Changes

==The hurricane==

==The hurricane==

Hurricane Katrina developed initially as a tropical depression (TD #12 of the season) in the southeastern [[Bahamas]] on August 23rd. This tropical depression strengthened into Tropical Storm Katrina the next day. It then moved slowly along a northwesterly then westerly track through the Bahamas, increasing in strength during this time. A few hours before landfall in south Florida at around 6.30 EDT on August 25th, Katrina strengthened to become a category 1 (windspeeds of 75mph or greater) hurricane. Landfall occurred between Hallandale Beach and North [[Miami]] Beach, [[Florida]], with windspeeds of approximately 80 mph (70 kts). Gusts of above 90 mph (78 kts) were measured as Katrina came ashore. As the storm moved southwest across the tip of the Florida peninsula, Katrina's winds decreased slightly before regaining hurricane strength in the Gulf of Mexico. Given that Katrina spent only seven hours over land, its strength was not significantly diminished and it quickly re-intensified shortly after moving over the warm waters of the Gulf.

Hurricane Katrina developed initially as a tropical depression (TD #12 of the season) in the southeastern [[Bahamas]] on August 23rd. This tropical depression strengthened into Tropical Storm Katrina the next day. It then moved slowly along a northwesterly then westerly track through the Bahamas, increasing in strength during this time. A few hours before landfall in south Florida at around 6.30 EDT on August 25th, Katrina strengthened to become a category 1 (wind speeds of 75mph or greater) hurricane. Landfall occurred between Hallandale Beach and North [[Miami]] Beach, [[Florida]], with wind speeds of approximately 80 mph (70 kts). Gusts of above 90 mph (78 kts) were measured as Katrina came ashore. As the storm moved southwest across the tip of the Florida peninsula, Katrina's winds decreased slightly before regaining hurricane strength in the Gulf of Mexico. Given that Katrina spent only seven hours over land, its strength was not significantly diminished and it quickly re-intensified shortly after moving over the warm waters of the Gulf.

Katrina moved almost due westward after entering the Gulf of Mexico. A mid-level ridge centered over Texas weakened and moved westward allowing Katrina to gradually turn to the northwest and then north into the weakness in the ridging over the days that followed. Atmospheric and sea-surface conditions (an upper level anticyclone over the Gulf and warm SSTs) were conducive to cyclone's rapid intensification, which lead to Katrina attaining 'major hurricane' status on the afternoon of the 26th.

Katrina moved almost due westward after entering the Gulf of Mexico. A mid-level ridge centered over Texas weakened and moved westward allowing Katrina to gradually turn to the northwest and then north into the weakness in the ridging over the days that followed. Atmospheric and sea-surface conditions (an upper level anticyclone over the Gulf and warm SSTs) were conducive to cyclone's rapid intensification, which lead to Katrina attaining 'major hurricane' status on the afternoon of the 26th.

Continuing to strengthen and move northwards during the next 48 hours, Katrina reached maximum windspeeds on the morning of Sunday August 28th of over 170 mph (150 kts, category 5), and its minimum central pressure dropped that afternoon to 902 mb - the 4th lowest on record for an Atlantic storm. Although Katrina, at its peak strength was comparable to Camille's intensity, it was a significantly larger storm and impacted a broader area of the Gulf coast.

Continuing to strengthen and move northwards during the next 48 hours, Katrina reached maximum wind speeds on the morning of Sunday August 28th of over 170 mph (150 kts, category 5), and its minimum central pressure dropped that afternoon to 902 mb - the 4th lowest on record for an Atlantic storm. Although Katrina, at its peak strength was comparable to Camille's intensity, it was a significantly larger storm and impacted a broader area of the Gulf coast.

