Powerful Storm Brewing

October 17, 2011

An extremely powerful early Fall weather system is brewing and will begin developing as early as tomorrow. A strong low pressure system induced by a strong polar vortex will merge and morph with a disturbance coming out of the Gulf of Mexico. This disturbance moving North out of the Gulf of Mexico will bring an abundant amount of moisture with it. As the warm and moist tropical air moves North, the warm and moist air (latent heat release) will help strengthen the morphed weather system as it travels North along the Spine of the Appalachian Mountains.

The water vapor imagery essentially tells the story this evening. You can see the large area of disturbed weather across portions of the Gulf of Mexico. The second system that will be a factor in this eventual large and phased weather system is a developing weather system across portions of Colorado. The extremely dry air across portions of Arizona and New Mexico is associated with our third player in this developing storm system and that is a very strong jet stream.

Nearly all of our forecast guidance has locked on to a solution of a strong weather system developing and moving into portions of the Midwest and Eastern Ohio Valley.

As the weather system begins to develop along the East Coast on Tuesday, strong and severe storms will be possible across the Southeastern United States. Increasing shear and an extremely tropical and buoyant atmosphere will lead to the threat of tornadoes from Florida into Georgia and eventually South Carolina.

This strengthening weather system will bomb out across portions of the Eastern Ohio Valley, strengthening possibly to as low or near 980 mb. This type of track is rare, as most storms that develop in this manner have a coastal low that transfers off the Mid Atlantic coast and tracks up the Northeast coast verses strengthening over land.

The track of his system means that a very large area will be impacted with heavy rain occurring from Florida all the way up the Appalachians, through the Ohio Valley and into portions of the Interior Northeast.

As the system reaches it’s peak intensity over the Eastern Ohio Valley and Eastern Great Lake states Wednesday and Thursday, extremely strong winds are also possible. You can see the tight wind field noted by the extremely close isobars around the low pressure.

With extremely impressive height falls as the low pressure deepens, it is not out of the question that some light snow could fall across portions of Northern Illinois, Southern and Eastern Wisconsin, Northern and Northwestern Indiana and Western Michigan. Obviously with extremely warm ground temperatures and fairly warm lower and mid level temperatures, no accumulation would occur, but the fact that some wet snowflakes are possible is definitely impressive.

Stay tuned to our facebook page for the latest on this developing storm system over the next 24-48 hours (www.Facebook.com/SWATChasers).

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Weather Wise: The Myth that is “Heat Lightning”

July 24, 2011

Often times during the summer months, lightning can be see across the distant sky. This distant lightning is often referred to as “heat lightning.” Tonight’s weather wise blog will focus on the real origins of heat lightning and how it can even be dangerous!

It’s a hot and humid summer night and you are sitting outside or sitting at the ball park and you notice lightning in the distance. You hear people around you referring to this as heat lightning. Folk weather mythology suggests heat lightning is caused by hot air expanding until it sparks on sultry summer nights. This is an incorrect hypothesis. Heat lightning was named because it is often seen on hot and humid summer nights, a time of year when thunderstorms are common. These flashes are often early warning sign that storms are approaching, because the lightning you see may be moving your way. Heat lightning is not a unique form of lightning, but normal thunderstorm lightning that flashes too far away for its thunder to be heard. So called heat lightning appears as sheet lightning which is actually a standard lightning bolt but the light is reflected off of thunderstorm clouds.

The typical summer weather pattern often promotes lightning to be seen for long distances away from the parent thunderstorm. During the summer, our atmosphere cools after sunset and often times warmer air settles over cooler air near the surface. This is called an inversion. Inversions have interesting properties as they can help bend radar waves and light waves. The curvature of the Earth often allows us to see the lightning but not hear the thunder as sound is more likely to be bounced off the Earth’s surface. With this in mind, lightning (what you know as heat lightning) from summer storms can be seen over 100 miles away from the actual thunderstorm itself!

It is also important to remember that cloud to ground lightning strikes can travel 50-100 miles away from the parent thunderstorm. The mythical heat lightning can often be an indicator that a dangerous storm is close by. A prime example of cloud to ground lightning strikes occurring well away from the parent thunderstorm occurred last night (July 23rd, 2011) in Eastern Indiana.

The radar image above shows a thunderstorm occurring over portions of Blackford and Jay Counties with some lightning strikes being detected close to and within the parent thunderstorm. More intriguing however were the cloud to ground lightning strikes indicated across Southeastern Madison County, over 40 miles away from the parent thunderstorm! For that reason, anytime you hear thunder or see lightning, seek shelter indoors. Most lightning fatalities occur when people are caught outside working or taking part in some recreational activity.

As a reminder, SWATTours.com is online and we are now taking reservations for the 2012 storm chase season!

Brandon Redmond