1. The University of South Alabama
Mesonet and its performance during the heavy rainfall event of Hurricane Ida (2009)
Dr. Sytske Kimball
Professor of Meteorology
Department of Earth Sciences
University of South Alabama
Credits:
Saphique Albert, David Brown,
Sean Huber, Meghan Mee,
Ivory Reinert, Russell White

3. University of South Alabama Mesonet Geographic details
26 fully operational weather stations
Average spacing between stations is about 30 km (19 miles)
Stations in 13 counties in 3 states: MS (3), AL (8), and FL (2)
325 km (203 miles) in east-west direction
km (19-62 miles) in north-south direction

5. 10 m
(30 ft)
10 m
(30 ft)

6. Data collected Variables: Saved every minute
1.5, 2, 9.5, and 10 m temperature
2 and 10 m relative humidity
2 and 10 m horizontal wind speed and direction
10 m vertical wind speed
Photsynthetically active radiation (400 – 700 nm)
Total solar radiation (400 – 1100 nm, visible spectrum)
Rainfall
Atmospheric pressure
Surface temperature
Saved every minute

7. Website http://chiliweb.southalabama.edu/
Archived data (csv Excel files)
(Near) real-time data
Time series
Station map
Meta-data (station photos etc)

8. Texas Electronics TE525
90 cm

9. Hydrological Services TB3
90 cm

10. Hurricane Ida History
Entered the Gulf of Mexico early on 9 November 2009 , encountered strong shear, and weakened to a tropical storm.
Regained hurricane strength at 1800Z (12:00 CST) on 9 November while approaching the mouth of the Mississippi River.
Weakened 6 hours later to a tropical storm due to cooler water and vertical shear associated with a short-wave trough.
Turned northeast and became extra-tropical about 3 hours before making landfall on the Alabama coast (Dauphin Island) at around 10:40Z (05:40 CST) on 10 November 2009.

11. GOES-12 visible image from 9 Nov
2009 at 1225 UTC (6:25 a.m. CST)

12. Hurricane Ida (Nov 2009)

13. KMOB WSR-88D derived rainfall totals (inch)
from 23:47Z (17:47 CST) on 8 Nov to 17:02Z (11:02 CST) on 10 Nov 2009

14. Flooding along the Fish River in South Baldwin County, AL

15. Radar 17:45 CST 8 Nov 11:02 CST 10 Nov Gauges: 07:00 CST 09 Nov
KMOB
Gauges:
07:00 CST 09 Nov
07:00 CST 11 Nov

16. Rain gauge rainfall totals (mm)
from 13:00Z (07:00 CST) on 9 Nov to 13:00Z (07:00 CST) on 11 Nov 2009

17. Providers ASOS Various MADIS CoCoRAHS USA Mesonet
2 National Estuary Program (NEP) sites

18. USA Mesonet Rainfall totals (mm)
Weeks Bay
Foley
Elberta

19. Flooding at the mouth of Weeks Bay in South Baldwin County, AL

20. Foley, Baldwin Co., AL

21. Flash Flood Guidance
an indication of the amount of rainfall over a period of time necessary to cause small streams to overflow their natural banks
based on an estimate of average soil moisture and stream flow conditions in a given county
e.g. if the 3-hour FFG = 2.5“ then flooding should begin on small streams if that amount or more falls in a 3-h period
issued twice daily at about 11 am and 9 pm CST

22. Foley, hourly rainfall on the hour

23. Foley, 3-hourly rainfall on the hour

24. Foley, 3-hourly rainfall by the minute

25. Foley, 6-hourly rainfall on the hour

26. Foley, 6-hourly rainfall by the minute

27. Conclusions
It can be challenging to issue flood warnings when relying just on ASOS observations
ASOS locations are spaced relatively far apart
ASOS rainfall totals are not always provided on a regular (e.g. hourly or better) basis
ASOS’s often go out in bad weather
Mesonet data are helpful because they are available at finer spatial and temporal resolutions
Flash flood warnings would improve further if FFG products were available more frequently

28. Thank You!!