Hindcasting the First Tornado Forecast in Europe: 25 June 1967

The tornado outbreak of 24–25 June 1967 was the most damaging in the
history of western Europe, producing 7F2–F5 tornadoes,232 injuries, and 15
fatalities across France, Belgium and the Netherlands. Following tornadoes in
France on 24 June, the Royal Netherlands Meteorological Institute (KNMI)
issued a tornado forecast for 25 June, which became the first ever—and first
verified—tornado forecast in Europe. Fifty-two years later, tornadoes are still
not usually forecast by most European national meteorological services, and a
pan-European counterpart to the NOAA/NWS/Storm Prediction Center (SPC)
does not exist to provide convective outlook guidance; yet, tornadoes remain
an extant threat. This article asks, “What would a modern-day forecast of the
24–25 June 1967 outbreak look like?” To answer this question, a model simu
lation of the event is used in three ways: 20-km grid-spacing output to produce
aSPC-style convective outlook provided by the European Storm Forecast Experiment (ESTOFEX), 800-m grid-spacing output to analyze simulated reflectivity and surface winds in a nowcasting analog, and 800-m grid-spacing
output to produce storm-total footprints of updraft-helicity maxima to com
pare to observed tornado tracks. The model simulates a large supercell on
24 June and weaker embedded mesocyclones on 25 June forming along a
stationary front, allowing the ESTOFEX outlooks to correctly identify the
threat. Updraft-helicity footprints indicate multiple mesocyclones on both
days within 40–50 km and 3–4 h of observed tornado tracks, demonstrating
the ability to hindcast a large European tornado outbreak.