Chapter News
July 2005


CENTRAL ILLINOIS

The July 28, 2005 meeting of the Central Illinois chapter of the American Meteorological Society (CIAMS) was held in conjunction with the Central Indiana Chapter of the AMS at the Beef House in Covington, Indiana. The meeting began at approximately 6:45 pm, after food was served. Approximately 41 people were in attendance, 15 CIAMS members, and 26 guests. After the business portion of the meeting, Dr. Patrick Francis of Bowling Green State University gave a talk entitled, "Association Between Seasonal Cycles of Teleconnections and Tornado Frequency in the United States." The meeting then concluded at 8:30 PM.


Business

Mike Kruk began the new membership year of the CIAMS with a presentation of the new officers. Mike is the new president, taking over for Chris Miller. In addition, Tom Bellinger is taking over the President-Elect position from Mike, Nancy Westcott is the new secretary, replacing Mike Spinar, and Llyle Barker is taking over the treasurer's position from Maria Peters.

The CIAMS is having the first Chapter Picnic Sunday August 28th at Weldon Springs State Park near Clinton, Illinois. The Chapter will provide the meat, buns, and the shelter. Attendees are asked to bring a dish or treat to pass. Interested persons are encouraged to visit the Chapter web site, http://www.c-il-ams.org/picnic.html for further details.

The new business year means that it is time to set up committees. All members are encouraged to volunteer. If you are interested, please contact the chairperson of one of the following committees:

Program and Activities: Dave Kristovich (dkristo@uiuc.edu)
Education and Public Outreach: Mike Spinar (mspinar@uiuc.edu)
Membership: Ed Kieser (edkieser@will.uiuc.edu)
Conference: Steve Hilberg (hberg@uiuc.edu)
Student: To Be Determined

The new student committee will be involved in several activities this year, including coordinating the student poster competition at the Midwest Extreme and Hazardous Weather conference. Suggestions for other activities this year include the design of a CIAMS Chapter logo and the coordination of a photography competition for all CIAMS members. The newly formed committee is currently in need of members and a chairperson. Please contact one of the officers if you are interested. Please contact Mike Spinar (mspinar@uiuc.edu), if you would like to help specifically with the student poster competition.

On June 2, 1924, Dr. Clarence Leroy Meisinger of the Weather Bureau and Lt. James T. Neely were killed when their balloon exploded after being struck by lightning in a thunderstorm near Monticello, Illinois. The researchers were investigating the path of airstreams through mid-latitude cyclones. The Meisinger Award is given each year by the American Meteorological Society (AMS) to recognize the tragic death of this scientist who died investigating the atmosphere. The CIAMS wishes to place a historical marker near the crash site in Monticello. A marker costs approximately $1800, half of which will be contributed by the AMS. It is up to the CIAMS to raise the other half of the money. Contact Tom Bellinger (Bellinger@iema.state.il.us) if you have any ideas.

The officers are also soliciting interested persons to design a chapter poster highlighting the people and activities that have contributed to the success of the CIAMS during the past several years. This poster would be excellent for presentation at the AMS annual meeting in January as well as the Midwest Extremes Conference in October. It would also serve to illustrate why the CIAMS should be selected as "Chapter of the Year." Please submit any photos or written documentation you may have to Tom Bellinger.

Llyle Barker gave the treasurer's report. The Chapter's account balance is currently $4000, of which $2800 is earmarked for the 2nd Midwest Extreme and Hazardous Weather Conference in October 2005. The new dues year has started; dues payment reminder notices will be sent out soon. Annual dues are $15 for general members and $6 for students.

Mike Spinar gave the report for the Education and Public Outreach Committee. Several student members on the committee have either graduated or pursued their careers outside Central Illinois, so new members are needed. The group will be working on many projects this year, including organizing and overseeing the student poster competition at the Midwest Extreme and Hazardous Weather Conference.

Invited Talk

Dr. Patrick Francis of Bowling Green State University gave a talk entitled, "Association Between Seasonal Cycles of Teleconnections and Tornado Frequency in the United States." During this talk, he presented a new tornado climatology based on tornado paths rather than on tornado reports, and also he examined the possible relationship between tornado frequency in the United States and teleconnective forcing mechanisms, such as El Nino/Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO).



