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Lake Ontario Unleashed: An Analysis of a February 2007 Lake Effect Event
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Lake Ontario Unleashed: An Analysis of a February 2007 Lake Effect Event


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Detailed discussion of the February 2-12, 2007 massive lake effect event off the east end of Lake Ontario, featuring details, analysis, photos and more.

Detailed discussion of the February 2-12, 2007 massive lake effect event off the east end of Lake Ontario, featuring details, analysis, photos and more.

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  • 1. Lake Ontario Unleashed: A Recap of the Historic February 2-12 Lake Effect Snow Event Matt Lanza, Meteorologist , WKTV- Utica, NY Eastern U.S. Weather Conference III: June 23, 2007
  • 2. Overview
    • Brief Primer on Lake Effect (LES) and Lake Ontario Geography
    • The Winter of 2006-2007 leading up to the event
    • Synoptic (Large Scale) setup for the event
    • Eleven Days of Snow: Highlights/Photos from long-duration event
    • Statistics from the event
    • Suggestions for improving handling of future events
  • 3. What is Lake Effect Snow?
    • Common convention: Cold air moving over the relatively warmer lake waters.
    • Cold air crossing the lakes is dry, and evaporation occurs near the surface.
    • “ Warm,” moist air near the surface of the lakes rises, cools slightly and forms into cumulus clouds.
    • Depending on intensity of the air mass, significant instability can enhance the process.
  • 4. What is Lake Effect Snow?
    • Air continues to rise, cool, and can eventually condense enough to produce precipitation.
    • Precip can fall as either rain or snow
    • Intensity is enhanced by frictional convergence at the lake shore, as well as upsloping (forcing air upward due to terrain).
  • 5. What is Lake Effect Snow?
    • So every time there’s an Arctic air mass, we get dumped on with LES, right? Wrong!
    • Factors that must be examined include: - Degree of instability - Fetch - Wind Shear (speed/vertical) - Upstream contributions - Ice cover? - Synoptic contributions? - Geography
  • 6. What is Lake Effect Snow?
    • A few specifics: - 850 mb temps should be 13°C cooler than the lake temperature (27-28° at 700 mb or 50° at 500 mb for major events). - Vertical wind shear from the surface to 700 mb level should be less than 30°.
    • - Speed shear not too significant
    • - Lake induced CAPEs usually about 300 J/kg
  • 7. What is Lake Effect Snow?
    • A few specifics: - Fetch over the lake should be over as much of it as possible!
  • 8. What is Lake Effect Snow?
    • A few specifics: - Upstream connections: Winds transporting moisture from Lake Superior to Lake Huron or Lake Huron/Georgian Bay to Lake Ontario. - Synoptic setup: Cyclonic flow and positive vorticity advection often acts to enhance snowfall. - High inversion level helps as well.
  • 9. Geography Lesson
  • 10. Geography Lesson
  • 11. Winter 06-07: Tale of Two Seasons
    • November 1-January 15 at UCA/RME: Temperature: +9.0° (38.0°) Snowfall: -31.1” (15.9”)
    • January 16-March 31 at UCA/RME Temperature: -4.1° (21.4°) Snowfall: +60.8” (108.0”)
  • 12. Winter 06-07: Tale of Two Seasons
    • Above normal air temperatures helped keep lake temperatures well above normal as well.
    • With limited LES through late January (biggest events were the Buffalo snows of October and early November snows off Ontario), lake snowbelts were primed to get hammered.
  • 13. Synoptic Setup for LES Event
    • With region primed, all it took was a seasonably cool air mass to kick start the lake.
    • January 29 th saw that occur as 20-40” fell near the lakeshore north of Syracuse.
    • What happens when you get an Unseasonably cold air mass?
  • 14. Synoptic Setup for LES Event Alberta Clipper swings through Synoptic snows wind down at 00Z.
  • 15. 00Z February 3 rd (Friday, 7 PM) Alberta Clipper dragged a cold front through Great Lakes Anomalously cold 850 mb temperatures driven south and eastward with Polar Vortex; -10°C was threshold for LES Deep synoptic moisture was in place
  • 16. 12Z February 3 rd (Saturday, 7 AM) Deepening Polar air mass over Lakes, as 850 mb temps fall to -18°C over Lake Ontario. Deep synoptic moisture remained in place Secondary push of Polar air seen with low pressure over U.P. of Michigan
  • 17. 12Z February 4 th (Sunday, 7 AM) Shortwave trough passed through Deepening 850 mb cold, as temps fall to -23°C Synoptic moisture in place across all the Lakes Core of upper level cold laid out near Lakes
