WEATHER BLOG: Hurricane Harvey final report issued

By Mike Clay, Bay News 9 Chief Meteorologist
Last Updated: Tuesday, January 30, 2018, 5:36 PM EST

The National Hurricane Center in Miami has issued their final report on Hurricane Harvey from late August of 2017. The statistics are incredible along the Texas Coast into Louisiana. The official report states: "Harvey started as a typical weak August tropical storm that affected the Lesser Antilles and dissipated over the central Caribbean Sea. However, after re-forming over the Bay of Campeche, Harvey rapidly intensified into a category 4 hurricane before making landfall along the middle Texas coast. The storm then stalled, with its center over or near the Texas coast for four days, dropping historic amounts of rainfall of more than 60 inches over southeastern Texas. These rains caused catastrophic flooding, and Harvey is the second-most costly hurricane in U.S. history, after accounting for inflation, behind only Katrina (2005). At least 68 people died from the direct effects of the storm in Texas, the largest number of direct deaths from a tropical cyclone in that state since 1919."

Harvey was the most significant tropical cyclone rainfall event in United States history, both in scope and peak rainfall amounts, since reliable rainfall records began around the 1880s.

- Maximum winds 137 mph several hours prior to landfall.
- Minimum pressure was 937 mb based on a dropsonde. Lowest observed pressure was 940.8 mph from a storm chaser in Rockport, TX.
- Maximum storm surge inundation levels of 6 to 10 ft above ground to the north and east of Harvey’s center landfalls in Texas in the bays between Port Aransas and Matagorda.
- Highest rainfall was s 60.58 inches near Nederland, Texas, with another report of 60.54 inches from near Groves, Texas.
- Both of these values (and from five other stations) exceed the previously accepted United States tropical cyclone storm total rainfall record of 52.00 inches at Kanalohuluhulu Ranger Station, Hawaii, in August of 1950 from Hurricane Hiki.
- For the continental United States, the previous tropical cyclone rainfall record was 48.00 inches in Medina, Texas from Tropical Storm Amelia in 1978. It is remarkable that during Harvey, eighteen values over 48 inches were recorded across southeastern Texas.
- One weather station in Southeast Houston reported an astounding 6.8” of rain in one hour!
- Harvey produced 57 tornadoes. Tornadoes were in Texas, Louisiana, Mississippi, Alabama and Tennessee as the cyclone moved near or over those states. Fortunately, almost all of the tornadoes were relatively weak, of EF-0 and EF-1 intensity, with generally minor damage, few injuries and no deaths attributed to them.

The meteorological set-up for heavy rain from Harvey was not unusual and was well predicted by all computer models. It was so unusual to see the models predicting 50 inches of rain. The extreme rainfall was well forecast by local National Weather Service offices and local broadcast meteorologists.

A stationary front that brought slightly drier and cooler air to the Southeastern U.S. sat over the Houston metro for two days. This combined with the slow movement of Harvey after landfall bring wave after wave of moist air inland well east of the center of Harvey. This meteorological set-up has been seen before with tropical cyclones producing heavy rain along the Gulf Coast.

Unfortunately, Harvey was just the beginning of a trio of major hurricanes that would bring more death and devastation to the Caribbean and Florida over the coming weeks of the 2017 Hurricane Season. Irma and Maria were just a few days and weeks from forming.