Squalls, Gales, and Hard Rain

Got to love these colorful graphics from the National Weather Service today after a summer of nothing but hot and dry weather. Above: Squally weather started before midnight last night -- as predicted -- and continues.

So what is a squall? The term "squall" is universally used to refer to a sudden wind-speed increase, both historically and in the present day. In 1962 the World Meteorological Organization (WMO) defined . . . that to be classified as a squall, the wind must increase at least 8 m/s and must attain a top speed of at least 11 m/s, lasting at least one minute in duration.

In Australia, a squall is defined to last for several minutes before the wind returns to the long term mean value. In either case, a squall is defined to last about half as long as the definition of sustained wind in its respective country. Usually, this sudden violent wind is associated with briefly heavy precipitation.

The word appears to be Nordic in origin, but its etymology is considered obscure. It probably has its roots in the word skvala an Old Norse word meaning literally, to squeal.



While we haven't heard any squealing winds this morning . . . we are 30 miles inland from the coast. . . we have received over 4.5 inches of rain (or about 115 mm) since the rains began at dusk yesterday. Above: The current radar estimate of rainfall over Volusia County, Florida. . . which is in the middle of the image.



For the remainder of today and into tomorrow the squalls are to continue. Currently it appears the heaviest bands of rain are to our south, coming ashore near Melbourne where a Gale Warning is in effect.

A gale is a very strong wind. There are conflicting definitions of how strong a wind must be to be considered a gale. The U.S. government's (NOAA) National Weather Service defines a gale as 34–47 knots (63–87 km/h, 17.5–24.2 m/s or 39–54 miles/hour) of sustained surface winds.

The most common way of measuring winds is with the Beaufort scale (pronounced /ˈboʊfərt). It is an empirical measure for describing wind speed based mainly on observed sea conditions. Its full name is the Beaufort wind force scale and it was devised in 1805 by Sir Francis Beaufort, an Irish-born Royal Navy Officer, while serving on HMS Woolwich.



30 miles inland there is no gale force wind blowing but the rain is steady and very welcome. We have desperately needed this rainfall. It will be interesting to see if the rain has resulted in any rise at all in our virtually dry lakes. . . which I intend to investigate this afternoon.

The talking weather guys on every imaginable media outlet would like for everyone to believe this is a developing tropical storm. However, the National Hurricane Center has the last word on tropical weather affecting the USA and they say in their 8:00 am advisory that the chance of this system becoming tropical is only 20% over the next 48 hours (below).



So what do the computers say?

GFS doesn't develop anything, drags moisture up the coast into the Carolinas.

ecmwf sticking with a blob going SW to NE over FL. . .ignoring any Bahamas development.

CMC~ Has changed it up a little. Going with a little stronger Bahama development over Florida.

Nogaps~ Mostly agrees with the CMC.