04/25/11 Unusual Moderate Risk

Today the Storm Prediction Center issued something that has only been issued 10 times in history.....and it's going to happen here. They issued a Moderate Risk of severe storms for the third outlook day. Since 2000, only 9 other Day 3 Moderate Risk outlooks have been issued since the SPC, which highlights just how rare this occurrence is. Here is a breakdown of the 9 times SPC has issued Day 3 Moderate risk outlooks:

Day 3 Moderate Risk Outlooks (01 January 2000 – Present)

• ** June 8, 2005 (Southern High Plains)
• ** December 31, 2005 (Southeast US)
• April 22, 2007 (Southern Plains)
• June 4, 2007 (Northern Plains)
• June 5, 2007 (Upper Midwest)
• **October 16, 2007 (Upper Midwest)
• April 8, 2008 (Southern Mississippi Valley)
• May 11, 2009 (Missouri/Illinois)
• April 8, 2011 (Upper Midwest)
• April 27, 2011 (Tennessee/Alabama/Kentucky)
• ** denotes Day 3 Moderate Risk that does not meet the current criteria for a Day 3 Moderate Risk. Prior criteria allowed for a probability of 30% of any type of severe weather occurring within 25 miles of a point.

Having a Day 3 Moderate Risk issued for our area does not guarantee that significant weather will occur all throughout Middle Tennessee. However, it should be noted that as rare as this is, and the fact that the expert severe weather forecasters at SPC have enough confidence to issue one this far in advance, the likelihood of severe weather is quite elevated. Stay tuned to Nashville's New 2 for more details on the storm as we get closer to Wednesday.

Sources: NWS and Patrick Marsh, Ph.D. Univeristy of Oklahoma

An SPC  Moderate Risk category detailed image below: within the 45% area, there has to be  a “Significant Severe” threat area, with a 10% probability of seeing either EF-2+ tornadoes, and/or 65 mph+ winds, and 2"+ diameter hail within that same 25 miles of a point threshold.