TY - JOUR
T1 - Extended US Tornado Outbreak During Late May 2019: A Forecast of Opportunity
AU - Gensini, Vittorio A.
AU - Allen, John
N1 - Funding Information:
The authors wish to acknowledge the pioneering work of Klaus Weickmann and Ed Berry, whose research and contributions more than a decade ago provided the basis for many of the ideas implemented to make the ERTAF project possible. The authors would also like to thank Paul Sirvatka for participation and discussions during the 2019 ERTAF project. MJO data are available for download from the Australian Bureau of Meteorology at http://www.bom.gov.au/climate/mjo/ website. NCEP/NCAR reanalysis data are available from the Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory (http://rda.ucar.edu/datasets/ds090.0/). Archived National Weather Service tornado warnings can be obtained from the Iowa Environmental Mesonet page at https://mesonet.agron.iastate.edu/request/gis/watchwarn.phtml website. Patrick Marsh (SPC) provided the preliminary tornado counts for 2019. Two anonymous reviewers provided valuable feedback on an initial draft of this manuscript. Author B. Barrett was partially supported by the Office of Naval Research, award N0001416WX01752.
Publisher Copyright:
©2019. The Authors.
PY - 2019
Y1 - 2019
N2 - The second half of May 2019 was an unusually active period for tornadic thunderstorms across the U.S. Great Plains, Midwest, and lower Great Lakes. While this period typically coincides with the peak climatological frequency of tornadoes, preliminary reports of tornadoes were over triple the expected 30-year average. Multiple-day outbreaks of tornadoes are not unprecedented in the United States; however, this event was perhaps the first to be forecast at subseasonal lead times (3–4 weeks) by the Extended Range Tornado Activity Forecast team. This forecast of opportunity was driven, in part, by anomalous convective forcing in portions of the tropical Indian and Pacific Oceans, causing subsequent changes in Northern Hemisphere atmospheric angular momentum. This manuscript analyzes the evolution of hemispheric-scale circulation features leading up to the event, examines teleconnection processes known to influence U.S. tornadoes, and provides insights into the forecast process at subseasonal lead times.
AB - The second half of May 2019 was an unusually active period for tornadic thunderstorms across the U.S. Great Plains, Midwest, and lower Great Lakes. While this period typically coincides with the peak climatological frequency of tornadoes, preliminary reports of tornadoes were over triple the expected 30-year average. Multiple-day outbreaks of tornadoes are not unprecedented in the United States; however, this event was perhaps the first to be forecast at subseasonal lead times (3–4 weeks) by the Extended Range Tornado Activity Forecast team. This forecast of opportunity was driven, in part, by anomalous convective forcing in portions of the tropical Indian and Pacific Oceans, causing subsequent changes in Northern Hemisphere atmospheric angular momentum. This manuscript analyzes the evolution of hemispheric-scale circulation features leading up to the event, examines teleconnection processes known to influence U.S. tornadoes, and provides insights into the forecast process at subseasonal lead times.
M3 - Article
SN - 0094-8276
VL - 46
SP - 10150
EP - 10158
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 16
ER -