Waterspout versus Tornado … What’s the difference?
It’s a question that get’s asked a lot and it can get really confusing when a tornado forms over water like one did Saturday night off Perdido Key. The most obvious answer is that spouts are weaker (winds generally less than 50 mph) while a tornado is much stronger (65-200+ mph).
But that doesn’t explain the why, which can be answered by how the two develop.
Waterspouts are spawned by low-based cumulus clouds that generally have no lighting (think typical rain cloud). Since these pop-up showers are most common in the summertime, waterspouts are also more common in the summer. Also, since these clouds only climb to around 20,000 ft. they have weak updrafts which can only create a weak circulation. Waterspouts are short-lived and generally dissipate when they reach land.
Sidebar: The “water” you see in a spout is not water being sucked up from the ocean. It’s actually condensation from water droplets (like a cloud). The spray at the base of a spout generally is only carried up a few yards.
Tornadoes are formed in a much different environment. A twister is spawned from a supercell cumulonimbus cloud that can reach 40,000+ ft. in height. These are severe storms with tremendous updrafts that create violent circulations in the atmosphere. These storms are far more likely in spring and fall when cold fronts crash into our muggy Gulf air. When a tornado happens to form over water it can move inland and create far more damage than a waterspout.
These are the “general” rules, but as you can imagine they are some grey areas where the line between a strong waterspout and a weak tornado can become blurred. I hope though, that this answers some of the questions about waterspout versus tornado….
A storm system organizing over Texas will head our way Friday night and Saturday. The stronger upper level low creating the rain will weaken, but we still expect the chances of heavy rain here across our area. Deep layer moisture and enhanced lift from the slow moving wave could bring soaking rains. The Hydrometeorological Prediction Center forecast predicts up to 7 inches in some areas through early next week.
Heavy rains have flooded roads in many parts of the area. The most significant flooding has been reported near Eight Mile and Whistler. Areas along HW 45 have seen nearly 8 inches of rain in a short period of time. A trained weather spotter reported water over a foot deep near Bearfork Road. Most of Mobile County was under a Flash Flood Warning this evening.
A mid level low pressure trough is slowly moving across Louisiana. Abundant moisture is streaming up form the Gulf of Mexico. We continue to see slow moving rain bands, with locally heavy downpours. While we have seen some flooding, the overall severe weather threat is low, and we don’t expect dangerous winds or tornadoes. Rain chances continue into Thursday. Friday should be much drier.
You probably figured the strong north wind we’ve had throughout the day on Sunday is ushering in some major changes… The next couple of mornings will be the coldest we’ve experienced since early March. Inland areas will be chilly enough Tuesday morning to experience frost! If you have some tropical potted plants outside it would be a good idea to bring them in the next couple of nights.
We might as well enjoy the chill because it’s unlikely we’ll get this cold again until about November… And morning lows this week will rebound to sixty by Thursday morning.
I took a nice vacation trip to Boston, Mass this past week. Temperatures were cold. Most days were in the 40′s… With lows near freezing each night. It was great to have a nice, warm jacket!
We did have a little light sleet early in the trip. It was nice to be able to use the public transportation system through the area. I took the “T” just about everywhere in the city. I also took the commuter rail out to Concord and up to Rockport.
I did a lot of walking! I hiked the freedom trail through the heart of the city, ending at Bunker Hill. The best day trips were to Walden Pond where Thoreau did much of his work. I also went up to Cape Ann to a wonderful small village called Rockport. We enjoyed the Atlantic Coast and the fresh seafood right off the boat.
Here are the dining highlights: Best Chinese: The Mongolian Hot Pot at “Q” in Chinatown. Best Clam Chowder: Nate’s at Front Beach, Rockport. Best Steak: Davio’s in Back Bay. Best Pizza: Ernesto’s North End. Best Breakfast: Cookin Cafe in Allston/Brighton. I also had good steamed lobster at Legal Seafoods and Durgin-Park. There
We recently had a video sent through “Report !t” and what looks to be the formation of a tornado is anything but. It’s a common mistake, but what we see in the video is actually a Scud Cloud.
A scud cloud is a cloud that shows up beneath cumulonimbus clouds (t-storm clouds) and appear very ragged. They form as warmer updraft of a t-storm lifts warm air near the surface. The main difference between spotting a scud cloud and a tornado is that there is no rotation with a scud cloud. However, if you spot a scud cloud then be advised that its parent cloud is capable of producing heavy rain, lightning, and gusty wind.
A very slow moving line of storms is producing some very impressive rain totals over the western half of the area. We also remain under a tornado watch until 5pm. No tornadoes have been reported in our area as of this afternoon. We did see some reports of damage overnight in Harrison County near Biloxi. Rain totals have exceeded 5″ in a few locations in George and Green counties. We are under a flash flood warnings for localized rains in these areas through this evening. Heavy rain will continue to be the main issue tonight and Friday. A slight risk of severe weather is also in play until the front gets out of here early Saturday.
A slow moving upper level low over Oklahoma has created a surface cold front that will stall just to our west over the next two days. The result will be heavy rain, especially over the western half of the forecast area. We have had some warnings issued with the thunderstorms over south Mississippi this evening. A tornado watch is in effect for Green, George, and Jackson counties until 6pm. The stronger upper dynamics lift to the north tonight, lowering the severe threat. The main issue for us will be heavy rain. Some areas may see 3″-5″ totals through Saturday morning.
A tight pressure gradient pattern is helping to create strong s’east winds across the forecast area today. Winds are gusty to near 30 mph in some locations. A Wind Advisory remains in effect through 6pm this evening. We will continue to see breezy conditions tonight and Wednesday. Scattered showers move in Wednesday afternoon. We expect to see a much higher rain chance Thursday.
May 13th, 2012 at 3:59 pm by Matt Barrentine under FOX10 Weather
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