Good evening all good people viewing I hope all storm chasers are chasing storms safely but at the same time having fun too. Today I am going to write an informative blog on Thunderstorms. Since we started meteorological summer earlier this month, I think it is appropriate to blog about thunderstorms, since so many of us are affected by thunderstorms in the summer. In fact, according to my studies there are 2,000 thunderstorms at any given moment around the planet, 45,000 per day and 16,000,000 million annually. Thunderstorms are concentrated where solar radiation budget is high between the equator 0 degrees Latitude to 38 degrees latitude on either Hemisphere. Other tidbits is that Florida leads the United States with the highest average of thunderstorms annually, It doesn’t surprise me because Florida is a hot humid and moist place and that’s what thunderstorms need to develop in.

I am going to break this into parts this evening.: Ingredients for Thunderstorms, Stages of a Thunderstorm, Types of thunderstorms from single cell to supercell which includes pictures or graphs, Characteristics of the types thunderstorms, and Hazards that they bring with them.


All thunderstorms require several ingredients for storms to develop.

A. MOISTURE – Especially at the low levels, Dewpoint temperature measures the moisture available, and anything over 60 degree dewpoint is considered acceptable, with 70 degree dewpoint or higher is considered ideal conditions for explosive development. The main moisture regions in the United States that provide moisture is :

Gulf Of Mexico: This makes sense because most thunderstorms take place here along the Gulf Coast to Florida.

Atlantic Ocean: This is a good moisture source for the Mid-Atlantic and Northeast.

Pacific Ocean: This is good moisture source for the Southwest US and western mountain ranges.

Great Lakes: The Great Lakes can provide moisture for the Midwest and upper Midwest. Also in the Midwest, evaporation from farmlands can enhance low level moisture.

B. INSTABILITY – Atmospheric stability is a just measure of the atmosphere’s tendency to enhance or deter vertical motion. A measure of buoyancy. Thunderstorms need unstable conditions, because if we had stable conditions it would never rain. So in unstable conditions, a lifted parcel of rising air will be WARMER than the surrounding air or ELR which is the environmental lapse rate. Simply put if a parcel of air is warmer than the surrounding air the air will rise since it is less dense than the ELR. Thus instability favors updrafts and downdrafts.

C. LIFTING MECHANISM –  This provides a source for air to rise. Lift can come from the Sun. The Sun causes heating of the surface and air rises if heated especially in Florida where I live. I live below the westerlies and synoptic scale systems that have Jetstream support so the Sun is the MAIN driver of weather here. COLD FRONTS – provide lift as it acts as a WEDGE, lifts the warm humid and moist air, cools and condenses and waa laa thunderstorms. WARM FRONTS – Warm fronts to a lesser degree than cold fronts can initiate thunderstorms by a process called Overriding. That is the warm less dense air has to go over the top of the colder dense at at the surface, usually not as severe as cold front due to lack of instability. Other Parameters are DRYLINES, OUTFLOW BOUNDARIES, And OROGRAPHIC UPLIFT.

Drylines are found in the southern plains and are the mechanism for severe thunderstorms and tornadoes. Outflow boundaries from thunderstorms propagate other thunderstorms by sending cold dense air sweeping down from the storm and acting like a mini cold front wedging other storms to start. Orographic lift is found east of the Rockies where air rises up the slope of mountains causing air to rise, cool and condense and storms to initiate.



Sources of moisture in the contential U.S.


These two graphics depict instability needed for the thunderstorms to develop, and the second graphic shows moisture sources for thunderstorms to initiate.

Graphics provided by The National Weather Service.

Next, I am going to first discuss three basic stages of a thunderstorm. This DOES NOT pertain to Supercell Thunderstorms, for they are a Beast onto their own.


A. DEVELOPING STAGE or CUMULUS STAGE – Growth of cumulus clouds. This stage is Dominated by rapidly rising warm, humid air. UPDRAFTS dominate this stage, where vigorous turbulence is present. Updrafts can be from 10 mph, to 20 mph, to an incredible 100 mph at this stage. Another important aspect of this phase is the LATENT HEAT OF CONDENSATION -this process takes over after the air has risen from surface heating from the Sun. Remember from above we needed instability, here we see water changing from different states from a gas to a liquid. So the warm parcel is rising, its warmer than the surrounding air, it continues to rise , WHY? Because there is a HIDDEN heat or LATENT(which means hidden in LATIN) Heat which is given off when water changes from a liquid to a gas. In fact thunderstorms use this energy from water as its fuel. When water changes from a liquid to gas(latent heat of condensation) it gives off 600/calories per gram!! That’s incredible because for humans water gives us 0 calories. For us to absorb 600 calories we need to eat a cheeseburger with fries for fuel and we can burn that off in an hour run. Can you imagine how many calories Thunderstorms use!!! An astronomical amount!!! A gram of water is so small its unbelievable and that’s 600 calories for these storms WOW!! 600 calories is a lot for a human being, I couldn’t even fathom if we ingested 600 calories per gram in food we would all be in serious trouble!!

B. MATURE STAGE – This stage is where thunderstorms have both updrafts and downdrafts. The top of the cloud reaches an “mixed level” where liquid water, supercooled water droplets, grauppel or soft hail and ice crystals are present. This process initiates precipitation through the Bergeron Process. This process is where relative humidity reaches 100% and precipitation begins through the mixed level stated in prior sentence. I stated DOWNDRAFTS are present here as well because a process called ENTRAINMENT where dry air that surrounds the storm gets entrained into the storm. And since dry air is more dense than warm air it descends and forms downdrafts or microbursts. Microbursts are the Bane of the aviation industry’s existence, since planes have trouble landing with downdrafts from thunderstorms present. In this stage Gusty to Damaging winds can be present, Heavy Precipitation, Thunder and Lightning, and even Hail.

