This project and presentation was done for the Foundations of GIS (Geographical Information Systems) class at the University of Florida in Summer 2008. This project looked at the radar reflectivity relationships with Hurricanes Frances just before landfall in 2004.

1. By Charles E. Roop, University of Florida
COMPARING WIND AND PRECIPITATION
FIELDS IN HURRICANE FRANCES (2004)

2. CONTENTS
Intro on Frances
What we are looking for
Steps and tools
Data
Results
Conclusions
Further Research

3. ABOUT HURRICANE FRANCES
Formed out in Atlantic
24 Aug. 2004 South
of Cape Verde Islands
Became T.S. next day,
then Hurricane on 26
Aug. as it moved west
Made landfall near
Hutchinson Island,
Fla. On 4 Sept. as Cat
2 (96-110 mph) with
MCP of 960 mb Source: Unisys Weather

4. SO…WHAT ARE WE LOOKING FOR?
Main question: How do the wind fields compare
to the WSR-88D reflectivity readings?
Do the stronger winds correlate with higher
reflectivity readings or vice versa?

5. INTENDED AUDIENCE
Tropical Meteorology researchers
Atmospheric Science students
Meteorology
Geography

6. METHODOLOGY – GIS
Gather Layout Analyze Interpret
Data Data Data Data
Place vector of radar View and count data
NWS, NOAA, other third data values in and out of
party buffers by selecting
attributes using Select
Layer by Location in
ArcMap
Plot COC using Editor
based on radar data
Create different vectors
of different reflectivity
levels (i.e. 30 dZB +, 40
dBZ +, etc) by selecting
appropriate attributes
Extract data at time of using ArcMap
radar image based on
plotted Center of
Circulation
Create buffer of
average distance of
R34, R50, and R64, as
well as ROI

7. EXPLANATION OF DATA
Reflectivity
Taken from WSR-88D radar station: probably from
NWSFO in Melbourne, Fla.
Units: dBZ (decibels)
Date/Time: 4 Sept. 2004 at 1200 Z (8 a.m. EDT)
Radii
Gale (R34): Winds of 34+ knots (39+ mph)
“Damaging” Gale (R50): Winds of 50+ knots (57+
mph)
Hurricane (R64): Winds of 64+ knots (74+ mph)
Radii split in certain
quadrants. Radii (in
kilometers) per attribute was
averaged to get one radius
for a certain wind field.

8. WIND FIELDS (AVERAGE)
Average wind ranges from center of circulation
(COC)
Gale (R34): 284 km
“Damaging” Gale (R50): 192 km
Hurricane (R64): 125 km

9. RADIUS OF OUTER-MOST CLOSED ISOBAR
Isobar: Lines of
equal
barometric
pressure
ROI: farthest
closed isobar
surrounding the
tropical cyclone
Graphic Source: NOAA

10. FRANCES – REFLECTIVITY AND WIND BANDS

11. ANALYSIS 1 – 30+ DBZ AND WIND
COMPARISON
Inside 346 16%
Hurr
Hurr to 516 24%
Stg Gale
Gale to 649 30%
Stg Gale
Outside 496 23%
Gale
Total
attributes:
2116

12. ANALYSIS 2 – 40+ DBZ AND WIND
COMPARISON
Inside 100 18%
Hurr
Hurr to 121 21%
Stg Gale
Gale to 175 31%
Stg Gale
Outside 154 27%
Gale
Total attributes:
571

13. ANALYSIS 3 – 50+ DBZ AND WIND
COMPARISON
Gale to Stg 12 32%
Gale
Outside Gale 24 63%
Total attributes:
38

14. ANALYSIS 4 – ROI AND REFLECTIVITY
TOTAL
ATRIBUTES:
4690
Inside ROI:
4519 (96%)
Outside ROI:
171 (4%)

15. WIND AND REFLECTIVITY CHART
30+ dBZ Inside Hurr 346 2116 16%
Hurr to Stg Gale 516 2116 24%
Gale to Stg Gale 649 2116 30%
Outside Gale 496 2116 23%
40+ dBZ Inside Hurr 100 571 18%
Hurr to Stg Gale 121 571 21%
Gale to Stg gale 175 571 31%
Outside Gale 154 571 27%
50+ dBZ Gale to Stg Gale 12 38 32%
Outside Gale 24 38 63%
55+ dBZ Outside Gale 4 4 100%

16. FINDINGS
Strongest reflectivity readings are further away
from the COC.
50+ dBZ not near center, but in east central Florida
near the gale wind radius edge
ROI: 96 percent of precipitation occurred inside
the radius.

17. FINDINGS (CON’T)
Before 8 a.m.,
the Melbourne
Airport
received
reports of
winds gusts at
47 knots (54
mph)…well
before landfall
and with the
COC nearly 160
miles away
Source: Weather Underground

18. POSSIBLE ISSUES
Reflectivity near the COC might not be as
accurate
Distance
Attenuation
Possible slight differences in counting
attributes
However, will not be enough to make a difference in
analyzing this storm

19. FUTURE ANALYSIS
More TCs need to be analyzed to for finding out
similar wind-reflectivity relationships
Every storm is different
Closer radar data for more accurate readings
Hope the next storm hits closer to a NWS office
Doppler On Wheels (DOW), anyone?
New technologies

20. CONCLUSION
Using ArcGIS, we were able to determine the
relationships between the WSR-88D radar
reflectivity and the wind fields of Hurricane
Frances
The findings showed that most of the higher
reflectivity readings were further away from the
COC.
More research is needed in terms of wind-
reflectivity relationships with other storms to see a
common pattern for TCs.