The images in this Envirocast® Bulletin were taken by NOAA's P-3 Hurricane Hunter when Katrina was a category 5 hurricane on August 28, 2005, the day before the powerful and destructive storm made landfall on the USA Gulf Coast.   Credit: NOAA Hurricane Research Division and Envirocast®

Sea surface as observed by NOAA's P-3 hurricane hunter

This image was taken at 5:11pm CDT August 28, 2005 from the eye of Katrina. The waves below are between 40 and 60 feet tall.

Sunset & Swirl in the Eyewall

The swirls around this incredible image and the height of the eyewall indicate a very intense hurricane. Katrina was the 4th most intense storm on record in the Atlantic basin with a central pressure of 902 millibars (mb) and winds near 165 mph. This view and presentation of the eyewall is known as the "stadium effect" which illustrates its similarity to a football or baseball stadium.

 

Ferocious Hurricane Katrina at its Most Intense

This stunning image from the NOAA P-3 Hurricane Hunter aircraft shows the power of nature with the spiral bands surrounding the eye of Hurricane Katrina. At this point the hurricane was transitioning to an outer eyewall which increased the central pressure and the pressure gradient. The result was a spreading out of the wind field and a much larger storm surge once Katrina came ashore the next day.
 

Sunset in the "Stadium"

This image shows the increased sun angle highlighting the inner eyewall. Hurricane Kartina is a powerful category 5 hurricane in this series with winds 165-175 mph and a central pressure of 902 mb.
 

Powerful Storms Near the Eye

This image shows the turbulence associated with Hurricane Katrina. The NOAA P-3 aircraft dropped 30+ dropsondes into the storm to gather a high resolution dataset of the wind field associated with the storm. The wide wind field resulted in a tremendous storm surge along the Gulf coast.

 

Katrina's Spiral Bands

The spiral bands shown here are the same bands that are seen in radar as intense storms. The bands surround the eye and propagate outward as spiral bands that produce severe wind gusts on land.

 

NOAA hurricane hunter WP-3D Orion and Gulfstream IV aircraft in flight

Environmental Impact:

When these pictures were taken:

• NOAA P-3 Plane took off at 12:30pm EDT August 28, 2005 and landed at 9:30pm EDT August 28, 2005 from McDill AFB in Tampa. This is where the NOAA P-3 planes are based.
   

• Hurricane Katrina’s central pressure was 902 millibars, the fourth lowest on record in the Atlantic Basin behind Hurricane Gilbert (1988), The Labor Day Hurricane of 1935 and Hurricane Allen in 1980
   

• The clear blue sky above is a result of air being evacuated from the upper levels of the storm and sinking air in the eye.
   

• The spiral bands around the eyewall contain the most intense winds. Thunderstorms and heavy rain force the intense winds to the surface.
   

• Many of these “tube clouds” show up on radar as the intense spiral bands rotating around the hurricane.
   

• Hurricanes do not maintain such great intensity for long (i.e. 175 mph winds and central pressure of 902 mb) without going through oscillations in intensity.
   

 Hurricane Intensity Issues

• During landfall Katrina’s wind field expanded while the storm was undergoing an eyewall replacement
   

• The eyewall replacement was likely underway as these pictures were taken which was causing the central pressure to rise and the wind field to mildly collapse.
   

• The result of a collapsing wind field is to decrease the overall intensity of the wind around the center of the storm (due to a broadening of the pressure gradient) HOWEVER, the wind field expanded to cover a very large area which ultimately affected more of the coastline with a ferocious storm surge.
   

• The larger wind field pushed a tremendous amount of water toward the coastline.
   

• During the previous flight on August 27, 2005 (from the one that these pictures were acquired), the Scanning Radar Altimeter (SRA), which measures the topography of ocean surface (wave height), measured 60 foot waves.
   

• It is likely that these 60 foot wave heights did not affect the coastline directly but wind-driven wave heights of significant size did occur
   

• The large (60 foot waves) did significantly affect off shore oil rigs.
   

• Much of the devastation in coastal Mobile, Ocean Springs, Biloxi, Gulfport, Long Beach, Pass Christian, Bay St. Louis and Waveland was caused by storm surge and intense pounding wave action
   

• Below is a list of the top 10 most intense hurricanes to strike the mainland US: Katrina will likely become the 3^rd most intense storm to ever strike the mainland US (from a central pressure standpoint).
   

• At 6AM August 29, 2005 (First Landfall) Katrina’s central pressure was 918 mb with estimated winds of 145mph.
   

• The final wind field analysis likely will fall into the Category 4 range at landfall, not category 5.
   

• NOAA’s Hurricane Research Division dropped 30+ dropsondes in all quadrants of the storm and confidence in the wind field at landfall is pretty high of course official wind analysis will be forthcoming from NOAA's National Hurricane Center and HRD.

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Sea surface as observed by NOAA's P-3 hurricane hunter

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Sea surface as observed by NOAA's P-3 hurricane hunter

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NOAA hurricane hunter WP-3D Orion and Gulfstream IV aircraft in flight