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Analysis of Precipitation Distributions Associated with Two Cool-Season Cutoff Cyclones

Analysis of Precipitation Distributions Associated with Two Cool-Season Cutoff Cyclones. Melissa Payer, Lance F. Bosart, Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany, SUNY Neil A. Stuart and Thomas A. Wasula NOAA/NWS, Albany, NY NROW XI

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Analysis of Precipitation Distributions Associated with Two Cool-Season Cutoff Cyclones

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  1. Analysis of Precipitation Distributions Associated with Two Cool-Season Cutoff Cyclones Melissa Payer, Lance F. Bosart, Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany, SUNY Neil A. Stuart and Thomas A. Wasula NOAA/NWS, Albany, NY NROW XI 5 November 2009 NOAA/CSTAR Grant NA07NWS4680001

  2. Motivation • Forecasting precipitation distributions associated with 500 hPa cool-season cutoff cyclones can be a challenge in the Northeast • Forecast uncertainties often arise due to variation in cutoff speed and interaction with the complex topography in the Northeast • Identifying signatures differentiating between precipitation distributions would help forecasters

  3. Objectives Determine how synoptic and mesoscale features affect precipitation distributions through several case studies of difficult-to-forecast cutoffs as well as cutoffs associated with varying precipitation distributions Identify common signatures differentiating between various precipitation distributions

  4. Data • 1.0° GFS • 2.5° NCEP–NCAR reanalysis data • Climatologies created for 1979–2008 • Standardized anomalies fields were created from the 1.0° GFS analyses with respect to climatology • 6-h National Precipitation Verification Unit (NPVU) QPE

  5. Methodology • Cool-season:Oct 1–Apr 30 • Analysis period:2004/05–2008/09 • Cutoff domain: 35–52.5°N, 90–60°W • Cutoff criteria: • Duration > 12 h • 30-m height rise in all directions • Precipitation domain:New England, NY, PA, NJ • Heavy precipitation: > 25 mm of precipitation over the Northeast in a 24-h period from 1200 UTC to 1200 UTC

  6. Case Study 1: 8–9 March 2008 Fast-moving cutoff Widespread flooding event with some icing reported in the Adirondacks Numerical models showed considerable variability in forecasting the cutoff 3–8 days prior to the event Forecasts confined the heavy precipitation to coastal regions; however widespread heavy precipitation was observed throughout much of the Northeast

  7. 8–9 March 2008 Cutoff 8–9 March 2008 500 hPa Mean Heights (dam) and Track of Cutoff 8–9 March 2008 2-day NPVU QPE (mm)

  8. 080307/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  9. 080307/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  10. 080307/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  11. 080307/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  12. 080308/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  13. 080308/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  14. 080308/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  15. 080308/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  16. 080309/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  17. 080309/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  18. 080309/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  19. 080309/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  20. 080310/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  21. 1800 UTC 8 March 0000 UTC 9 March 6-h NPVU QPE (mm)

  22. 1800 UTC 8 March 0000 UTC 9 March 250 hPa Geo. Heights (dam, solid contour), Winds (ms-1, shaded), and Divergence (x 10-5 s-1, dashed contour)

  23. 1800 UTC 8 March 0000 UTC 9 March 500 hPa Geo. Heights (dam, solid contour), Absolute Vorticity (x 10-5 s-1, shaded), Absolute Vorticity Advection (x 10-5 s-1 3 h-1, dashed contour), and Wind (kt, barbs)

  24. 1800 UTC 8 March 0000 UTC 9 March 700 hPa Geo. Heights (dam, solid contour), Temperature (°C, dashed contour), Q-vectors (arrow), and Q-vector Convergence/Divergence (K m-2 s-1, shaded)

  25. 1800 UTC 8 March 0000 UTC 9 March Surface MSLP (m, solid contour), 1000–500 Thickness (m, dashed contour), and Precipitable Water (mm, shaded)

  26. 1800 UTC 8 March 0000 UTC 9 March 925 hPa Frontogenesis (K/(100 km * 3 h), shaded), Potential Temperature (K, solid contour), and Wind (kt, barbs)

  27. 1800 UTC 8 March 0000 UTC 9 March Standardized Anomaly of Precipitable Water (SD, shaded), 850 hPa Geo. Heights (dam, solid contour), and Precipitable Water (mm, dashed contour)

  28. 8–9 March 2008 Summary • Three primary regions of heavy precipitation: • Precipitation maximum east of Lake Ontario due to lake effect • North-south band of precipitation in eastern New York and western New England collocated with strong cyclonic absolute vorticity advection and favorable QG forcing for ascent associated with strong Q-vector convergence • Heavy precipitation over Cape Cod and Maine associated with strong frontogenesis ahead of warm front • Exit and entrance regions of upper-level jet streaks provided favorable forcing for ascent • Anomalous Atlantic moisture advected by low-level jet contributed to heavy precipitation

  29. Case Study 2: 2–3 February 2009 • Considered a forecast bust for the Northeast • Numerical models exhibited large disagreement in the speed and track of the cutoff, which directly impacted forecasts of precipitation type and amount • Heavy precipitation was forecast to occur with this event; however most locations received less than 5 mm

  30. t–108 h t–96 h t–90 h NCEP Global Ensemble Forecast System Valid 090203/1200 Source: Grumm et al. (2009)

  31. 2–3 February 2009 Cutoff 2–3 February 2009 500 hPa Mean Heights (dam) and Track of Cutoff 2–3 February 2009 2-day NPVU QPE (mm)

  32. 090201/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  33. 090201/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  34. 090202/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  35. 090202/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  36. 090202/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  37. 090202/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  38. 090203/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  39. 090203/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  40. 090202/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  41. 090203/1800F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  42. 090204/0000F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  43. 090204/0600F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  44. 090204/1200F000 DT Potential Temperature (K, shaded), Winds (kt, barbs), and LL Relative Vorticity (black contours), 500 hPa Heights and Absolute Vorticity (inset)

  45. 1800 UTC 3 February 0000 UTC 4 February 6-h NPVU QPE (mm)

  46. 1800 UTC 3 February 0000 UTC 4 February 250 hPa Geo. Heights (dam, solid contour), Winds (ms-1, shaded), and Divergence (x 10-5 s-1, dashed contour)

  47. 1800 UTC 3 February 0000 UTC 4 February 500 hPa Geo. Heights (dam, solid contour), Absolute Vorticity (x 10-5 s-1, shaded), Absolute Vorticity Advection (x 10-5 s-1 3 h-1, dashed contour), and Wind (kt, barbs)

  48. 1800 UTC 3 February 0000 UTC 4 February Surface MSLP (m, solid contour), 1000–500 Thickness (m, dashed contour), and Precipitable Water (mm, shaded)

  49. 1800 UTC 3 February 0000 UTC 4 February 850 hPa Equiv. Potential Temperature (K, solid contour), Equiv. Potential Temperature Advection (K 3 h-1, shaded), and Wind (kt, barbs)

  50. 1800 UTC 3 February 0000 UTC 4 February Standardized Anomaly of Precipitable Water (SD, shaded), 850 hPa Geo. Heights (dam, solid contour), and Precipitable Water (mm, dashed contour)

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