An Analysis Of Record Hurricane Patricia

patricia_a2015296_2035_1kmHurricane Patricia has been one of the strongest tropical cyclones ever recorded anywhere on the globe. It was certainly the strongest ever to be recorded in the National Hurricane Center’s area of responsibility (Atlantic and eastern Pacific basins), with faster intensification and lower pressure than Linda in 1997. It made landfall in western Mexico early this morning, thankfully having weakened slightly, but still as a Category 5 hurricane and currently bringing life-threatening rainfall to central Mexico. Its lifetime has been short but remarkable, as described below.

It was first noted as an area of enhanced convection in a slack area of low pressure at 1500 UTC on Tuesday 20th October. It was located in an area of warm seas and low shear, which caused it to strengthen rapidly to a Tropical Storm of 35 knots just 12 hours later. It strengthened steadily as it tracked westwards over the next 30 hours, reaching hurricane status by 0900 UTC on Thursday. That is from Tropical Depression to Hurricane in around 42 hours. Even at that stage the NHC was forecasting it to max out at “only” 110 knots (high-end Category 3) by Friday evening.

It is from there that all hell broke loose. Sea-surface temperatures of up to 31 °C and still non-existent shear allowed this monster energy-transducer to convert warmth and latent heat from the warm sea to kinetic energy in the form of increasing winds, with the pressure freefalling just like the dropsondes released from the Hurricane Hunter aircraft sent out on recon missions into the eye. By 0900 UTC on Friday the NHC were shocked to name the 175-knot monster the strongest hurricane ever recorded in their forecast area.

US stormchaser Josh Morgerman, who witnessed landfall from a hotel in Emiliano Zapata, describes how seven people huddled under a matress in the bathroom as the hotel was falling apart around them. IWO’s Peter O’Donnell pinpoints the location of the eye at landfall to be at Costa Cayeres, just a few kilometres north of there. This is between the hotel and an automatic weather station at Chemela (at an elevation of 95 m) that reported an unofficial sustained wind of 161 kt and a gust of 183 kt.

image

INTENSITY HISTORY (sustained winds)

  • 20th, 1500 UTC: 30 kt (Tropical Depression)
  • 21st, 0900 UTC: 35 kt (Tropical Storm)
  • 21st, 2100 UTC: 50 kt
  • 22nd, 0300 UTC: 55 kt
  • 22nd, 0900 UTC: 75 kt (Cat. 1)
  • 22nd, 1500 UTC: 85 kt (Cat. 2)
  • 22nd, 2100 UTC: 115 kt (Cat. 3)
  • 23rd, 0300 UTC: 140 kt (Cat. 5)
  • 23rd, 0530 UTC: 160 kt (Cat. 5)
  • 23rd, 0900 UTC: 175 kt (Cat. 5)
  • 23rd, 1500 UTC: 175 kt (Cat. 5)
  • 23rd, 2100 UTC: 165 kt (Cat. 5)
  • 24th, 0300 UTC: 115 kt (Cat. 3, inland. Landfall at 2315 UTC with 145 kt winds)
  • 24th, 0900 UTC: 65 kt (Cat. 1, inland)
  • 24th, 1500 UTC: 30 kt (Tropical Depression)
Shear01
Shear (coloured) at various stages throughout Patricia’s lifetime. Blue signifies no shear, which helped Patricia deepen. Olaf is another hurricane well off to the west. Image from CIMSS

shear02 Shear03 shear04 shear05shear06

SST
Sea-surface temperatures of up to 31 °C fed Patricia’s ferocious appetite. Image from CIMSS

A notable factor has been the inaccuracy of the forecasts from early on. Despite their best efforts, the NHC had initially forecast Patricia to max out at 110 knots, but had to continually correct upwards in subsequent forecasts. The models were well off the mark early on, grossly underestimated how ferocious Patricia would become. This shows how meteorology – especially over the data-sparse oceans – is still in inexact science, despite the huge increases in technology.

Aside from forecasts, the satellite estimates of actual intensity were also well off the calibration scale, as shown in the chart below. These different systems estimate the current strength of the storm by examining its satellite signature, but it is clear that, even today, there is a long way to go when it comes to high-end hurricanes. The Recon datapoints from the aircraft missions (black triangles) were the only reliable data in plotting how low the central pressure got, with the ADT the best of the rest.

 

SATCON pressure

Patricia is now a remnant low but its moisture will interact with a low pressure system over the Texas gulf coast, bringing heavy rains and possible flooding over the next 48 hours. There are no further tropical developments forecast in either the eastern Pacific or Atlantic basins over the next few days, but with El Nino waters still in place we could be seeing more activity in this area during the rest of the season.

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