Comparison of Tropical Cyclones Cindy (2005) and Ivan (2004)

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 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 – Widespread 4-7” (locally up to 10”) rainfall amounts from the Ohio Valley / WV, across PA, Southern / Eastern NY, and Northern NJ in a 12-18 hour period – Already wet heading into this event • Ivan: Major impact Ivan’s Track Ivan Rainfall Totals Localized Multi-Sensor Estimates Cindy’s Track Cindy Rainfall Totals Storm Total Estimates from KBGM WSR-88D 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 Schematic from CSTAR Research Cindy Frontal-waves: Ivan Upper-level Jets: Cindy Ivan Stratiform Heavy Rain Bands Cindy Ivan FGEN and Banded Heavy Rainfall Cindy Ivan 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 Ivan and its Proximity to Mid-level Short-wave Energy (Frame #1) Ivan (Frame #2) Ivan (Frame #3) Cindy and its Proximity to Mid-level Short-wave Energy (Frame #1) Cindy (Frame #2) Upper-level Jets: Cindy Ivan Low-level Jets and Total PW Cindy Ivan Radar Composite from Ivan Temperature / RH Cross-section and Sounding analysis (Ivan) Warm Cloud Layer of 4+ km Radar Composite from Cindy Temperature / RH Cross-section and OKX Sounding analysis (Cindy) Warm Cloud Depth of Warm Cloud Layer 2.5 to 3 km of 2.5 to 3 km 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 4550 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 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 30-35 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 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 (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 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 Katrina’s Track Katrina’s Rainfall Storm Total Estimates from KTYX WSR-88D Surface Analysis Upper-level Jet Mid-level Vorticity / PV Coupling Low-level Jet and Theta-E FGEN and Banded Heavy Rainfall Radar Composite from Katrina Temperature / RH Cross-section and Sounding analysis (ALY) Warm Cloud Warm Cloud Depth of 3.5 to Layer 4 of 3.5 to 4 km km 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 / 40-50 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 excessive flooding event • Rapid system movement / dry antecedent conditions prevented an 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 – Warm cloud depth / rainfall efficiency – Progressiveness of overall system • Modulating factors for any given area : • Is there a way to categorize / package all of this information to better inform / serve the public ??