#14,020
Early on Monday, October 8th 2018, not-yet-quite-a-hurricane Michael was centered over the western tip of Cuba, with tropical storm force winds of 70 MPH. The forecast was for the storm to strengthen to CAT 2 (110 MPH) winds, as it moved towards an expected Thursday landfall on the Florida panhandle.
While the NHC made a remarkably accurate forecast track, things did not go exactly as forecast.A late season storm, the waters of the Gulf of Mexico were still quite warm and wind sheer was low, providing plenty of fuel and an ideal environment for rapid intensification. Within a few hours (see NHC 11am Key Messages: Hurricane Michael Now Expected To Become A Major Storm) the National Hurricane Center upped the ante.
Although track forecasting has become much better over the last decade, the ability to accurately forecast rapid changes in intensity remains elusive.At 11am on Tuesday, the NHC was still forecasting a CAT 3 storm, landfalling now on Wednesday afternoon. What residents of the panhandle woke up to on Wednesday morning - just hours before landfall - was the news that Michael Was Now A Cateogry 4 storm.
The good news was, Michael came ashore very close to where the NHC predicted, and many residents got out of the way. The bad news was, Michael proved far worse than anyone expected.
I provide this recap - not to at all criticize the forecast - but to remind people that hurricanes are complex systems and forecasts are not perfect. If a storm is only forecast to be a CAT 3, I always prepare as if it could be CAT 5 on arrival.Which, according to the following press release from NOAA, is exactly what made landfall a little over 6 months ago on the Florida panhandle.
Hurricane Michael upgraded to a Category 5 at time of U.S. landfall
Post-storm analysis estimates sustained winds of 160 mph
April 19, 2019
Scientists at NOAA’s National Hurricane Center conducted a detailed post-storm analysis on all the data available for Hurricane Michael and have determined that the storm’s estimated intensity at landfall was 140 knots (160 mph). This final wind intensity is a 5 knot (5 mph) increase over the operational estimate and makes Michael a category 5 storm on the Saffir-Simpson Hurricane Wind Scale at the time of landfall on October 10, 2018, near Mexico Beach and Tyndall Air Force Base, Florida.
Michael is the first hurricane to make landfall in the United States as a category 5 since Hurricane Andrew in 1992, and only the fourth on record. The others are the Labor Day Hurricane in 1935 and Hurricane Camille in 1969. Michael is also the strongest hurricane landfall on record in the Florida Panhandle and only the second known category 5 landfall on the northern Gulf coast.
The real-time operational intensity estimate was 135 knots (155 mph). The final best track intensity estimate of 140 knots (160 mph) was determined by a review of the available aircraft winds, surface winds, surface pressures, satellite intensity estimates and Doppler radar velocities – including data and analyses that were not available in real time. The 5 knot (5 mph) increase in the estimated maximum sustained wind speed from the operational estimate is small and well within the normal range of uncertainty.
Category 5 winds were likely experienced over a very small area at and near the coast, and the change in estimated wind speeds is of little practical significance in terms of the impacts associated with the storm. Michael produced devastating winds and storm surge and was directly responsible for 16 deaths and about $25 billion in damage in the United States. Before hitting the United States, the cyclone brought hurricane-force winds to the western tip of Cuba when it was a category 2 Hurricane.
Along with wind speed, atmospheric pressure is a measure of storm intensity. In general, the lower a storm’s central pressure, the higher the winds. Michael’s central pressure of 919 millibars (mb) at landfall is the third lowest on record for a landfalling U. S. hurricane since reliable records began in 1900, trailing only the Labor Day Hurricane of 1935 (892 mb) and Hurricane Camille of 1969 (900 mb).
A side note: I (along with tens of millions of other across the Southeast) are under severe weather warnings today. Since power outages are common here following severe storms, I may find myself offline later today.
If you live or work anywhere in the shaded areas of the map below, today is a good day to keep your NOAA weather radio on, and a weather eye out.
And next month, we'll begin our annual pre-hurricane season preparedness checklist.
