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Michael L. Jurewicz, Sr. WFO Binghamton, NY Northeast Regional Operational Workshop

The Evolution of Predecessor Rainfall Events (PRE) with Tropical Cyclones Danny and Bill from the 2009 Season. Michael L. Jurewicz, Sr. WFO Binghamton, NY Northeast Regional Operational Workshop November 5, 2009 . AR TC Tracks and PRE Locations. All AR TC Tracks.

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Michael L. Jurewicz, Sr. WFO Binghamton, NY Northeast Regional Operational Workshop

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  1. The Evolution of Predecessor Rainfall Events (PRE) with Tropical Cyclones Danny and Bill from the 2009 Season Michael L. Jurewicz, Sr. WFO Binghamton, NY Northeast Regional Operational Workshop November 5, 2009

  2. AR TC Tracks and PRE Locations All AR TC Tracks All AR PPTC Tracks; with PRE centroids (colored dots)

  3. Conceptual Model: LOT PREs Ahead Of SR Or AR TCs UL Jet LL θe-Ridge Axis PREs See inset Mid-level Streamlines TC Rainfall Revised and updated from Fig. 13 of Bosart and Carr (1978) Representative TC Tracks

  4. Bill

  5. Brief History of Bill Himself • Bill was initially a Cape Verde tropical wave, which became a named storm on 15 August • From 19-23 August, Bill attained hurricane status well off the U.S. East Coast (briefly reached Category 3) • From 23-25 August, Bill transitioned to an extra-tropical system, as it recurved into the westerlies southeast of the Canadian maritime provinces

  6. Bill’s Approximate Path

  7. Heavy Rainfall Event across New England

  8. Afternoon Rainfall on 22 August Up to 7” (175 mm) rainfall

  9. Radar Loop

  10. Water Vapor Loop

  11. 250 mb at 12z, 22 August

  12. 250 mb at 00z, 23 August

  13. 200 mb Height/Wind/PV, 14z, 22 August

  14. 200 mb Height/Wind/PV, 22z, 22 August Height Rises / PV Destruction

  15. Surface Analysis, 18z, 22 August Possible PRE

  16. 850 mb Moisture Transport Possible PRE

  17. 700 mb Heights, 925 mb Winds/Theta-E, at 21z, 22 August Near intersection of Bill’s moisture and pre-existing moist plume

  18. Parcel Trajectories into Central New England Bill’s Track

  19. Bill Summary • Bill fit into the AR track for potential PRE-producing systems • One main heavy rain episode took place on the periphery of Bill’s influence • Southern NH on 22 August • 4-7” (up to 175 mm) of rain fell within just a few hours, causing flash flooding • Transient nature of heavier rain bands precluded excessive rainfall/runoff problems elsewhere

  20. Danny

  21. Brief History of Danny Himself • Danny was initially a Cape Verde tropical wave, and took several days to become a named storm • Finally, on 26 August, it attained Tropical Storm status east of the Bahamas • From 26-29 August, Danny remained a Tropical Storm well off the Southeast U.S. coast • From 29-31 August, Danny weakened to a Tropical Depression, and ultimately transitioned to an extra-tropical system, as it recurved off the U.S. East Coast

  22. Danny’s Approximate Path

  23. Heavy Rainfall Event across the Mid-Atlantic Region

  24. Late Night/Early Morning Rainfall, 27-28 August 4-8” (100-200 mm) rainfall

  25. Radar Loop

  26. 250 mb at 00z, 28 August

  27. Water Vapor Loop

  28. 700 mb Heights, 925 mb Winds/Theta-E, at 05z, 28 August Separate moist axis Axis of tropical moisture

  29. 850 mb at 00z, 28 August

  30. Parcel Trajectories into the Mid-Atlantic Region

  31. 200 mb Height/Jet/PV, 02z, 28 August

  32. 200 mb Height/Jet/PV, 09z, 28 August

  33. SB CAPE Analysis, 06z, 28 August

  34. Heavy Rainfall Event Just off the Mid-Atlantic Coast

  35. Late Afternoon/Overnight Rainfall, 28-29 August Widespread 5-10” (up to 250 mm) rainfall

  36. Radar Loop, 28-29 August

  37. 250 mb at 00z, 29 August

  38. Water Vapor, 28-29 August

  39. 700 mb Heights, 925 mb Winds/Theta-E, at 03z, 29 August Tropical Moisture Axis

  40. SB CAPE Analysis, 00z, 29 August Possible PRE

  41. Surface Analysis, 00z, 29 August Possible PRE

  42. 850 mb Analysis, 00z on 29 August

  43. Parcel Trajectories into the Mid-Atlantic Coastal Region Danny’s Track

  44. Danny Summary • Danny fit into the AR track for potential PRE-producing systems • Two distinct heavy rain episodes took place on the periphery of Danny’s influence • Event that most resembled a PRE took place just offshore, 28-29 August • Heavy rain/flash flooding that occurred in the Baltimore area appeared to lack sufficient moisture contributions from Danny or jet interactions • Lack of a direct moisture connection with the TC, as well as a relatively cool stable air mass, seemed to protect much of the Northeastern U.S. from excessive rainfall

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