變更

美国国家飓风中心起初预测飓风卡特里娜会在登陆后转向北上，最终于3到4天后吹袭佛罗里达州西北部的狭长地带<ref name="NHC disc 005">{{cite web | author = Stewart, Stacy | publisher = National Hurricane Center | title = Tropical Storm Katrina Discussion No. 5, 5:00 p.m. EDT | date = 2005-08-24 | accessdate = 2014-03-17 | archivedate = 2013-10-01 | url = http://www.nhc.noaa.gov/archive/2005/dis/al122005.discus.005.shtml? | deadurl = no | archiveurl = https://web.archive.org/web/20131001212711/http://www.nhc.noaa.gov/archive/2005/dis/al122005.discus.005.shtml}}</ref>。然而风暴实际上却继续西进并转向西南偏西，气象部门最终预测其行进轨迹将指向新奥尔良<ref name="NHC disc 014">{{cite web | author = Stewart, Stacy | publisher = National Hurricane Center | title = Hurricane Katrina Discussion No. 14, 5:00 p.m. EDT | date = 2005-08-26 | accessdate = 2014-03-17 | archivedate = 2013-11-05 | deadurl = no | archiveurl = https://web.archive.org/web/20131105003526/http://www.nhc.noaa.gov/archive/2005/dis/al122005.discus.014.shtml | url = http://www.nhc.noaa.gov/archive/2005/dis/al122005.discus.014.shtml?}}</ref>。

风暴进入墨西哥湾后立即由于风切变较少，良好的上层外流，以及[[墨西哥湾暖流]]较高的[[海面温度]]而开始爆发性增强，到了8月27日，卡特里娜已经升级为三级飓风<ref name="NHC pa 016">{{cite web | author = Knabb, Richard | publisher = National Hurricane Center | title = Hurricane Katrina Advisory No. 16, 5:00 a.m. EDT | date = 2005-08-27 | accessdate = 2014-03-17 | url = http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.016.shtml? | archiveurl = https://web.archive.org/web/20131001213611/http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.016.shtml | deadurl = no | archivedate = 2013-10-01}}</ref>，成为2005年大西洋飓风季的第三个大型飓风。接下来飓风进入一段[[眼墙置换]]周期，这一周期虽然令其[[最大持续风速]]的增强放缓了18个[[小时]]，但[[风暴]]的[[半径]]却几乎翻了一番<ref name="KatrinaTCR" />。[[美国中部时区|中部日间时间]]（简称{{lang|en|CDT}}）8月27日下午19点，飓风进入第二轮爆发性增强期，到了{{lang|en|[[美国中部时区|CDT]]}}次日中午12点40分，卡特里娜已升级为四级飓风，最大持续风速达到每小时233公里<ref name="NHC pa 020">{{cite web | author = Knabb, Richard | publisher = National Hurricane Center | title = Hurricane Katrina Advisory No. 20, 1:00 a.m. CDT | date = 2005-08-28 | accessdate = 2014-03-17 | archiveurl = https://web.archive.org/web/20131001213920/http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.020.shtml | deadurl = no | archivedate = 2013-10-01 | url = http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.020.shtml?}}</ref>，风暴之前还曾于{{lang|en|CDT}}8月28日早上7点达到五级飓风强度，成为继[[1980年大西洋飓风季]]的[[飓风艾伦]]以来墨西哥湾内形成的第一个五级飓风<ref name="NHC pa 022">{{cite web | author = Knabb, Richard | coauthors = Richard Pasch | publisher = National Hurricane Center | title = Hurricane Katrina Special Advisory No. 20, 7:00 a.m. CDT | archiveurl = https://web.archive.org/web/20131001213938/http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.022.shtml | date = 2005-08-28 | accessdate = 2014-03-17 | url = http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.022.shtml? | archivedate = 2013-10-01 | deadurl = no}}</ref>，这时距其第二轮爆发性增强期开始还只过了12小时。{{lang|en|CDT}}下午13点，卡特里娜达到最高强度，最大持续风速达每小时280公里，阵风时速更高达344公里，中心气压低至902[[巴|毫巴]]（[[帕斯卡|百帕]]，26.64[[英寸汞柱]]）<ref name="NHC pa 023a">{{cite web | author = Pasch, Richard | publisher = National Hurricane Center | title = Hurricane Katrina Intermediate Advisory No. 23a, 1:00 p.m. CDT | date = 2005-08-28 | accessdate = 2006-09-16 | url = http://www.nhc.noaa.gov/archive/2005/pub/al122005.public_a.023.shtml? | archiveurl = https://web.archive.org/web/20131225020052/http://www.nhc.noaa.gov/archive/2005/pub/al122005.public_a.023.shtml | archivedate = 2013-12-25 | deadurl = no}}</ref>。这一最低气压令卡特里娜成为当时有纪录以来第四强烈的大西洋飓风，不过同年晚些时候出现的[[飓风丽塔]]和[[飓风威尔玛]]都会在强度上越越卡特里娜<ref name="KatrinaTCR" />。随着飓风逼近新奥尔良，位于[[路易斯安那州]][[斯莱德尔 (路易斯安那州)|斯莱德尔]]的天气预报办公室发布了两份措辞强烈的警报<ref>''National Weather Service/New Orleans, Louisiana.'' August 28, 2005.</ref><ref>{{cite news|last=Whittell |first=Giles |url=http://www.timesonline.co.uk/article/0,,23889-1770245,00.html |title=Warnings were loud and clear—but still city drowned |work=The Times |location=UK |date=2005-09-08 |archivedate=2008-01-13 |deadurl=yes |archiveurl=https://web.archive.org/web/20080113002946/http://www.timesonline.co.uk/article/0%2C%2C23889-1770245%2C00.html }}</ref>。

== 第二次和第三次登陆 ==