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DTSTAMP:20240425T034228Z
DESCRIPTION: \n\nStudent Seminar Series\n\nDepartment of Atmospheric & Ocea
 nic Sciences\n\npresents\n\na talk by\n\nDaniel Tootill\n	PhD student\n\nEn
 semble predictability of a major freezing rain event in Montreal\n\nAccura
 te forecasts of precipitation in winter storms are required for suitable p
 reparations to be made by society. However\, these forecasts are prone to 
 large errors due to model physics parameterizations\, uncertainty in the i
 nitial conditions and numerical error growth. One aspect of precipitation 
 forecasts that has been less studied is the uncertainty in diagnosing the 
 type of precipitation the forecasts predict. To further our understanding 
 of sources of model uncertainty\, we produce an ensemble forecast for a si
 gnificant freezing rain event in Montreal (24th January 2017). The case ch
 osen is notable as it represents a major forecast bust\, with a Snowfall W
 arning having been issued by Environment Canada the day before the event. 
 Regional soundings during the event reveal an elevated frontal inversion c
 haracteristic of freezing precipitation\, with near-zero temperatures near
  the 850 hPa level. This layer was responsible for melting snowfall genera
 ted aloft into rain\, which froze upon impact with the subzero ground surf
 ace. The marginal nature of the warm layer aloft with respect to the freez
 ing point (0oC) promoted a large degree of uncertainty in the precipitatio
 n-type forecast. This uncertainty\, and the resulting lack of predictabili
 ty in precipitation type\, is reflected by a large degree of variation in 
 the dominant precipitation type over the six-hour period of heaviest preci
 pitation in different members of the ensemble. We use ensemble sensitivity
  analysis to relate the variability with concurrent synoptic-scale fields 
 to highlight atmospheric conditions for which errors may exert significant
  influence on the precipitation type.\n\nWednesday Feb 19/ 2.30 PM/ Room 9
 34 Burnside Hall\n\n \n
DTSTART:20200219T193000Z
DTEND:20200219T203000Z
LOCATION:Room 934\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue 
 Sherbrooke Ouest
SUMMARY:Ensemble predictability of a major freezing rain event in Montreal
URL:https://www.mcgill.ca/meteo/channels/event/ensemble-predictability-majo
 r-freezing-rain-event-montreal-320385
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