Active Tornado Season = Active Hurricane Season?

[Windtalker1]

A few years ago I tried to find some coralation between an active Tornado Season = An active Hurricane. There really wasn't much scienctific data to support that unless you look at the 2004 & 2005 season. 2004 was the most active season for tornados on reacord. A total of 1717 Tornados touched down in the USA. Previous was 1424 in 1998 and 1368 in 2003. 445 Tornados touched down toward the end of May alone in 2004. The 2004 Season produced 15 Storms of which 9 impacted the USA http://www.ncdc.noaa.gov/oa/climate/res ... nes03.html In comparason, 1998 had only 14 named storms but a number of them hit the USA...TX, Outer Banks, LA, MS ect http://www.outlook.noaa.gov/98hurricanes/hilites.html In 2003, we saw 16 Named Storms and 6 impacted the USA http://www.ncdc.noaa.gov/oa/climate/res ... nes03.html As well, 2005 was a very active season in many parts of the country http://www.srh.noaa.gov/lub/climate/Loc ... htm......I am not sure if I am on to something or just grasping at straws. It just seems that following a very active Tornado season, you get a very active Hurricane season with 6 or more storms that impact the USA. I am going to research this further and try to make a chart and go back in the years to see if this has any merrit. I'm just doing this as a hobby and thought some of you might enjoy my research.

[HURAKAN]

I would argue about the opposite, an active hurricane season could mean an active tornado season as we saw in 2004.

[Windtalker1]

I would argue about the opposite, an active hurricane season could mean an active tornado season as we saw in 2004.

I can see your point...but because there is such a large span between the end of Hurricane season to the start of Tornado season, I tend to believe that what is occuring during Tornado season will follow into Hurricane season because there is no time inbetween them. The forces are just about in place and in play to follow into Hurricane season.

[HURAKAN]

Furthermore, unlike hurricanes, tornadoes thrive with lots of shear in the atmosphere. Therefore, we could see an increase in tornadoes because there is an increase in the windshear pattern. Then, if this windshear pattern lasts until the hurricane season, hurricane activity will remain low. Maybe in some seasons we could argue that your point is valid, but since tornadoes arrive from a chemistry that is adverse to hurricanes, it's difficult to make a solid point.

[wxmann_91]

An active tornado season implies a southwesterly flow over the Plains and thus a ridge across the east - greater possibilities of landfalling storms especially along the Gulf Coast.

[Rainband]

also warmer than normal SST were responsible for the tornado outbreak yesterday and over the weekend.

[weatherwoman132]

so, this could be true, eh?

[Hurricaneman]

It seems like a possible scenerio

[Dr. Jonah Rainwater]

2005 was a down year for tornadoes, if anyone forgot.

[Windtalker1]

2005 was a down year for tornadoes, if anyone forgot.

Tell that to the people of TX & AL

[bvigal]

This is very interesting research! I've often wondered about this, as well. To make any kind of correlation, my instinct would be to specifically examine:

onset of "outbreaks" of tornadoes (such as on Saturday), and supercell/dryline majors
* how early
* how many through May
* what areas
compared to:
* prior years
* onset of tropical cyclone activity,
* Bermuda high
* shear patterns over US mainland

My reasoning for this is, many different types of weather cause conditions conducive to small tornadoes, and they occur all 12 months of the year in nearly all states. Also, as previously mentioned, hurricanes themselves spawn tornadoes. The violent spring outbreaks and mega-supercells are what would interest me most as climatology.

Please keep us informed, I, for one, will be most interested to hear what you discover!

[Windtalker1]

This is very interesting research! I've often wondered about this, as well. To make any kind of correlation, my instinct would be to specifically examine:

onset of "outbreaks" of tornadoes (such as on Saturday), and supercell/dryline majors
* how early
* how many through May
* what areas
compared to:
* prior years
* onset of tropical cyclone activity,
* Bermuda high
* shear patterns over US mainland

My reasoning for this is, many different types of weather cause conditions conducive to small tornadoes, and they occur all 12 months of the year in nearly all states. Also, as previously mentioned, hurricanes themselves spawn tornadoes. The violent spring outbreaks and mega-supercells are what would interest me most as climatology.

Please keep us informed, I, for one, will be most interested to hear what you discover!

I will...Thanks for the vote of confidence that this will not be a waste of time.

[stu]

Interesting debate but I would have to say that there is no correlation between Tornado and hurricanes but there is between Hurricanes and tornadoes – I will try to explain.

