El Nino's Impact on the Coming Chase Season

[Adam Lucio]

Actually 2003 featured several nice events in the southern Plains.

April 15 - several tornadoes in the Texas panhandle and western Oklahoma.

April 19 - strong tornado near Copan, OK

May 1 - weak tornadoes in eastern OK

May 3 - tornadoes in west Texas

May 4 - significant tornado outbreak in eastern Kansas and western Missouri

May 8 - significant tornado outbreak in central OK and eastern Kansas

May 9 - second day in a row with tornadoes in OKC metro area

May 15 - significant tornado outbreak in Texas panhandle


While most of the tornado activity (numbers wise) hit the midwest (MO, IL, TN), the southern Plains saw several significant events from mid April to mid May. 2003 and 2004 is by far the best two successive tornado seasons for storm chasers.

I keep telling people I hope for a repeat of '03 when I see a discussion of El Nino springs. 96' had a couple decent setups around here too. I can only hope for a repeat as I don't believe there are enough case studies to draw conclusive evidence. Tom Skilling posts a ton of local el nino facts for local weather here, and while the majority of the winters are milder/drier the numbers arent that far off [like 60/40] So going off all the numbers I see him post it seems that around here there is nearly an even split with a slight bias towards one direction. Anything is possible though.

 

[Mark Blue]

Not to go against the grain here as a huge 2010 would make everyone happy after last year, but page 286 of Tim Vasquez's Storm Chasing Handbook (2nd Edition) indicates that 2003 was a La Nina season while 2004 was a neutral El Nino/La Nina season. I know for certain that El Nino and La Nina can have a huge impact on prevailing weather patterns and trends, but as far as 2003 is concerned, what were the prevailing conditions in the months leading up to spring?

The graph on page 22 of this document http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf would seem to indicate 2003 was primarily an El Nino year, I guess I'm just not sure about the way it was characterized in the Storm Chaser Handbook.

 

[Drew.Gardonia]

Not to go against the grain here as a huge 2010 would make everyone happy after last year, but page 286 of Tim Vasquez's Storm Chasing Handbook (2nd Edition) indicates that 2003 was a La Nina season while 2004 was a neutral El Nino/La Nina season. I know for certain that El Nino and La Nina can have a huge impact on prevailing weather patterns and trends, but as far as 2003 is concerned, what were the prevailing conditions in the months leading up to spring?

The graph on page 22 of this document http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf would seem to indicate 2003 was primarily an El Nino year, I guess I'm just not sure about the way it was characterized in the Storm Chaser Handbook.

2002 Was the El Nino year, with the active season follow up being 2003 when it was pretty busy.

http://epod.usra.edu/blog/2002/03/2002-el-nino-1.html

 

[Jennifer Jackson]

I dont care where or when they form, as long as they form!!!

 

[Darren Addy]

Here's some very up-to-date info...
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

Note page 13:

(January) Over N. America, strong ridging contributed to above-average temperatures over much of N. America. During February, troughing and below-average temperatures became reestablished over the middle latitudes, along with ridging and above-average temperatures over higher latitudes.

Page 23 gives you the months/years of the strongest El Nino and La Nina events with comparative values.

Quote from page 28:

CFS ensemble mean (heavy blue line) predicts El Niño will last through the Northern Hemisphere spring 2010.

(issued 2/28/2010)

Seasonal outlooks on Temp and Precip for march-may 2010 on page 29. Also interesting is page 36 (U.S. Precipitation Departures (mm) and Frequency of Occurrence (%) for El Niño during Feb.-Apr.) and page 37 (U.S. Temp. Departures (°C) and Frequency of Occurrence (%) for El Niño during Feb.-Apr.)

The precip. down south looks very favorable for active pattern, but I fear they also mean a lot of HP mode storms down there this year. (Pure conjecture on my part).

 

[Scott Olson]

Will June be the real chasing season?

Using proxies that approach Spring with positive El Nino Conditions.

The closest proxies for this year are 1958 (slightly stronger), 1966 (.5C by March but still would affect May pattern), 1969 (Similar), 1983 (Stronger), 1987 (This is a non-weakening El-Nino), 1992 (Slightly stronger), 1998 (Adendum: 1998 swung quickly to La-Nina during the early part of Spring but the delay in large scale changes should not reflect for the May timeframe.)



[Comparsion of similar ENSO years with past observed conditions and consensus model forecast for 2010]

Tornadoes in similar ENSO years:

1958: 68 May / 128 June
1966: 98 May / 126 June
1969: 145 May / 137 June
1983: 249 May / 178 June
1987: 126 May / 132 June (163 August)
1992: 137 May / 399 June (213 August)
1998: 287 May / 303 June

May = 158 AVG
Jun = 200 AVG

I won't speculate or say that somehow this is definitive by any means, they are issues of the disturbution of the temperature anomalies and are also greater issues of the long-scale pattern. However, I would tend to think that Chasecations planned in June will have an overall greater chase day ratio.

A bit into conjecture but I believe, based on a bit of preliminary looking, that if you parsed tornado days from May/June of the proxies I have selected, you would see a significant increase in the difference between May & June for the majority of the years. That is to say, the May's typically featured a couple outbreaks and the June's typically featured a more active day to day pattern.

(2003 while having an El Nino going into the next year, wasn't picked as a proxy since I wanted ENSO positive for the three month rolling on March. I generally consider a couple months for the tempature anomalies to work into the atmosphere and start showing changes in the larger scale pattern. But, I didn't want to go too far back with that when the ENSO conditions were getting more neglibile, as is the case in 2003.
-Scott Olson

 

[Bill Tabor]

Much of this thread's subject is also covered under thread: 'Thoughts on Activity for 2010". My comments in relation to El Nino are on this page:
http://www.stormtrack.org/forum/showthread.php?t=22125&page=5