Wednesday, May 25, 2011

Week in Review: Tornadoes across the Midwest

It was quite the active weekend across the Twin Cities metro area for storms.  From a forecasting standpoint, it was very frustrating trying to predict when and where storms were going to initiate because off morning rains and cloud cover, we never got the heating that is usually required to get the instability and violent storms.  This was definitely not a textbook case for favorable severe weather conditions.  Saturday saw enough afternoon heating to create storms that did put down a brief tornado in the city of Medina and Sunday had enough wind energy to keep storms turning, which produced a 14-1/4 mile EF-1 tornado across St. Louis Park, Golden Valley, northern Minneapolis, Fridley, and Blaine.  The Minneapolis tornado ended up being the weakest of the weekend tornadoes if you can believe that.  The storm system also produced tornadoes in Midwestern cities such as La Crosse, Wisconsin (EF-2) and the hardest hit area, Joplin, Missouri, which took the brunt of an EF-5 tornado.  The tornado has killed at least 125 people as of this writing.

TWC Severe Weather Expert, Dr. Greg Forbes (Find him on Facebook) now says the Joplin, Mo. tornado is the deadliest single U.S. tornado in 64 years, since 181 were killed in Woodward, Okla. on Apr. 9, 1947.

Top 10 deadliest tornadoes

  1. Mar. 18, 1925 (Tri-State Tornado): 695
  2. May 6, 1840 (Natchez, Miss.): 317
  3. May 27, 1896 (St. Louis, Mo.): 255
  4. Apr. 5, 1936 (Tupelo, Miss.): 216
  5. Apr. 6, 1936 (Gainesville, Ga.): 203
  6. Apr. 9, 1947 (Woodward, Okla.): 181
  7. Apr. 24, 1908 (Amite, La., Purvis, Miss.): 143
  8. May 22, 2011 (Joplin, Mo.): 125
  9. Jun. 12, 1899 (New Richmond, Wisc.): 117
  10. Jun. 8, 1953 (Flint, Mich.): 115

On Tuesday, more deadly tornadoes spawned across the south in Oklahoma, Kansas, and Arkansas. These storms killed 13 people and brought the death toll for 2011 at more than 500 with 501 fatalities reported.  The hardest hit area from these storms was the Oklahoma City metro, where a family of at least EF-3 tornadoes touched down.

Wednesday brought the second consecutive day of severe weather to the Midwest states with several tornadoes across Missouri – including the Kansas City and St. Louis metro areas.


As of May 24th, there have been over 1,200 this year.  The country typically averages around a 1,000 per year and we are not even into the summer months yet!


What’s the cause of all these particularly violent storms this year?  La Nina is said to blame, but a new study shows that the affects of the surface sea temperature phenomenon on tornado activity is inconclusive:

What is the current understanding of La Niña effects on US tornado occurrences? There are suggestions that winter (January-March) tornado counts may change their preferred geographical location depending on the phase of the El Niño/Southern Oscillation (ENSO). However, that study's analysis covering 1950-2003 found that neither the frequency of tornado days nor of violent tornado days (days with 5 or more F2+ tornadoes) is affected systematically by the phase ENSO for the US as a whole. A separate investigation that used data for a shorter period of 1950-1992, but covering all seasons, argued that La Niña events increase tornadic activity in the Ohio River Valley and the Deep South during spring, and that La Niña facilitates large tornadic outbreaks and is associated with more destructive storms.

It’s been a rather unbelievable year so far with an unprecedented amount of death and destruction, particularly to metro areas.  Hopefully this year will break the myth that metropolitan tornadoes can’t happen.  There is not such thing as a shield.  Tornadoes touchdown wherever the conditions come together, whether it is the middle of nowhere or a downtown district.  We still have more open land than cities across the United States, so that’s why you hear more reports (or go unreported) of tornadoes in rural areas.  That might also explain the spike in tornadoes over the last 50-60 years.  Urbanization and the advancement of technology in the information age makes it difficult for any tornado to go undetected anymore.

As we head into June, I recommend checking your insurance policy of your dwelling and make sure you’re adequately covered - that includes renters.  If you have not purchased a NOAA weather radio this year, I HIGHLY, HIGHLY recommend it.  It’s the cheapest form of life insurance you can buy for yourself and family.  Outdoor sirens were meant to be heard OUTDOORS, and as we saw in Washington County over the weekend, they can be prone to failure.  Sign up for free cell phone alerts from Cell Warn (texting rates apply).  From my observations with the Minneapolis tornado, there were far too many people that did not have the early warning.  Don’t let that happen to you!


No comments:

Post a Comment