The Great Waterspout Outbreak of The Great Waterspout Outbreak of 20112011

(Lake Michigan, Sept. 24, 2011) (Lake Michigan, Sept. 24, 2011) Wade Szilagyi, MeteorologistWade Szilagyi, Meteorologist

Meteorological Service of CanadaMeteorological Service of CanadaDirector, International Centre For Waterspout ResearchDirector, International Centre For Waterspout Research

HighlightsHighlights

• Major waterspout outbreakMajor waterspout outbreak

• 20+ waterspouts!20+ waterspouts!

• Major media eventMajor media event

• Highlight of a larger event over lower Great Highlight of a larger event over lower Great Lakes (Sept. 23-30)Lakes (Sept. 23-30)

• 33rdrd largest outbreak since studies began in largest outbreak since studies began in 19941994

• Last major outbreak 2003 (21+ waterspouts)Last major outbreak 2003 (21+ waterspouts)

• 58 photos / videos58 photos / videos

Atmospheric ConditionsAtmospheric Conditions

• Major upper low (4 closed contours at 500 Major upper low (4 closed contours at 500 mb) over southern Lake Michiganmb) over southern Lake Michigan

• Cool air mass (TCool air mass (T850850 = 4 C) = 4 C)

• Unseasonably warm water (Unseasonably warm water (TTlakelake =19 C) =19 C)

• Moderate thermal contrast (Moderate thermal contrast (T = 15 T = 15 C)C)

• Convection to tropopause (Convection to tropopause (ZZ = 23,900 ft) = 23,900 ft)

• Light winds (850Light winds (850wind wind = 170= 170° / 6 kts)° / 6 kts)

Event PredictabilityEvent Predictability(Synoptic Pattern Recognition / Climatology)(Synoptic Pattern Recognition / Climatology)

• Alerted to waterspout Alerted to waterspout potential days in potential days in advance through advance through synoptic pattern synoptic pattern recognition and recognition and waterspout climatologywaterspout climatology

Major upper low, above Major upper low, above ave. water temps., ave. water temps., peak of waterspout peak of waterspout season (Sept.)season (Sept.)

Event PredictabilityEvent Predictability(Waterspout Nomogram)(Waterspout Nomogram)

• Confirmation of Confirmation of waterspout waterspout potential using the potential using the Waterspout Waterspout NomogramNomogram

T = 15 T = 15 CCZZ = 23,900 ft = 23,900 ft850850wind wind = = 6 kts6 kts

Event PredictabilityEvent Predictability(Szilagyi Waterspout Index (SWI))(Szilagyi Waterspout Index (SWI))

• Quantifies waterspout Quantifies waterspout potentialpotential

• Based on the Based on the Waterspout NomogramWaterspout Nomogram

• -10 ≤ SWI ≤ +10-10 ≤ SWI ≤ +10

• Waterspouts are likely Waterspouts are likely when SWI ≥ 0when SWI ≥ 0

SWI ranged from 2 to 6SWI ranged from 2 to 6

Szilagyi Waterspout Index (SWI) Favorable Waterspout Conditions for SWI ≥ 0

Wade Szilagyi, Meteorological Service of Canada (updated 2010)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0 5 10 15 20 25 30 35 40Water - 850 mb Temperature Difference (C)Additional criterion: 850 mb Wind ≤ 35 kts

Con

vect

ive

Clo

ud D

epth

(EL

- LC

L)

(ft)

Event PredictabilityEvent Predictability(New Experimental Waterspout Prognostic (New Experimental Waterspout Prognostic

System)System)

• Geographical display of SWIGeographical display of SWI• Dramatically reduces Dramatically reduces

diagnosis timediagnosis time• Dramatic increase in Dramatic increase in

temporal and spatial temporal and spatial resolution (3hr time steps for resolution (3hr time steps for 2143 points out to 48 hours)2143 points out to 48 hours)

• More efficient coordinationMore efficient coordination• Upstream events identifiedUpstream events identified

Much of Lake Michigan Much of Lake Michigan showed waterspout potentialshowed waterspout potential

Confirmed SightingsConfirmed Sightings

MilwaukeeMilwaukee

MilwaukeeMilwaukee

ChicagoChicago

KenoshaKenosha

ConclusionsConclusions

• Outbreak occurred because:Outbreak occurred because:

1.1. Cool air massCool air mass2.2. Unseasonably warm waterUnseasonably warm water3.3. Major upper lowMajor upper low4.4. Improved reporting technology Improved reporting technology

(Twitter, Facebook, media web (Twitter, Facebook, media web sites, cell phone cameras, etc.)sites, cell phone cameras, etc.)

Questions ?Questions ?

• Contact Wade at:Contact Wade at:– wade.szilagyi@ec.gc.ca– www.icwr.ca (International Centre For (International Centre For

Waterspout Research)Waterspout Research)