Weather Talk: Sunday's severe weather
POSTED: Monday, November 18, 2013 - 4:21pm
UPDATED: Monday, November 18, 2013 - 6:33pm
(KETK) - Tyler Tx —
This past Sunday, a powerful storm system moved across the Midwest and Ohio Valley regions. As early as 8:40 AM Central Time, the first Tornado Watch was issued for much of Illinois and a few counties in surrounding states. This set up was going to be a day that people would never forget.
The Storm Prediction Center (SPC), who is responsible for issuing the possibility of a severe weather outbreak, had the Midwest/Ohio Valley under a risk of severe storms as early as Thursday, November 14. Forecasters were already beginning to talk about the potential for this weather system to be a possibly severe weather situation. By early Sunday morning, the SPC had put much of Illinois and Indiana under a High Risk of severe weather. It is only during significant weather events that the SPC will issue a High Risk. This means that the chance of seeing tornadoes within 25 miles of any given point is between 30-60%, and that’s good confidence.
Multiple reports of tornado touchdowns across that region and the members of the National Weather Service will be out surveying damage on Monday. As of blog post time, the number of people confirmed dead was at seven.
Severe Weather Season(s)
In the United States, there are two severe weather seasons, Spring and Fall. The Spring season is considered the primary severe weather season because of the favorable jet stream pattern when we are making a transition from colder to warmer conditions and it is just the opposite for the Fall. We transition from warmer to much colder conditions.
November is the peak month in the Secondary Severe Weather Season. The battle of cold air versus warm air clash, and along with lots of upper level wind supporting the mixing of these two airmasses, severe storms become more likely to occur. Take a look at the graph below provided by the Storm Prediction Center. In the past 8 years, the highest peak of tornadoes during this secondary season is November. It just goes to show how quickly the weather can change across the United States.
East Texas November Weather Outbreaks
Since 2000, there were 4 major severe weather days in East Texas. They are the following:
• November 17, 2003
• November 23, 2004
• November 27, 2005
• November 8, 2011
The one you will recall most recently was the 2011 storm. There were multiple reports of tornadoes that touched down in Nacogdoches County on that day. Specifically 5 miles Southwest of Mount Enterprise that was rated an EF1 with winds at 90 mph. Just a hour later another tornado touchdown 3 miles West of Mount Enterprise. This one was rated an EF-0 with winds at 80 mph. Other reports included a downburst—a localized area of winds caused by air flowing down and out of a thunderstorm—occurred in Wood County in the city of Winnsboro. Most of the damage was done to chicken houses in the area with winds near 85 mph.