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simulation domains |
observed rainfall |
3D @ 77hr / color |
Volume rendering |
radar imagery / source |
radar/tornadoes |
visible sat |
another view. |
Research Description
Opal struck near Pensacola, Florida on Oct. 4, 1995 as a Category 3 storm with 125 mph winds, accompanied by extensive ($2 billion) damage, 9 fatalities and over 12 inches of rain over parts of Florida, Alabama and Georgia. Opal also spawned 22 tornadoes. While offshore in the Gulf of Mexico, Opal had sustained winds of over 150 mph, making it a Category 4 hurricane on the Saffir-Simpson scale.
The modeling study made use of a large outer domain and 4 nested grids, with an innermost horizontal resolution of 1.1 km in a domain 540 km (870 miles) on a side. The simulated storm reached Category 4 status with maximum surface winds exceeding 66 m/s (148 mph) prior to landfall. The highest-resolution grid was moved to follow the storm. The Penn. State/NCAR MM5 mesoscale model is being used in our study.
The simulations were carried out on the NCSA Origin2000. The modeled rainfall will be used with a runoff model to simulate the actual flooding that took place on this day. Further experiments with higher resolution are anticipated and studies of the tornadic environment after landfall are planned.
In addition, the Convective Modeling Group is working with members of the
NCSA Visualization and Virtual Environments Team as well as the
Laboratory for Computational Science and Engineering of the
University of Minnesota to explore different visualization
techniques while studying modeled evolution.
From the NHC ftp site:
View is to northwest. Domain is 487x487x27. Slight shading (based on
water vapor field) identifies lower clouds as darker, higher clouds as
brighter white. Peak surface wind at this time is 58.9 m/s (114 knots),
minimum pressure 947 mb, which is borderline category 3/4 on the Saffir-Simpson
scale.
Latest Developments
Visualization
Verification data
For reference, the actual
hurricane had a wind
max of 130 knots, and a minimum central pressure of 916 mb. The Nat'l
Hurricane center has a full
report on Opal online.
Results at 81.75 hr
At this time, the peak simulated surface winds were 66.4 m/s (129
knots, 148 mph), and the minimum central pressure 945 mb.
Same time, grid 4, 3.3-km resolution (larger area):
3-D view of eye at 77 hr
Image (from explorer) of cloud+rain field, innermost (1.1 km) grid: jpeg
/ gif / tiff
/ small version.
Plan views
Participating Members
Brian Jewett,
Robert Wilhelmson,
Mohan Ramamurthy,
Glen Romine,
Crystal Shaw,
Dave Bock,
Rob Stein,
David Porter
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