The Understanding Severe Thunderstorms and Alberta Boundary Layers Experiment (UNSTABLE): Overview and Preliminary Results Neil M. Taylor 1, D. Sills 2, J. Hanesiak 3, J. A. Milbrandt 4, C. D. Smith 5, G. Strong 6, S. Skone 7, P. J. McCarthy 8, and J. C. Brimelow 3 1 Hydrometeorology and Arctic Lab, Environment Canada 2 Cloud Physics and Severe Weather Research Section, Environment Canada 3 Centre for Earth Observation Science (CEOS), University of Manitoba 4 Recherche en Prévision Numérique [RPN] (Numerical Weather Prediction Research Section), Environment Canada 5 Climate Research Division, Environment Canada 6 Department of Earth and Atmospheric Sciences, University of Alberta (Adjunct) 7 Department of Geomatics Engineering, University of Calgary 8 Prairie and Arctic Storm Prediction Centre, Environment Canada 24 th Conference on Severe Local Storms 31 October, Savannah, GA

24 th Conference on Severe Local Storms 31 October, Savannah, GA UNSTABLE Rationale Canada’s Population Density (2006) > Existing real-time surface observations over a region of the AB foothills

24 th Conference on Severe Local Storms 31 October, Savannah, GA Calgary Red Deer Experimental Design UNSTABLE Goals Improve understanding of ABL processes and CI Improve accuracy and lead time for warnings Assess utility of high-res NWP to resolve processes and provide guidance Revise conceptual models for CI and severe wx 3 Main Science Areas 1. ABL moisture and convergence boundaries 2. Surface processes (heat flux) 3. High resolution NWP model forecasts of CI and severe weather Secondary Domain Targeting Storm Evolution Primary Domain Targeting Storm Initiation 15km Spacing 25km Spacing

24 th Conference on Severe Local Storms 31 October, Savannah, GA AMMOS ATMOS Tethersonde Balloon CRD Mobile Radiosonde Trailer and Interior MARS Trailer (AERI, WV Radiometer, Radiosondes, Cloud Base Temp.) Special Instrumentation WMI aircraft w/ AIMMS-20 Instrument Package (T, P, RH, 3-axis wind & acceleration) (Automated Transportable Meteorological Observation System) (Automated Mobile Meteorological Observation System)

Some (Very) Preliminary Results

24 th Conference on Severe Local Storms 31 October, Savannah, GA Science Question 1 (Taylor and Sills) 2000 UTC 13 July 2008 Existing Stations T d (°C) Indications of moisture gradient and convergence 50 km

24 th Conference on Severe Local Storms 31 October, Savannah, GA Science Question UTC 13 July 2008 Fixed Stations Indications of a convergence boundary with T d difference 8.4 °C over 10.3 km (0.8 °C km -1 ) 50 km T d (°C)

24 th Conference on Severe Local Storms 31 October, Savannah, GA Science Question UTC 13 July 2008 Mobile Stations Delineation of the boundary enhanced by addition of mobile observations From AMMOS overall moisture difference of 8.7 °C over 0.5 km (16.8 °C km -1 or 7.2 g kg -1 km -1 ) Aircraft and other data undergoing analysis Td (°C) 40 km T d (°C)

24 th Conference on Severe Local Storms 31 October, Savannah, GA Science Question 1 20:48:02 Z to 20:48:38 Z AMMOS Two-second sample observations Transect nearly perpendicular to orientation of boundary Embedded dewpoint change of 4.8 °C over 179 m (26.9 °C km -1 or 11.0 g kg -1 km -1 ) Boundary traversed by multiple vehicles with similar moisture gradients 518m Strongest T d change 4.8 °C over 179 m (26.9 °C km -1 ) 7 8

24 th Conference on Severe Local Storms 31 October, Savannah, GA 00Z MB1 and MB2 Soundings Science Question 1 00 UTC MB1 and MB2 Radiosondes Evidence of elevated residual layer of warm air from dry side of boundary ~ 3700 m AGL dry and warm ABL with westerly wind ~ 1400 m AGL moist and cool with veering winds and cap ~ 700mb

24 th Conference on Severe Local Storms 31 October, Savannah, GA Science Question 2 (Hanesiak) 20 July 2008 Crops vs. Forest Research Flight Tracks 20 July UTC Soundings - MB1 and MB Crops Forest Potential Temperature and Mixing Ratio from Research Flight at ~ 1400 m ASL Forest Crops MB1 MB2

24 th Conference on Severe Local Storms 31 October, Savannah, GA Real-time 2.5-km limited-area forecast runs are produced daily by Environment Canada Nested 1-km runs were performed daily from June 1 – August 31, 2008 for a special grid over the UNSTABLE domains Science Question 3 (Milbrandt) Nested 1-km LAM Runs Standard and experimental forecast fields available via website each morning Images and model data archived for future analysis and comparison to data collected during the UNSTABLE IOP T d + WINDS Synthetic Reflectivity Surface Dewpoint and Wind

24 th Conference on Severe Local Storms 31 October, Savannah, GA In Conclusion… And Finally….

24 th Conference on Severe Local Storms 31 October, Savannah, GA Thank You! Photo courtesy Heather Rombough