Event Summary
     National Weather Service, Raleigh NC


Tropical Storm Cindy, July 2005
Preliminary - updated 2005/07/18



Satellite Imager of Tropical Storm Cindy on 2005/07/06 - Click to enlarge
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Event Headlines

...The remnants of Cindy had a minimal impact on Central North Carolina...
...The preferred location for the development of tornadoes was close to Cindy’s center of circulation and in close proximity to a west to east surface boundary just south of the Virginia – North Carolina state line...
...Warning decision criteria for tornadoes associated with Cindy were modified in real-time based on situational awareness...


Overview

Tropical Depression three developed in the northwestern Caribbean Sea, late in the afternoon on Sunday, July 3, 2005, 145 miles south of the Cozumel, Mexico. Tropical Depression three moved northwest at around 10 MPH, and made landfall on the east coast of the Yucatan Peninsula in the early morning hours Monday, July 4, 2005. The depression emerged in the southern Gulf of Mexico during the day Monday, and was named Cindy, the 3rd tropical storm of the Atlantic season at 400 AM CDT, Tuesday, July 5, 2005, approximately 255 south-southwest of the mouth of the Mississippi River. Cindy was moving north near 15 mph, with a minimum pressure of 1002 MB. Cindy was located 125 miles southwest of the mouth of the Mississippi River early Tuesday afternoon. Maximum sustained winds had increased to near 60 MPH, while the pressure had dropped to 1000 MB.

By 7 PM CDT Tuesday, July 5, 2005, Cindy’s minimum pressure was down to 992 MB, and maximum sustained winds up to near 70 mph. Cindy was located about 55 miles south-southwest of Grand Isle Louisiana, moving north-northeast near 15 MPH. Cindy moved onshore the southeastern Louisiana coast shortly after 10 PM CDT Tuesday night, July 5, 2005, with maximum sustained winds near 70 MPH.

Cindy was downgraded to a tropical depression as it moved northeast across central Alabama into northern Georgia Wednesday and Wednesday night, July 6, 2005. Very heavy rain bands associated with the system produced flash flooding over portions of north Georgia including Atlanta.

The remnant low pressure system continued moving northeast during Thursday, July 6, 2005, tracking along the eastern slopes of the Appalachians of North Carolina. The circulation associated with the remnant low combined with a frontal boundary over western and northern North Carolina to produce several high precipitation supercell thunderstorms. These thunderstorms formed along the boundary and east of the remnant low pressure system track during Thursday afternoon and evening. Several of these storms produced tornadoes. The low pressure system moved into Virginia Thursday evening and northeast across Virginia reaching the northern Chesapeake Bay Friday morning July 8, 2005. The remnant low finally moved northeast and off the New Jersey coast on Friday night, July 8, 2005.


Additional Details

Additional details may become available at the NWS offices directly affected by the storm...
The National Weather Service Greenville/Spartanburg



Cindy's Track



Tropical Storm Cindy Track
Tropical Storm Cindy Track - Click to enlarge
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Detailed Tropical Storm Cindy Track
Tropical Storm Cindy Track - Click to enlarge
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Maps of Precipitation Totals, and Severe Weather Reports from Tropical Storm Cindy


Precipitation Totals from Tropical Storm Cindy

The map below contains precipitation totals during the period in which Cindy impacted North Carolina

Maximum wind gusts from Tropical Storm Cindy




Severe Weather reports from Tropical Storm Cindy

The map below contains severe weather reports received by the National Weather Service during the period in which Cindy impacted North Carolina on Thursday, July 7, 2005.


Severe Weather reports from Tropical Storm Cindy




Mesoscale Features


One of the key mesoscale features during this event was a west to east surface boundary that was located across the northern Piedmont during the afternoon and evening of Thursday July 7, 2005. A plot of surface observations and LAPS objective analysis clearly shows the location of a boundary, located from Alexander County through the Triad area to Halifax County.

Along and north of this boundary, the environment was more favorable for tornadoes. The LCL heights were on the order of 1000 meters (less than 1000 meters is favorable for tornadoes), surface dewpoint depressions were 10 degrees or less, and a northeast wind enhanced low level helicity.

To the south of the boundary, LCL's were 1400 meters or higher, surface dewpoint depressions were 15 to 20 degrees (10 or lower is favorable for tornadoes), and the surface wind was from the south, resulting in less helicity. Not surprisingly, the majority of tornado reports were from locations along and north of the boundary, while south of the boundary there were mainly funnel cloud reports and minor straight-line wind damage.



Analyzed mean sea level pressure (black) and surface wind barbs from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
The surface circulation center of the remnants of Cindy is clearly visible across western NC. A surface boundary stretches west to east across NC from near Winston-Salem to near Rocky Mount.

SPC Analysis at 21Z on Thursday, July 7, 2005.



