While the peak occurrences for severe weather events in the United States happen between March and October, severe weather can occur at any time. In order to save lives, branches of the National Oceanic and Atmospheric Administration (NOAA) will issue public watches and warnings.
Knowing the difference between the two can prepare individuals for the necessary steps to take when considering the threat of severe weather. Watches and warnings issued to the public are based on different criteria.
"A watch is issued when conditions are favorable, for example, either for a severe thunderstorm or tornadoes," AccuWeather.com Senior Meteorologist Dan Kottlowski said. "It doesn't mean severe weather is imminent."
"Typical watches cover about 25,000 square miles, or about half the size of Iowa," according to the SPC.
Kottlowski said there are no set criteria for issuing watches, but if the conditions seem consistent with a developing severe weather pattern, watches can be changed and altered by monitoring ongoing developments.
"It can vary," he said. "There is not just one set of ingredients; every watch may have a different set of perimeters from one day to the next since it is based on a synoptic situation that may change within several hours."
Warnings mean that severe weather is imminent and is based on specific criteria and existing reports received by the NWS.
The criteria include hail that totals more than 1 inch in diameter and wind speeds of 55 mph.
"Lightning is not a criteria for a severe thunderstorm warning," Kottlowski said. "Heavy rain is not either."
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Warnings must follow the two main criteria, he said, adding urban flood and stream advisories, flash flood watches and warnings, and flood watches and warnings, may accompany a storm with heavy rain.
Warnings are issued through the efforts of individuals working for the NWS.
"The way a warning is issued is that a meteorologist will monitor the weather by radar and look for particular areas where there could be high impact damage," Kottlowski said. "They will issue a warning and there will be a signature for an existing storm or developing tornado."
Trained NWS spotters will verify reports of rotation or storm damage.
"This gives the meteorologists confidence in what they are seeing on radar," he said.
The thumbnail image is courtesy of J. Pat Carter/AP Photo.
Another round of rain is expected to move through the Carolinas on Saturday, which may lead to rises on some small streams and creeks.
A strengthening storm system will bring the threat for flooding, mudslides and severe thunderstorms to areas from Italy into the Balkans later Friday into the weekend.
Winter will kick off with mild weather in the Northeast and mid-Atlantic as an intensifying El Nino influences the weather pattern across the country.
A "blob" of abnormally cold water in the North Atlantic, located near Greenland, has the potential to put enough drag on the ocean current to impact weather conditions in the years to come.
“It was by far the most intimidating natural disaster I have ever chased,” Storm Chaser and Extreme Meteorologist Reed Timmer said of the historic flooding in South Carolina.
Cool weekend weather is in store for the Northeast after rain and thunderstorms dampen the region on Friday.
Early season snowfall dropped up to 12" on Webster County, WV; 9" at Staunton, VA; 1" at Dulles Airport, 0.3" in Washington, DC and 2.1" at Philadelphia. Whitened the ground throughout MD, Northern VA, Eastern WV, Eastern PA, NJ, NY and S. New England. Philadelphia broke 84 year low temperature record in mid-afternoon. Snow as far south as Richmond, VA (earliest on record). World Series Game in Baltimore postponed.
St.Augustine, FL (1989)
16.08" of rain fell.
Record Heat Wave Temp San Francisco 96 Sacramento 100 Bakersfield 101 LA Civic Center 107 Red Bluff 103 Riverside 106