Firstly we need to look at the past few years tornado numbers in context. 2003 was extremely active for the first 10 days of May which skewed the over count. 2004 was actually a below average year once you take out the tornado outbreak that Ivan (and I forget the other one) produced. 2005 was a record low tornado count for May and again overall a low tornado producing year.

2006 is currently a record high tornado count for March. And by tonight will have surpassed the April count for 05,04 and 03 already.

Any tornado forecaster will tell you that first thing they look at is 500mb wind speeds for an upper air trough – these troughs form and cross the US mainland and are a primary ingredient for tornadic activity. Now 500mb > 40knots would rip a hurricane apart so what is good for tornadoes is bad for hurricanes (as mentioned a few post ago) but then you don’t get screaming 500mb jets across the tropics.

Landfalling hurricanes can and do produce tornados – 2005 was an active hurricane landfall year – but still the over 2005 count is below average.

Some reference to back up my wild claims


http://www.spc.noaa.gov/climo/torn/mont ... stats.html

[HurricaneHunter914]

Even thought the landfall count was below average which I doubt remember it only takes one to cause a crisis.

[stu]

The landfall count ??

[HurricaneHunter914]

Sorry I was refering to your post above.

[rainstorm]

i dont think it means much. for one thing, more tornados are detedted now than in the past

[Air Force Met]

2005 was a down year for tornadoes, if anyone forgot.

Tell that to the people of TX & AL

But...the point is...if you are trying to make a correlation...you can't just take some isolated areas ("tell that to..."). The season has to be judged as a whole. RIght? Yeah, some areas might be higher than average but overall it can be down and if you are going to make a correlation between an active hurricane season and an active tornado season...that is what you have to base it on...NOT it being active in one or two areas.

1983 saw 4 names storms...well below normal...but tell it to the people in SE Texas. Same thing for FL/LA in 1992 with Andrew. However, when making a correlation with SEASONS...you have to disregard that fact.

1994 was a lull year for Tornadoes. 1995 was an active year for hurricanes. Now in most of these years, there is not much difference b/w 5 storms making landfall and 6 storms making landfall. Maybe 50 miles south of the border...or maybe a miss on Cape Hat by 40 miles...etc. So...in the GRAND SCHEME of things...and the atmosphere is NOT that fine tuned...I really would not even correlate landfalling storms with tornadoes....especially when the number of 5 landfalling storm seasons could have easily been greater had a storm moved 50 miles this way or that way. NOTHING that happens in the tornado season is going to impact that storm by 50-100 miles on it's track.

OK...so look at active years....and maybe seasons with 5 landfalling storms. Well, you can't go back too far because there have been a lot more tornadoes (reported and recorded) since doppler radar. The number of tornadoes has not doubled or tripled since 1985, just the reporting of them. So, you have to only look from 1990 on...which is not a large enough sample size to do anything with.

But let's say you do anyway. 1997 was a low year for hurricanes. 1996 was slightly above for tornadoes. 1998 was high for landfalling storms. 1999 was 5/above normal (1998). 2000 was a low year for hurricanes and 1999 was a HIGH HIGH year for tornadoes. 2001 another low year with a normal season for torn. before it. 2002 high for hurricanes and 2001 was abv. norm for torn. 2003 was a hard year for hurricanes BUT there was a LULL in tornado activity the year before. 2004...very acvtive and 2003 was active. 2005 was avtive and the 2004 tornado season was acvtive.

So...looking at correlations? There are none. An active year my have a lull in tornadoes before it or vice versa...and you can't go back before doppler to have a good correlation. You also can't look at the last two years alone. So, in my opinion, no correlation on landfalling storms and tornadoes. Now, location of tornadoes (and whether an area was more active or not) and landfalling storms might have more merit than just raw numbers...given steering flows are what determine landfall. That might be a better study.

[stu]

AFM - I agree with your assessment - After some thought the only loose connection between active Tornadoes and hurricane years is perhaps the position and number of oscillations in the 250mb jet.. i need to dwell on this but really the more I think, the more I am convinced that there is no correlation.

However what about a correlation between drought years in the South US and active hurricane years ?

[Air Force Met]

AFM - I agree with your assessment - After some thought the only loose connection between active Tornadoes and hurricane years is perhaps the position and number of oscillations in the 250mb jet.. i need to dwell on this but really the more I think, the more I am convinced that there is no correlation.

However what about a correlation between drought years in the South US and active hurricane years ?

I'm sure there is some correlation there because you are then talking about subtropical highs resting over that area. I'm not a research met...and don't get into it much so I can't comment on it. I'm a forecaster...not a researcher.