   

   

Although tropical cyclones of category 5 strength are rarely sustained for long durations (due to internal dynamics), Katrina remained a strong category 4 strength hurricane despite the entrainment of dryer air and an opening of the eyewall to the south and southwest before landfall on the morning of the 29th. Landfalling windspeeds at Grand Isle, Louisiana were approximately 125 mph (110 kts) (strong category 3 intensity) with a central pressure of 920mb - the 3rd lowest on record for a landfalling Atlantic storm in the US. Rainfall amounts for Louisiana and along the Gulf are described below along with other impacts of the storms.

Although tropical cyclones of category 5 strength are rarely sustained for long durations (due to internal dynamics), Katrina remained a strong category 4 strength hurricane despite the entrainment of dryer air and an opening of the eyewall to the south and southwest before landfall on the morning of the 29th. Landfalling wind speeds at Grand Isle, Louisiana were approximately 125 mph (110 kts) (strong category 3 intensity) with a central pressure of 920mb - the 3rd lowest on record for a landfalling Atlantic storm in the US. Rainfall amounts for Louisiana and along the Gulf are described below along with other impacts of the storms.

   

   

==Rain, wind, and storm surge==

==Rain, wind, and storm surge==

Rainfall from Katrina's outer bands began affecting the Gulf coast well before landfall. As Katrina came ashore on August 29th, rainfall exceeded rates of 1 inch/hour across a large area of the coast. NOAA's Climate Reference Network Station in Newton, MS (60 miles east of Jackson, Mississippi) measured rainfall rates of over an inch an hour for 3 consecutive hours, with rates of over 0.5 in/hr for 5 hours during August 29th. Precipitation analysis from NOAA's Climate Prediction Center show that rainfall accumulations exceeded 8-10 inches along much of the hurricane's path and to the east of the track.  

Rainfall from Katrina's outer bands began affecting the Gulf coast well before landfall. As Katrina came ashore on August 29th, rainfall exceeded rates of 1 inch/hour across a large area of the coast. NOAA's Climate Reference Network Station in Newton, MS (60 miles east of Jackson, Mississippi) measured rainfall rates of over an inch an hour for 3 consecutive hours, with rates of over 0.5 in/hr for 5 hours during August 29th. Precipitation analysis from NOAA's Climate Prediction Center show that rainfall accumulations exceeded 8-10 inches along much of the hurricane's path and to the east of the track.  

Windspeeds over 140 mph were recorded at landfall in southeastern Louisiana while winds gusted to over 100 mph in New Orleans, just west of the eye. As the [[hurricane]] made its second landfall on the Mississippi/Louisiana border, windspeeds were approximately 110 kts (125 mph). Gusts of over 80mph were recorded in Mobile and 90 mph in Biloxi, Mississippi.  

Wind speeds over 140 mph were recorded at landfall in southeastern Louisiana while winds gusted to over 100 mph in New Orleans, just west of the eye. As the [[hurricane]] made its second landfall on the Mississippi/Louisiana border, wind speeds were approximately 110 kts (125 mph). Gusts of over 80mph were recorded in Mobile and 90 mph in Biloxi, Mississippi.  

The central pressure at landfall was 920 mb, which ranked 3rd lowest on record for U.S.-landfalling storms behind Camille (August 17, 1969, 909 mb) and the Labor Day hurricane that struck the Florida Keys on September 2, 1935 (892 mb). Hurricane Andrew in 1992 dropped to fourth, as its central pressure was 922 mb at landfall. Katrina also reached a minimum central pressure of 902 mb at its peak, ranking 4th lowest on record for all Atlantic basin hurricanes.

The central pressure at landfall was 920 mb, which ranked 3rd lowest on record for U.S.-landfalling storms behind Camille (August 17, 1969, 909 mb) and the Labor Day hurricane that struck the Florida Keys on September 2, 1935 (892 mb). Hurricane Andrew in 1992 dropped to fourth, as its central pressure was 922 mb at landfall. Katrina also reached a minimum central pressure of 902 mb at its peak, ranking 4th lowest on record for all Atlantic basin hurricanes.