A New Great Lakes Waterspout Prognostic System
(Automation of the Waterspout Nomogram) Wade Szilagyi and Victor Chung Presented by: David Rodgers Meteorological Service of Canada 20th U.S. Canadian Great Lakes Operational Meteorology Workshop March 14-16th 2012 The title is which is essentially the automation of the waterspout nomogram Im presenting this talk on behalf of Wade and Victor Introduction Purpose To develop an algorithm that produces a waterspout prognostic field for the Great Lakes Advantages Dramatically reduces diagnosis time More efficient coordination between forecast offices Precursor upstream forecast events viewable Purpose Advantages dramatically reduces diagnosis time and compared to looking at model forecast soundings, it increases temporal and spatial resolution a web based interface is planned that will make coordination between offices more efficient Forecasters will easily be able to see favourable conditions for waterspouts over upstream lakes Waterspout Climatology over the Great Lakes
Just wanted to touch on waterspout climatology over the great lakes The diagram on the left shows all confirmed water spout reports over the great lakes by month from 1994 to 2010 Waterspout season goes from June to Nov with the peak being in Aug and Sep when the great lakes are typically at their warmest Winter time observation of waterspouts is limited likely because of minimal marine activities Waterspouts that occurred in summer are usually associated with severe weather Waterspouts that occurred in the Fall are usually associated with non-severe weather like upper lows or land breezes The map on the right shows all waterspout sightings from 1957 to 2011 Youll notice that theyre more likely to be sighted near populated areas Development History 1994 Intensive investigation initiated intowaterspout activity over the Great Lakes 1996 Waterspout Nomogram 2004 Szilagyi Waterspout Index 2011 Experimental Waterspout PrognosticSystem Waterspout Nomogram An empirical technique to forecast waterspouts
Based on 207 events over the Great Lakes from 1988 to 2011 Predictors: Water-850 mb temperature difference (T) Convective cloud depth(EL-LCL = Z) 850 mb wind speed (W850 ) Now well go into some of the details of the waterspout nomogram that some of you may be familiar with Its an empirical technique to forecast waterspouts Its based on 207 events over the great lakes from 1988 to 2011 The predictors are delta t found on the x axis delta z found on the y axis No waterspouts are expected if 850 mb winds are stronger than 35 kts. Szilagyi Waterspout Index (SWI)
Quantifies the likelihood of waterspout formation A set of dimensionless SWI values (from -10 to +10) are plotted on the Waterspout Nomogram Waterspouts are likely to occur when SWI 0. The larger the SWI the greater the potential SWI is a function of both T and Z the szilagyi waterspout index is based on the waterspout nomogram It quantifies the likelihood of waterspout formation Set of dimensionless SWI values from -10 to +10 is plotted on the nomogram Waterspouts are likely to occur when SWI is greater than 0 The larger the SWI, the greater the potential SWI is a function of both delta t and delta z A New Waterspout Prognostic System Development based on the SWI
Continuing along the development path, we come to the new waterspout prognostic system which is based on the SWI An Overview of the Waterspout Algorithm
CMC GemReg Output OR CMC GemLam Output Central Command Program Gridded Water Temp Surface data Upper Air data Sounding Profile (at every grid) PGSM [CMC] Sort NinJo Parcel trajectory (parameters required for the index) Output display SWI output fields Heres an overview of the waterspout algorithm It consists of 3 main modules shown here in the yellow ovals...PGSM, Sort and Parcel trajectory PGSM is a CMC utility program designed to perform horizontal interpolations between model grid points In the algorithm, its used to interpolate model data to a finer resolution grid for the great lakes So it does this for parameters like water temperature, air temperature, and pressure Sort is a program that converts the extracted data from PGSM to sounding profiles at each of the finer resolution grid points Parcel trajectory is a program that performs parcel lifts and calculates the predictors (T, Z). These two predictors are then matched with the SWI lookup table to come up with the correct waterspout index From there the SWI can be displayed on a workstation or eventually on a web based interface Web SWI lookup table (derived from nomogram) Output display Conversion of Nomogram to SWI
