Weather experts normally talk of rainfall predictions in terms of inches, but the effects Hurricane Florence had on North Carolina called for a different unit of measurement.
Prior to the storm’s arrival, Weather.us meteorologist Ryan Maue crunched some numbers and tweeted that North Carolina’s 7-day rainfall forecast by the National Weather Service’s Weather Prediction Center would be like getting “a total of over 10 trillion gallons” of rain from Florence. The math was based on the projected state average of 10.1 inches of rainfall for that time span.
On Tuesday, after the skies cleared over North Carolina, the National Weather Service’s Raleigh forecast office tweeted an image of radar-estimated total rainfall, saying, “Florence dropped about 8.04 TRILLION gallons of rain on NC.”
The image showed the most severe rainfall totals in the southeastern portion of the state, listing Wilmington in the 30-50-inch range and Morehead City at 20-30 inches.
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The WPS forecast Maue shaped his tweet around before the storm actually showed a smaller area of extreme rainfall than a forecast graphic he had previously shared, but the newer forecast called for more of North Carolina to see at least 5 inches of rain over the week ahead.
The Weather Prediction Center tweeted a version of the same seven-day rainfall forecast.
The forecast indicated coastal North Carolina could see 20-30 inches of rain with up to 40 inches in isolated areas, which proved true in some locations.
“This rainfall would produce catastrophic flash flooding and significant river flooding,” the WPC tweet said.
The National Weather Service’s Newport/Morehead forecast office warned the rainfall totals from Florence could also be historic, “with UNPRECEDENTED flooding.” That, too, became reality.