The author began with a review of past research, discussing the climatologies of Brooks (1999) and Concannon, Brooks, and Doswell (2000). Both studies determined the frequency of occurrence of tornadoes using a similar methodology. Brooks (1999) examined all tornadoes, while the later Concannon et al. (2000) study considered the occurrence of strong F-2 or greater tornadoes on the Fujita Scale. The authors divided the country into 80 square kilometer grid boxes and examined days of tornado reports within each grid. The data were smoothed spatially and temporally. Maxima in tornado frequency were found in Colorado, Florida, and the traditional Central Plains "tornado alley" region of the United States. These two studies did not examine the possible relationship between tornado frequency and teleconnective forcing mechanisms. Dr. Francis referred to the Schaefer and Marzban (2000) paper as one study that examined the relationship between tornadoes in the United States and teleconnections. This study found no statistical significance between tornado frequency and teleconnective forcings.

Dr. Francis reviewed the methodology employed by Schaefer and Marzban (2000) and drew inspiration from his own experiences as a storm chaser, to develop a new statistical approach to the same topic. He re-examined the same data used in the aforementioned climatologies. Instead of looking at individual days of tornado reports, however, he investigated actual tornado paths using statistical techniques borrowed from the U.S. Geological Service. Employing Kernel Home Range and Least Squares Cross Validation techniques, he produced a map of tornado probability on a 1 km grid. This grid suffered from population biases in tornado reporting. For example, there were elevated probabilities near larger cities such as Houston, TX; Oklahoma City, OK; and Tampa Bay, FL. Thus, these data were smoothed, resulting in a plot that compared favorably with Brooks (1999) and Concannon et al. (2000).

Upon dividing the data into subsets based on positive, neutral, and negative ENSO and NAO anomalies, fascinating patterns began to emerge. For all tornadoes, the largest frequency of occurrence appeared during times when both ENSO and the NAO were in neutral phases. The smallest tornado probabilities took place during positive ENSO and positive NAO periods. Further examination of each of these possible phases showed that the spatial distributions of the tornado frequency also changed. There was a decrease in total frequency of occurrence when both ENSO and the NAO were negative, with peaks in Colorado, Florida, and locations just west of the Mississippi River in Arkansas and Louisiana. A teleconnection consisting of a positive ENSO and a negative NAO phase showed an increase in tornado probability, with a peak in Colorado and a broad area of high probabilities across the Gulf Coast and Southern Plains states. However, when a negative ENSO and a positive NAO were coupled, the tornado frequency peak in Colorado vanished and a strong localized peak in the lower Mississippi River Valley emerged. Finally, when both ENSO and NAO were in their positive phases, the peak region of activity was in Oklahoma and Arkansas.

The analysis was repeated for the F2 to F5 tornado reports only. Dr. Francis noted that a possible shortcoming in this analysis stems from the low frequency of reports for these stronger, rarer, tornado events. Nonetheless, similar patterns were present in the data for the F2 to F5 tornado reports. The negative ENSO and positive NAO pattern demonstrated a shift to the southeast in the location of the peak frequency of tornadoes, primarily over Alabama, southern Georgia, and the panhandle of Florida. No other significant deviation from the analysis for all tornado reports was found for the rest of the continental United states.

Finally, the analysis of the F4 and F5 tornado paths suggests that tornado alley may exhibit a "ring of fire" type of phenomenon, with a peak in distribution stretching from western Iowa southward to Oklahoma, eastward through Mississippi and Alabama, and northward into central and southern Indiana. It is not known at this time whether this is an artifact of the data bias or reporting issues, inconsistent damage analyses based on the Fujita Scale, or the result of something as substantive as elevation changes.

References

Brooks, H.E., 1999: Severe thunderstorm climatological probabilities. URL: http://www.nssl.noaa.gov/hazard/

Concannon, P. R., H. E. Brooks, and C. A. Doswell III, 2000: Climatological risk of strong and violent tornadoes in the United States. Preprints, 2nd Symposium on Environmental Applications, Long Beach, CA, Amer. Meteor. Soc,, 212-219.

