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Looking ahead at a possible ElNino and some possible severe weather aspects

 

2) Ohio Valley and Deep South — La Niña

Conversely, seasonal differences of tornado events in the Ohio and Deep South over late winter and spring show that there is an increase in tornado occurrences during warm phase as compared to neutral conditions. The changes in activity are already apparent during JFM (Figure 8a). A line of increased activity can be seen extending from Louisiana northeast into Indiana and Michigan. The greatest increases appear in Louisiana and Mississippi, with another maximum in Indiana.

As spring approaches, the total area seeing more tornadoes spreads eastward while the number of La Niña seasonal tornado event increases (Figures 8b-d). The area seeing an increase in tornadoes during FMA has more than doubled, completely enveloping Mississippi, Tennessee, Kentucky, and Indiana and large sections of surrounding states. The region of maximum increase (upwards of 4 more tornadoes per La Niña season) shifts northeast, centered in Indiana, Kentucky, and Tennessee.

MAM sees the area of increased tornado activity decline in the western areas, such as Louisiana, Arkansas and Illinois. The maximum centered along the Ohio River remains, while increase move southward into Florida. The region of maximum increase of tornadic activity shifts southward during AMJ, into eastern Tennessee. Georgia and the Carolinas see an increase in tornadic activity, upwards of 3 more per La Niña season.

Differences in Tornado days show the same pattern, but is more apparent in the early seasons. During JFM (Figure 9a), the southwest-northeast patter is discernable, but the increases in tornado days also spread along the Gulf of Mexico coast. The largest increases are also along the Gulf coast, with the largest change in Louisiana.

The increase of tornado days becomes more apparent during FMA, but begins to weaken during MAM and into AMJ (Figures 9b-d). FMA sees a large continuous area of increased tornado days from Louisiana north through Michigan. The largest change is in Tennessee, and coincides with the maxima of tornado event differences as seen in Figure 8b. Overall, most of a region from Louisiana to Indiana sees at least one more tornado day per La Niña year. The MAM season shows a reduction in increased tornado days in the southwest area of the region. However, the number of tornado days starts increasing in north Florida and Georgia during the same time. The maxima continues to occur in Tennessee. The increase tornado days continues to weaken in area and intensity into AMJ, with area of Ohio, Indiana, and Illinois returning to normal. The increases in the Deep South continue to hold on through this season.

The statistically significant changes in tornadic activity once again parallel the results of the previous two analyses. The JFM season (Figure 10a) shows more tornadoes at the 95% significance level over Louisiana and Arkansas, as well as Indiana and central Kentucky and Tennessee. A weaker band of 80% significance extends over the Gulf Coast. Regions of 95% confidence expands dramatically into FMA (10b), stretching from Arkansas to North Carolina, and extending northward into Michigan. The region shrinks slightly and moves eastward during MAM (10c), with areas of Georgia and the Carolinas now witnessing more tornadic activity at the 95% confidence level. Confidence levels west of the Mississippi River, however, begins to wane, and continues as we enter AMJ (10d). The southern and central regions, however, still maintain 95% confidence of reduced tornadic activity.

The histograms further show the increases of tornadic activity within the Ohio and Tennessee River valleys. Around Nashville, Tennessee (Figure 11a), the probability of 3 or more tornadoes during a neutral MAM season is 12.5%, but the probability increases to 37.5% for La Niña MAM, a three-fold increase. Towards the tail of the curve, the histogram shows that the probability of a neutral MAM season around Nashville producing nine or more tornadoes is 2%. However, the chance of a La Niña MAM producing 9 or more tornadoes around Nashville is 12%, a six-fold increase.

The changes around Indianapolis, Indiana (Figure 11b) are even more dramatic than those at Nashville. The probability of four or more tornadoes during neutral MAM in Indianapolis is 16%, but increases to 51% for La Niña MAM, over a three-fold increase. Five or more tornadoes during neutral MAM has a probability of 6%, but increases to 40% for La Niña MAM seasons, over a six-fold increase.

The largest differences in Indianapolis, though, are the chances for large outbreaks of tornadic activity during La Niña MAM compared to neutral MAM. The probability of six or more tornadoes in the Indianapolis area during neutral MAM is 3%. Meanwhile, the chance of six or more tornadoes during La Niña MAM around Indianapolis is 38%, an increase of over 1300%. For seven or more tornadoes, neutral MAM seasons are at 2%, while La Niña MAM seasons are at 30%, a 1500% increase.

Further, no recorded neutral MAM has produces more than 7 tornadoes in the Indianapolis area during MAM. However, the region still have a 25% chance of seeing 8 or more tornadoes during a La Niña MAM.

http://coaps.fsu.edu/papers/impacts_enso_tornadic_activity/index.html#flink9

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Section 5: Conclusions is also an informative read. Even today the hypothesis about why still appear valid. Section 1: El Nino is interesting for the Plains. Section 2 is indeed the most relevant to our region. A subtle SER (not too much) would probably help establish some baraclinicity, but let's be careful what we wish for. I prefer to chase the Plains for many reasons including visibility, lower population density (usually less human impact), and it being home. Cheers!

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I'm not a UT fan like the rest of y'all(Virginia Tech) but this has been a heck of a tournament. My bracket is busted but I still have all my Final Four teams left (AZ,FL,MSU,UL). This tournament is the best moment in sports in my opinion. So much excitement and passion.

Anyways tomorrow looks like winter's last gasp. Advisories are up for the mountains and even some of the valley counties. I think everyone will see flakes fly in the morning. This is really close to giving us an advisory criteria snowfall.

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