ELBOW 2001 The Effects of Lake Breezes On

Weather Project

David Sills, MSC-MRBPeter Taylor, York University

Patrick King, MSC-MRBWayne Hocking, University of Western

OntarioArt Schaafsma / Ian Nichols, University of

Guelph - Ridgetown College

Motivation - Flash Floods

Punkeydoodles Corners flash flooding case from ELBOW 1997 - lake breeze fronts found to be one of the most important factors

Motivation - Flash Floods

Punkeydoodles Corners flash flooding case from ELBOW 1997 - lake breeze fronts found to be one of the most important factors

Motivation - Flash Floods

Punkeydoodles Corners flash flooding case from ELBOW 1997 – 24h precipitation accumulation. Note area of maximum precipitation.

Motivation - Flash Floods

Motivation - Tornadoes

Guelph F2 tornado case from 17 July 2000 - lake breeze fronts important for convective initiation and suspected factor in tornadogenesis

Motivation - Tornadoes

Motivation - Tornadoes

Guelph F2 tornado case from 17 July 2000 - lake breeze fronts important for convective initiation and suspected factor in tornadogenesis

Motivation - Tornadoes

ELBOW 2001 Objectives

• To improve our understanding of the way in which low-level boundaries such as lake breeze fronts interact among themselves and with synoptic-scale weather features to initiate or enhance convective storms and generate severe to extreme weather events, including flash floods and tornadoes.

• To evaluate and improve current methods of short-range forecasting and nowcasting for lake breeze occurrence, location of lake breeze frontal boundaries and circulations, and the initiation and enhancement of thunderstorms and related severe weather at lake breeze fronts.

Investigators (Field program)MSC-MRB (MSC Funding)

• NRC Twin Otter aircraft time• portable 3 cm Doppler radar• boundary-layer profiler, radiosondes• scientists, computer resources, etc.

York University (CFCAS Funding)• Mesonet, radiosondes, light aircraft, mobile

surveys• PDF / graduate students / summer students

University of Western Ontario (CFCAS Funding)• wind profiler, surface observations, kite

observations, radiosondes

University of Guelph - Ridgetown College (CFCAS Funding)

• assistance with mesonet, additional surface data

The Weather Network• Mobile surveys

Observing Platforms• Most instrumention will be sited within the effective

Doppler range of the Exeter radar (~100 km radius)• Mesonet stations, upper-air launches and aircraft flights

will be along lines between Lake Huron and Lake Erie• Three simultaneous upper-air releases at 15Z, 18Z and

21Z• Aircraft flights at various altitudes to build vertical

cross-section through lake breeze circulations and across fronts

• A 3 cm (X-band) Doppler radar, two profilers, and mobile surface and upper-air observations will be located within the effective clear-air return range of Exeter radar (~50 km radius)

Study PeriodGeneral Obs: Jan 2001 - Dec 2002

- archive operational data for climatological study

Enhanced Obs: June 2001 - Aug 2001- data from profilers, radars,

mesonet

Intensive Obs: 11 June - 20 July+ (window)- data from mesonet, upper-air

stations, portable Doppler, aircraft, profilers, mobile observations

Evaluation, Modelling and Analysis: Aug 2001 - Dec 2002

Study Location

Study Location

Instrument Siting

Instrument Siting

Model Evaluation

Will be evaluating the skill of several current operational and semi-operational models to predict lake breezes and associated convective weather eg. HIMAP

MC2 Hi-Res Modelling

Will be using the MC2 model to both better understand lake breeze / severe storm dynamics and evaluate MC2’s ability to predict these phenomena

Lake Breeze Forecast Utility

The forecaster aid called the Lake Breeze Forecast Utility will also be improved by adding cases from ELBOW 2001.

Summary• ELBOW 2001 will build on the experience

gained with the 1997 ELBOW pilot project• A greater variety of observation

platforms will be used including the Exeter Doppler radar, a portable Doppler radar and the Twin Otter aircraft

• Modelling, analysis and evaluation will be conducted after the field program ends

• Strong emphasis on knowledge / technology transfer