WFO Paducah Science Page

Radar image of May 6, 2003 supercell

Radar image of the May 6, 2003 tornadic supercell in Massac County, IL

Information on Local Studies and Presentations

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

NOAA Education for Students

NOAA Education for Teachers

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Note: The information in this section has not been peer reviewed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.

Severe Weather Timeline for WFO PAH 2000-Current

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

2000

2001

X(F)

2002

X(F)

2003

X(F)

2004

2005

2006

2007

X(F)

2008

2009

2010

This table indicates the number of months when severe weather (TOR, SVR, FFW) occurred anywhere in the WFO PAH CWA from January 2000 to September 2008. An "X" indicates that severe weather was reported during that month.An X(F) indicates flash flooding only. Severe weather is defined as tornadoes, hail ¾ inch or larger, thunderstorm winds 58 mph or greater.

Longest streak with severe weather =18 months (Apr 2001 – Sep 2002)

Longest streak without severe weather = 3 months (Dec 2003 – Feb 2004)

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.

graphic of the Paducah weather office county warning area

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.

National Weather Service Weather Forecast Office