A 9-Year Summary of Radar Characteristicsof Mesocyclonic Storms and of

Deep Convection in Southern Quebec (1993-2001)

Mesocyclone: Small-scale (~ 5 km) rotation over a Sufficient depth (> 2.0 km) and Lasting at least 10 minutes

UVIL : Vertical integration of Z4/7 from a height of 5 km

Example of severe weather

MESOCYCLONES: small-scale rotating flows

Radar

Mesocycloneradar signature

Mesocycloneflow

2.5 km CAPPI7.0 km CAPPI

VIL: from 2.5 kmUVIL: From 5.0 km

2.5 km Refl. CAPPI 2.5 km Doppler CAPPI

Doppler CAPPI Height Animation

Lagrangian Time Animation

20:30 GMT 28-Aug-1994

2.5 km Reflectivity CAPPI 3.0 km Doppler CAPPI

Tracking mesocyclones and extrapolating their position

Lagrangian Doppler CAPPI

VIL Animation

Climatology of MesocyclonesClimatology of Mesocyclones

Yearly distribution of the tracked mesocyclones and of the 'mesocyclone hours'

Climatology of MesocyclonesClimatology of Mesocyclones

Distribution of the lifetime of the tracked mesocyclones and of their path length

Distribution of the diameter and of the vertical depth of the 'm5' detections that are part of the tracked mesocyclones

Distribution of the peak rotational velocity and of the average maximum shear (as defined in section 3.4a) of the 'm5' mesocyclones

Hourly and monthly distribution of mesocyclones in the Montreal area.

Climatology of MesocyclonesClimatology of Mesocyclones

Geographical distribution of mesocyclonic vortices around the McGill Doppler radar for 1993 to 2000 inclusively. Range rings are 20 km apart. Divide the "Mesos" scale by 10 in order to obtain the number of mesocyclones affecting each pixel of the map.

Planetary scale precursors

Composite 500 hPa maps. Thin solid lines are heights [decameters]. Thick solid (dashed) positive (negative) anomalies from 30 years climatology. Shaded is statistical significance to 95% and 99% level.

Thunderstorm dayswith mesocyclones(22 days)

Thunderstorms dayswithout mesocyclones(27 days)

Day before

Same day

Topography Around Montreal

9/27

DEM of Study Area (Red spots are streamflow stations)

Chateauguay

Geographical distribution of convective precipitation for each of the 9 years analyzed interms of the number of minutes that a value of 10 kg/m2 has been exceeded on the UVIL map

Geographical distribution of deep convection for the years 1993 to 2001 inclusively in termof the number of minutes that the UVIL exceeded 15 km/m2 . Range rings are 40 km apart.

Diurnal and Yearly distribution of intense convection

The color version of the yearly UVILs are not range-corrected

Geographical distribution of deep convection for the years 1993 to 2001 inclusively in termof the number of minutes that the UVIL exceeded 15 km/m2 . Range rings are 40 km apart.