Schaefer, J.T., and C. Marzban, 2000: Tornadoes in the United States as related to the tropical pacific sea surface temperature. Preprints, 20th Conf. on Severe Local Storms, Orlando, FL, Amer. Meteor. Soc., 18-121. ---Mike Spinar and Nancy Westcott.


NEW YORK CITY/LONG ISLAND (NYC/LI)

On Sunday morning, July 10, prior to the National Weather Service's Open House, Michael L. Ekster of the NOAA/National Weather Service Forecast Office, located in Upton, NY presented a talk to the NYC/LI Chapter entitled, "Elevated Mixed Layers and their Role in Significant Severe Thunderstorm Episodes in the Northeastern U.S. - What Has History Taught Us?"

The elevated mixed layer (EML) is a common attribute of severe weather proximity soundings in the Great Plains region of the United States. These layers of relatively warm, dry continental air and steep, nearly dry adiabatic lapse rates are generated during the spring and summer in the high terrain of the U.S. and Canadian Rockies, as well as the Mexican Plateau. They are then advected downstream by the mean westerly flow. The EML is a necessary ingredient in the formation of the classic Miller Type I "loaded gun" sounding, which is thermodynamically favorable for high-end severe convection.

While the EML is a widely known contributor to Great Plains severe weather outbreaks, limited research to identify these important features in the Northeastern U.S. has been conducted. Typically, the EML is destroyed by deep convection or other diabatic effects across the Plains or Midwest. However, traceable "plumes" of EML air can, on rare occasions, reach the Northeastern U.S. despite traveling distances of 2,000 - 3,000 km from their source. It was hypothesized that the presence of an EML in the Northeastern U.S. results in greater than normal potential instability, as well as a stronger than normal capping inversion. The eventual release of high potential instability under such circumstances would allow for higher-end severe weather episodes reminiscent of those witnessed in the Great Plains - given a favorable mesoscale and synoptic scale environment for convection initiation. Identification of flow regimes favorable for advection of EML air into the Northeastern U.S. would therefore be of interest and utility to operational forecasters.

The presentation focused on an ongoing research project that will help identify these rare Northeastern United States EML and its contribution to higher-end severe weather episodes. The origin, advection, and maintenance of the EML were discussed. EML characteristics and structures that allow "ordinary" severe weather soundings in the Northeast to become more representative of what might be seen in the Great Plains was presented. A number of case studies were shown to illustrate specific Northeastern U.S. warm season EML occurrences and their suspected contribution to higher-end severe weather episodes.

The NWS Open House directly after the technical presentation was attended by all officers of the Chapter (Mark L. Kramer, Frank P. Castelli, Jeffrey Tongue and Sam Abrahamer) plus members, Brenda Tait-White, Lisa Bastiaans, John Drohan, Edward, Heidelberger, and Frank Martino. These AMS Chapter members manned a booth, "Ask a Forecaster." With over 1,000 attendees, the AMS members were especially busy due to landfall of Hurricane Dennis at 3:25 p.m. EDT on Santa Rosa Island between Navarre Beach and Pensacola Beach, Florida. Live radar images of the hurricane were available at the chapter display.---Mark L. Kramer.


SMOKY MOUNTAIN

The Smoky Mountain Chapter of the AMS met on Monday, July 25th around 6:15 p.m. for dinner at Barley's Taproom in the Old City section of Knoxville. After dinner, the meeting commenced at the Univ. of Tennessee Agricultural Engineering Building to hear T.J. Blasing (Oak Ridge National Laboratory) and Kim Hand (Georgia Institute of Technology) speak about "The Latest on Global Warming: Hot Air and Cold Facts". T.J. and his summer student, Kim, gave an update of what's happening with their research on global warming and the global carbon cycle. Subjects learned included how greenhouse gases can cool the atmosphere, how opening bottles of vintage wine is useful in carbon- cycle research, and other amazing things.---David Gaffin.


 



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