Analyzed surface temperatures (red/purple), dewpoints (green/yellow), and wind barbs from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
Note the area of temperatures in the 90s across central and southeastern NC with dewpoints in the upper 60s to lower 70s.

SPC Analysis at 21Z on Thursday, July 7, 2005.



0-3 Km Storm Relative Helicity (blue) and storm motion (brown) from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
Note the area of greatest Storm Relative Helicity across western and northwestern NC with a large area of values in excess of 250 units with maximum values greater than 600.

SPC Analysis at 21Z on Thursday, July 7, 2005.



100 MB Mean CAPE values from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
Note the axis of higher CAPE values across the western Piedmont of NC and another axis in the Coastal Plain.

SPC Analysis at 21Z on Thursday, July 7, 2005.



100 MB Mean Parcel LCL Height from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
Note the LCL maximum south of the boundary, with a minimum just north of the boundary. Favorable values of LCL height for tornadoes are 1000 m or lower.

SPC Analysis at 21Z on Thursday, July 7, 2005.



Analyzed precipitable water (green) and wind barbs from SPC at 21Z on Thursday, July 7, 2005 (5 PM EDT).
Note the axis of maximum precipitable water across the western Piedmont of NC.

SPC Analysis at 21Z on Thursday, July 7, 2005.





Radar Imagery

National Weather Service regional radar composite from 2100Z on Thursday, July 7, 2005.

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Base reflectivity radar imagery from the krax WSR-88D at 2102Z on Thursday, July 7, 2005.

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The Loop of 0.5 Degree Reflectivity Imagery from the krax WSR-88D from 1559Z (1159 AM EDT) Thursday, July 7 through 0500Z (100 AM EDT) Friday, July 8, 2005 highlights the development and progression of the convection associated with Cindy.




Weak rotation can be seen in the 1949Z 07 JUL 0.5 degree Storm Relative Velocity imagery on the right with the storm in Forsyth County. A tornado was reported around this time in Rural Hall. As the storms moved north of the boundary, these rotation signatures strengthened.

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A pronounced hook can be seen in the 0038Z 08 JUL 0.5 degree reflectivity image on the left, with strong rotation in the Storm Relative Velocity image on the right. This storm produced a tornado in Cokesbury.

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Warning Decision Process


The recommended warning criterion of a rotational velocity of 20 kts for tropical cyclone tornadoes was initially used. This worked well for storms along and north of the boundary, but was too low for storms south of the boundary. Several reports of wind damage and tornadoes were reported in the foothills close to the boundary, and since these storms were moving into our western border counties and had good rotation signatures, tornado warnings were issued. Near the boundary, tornadoes were reported in Forsyth and Person counties.

As the event unfolded and there was no verification coming in south of the boundary, the rotational velocity warning threshold was raised for counties south of the boundary, to around 30-35 kts. It was realized at this time that the environment south of the boundary was not as conducive to tornadoes. Severe thunderstorm warnings were issued instead. The storms continued to exhibit good rotation, and there were some funnel cloud reports, but there were no touchdowns and only isolated minor wind damage.

One storm in western Harnett County strengthened and had over 80 kts inbound velocity along with a good hook signature, and a tornado warning was issued. A tornado was spotted with this storm along with some minor damage, but as it moved into Wake county, it lost its rotation and fell apart.

Items that worked during the event include...

  • Excellent situational awareness. MSAS and frequent surface analysis helped to define the surface boundary as well as low level circulation center. These two key features enhanced the low level helicity, leading toward greater threat of tornadic cells.
  • Augmented staffing was well thought out. The versatility of staff members who can update the GFE database and still perform HMT duties was very beneficial. Once new employees arrive this fall and have finished their office orientation, it would be to our advantage to train them in grid manipulation so that they can help out in similar scenarios in the future. Also, assigning office personnel to tasks that utilized their strengths was beneficial to the event.
  • Having an assigned storm coordinator helped to facilitate the flow of information and keep track of pertinent information.
  • Good communication among operational staff by relaying new warnings and other information among forecasters.
  • Sectorization of radar helped to take some of the pressure off the radar operators.
  • Timeliness of soliciting ground truth.
  • Flood watch was very accurately issued spatially and temporally.
  • The potential for severe weather was highlighted the night before it occurred via SPS.
  • SPC analysis page was open at workstations and high lighted very well trends in the helicity, LCL, and dew point depression fields.
  • Hourly surface analyses were completed during the event.
  • Skywarn coordinators were called into the office and stayed through 10 PM.
  • Utilizing “spin-up” time for new radar operators arriving at the office “cold”.




Case Study Team

Douglas Schneider
Phill Badgett
Michael Strickler
Michael Brennan
Kermit Keeter
Darin Figurskey
Jonathan Blaes


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