Each (T,Z) pair has an associated SWI value SWI Lookup Table Conversion of nomogram to SWI through a lookup table TCloud Depth (Z)SWI . Each delta t and delta z pair has an associated SWI value The graph at the bottom left was manually converted to a lookup table This was a fairly labour intensive process, Wade told me this took him a week do Two Cases August 21, 2011 The Goderich Tornado Event
September 24, 2011 The Lake Michigan Outbreak Now well take a brief look at 2 cases August 21, 2011 The Goderich Tornado Event
Case 1 August 21, 2011 The Goderich Tornado Event GEMREG Model Output for 12Z Aug 21 and 00Z Aug 22, 2011
500 mb Height / Vorticity 12Z, Aug 21, 2011 500 mb Height / Vorticity 00Z, Aug 22, 2011 These are plots of 500 mb height and vorticityfor 18z Aug 21 and 00z Aug 22 Weve got a broad upper trof over the great lakes with a strong jet over the lower great lakes Upstream signals for Goderich waterspout. Also, a waterspout spotted 2
Upstream signals for Goderich waterspout. Also, a waterspout spotted 2.5 km off shore from Massassauga Provincial Park at ~1645Z Waterspout Index at 15Z Aug 21, 2011 SWI Color Scale 1645Z: 1 waterspout 2.5 km off of Massassauga Provincial Park This is the SWI for 15z on Aug 21st The yellow squares represent values of 7 or 8 while red represents 9 or 10 this was an early indicator 5 hours ahead 3 hours ahead of the georgian bay waterspout Upstream signals for Goderich waterspout Hook Echo evident from 1930-1955Z northwest of Goderich
Waterspout Index at 18Z, Aug 21, 2011 This is a 18z plot of SWI...values are around 7 or 8 along the eastern shore there was a report of the waterspout northwest of Goderich at ~ Z. The tornadic waterspout made landfall at ~ 19:55Z. SWI worked very well for this event. Hook echo was evident at 1950 and 2000Z as the storm cell moved onshore
Heres conventional and doppler images for 1950z and 2000z You can see the hook echo and couplet well as the storm moved onshore Cold air advection behind front increasing area of waterspout potential
Waterspout Index at 21Z, Aug 21, 2011 The potential for waterspouts increased after the cold frontal passage SWI ranges from 5 to 8 Cold air continues to advect south area of waterspout potential more extensive
Waterspout Index at 00Z, Aug 22, 2011 September 24, 2011 Waterspout outbreak over Lake Michigan
Case 2 September 24, 2011 Waterspout outbreak over Lake Michigan This is the same case that Haizhen looked at in the previous talk Upper Low near Chicago, 12Z September 24
Waterspout Index at 12Z, Sept 24, 2011 Z: 4 waterspouts off Fort Sheridan The top left plot is 500 mb height and vorticity for 12z Sep 24 At the bottom is the radaryou can see scattered echos On the right is the SWI with values ranging from 0 to 4 There were a number of waterspouts reported this day4 off Fort Sheridan, 5 east of Chicago 1200Z: 1 waterspout 2 miles east of Waukegan 1200Z: 4+ waterspouts distant east of LI pier in Chicago Z: 1 waterspout 3-4 miles east of Chicago 18Z September 24 Waterspout Index at 18Z, Sept 24, 2011
Z: 7 waterspouts off of Milwaukee These are 18z plots of 500 mb height and vorticity, radar, and SWI 7 waterspouts were reported east of Milwaukee 1625Z: 1 waterspout 2 miles northeast of Chicago 21Z September 24 Waterspout Index at 21Z, Sept 24, 2011
These are 21z plots One more report at 2015z 2015Z: 1 waterspout 1 mile southeast Kenosha 00Z September 25 Waterspout Index at 00Z, Sept 25, 2011
Lastly these are plots from Sep 25 at 00z One more report 0010Z: 1 waterspout 2 miles east of Kenosha Conclusion The new waterspout prognostic system speeds up the process for diagnosing waterspout potential The applicability of the algorithm has been demonstrated positively through a number of case studies The Goderich case showed that the SWI field could be used as a precursor signal of tornados downstream This new waterspout prognostic system The applicability of the algorithm The Goderich case has showed that the SWI field Future Adopt a higher resolution grid (0.1 lat x long) and use GemLam Distinguish between tornadic vs non-tornadic waterspouts Include surface convergent fields(GemReg/GemLam) Refinerisk area Automated output 24/7 Expand to other marine areas: Atlantic/Pacific coasts, globally Relate SWI to landspouts Adopt a higher resolution grid and use model data from the GemLam Distinguish between Include surface convergent fields to help refine the risk area.this would probably be in the form of a second field to overlay on the SWI Automated output Expand to other marine areas including Atlantic and Pacific coasts and eventually globally Relating SWI to landspouts