and violent tornadoes destroy weather instruments. Mobile Doppler radars such as the OU Doppler on Wheels have remotely sensed tornado wind speeds above ground level as high as about 302 mph (on 3 May 1999 near Bridge Creek OK)–the highest winds ever found near earth’s surface by any means. [That tornado caused F5 damage.] But ground-level wind speeds in the most violent tornadoes have never been directly measured.”
• The costliest tornado: The Topeka (KS) tornado of 8 Jun 1966 is believed to be the costliest. The tornado caused damage estimated at  $1,599,537,000 in 2007 dollars, after adjusting for inflation. “The Bridge Creek-Moore-Oklahoma City-Midwest City, OK, tornado of 3 May 1999 currently ranks first in actual dollars but third when inflation adjusted.  A list of  top-10 tornado damage in 2007 dollars is posted here. SOURCE: Storm Prediction Center