  • 18. 00Z February 5 th (Sunday, 7 PM) Another weak shortwave crossed over Lakes Winds shifted aloft from WSW to more Westerly direction 850 mb cold continued to deepen with temperature range of -28°C to -24°C across the Lakes Synoptic moisture continued to reload across the Lakes
  • 19. 12Z February 5 th (Monday, 7 AM) Final major shift occurred, shifting winds into broad west and west-northwest direction; 850 mb cold continued to hold Synoptic moisture continued to remain deep and in tact
  • 20. Synoptic Setup for LES Event
    • Over the next 7 days, shortwave troughs acted to move the band north and south at about 12-18 hour intervals.
    • Wind flow on average stayed between 225 degrees and 325 degrees.
    • The following are 24 hour radar loops from Weather Underground of the entire event.
  • 21. February 2
  • 22. February 3
  • 23. February 4
  • 24. February 5
  • 25. February 6
  • 26. February 7
  • 27. February 8
  • 28. February 9
  • 29. February 10
  • 30. February 11
  • 31. February 12
  • 32.  
  • 33. Results… Point Rock, NY, February 6
  • 34. Results… Point Rock, NY, February 6
  • 35. Results… Westernville, NY, February 6
  • 36. Results… Westernville, NY, February 6
  • 37. Results… Lake Delta, NY, February 6 Lawn Chairs!
  • 38. Results… Lake Delta, NY, February 6
  • 39. Results… Westdale, NY, February 7
  • 40. Results… Turin, NY, February 10
  • 41. Results… Mexico, NY
  • 42. Results… Oswego, NY
  • 43. Results… Oswego, NY
  • 44. Results… Mexico, NY
  • 45. Results… Camden, NY
  • 46. Results… Camden, NY
  • 47. Results… Williamstown, NY
  • 48. Results… Viewer in Deerfield, NY
  • 49. Stats…
    • Top 5 Snow Totals (2/2 – 2/12): 1.) Redfield: 141.0” * 2.) Parish: 121.0” 3.) North Osceola: 106.0” 3.) Mexico: 106.0” 5.) Westdale: 100.0” * Would have set a record for most snow from a single lake effect event, but due to the length of time it lasted, the NWS stated it would be impossible to consider it a record.
  • 50. Official Snowfall Map
  • 51. Matt’s Unofficial Snowfall Map
  • 52. What We Learned
    • Computer Models, even the finer resolution mesoscale models are great, but they can’t pick up every single disturbance that will come through and shift winds.
    • Example of 36 hour QPF that was 20 miles too far south.
    NWS Buffalo WRF Model Saturday night through Sunday afternoon
  • 53. What We Learned
    • The models were good with QPF in the sense that it was obvious something big was going to occur.
    • The models were off on placement.
    • If you exclusively used surface and upper air analysis maps to do short-fuse 24-48 hour forecasts, your accuracy would have likely been better than by using the models.
  • 54. What We Learned
    • Not unusual to have LES mega-events off the lakes.
    • Very unusual to have 10 day mega-events with such a large spatial expanse receiving 60-80”+ of snow.
    • Upper lakes connections (Huron/G-Bay) helped deliver 6-8” per hour snowfall rates in spots.
    • Not too difficult to say when upper lakes may come into play, but very difficult to determine how prolific snowfall rates will be.
  • 55. What We Learned
    • Bottom line: Snowfall forecasts beyond the 18-24 hour range were extremely difficult due to band movement as well as model difficulties.
    • Snow reports in strategic locations difficult due to sparse population.
  • 56. For Future Events…
    • More must be done to encourage snow spotting in Upstate New York, specifically in the Tug Hill Region.
    • Not impossible to do, as NWS Albany claims that 1% of population of Hamilton County (Adirondacks) is SKYWARN certified.
    • Reports need to be received in a more timely manner as well.
  • 57. For Future Events…
    • Economic dependence on snow in Upstate New York should encourage more SKYWARN participation.
    • Better reports will lead to better forecasts and publicity of snowfall totals, which could lead to more tourism.
    • Percentage of economy dependent on winter tourism is far greater than almost anywhere else in the East.
  • 58. For Future Events…
    • Forecasters must use computer models as a rough guide, not as a crutch.
    • A 2.00” liquid QPF bullseye on Montague might not mean Montague gets 40” of snow, but someone in the Lakes could.
    • They will tell you that it’s favorable for major LES, but they cannot give you specifics.
    • Watch surface and upper air analysis very closely.
  • 59. Entire February LES Study Online
    • Features day by day analysis, every 3 hour Montague radar images, numerous satellite images and other fun things.
    • Mandatory viewing for snow junkies!
  • 60. Thank You! Questions or comments: