1. Comparison of Tropical Cyclones Cindy (2005) and Ivan (2004)
By: Michael L. Jurewicz, Sr.
Northeast Regional Operational Workshop (NROW)
Albany, NY
November 1-2, 2005
Title Slide.

2. Very Different Results for the Northeastern U.S.
Cindy: Little or no significant impact
Mainly 1-3” rainfall amounts (locally 4-5”) across the Delmarva Region, PA, NJ, and Eastern NY within a 24 hour period
Dry antecedent conditions going into the event
Ivan: Major impact
Widespread 4-7” (locally up to 10”) rainfall amounts from the Ohio Valley / WV, across PA, Southern / Eastern NY, and Northern NJ in a hour period
Already wet heading into this event
Summary of rainfall amounts / hydrologic consequences for each cyclone.

3. Ivan’s Track
Plot of Ivan’s track during its entire life cycle.

4. Ivan Rainfall Totals
Plot of rainfall amounts associated with Ivan, from the time it made landfall near the FL / AL border, to the time it exited the Mid-Atlantic coast.

5. Localized Multi-Sensor Estimates
Map of multi-sensor (radar estimates from the Binghamton, NY WSR-88D and rain gauge measurements) rainfall amounts for Sept. 18 and 19, 2004 over Central NY and Northeast PA.

6. Cindy’s Track
Plot of Cindy’s track during much of its life cycle.

7. Cindy Rainfall Totals
Plot of rainfall amounts associated with Cindy, from the time it made landfall over southeastern LA, to the time it exited the NJ coast.

8. Storm Total Estimates from KBGM WSR-88D
Storm total rainfall estimates (from the Binghamton, NY WSR-88D) for Cindy over Central NY and Eastern PA.

9. Both Cyclones Acquired Similar Structures during their ET
Increased frontal-wave structure with latitude at the surface
Upper-level jet cores were enhanced poleward of the cyclones
Due to warm outflow, rising upstream heights, increased shear
Bands of stratiform +RA developed north/west of the cyclone
Located where best combination of low-level fgen and elevated instability existed
A listing of common structural elements, between Ivan and Cindy, during each cyclone’s Extratropical transition (ET).

10. Schematic from CSTAR Research
A summary schematic of important atmospheric components for heavy rainfall, as tropical cyclones first make landfall and then transition Extratropical, over the Northeastern U.S.

11. Frontal-waves: Cindy Ivan
Comparison slides of Cindy and Ivan, showing each cyclone’s frontal-wave structure at the surface, over the Mid-Atlantic region.

12. Upper-level Jets: Cindy Ivan
Comparison slides of Cindy and Ivan, showing the strength of the upper-level jet core to the north of each cyclone.

13. Stratiform Heavy Rain Bands Cindy Ivan
Comparison slides of radar composite imagery for both Cindy and Ivan; showing stratiform heavy rain bands to the north and northwest of each cyclone over PA, NY, and NJ.

14. FGEN and Banded Heavy Rainfall Cindy Ivan
Comparison slides of Cindy and Ivan, each showing a NAM cross-section of 2-D frontogenesis (white contours), negative values of equivalent potential vorticity (EPV, shaded), and omega (light blue contours), for an axis bisecting each cyclone’s stratiform heavy rain bands.

15. Why Such a Disparity in Rainfall ?
Contrast in degrees of interaction with the Westerlies
Time of year played a role
Ultimately affected each cyclone’s ability to transport deep moisture northward
Could either enhance / mitigate rainfall efficiency
Explanation of some reasons why rainfall amounts differed so vastly, between Cindy and Ivan, over the Northeastern U.S.

16. Ivan and its Proximity to Mid-level Short-wave Energy (Frame #1)
A snap-shot of 500 mb heights and a NAM cross-section of potential vorticity (PV), about 24 hours after Ivan made landfall over the Gulf Coast.

17. Ivan (Frame #2)
A snap-shot of 500 mb heights and vorticity, as well as a NAM cross-section of potential vorticity (PV), about 12 hours after the previous slide for Ivan.

18. Ivan (Frame #3)
A snap-shot of 500 mb heights and vorticity, as well as a NAM cross-section of potential vorticity (PV), about 12 hours after the previous slide for Ivan.

19. Cindy and its Proximity to Mid-level Short-wave Energy (Frame #1)
A snap-shot of 500 mb heights and vorticity, as well as a NAM cross-section of potential vorticity (PV), as the remnants of Cindy were moving into the Mid-Atlantic region.

20. Cindy (Frame #2)
A snap-shot of 500 mb heights and vorticity, as well as a NAM cross-section of potential vorticity (PV), about 12 hours after the previous slide for Cindy.

21. Upper-level Jets: Cindy Ivan
Comparison slides of Cindy and Ivan, showing the strength of the upper-level jet core to the north of each cyclone. ** REPEAT OF EARLIER SLIDE **

22. Low-level Jets and Total PW Cindy Ivan
More comparison slides of Cindy and Ivan, displaying total precipitable water values (shaded and contoured) and 850 mb winds (tan wind barbs).

23. Radar Composite from Ivan
Large-scale radar composite from Ivan, along with a cross-section axis and sounding location (black dot) for the following slide.

24. Temperature / RH Cross-section and Sounding analysis (Ivan)
Warm Cloud Layer of 4+ km
A NAM cross-section of relative humidity values (shaded), temperatures (blue contours), frontogenesis (white contours), and ageostrophic streamlines (tan lines). Also, a NAM model sounding over central Pennsylvania at this same time.

25. Radar Composite from Cindy
Large-scale radar composite from Cindy, along with a cross-section axis for the following slide.

26. Temperature / RH Cross-section and OKX Sounding analysis (Cindy)
Warm Cloud Depth of 2.5 to 3 km
Warm Cloud Layer of 2.5 to 3 km
A NAM cross-section of relative humidity values (shaded) and temperatures (green contours). Also, an observed sounding for Upton, NY at this same time.

27. Consequences of Influx of Tropical Air (or lack thereof)
In the case of Ivan:
Stronger Upper-level jet (around 160 kt) lead to more pronounced lower-level response (850 mb flow of kt) and more backed flow into the jet-entrance region
Higher PW air / elevated freezing levels were transported northward into regions affected by stratiform rain bands
Greater Rainfall Efficiency / Accumulation Rates resulted
Reasoning of why influx of tropical air (or lack thereof) was important for these two cyclones.

28. Consequences of Influx of Tropical Air (or lack thereof) - Continued
In the case of Cindy:
Relatively weaker Upper-level jet (around 90 kt) lead to less pronounced lower-level response (850 mb flow of kt) and less backing of the flow
Highest PW air / freezing levels were thus shunted northeastward off the Mid-Atlantic coast; never reaching areas of NY / PA / NJ affected by stratiform rain bands
Lack of Tropical Rainfall Rates
Reasoning of why influx of tropical air (or lack thereof) was important for these two cyclones (continued).

29. Conclusions
Tropical cyclones Cindy (2005) and Ivan (2004) had several common elements
Fairly similar paths from the Gulf Coast region to the Mid-Atlantic states
They took on some of the same structures during their ET
Frontal-wave appearance at the surface
Enhanced upper-level jet cores poleward of the cyclones
Banded heavy rainfall north/west of the cyclone centers, within low-level fgen maxima
Conclusions slide for Cindy / Ivan comparisons and contrasts.

30. Conclusions (Continued)
Despite these similarities, rainfall and subsequent impacts were far different
Accumulation efficiency much greater with Ivan due to influx of tropical air / rainfall rates
Tropical rain rates were never ingested into the banded rainfall over NY / PA / NJ with Cindy
Conclusions slide for Cindy / Ivan comparisons and contrasts (continued).

31. In the Interest of Keeping Up with Current Events : A Quick Look at Katrina
A Band of Heavy Rain occurred generally along its track during ET
3-6” (locally up to 8”) of rain fell from the Ohio Valley to Upstate NY / Northern VT / Parts of Southern Ontario and Quebec within a 24 hour period
Introductory slide for Katrina.

32. Katrina’s Track
Plotted track of Katrina, from the time it made landfall along the Gulf Coast, to the time it exited the Northeastern U.S. into Quebec.

33. Katrina’s Rainfall
Total rainfall plots, associated with Katrina.

34. Storm Total Estimates from KTYX WSR-88D
Storm total rainfall estimates (from the Montague, NY WSR-88D) associated with Katrina.

35. Surface Analysis
A MSLP analysis, about the time that the remnants of Katrina were moving into the Northeastern U.S.

36. Upper-level Jet
A slide of Katrina, from the same time as the previous one, showing the strength of the upper-level jet core to the north of the cyclone.

37. Mid-level Vorticity / PV Coupling
A snap-shot of 500 mb heights and vorticity, as well as a NAM cross-section of potential vorticity (PV), at the same time as the previous slides for Katrina.

38. Low-level Jet and Theta-E
A plot of NAM 850 mb potential temperature values (contoured and shaded) and winds (tan wind barbs) for Katrina, at the same time as previous slides.

39. FGEN and Banded Heavy Rainfall
A slide of Katrina (same time as previous slides), showing a NAM cross-section of 2-D frontogenesis (white contours), negative values of equivalent potential vorticity (EPV, shaded), and omega (light blue contours), for an axis bisecting the cyclone’s stratiform heavy rain bands.

40. Radar Composite from Katrina
Radar composite for Katrina (same time as previous slides). The white line represents the cross-section axis for the following slide.

41. Temperature / RH Cross-section and Sounding analysis (ALY)
Warm Cloud Depth of 3.5 to 4 km
Warm Cloud Layer of 3.5 to 4 km
A NAM cross-section of relative humidity values (shaded) and temperatures (green contours). Also, an observed sounding for Albany, NY at this same time.

42. Final Thoughts
Katrina was, perhaps, a moderate example of a +RA event associated with ET Transition over the Northeastern U.S. (in between Cindy and Ivan)
Decent Westerly interaction (Some PV coupling / well developed jet circulation) with 120 kt / kt upper and lower-level jet cores
Polar jet not quite as far south, or as strong as was the case with Ivan (late August vs. mid to late September)
Allowed tropical air / rainfall rates to be ingested into regions affected by more persistent, stratiform type banding
Rapid system movement / dry antecedent conditions prevented an excessive flooding event
Some final conclusions for Katrina, relative to those made for Cindy and Ivan.

43. Future Possibilities
Magnitude of Heavy Rainfall with Transitioning Tropical Cyclones seems contingent on 3 main factors :
Strength of remnant cyclone itself
Strength of synoptic-scale fronts / jets
Degree of interaction between the above mentioned systems
Modulating factors for any given area :
Warm cloud depth / rainfall efficiency
Progressiveness of overall system
Is there a way to categorize / package all of this information to better inform / serve the public ??
Slide detailing prospects for future work / research.