I posted an update on the potential for severe weather last night before I left. Now, here’s an update on today’s storm potential.
The Storm Prediction Center, like yesterday, has us under a ‘Slight Risk’ for severe weather. Our best bets will come into the afternoon. Once we get onto the day of the event, the SPC breaks the risks down into percent chances for tornadoes, hail, and damaging winds. Here’s a look at those graphics.
Overall Outlook - Slight Risk
Damaging Wind Outlook - 30%
Tornado Threat - 5%
Severe Hail Threat - 15%
After a quiet weekend, the weather is changing into the coming week. Here’s a quick look at a couple of graphics that illustrate the timeframe of the passing of the cold front. The front will likely bring gusty winds and hail.
Here’s the first graphic showing the available energy in the atmosphere at each hour tomorrow. The actual name is called CAPE or Convectively Available Potential Energy. The higher the CAPE, the bigger the potential for storms.
CAPE (Convectively Available Potential Energy)
Notice the higher values come between 2:30 PM and 5:00 PM and then another spike with what appears to be the actual passage of the front at 7:00 PM or so. (Read More)
Photo Courtesy: RegesPhoto Photostream
7 inches in diameter
18.75 inches in circumference
Think this is big? Well, that’s the specs for the OLD record. There’s a new hail record and it happened on July 23rd in Vivian, South Dakota.
Here’s the report from the National Weather Service and NOAA…
NOAA’s National Climate Extremes Committee, responsible for validating national weather records, has declared a hailstone found last week in Vivian, S.D., to be the largest in diameter and heaviest ever recovered in the United States.
Found after a July 23, 2010, severe thunderstorm by Vivian resident Les Scott, the hailstone is 8.0 inches in diameter and weighs 1.9375 pounds (1 pound, 15 ounces) with a circumference of 18.62 inches. (Read More)
Warmer and more humid air made its way into the Alleghenies on Friday, and it made itself known during the afternoon. As a strong cold front approached from the west, showers and scattered strong thunderstorms developed and moved eastward. Some of the storms produced penny-sized hail, like this one did in the Johnstown area:
It’s a little early to be talking about severe thunderstorms, but the NWS recently made a change to their severe thunderstorm guidelines and it impacts everybody.
For years, the definition of a severe thunderstorm has been:
…a storm with hail equal to or greater than 3/4″ in diameter or convective wind gusts equal to or greater than 58 mph.
Now, they have bumped up the hail criteria to 1″ (or quarter-sized).
Severe Hail Criteria Changed