WFO Paducah Science Page
Radar image of the May 6, 2003 tornadic supercell in Massac County, IL
A detailed meteorological overview of the May 17, 1999 derecho
A detailed meteorological overview of the May 5, 1996 derecho
- The 4 May 2003 Tri-State Supercells (pdf version; large file)
- Observations of the 17 June 1997 Tornadoes
- Observations of Flow Structure and Mesoscale Circulations Associated with the 5 May 1996 Asymmetric Derecho in the Lower Ohio Valley
- Summaries from various research papers
Information on Studies with Universities (under construction)
Information presented at the National Weather Association Conference in Louisville Kentucky 2008
We collaborate with Murray State University, in particular, the Center for Environmental Education. We created a Thunderstorm and basin exercise. A link is upcoming.
We collaborate with the University of Missouri.
Basic Weather Training:
National Weather Service On-Line Weather School - Jetstream
UCAR Education for K-12
Advanced Science and Safety Training
Basic Winter Processes - Part 1 - WFO LMK
Basic Winter Processes - Part 2 - WFO LMK
Radar Training for Emergency Managers and Other Interested Parties
These presentations will be updated in the spring of 2009.Other major changes coming in the spring of 2009
For information on the NWS radar images (RIDGE) click here
Cool Season Tornadoes
Note: The information in this section has not been peer reviewed
In this part of the country, the tornado season is not the typical April-June time frame. Tornadoes have been recorded in our area every month of the year. In general, severe weather is quite common. The following table gives some basic facts on severe weather in our area.
|
Jan
|
Feb
|
Mar
|
Apr
|
May
|
Jun
|
Jul
|
Aug
|
Sep
|
Oct
|
Nov
|
Dec
|
2000
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
|
2001
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X(F)
|
2002
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
|
X
|
X(F)
|
2003
|
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X(F)
|
|
X(F)
|
|
2004
|
|
|
X
|
X
|
X
|
X
|
X
|
X
|
|
X
|
X
|
|
2005
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
2006
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
|
X
|
|
2007
|
X(F)
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X(F)
|
X
|
X
|
|
2008
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
|
|
X
|
2009
|
|
X
|
X
|
|
|
|
|
|
|
|
|
|
2010
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Source: Storm Data
For those who have lived in this area for a while, this is nothing new. However, if you are new to the area it may come as a surprise that severe weather is so common.
Local and regional studies are on-going concerning the severe weather in the southeast U.S. In this section, we will attempt to give you some insight into this research. At the forecast office in Paducah, we have been studying cool season tornadoes for several years. We consider the cool season to be during the months of November, December, January & February.
For the general public we suggest that keeping an eye on the weather can give you hints as to when tornadoes are possible. If is it warm and humid outside and it is unusual for that time of year...be aware that severe weather may be possible in the next day or two.
To back this statement up, we have been looking at dew point temperatures in Paducah and comparing that with severe weather within our county warning area. The dew point is a measure of the amount of moisture in the atmosphere. During the winter, it may "feel humid" when the dew point temperature reaches 60 degrees. During the summer, we commonly experience dew points in the 70s, but during the winter, when it is generally cool, the days with 60 degree dew points tend to stand out.
This is our county warning area
Here are some results from this study...
Dew Point Climatology for PAH from Nov-Feb 1996-2009 | |||
Category | # of Episodes | Hours | % of All Hours |
Hourly Tds >= 55°F | 2280 | 5.85% | |
Hourly Tds >= 58°F | 76 | 933 | 2.39% |
Hourly Tds >= 60°F | 53 | 663 | 1.70% |
Hourly Tds >= 62°F | 29 | 293 | 0.75% |
Hourly Tds >= 64°F | 14 | 98 | 0.25% |
Thunderstorm Days and Severe Weather Days vs. High Dew Point Events from Nov-Feb 1996-2009 | |||||||
Dew Points | Thunderstorms | Severe Weather | Tornado(s) | >=F2 Tornado(s) | Winds | Hail | FF |
Tds <55 | 30 | 2 | 0 | 0 | 0 | 2 | 4 |
Tds 55-57 | 15 | 5 | 0 | 0 | 5 | 2 | 1 |
Tds 58-59 | 10 | 4 | 1 | 1 | 0 | 3 | 1 |
Tds 60-61 | 14 | 8 | 5 | 2 | 7 | 6 | 2 |
Tds 62-63 | 11 | 5 | 1 | 0 | 4 | 4 | 3 |
Tds >=64 | 11 | 9 | 7 | 5 | 6 | 6 | 4 |
Total: | 86 | 30 | 14 | 8 | 20 | 21 | 15 |
Dew Point Thresholds for Thunderstorms from Nov-Feb 1996-2008 | |||
% of Time | % of Time Severe | % of Time | |
Dew Point Category | T-Storms Occur | Wx Occurs | Tornadoes Occur |
Td >=58 | 61% | 34% | 18% |
Td >=60 | 68% | 42% | 25% |
Td >=62 | 76% | 48% | 28% |
Td >=64 | 79% | 64% | 50% |
Severe Weather vs. Dew Point Thresholds for PAH from Nov-Feb: 1996-2008 | |||||
Weather | >=55° | >=58° | >=60° | >=62° | >=64° |
Severe Weather | 94% | 79% | 67% | 42% | 27% |
Tornadoes | 100% | 100% | 93% | 57% | 50% |
>=F2 Tornadoes | 100% | 100% | 88% | 63% | 63% |
Wind | 100% | 77% | 77% | 45% | 27% |
Hail | 91% | 83% | 70% | 43% | 26% |
Flash Flooding | 73% | 67% | 60% | 47% | 27% |
We also decided to look at some of these numbers with a slightly shortened cool season (November 15 - end of February)
Dew Point Thresholds for Thunderstorms from Nov 15-Feb, 1996-2008 | |||
% of Time | % of Time Severe | % of Time | |
Dew Point Category | T-Storms Occur | Wx Occurs | Tornadoes Occur |
Td >=58 | 59% | 43% | 20% |
Td >=60 | 58% | 39% | 21% |
Td >=62 | 73% | 53% | 27% |
Td >=64 | 100% | 83% | 67% |
So, what does all of this mean? During the cool season the potential for tornadoes increases as the dew point temperature increases. It is rare to get tornadoes if the dew point is less than 58 degrees. However, looking at the data for the past 12 years...when the dew point reached 64 degrees, half the time a tornado was reported somewhere in our county warning area.
This is a very basic study and it is not intended, nor does it, cover every situation. This information is intended to help people understand when severe weather is possible during the cool season in our area.