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Hurricane Katrina: The Day the Forecast Shifted

Hurricane Katrina's record-setting storm surge along the Mississippi Gulf Coast and overwhelming of the flood protection system in New Orleans on August 29, 2005 is burned in memory.

(SPECIAL REPORT: Katrina 10)

Three days prior to landfall, Katrina's forecast made a troubling shift, one which many meteorologists, myself included, will never forget.

Here at The Weather Channel, we have weather briefings at certain times of the day to prep for our various shows. During a mid-afternoon briefing on August 26, 2005, senior meteorologist Tom Moore started simply with the phrase, "New Orleans is now in the cone."

Suffice to say this was quite a shock for our on-air production crew which had certainly heard a different story just 24 hours prior.

Below is the Katrina forecast path from the National Hurricane Center (NHC) issued 11 a.m. EDT, August 26.

Hurricane Katrina forecast path on August 26, 2005 at 11 a.m. EDT. Note the center of the cone is pointed toward the western Florida panhandle.
(National Hurricane Center)

Up until that afternoon, the concern was for the storm-weary Florida Panhandle, lying near the center of the forecast cone.

They were clobbered by Hurricane Ivan in 2004, and had just been hit in early July 2005 by Hurricane Dennis. How much more could they take?

The left edge of the forecast cone scraped the New Orleans metro area at that time.

Six hours later, the 5 p.m. EDT forecast advisory shifted the entire swath almost 175 miles west of the 11 a.m. forecast. Continuing that trend, the center of the 11 p.m. EDT forecast swath, indicating the most path of highest confidence was, as it turns out, almost exactly the eventual path of Katrina, through southeast Louisiana and into the Mississippi Gulf Coast.

Hurricane Katrina forecast path on August 26, 2005 at 11 p.m. EDT. Note the center of the cone is pointed toward the Mississippi and Louisiana Gulf Coasts.
(National Hurricane Center)

Senior meteorologist Stu Ostro said, "The atmospheric die had been cast. This time, the models had grasped the meteorological reality."

This case clearly illustrates the importance of checking back frequently for forecast updates, whether it involves hurricanes, winter storms, or severe weather outbreaks.

States of emergency were declared based on this forecast shift by Mississippi Governor Haley Barbour and Louisiana Governor Kathleen Blanco.

After emerging into the Gulf of Mexico, Katrina embarked on its first phase of rapid intensification on August 26.

By the 11 p.m. August 26 advisory, Hurricane Katrina had strengthened to a strong Category 2 storm, with maximum sustained winds of 105 mph.

Central barometric pressure, a common measuring stick for hurricane intensity, had dropped from 990 to 965 millibars during the day, a significant strengthening phase, but not the hurricane's last such growth spurt.

High-resolution satellite image of Hurricane Katrina on August 26, 2005 from the NASA Aqua satellite.
(NASA)

The Florida Keys took a hard hit from Katrina on Aug. 26, experiencing wind gusts from 70-80 mph. The Dry Tortugas experienced gusts to 97 mph, with sustained hurricane-force winds. Flooding and downed power lines were common.

Late that night, Katrina was about 460 miles southeast of the mouth of the Mississippi River and was about to embark on a more menacing period of rapid intensification.

(INFOGRAPHIC: Katrina's Impacts/Stats)

The Weather Channel, weather.com and Weather Underground will have continuing coverage of the anniversary of Hurricane Katrina.