Hurricane Katrina was one of the deadliest and most destructive hurricane to hit the US. After looking into the minimum sea-level pressure (MSLP) and maximum wind speed (MWS) intensity data from NOAA's HURDAT database, I am confused with the pattern or whether there actually is one.

For Katrina specifically, is there a pattern in the relationship between MSLP and MWS intensity? What role does a low or high air pressure system play in the velocity vector of the hurricane?

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    $\begingroup$ It may be helpful if you could provide a link to the actual data you are referring to and maybe describe what you think is the pattern. $\endgroup$ – Isopycnal Oscillation Feb 23 '15 at 7:42
  • $\begingroup$ Are you interested in the hurricane motion (velocity vector of the hurricane) or the wind field around the hurricane? $\endgroup$ – casey Feb 23 '15 at 14:06
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    $\begingroup$ Katrina was the 3rd deadliest, after the 1900 Galveston hurricane which killed 8000 and the 1928 Lake Okeechobee hurricane which killed 2500. nhc.noaa.gov/pdf/nws-nhc-6.pdf $\endgroup$ – DavePhD Feb 23 '15 at 17:21
  • $\begingroup$ Minimum pressure definitely effects maximum wind in a tropical cyclone (lower pressure -> higher pressure gradient -> stronger wind)... but there are other significant factors as well, such as inner core structure, land interactions, and background pressure. So it indeed that lower pressures tends to match stronger winds, it's just not a one-to-one correlation. $\endgroup$ – JeopardyTempest Oct 21 '16 at 1:59
  • $\begingroup$ See also Figures 2 and 3 in nhc.noaa.gov/data/tcr/AL122005_Katrina.pdf $\endgroup$ – JeopardyTempest Sep 3 '17 at 3:21

Generally the relationship is the lower the air pressure the more intense the hurricane. For example during the same hurricane season as Katrina (2005) which also happened to be a record breaking season for the number of hurricanes recorded in the Atlantic basin, hurricane Wilma was recorded as being the most intense hurricane ever to form in the Atlantic. It reached a minimum air pressure of 882 millibar which was a record low. The corresponding maximum wind speed during this period of intensification was 185 mph. Hurricane Katrina was also a category 5 hurricane and reached a minimum air pressure of 902 millibar with maximum wind speeds at this pressure of 175 mph. Katrina of course striking where it did caused far more destruction even though it was the less intense hurricane of the two:




By Bernoulli's Theorem neglecting friction a fluid of density D initially at rest flowing from higher pressure P to lower pressure P mimus delta P can attain a speed of SQRT[2(delta P)/D]. In the case of hurricanes D decreases as air spirals inwards towards lower pressure, but it is sufficiently accurate to take D as the average value of the density. Allowing typical losses for friction, for stationary vortex-type storms such as hurricanes, tornadoes, waterspouts, and dust devils, approximately, maximum wind speed MWS in mph = 100 SQRT(delta P in inches of mercury), where delta P is the drop is sea-level barometric pressure from the periphery to the eye. If the vortex is moving, its velocity of motion V should be added on its right side if its winds circulate counterclockwise and on its left side if they circulate clockwise.


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