C. DISSIPATING STAGE  – This stage is Dominated by Downdrafts. Energy source is cut off(latent heat), storm collapses and dissipates. Remember when downdrafts dominate they cutoff the rising air needed to fuel the storm and instability is gone and stable conditions resume. Now the TOTAL time from Developing to Dissipating stage is 20-40 minutes give or take 5 minutes.

I get people asking me Brandon in Florida it rained 15- 20 minutes and that’s it. Or the storm rained itself out. Because the storm went through the entire life cycle from Development to Dissipation.

Here is a graphic,  showing the 3 stages of thunderstorms,  brought to us by the good people at Wikipedia.


A Ordinary Cell or Single Cell – Common in Florida. Short life generally lasting 30-40 minutes. Downdrafts form after 15-20 minutes. The updraft weakens in 20-30 minutes, stability commences with downdrafts dominating, Gusty winds and small hail, not usually severe, but strong. There can be wind gusts to 50-55 mph just under severe limits. Pulse storms can occur with single cell thunderstorms can can sometimes reach severe limits briefly, storm weakens and can generate another pulse storm due to its outflow boundary.

This is an impressive pic of a single cell storm just below severe criteria. Pic is from NOAA.

B. Multicellular Cluster– This is most common especially above 30 degrees latitude. This is in association with a frontal system or a MID LATITUDE CYCLONE. Here you have groups of thunderstorms moving as a unit, Heavy Rain and Hail are the primary threats with a possibility of a weak tornado spinning up as well. Severe thunderstorms can occur here with new cells initiating on thewest to southwest side and storms weakening on the east to northeast side. Each cell lasts 20-30 minutes. In multicellular thunderstorms MCS and SQUALL LINES  can develop. MCS are called Mesoscale Convective Systems and they are a group of storms that consolidate and can travel long distances. Bow Echoes can form in Multicelluar and MCS too – They occur due to differences in wind, stronger winds at center of storm surge forward and to the center. On the radar it looks like a backwards C. I will try to get an  image of bow echoes and derechoes. DERECHOES  – thunderstorms advancing in a SQUALL LINE, which is an elongated line of strong thunderstorms even severe thunderstorm that combine energies to form a line or cluster of ferocious winds with hurricane force wind gusts in a Mesoscale Convective System. They can extend at least 250 miles long and record winds up to 150mph!!

Here is a graphic by showing the life cycle of a multicellular thunderstorm.

Here is an Awesome Doppler Radar image of a Bow Echo with damaging winds brought to us by


The National Weather Service has three criteria for thunderstorms to become severe. Thunderstorms have to meet at least one of them. They are as follows:

Hail that is 1 inch or larger; the size of a quarter

Wind Gusts of at least 58 mph or greater: 50 knots


There are several features or characteristics of severe thunderstorms they are as follows:

A. Anvil – The anvil is the elongated or flat cloud at the top of the thunderstorm that spreads downwind or leeward with the upper level winds. Its also called the Equilibrium Level.

B. Overshooting Top – The overshooting top is the dome of cloud directly above the main updraft tower and above the anvil. If the overshooting top persists and lasts longer than 10 minutes its a sign of a severe thunderstorm and a very strong updraft. In fact, an overshooting top can reach the inversion layer into the lower stratosphere.(really high about 70K).

C. Main Storm Tower– Visible updraft area where thee is a vertically oriented tower, with sharp defined edges. and possible rotation of the middle and lower clouds.

D. Wall Cloud – A wall cloud is an isolated lower cloud attached to the rain free base or bottom cloud and below the main storm tower. It usually persists for 10+minutes, rotates sometimes, and it is accompanied by rising and sinking air.

E. Shelf Cloud – Shelf cloud is an ominous looking cloud that is low based at the leading edge of a thunderstorm or cluster of thunderstorms. the shelf cloud is associated with strong outflow from a thunderstorm.

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Here is a picture of a severe thunderstorm with an overshooting top and an anvil clearly present. Image is by

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And this image is a Shelf Cloud by it clearly depicts a low based outflow cloud associated with gusty winds at the leading edge of the thunderstorm.

E. SUPERCELL – These thunderstorms are the strongest of all storms. These thunderstorms are responsible for the deadly tornadoes, large and damaging hail and great wind destruction. Supercells are most likely to occur in the southern plains and upper Midwest of the United States.

Some statistics on Supercell Thunderstorms:

1. Only 2000-3000 a year form in the U.S., thus there are a disproportionate share of death, injury and destruction with these storms because they are incredibly powerful

2. Less than 1/2 of Supercell t/storms produce tornadoes, but almost all VIOLENT TORNADOES EF3-EF5 come from them.

3. Supercell thunderstorms can grow to 65-70 thousand feet into the Stratosphere!!

Vertical wind profile causes cyclonic rotation in the updraft and speed/direction change with height. So essentially speed and directional shear is needed to form these monsters.

Development of Supercell Thunderstorms

1. In addition to speed and directional shear Supercells need a HUGE quantity of latent heat supplied by the Gulf of Mexico, The Atlantic Ocean and Pacific Ocean.

2. Upper Level Jetstream – Winds aloft from the Jetstream travelling sometimes at 150mph+ TILT the Supercell storm so the Updrafts and Downdrafts can extend for a long time, in terms of hours not minutes.

3. Inversion – this helps to provide the basics, a warm layer at about 8-10 thousand feet shallow keeps air from rising to early and inhibits other smaller storms from forming, as surface heating continues and the Sun continues to work its magic moisture continues to build and traps the air beneath the inversion.

** eventually an “eruption” produces an explosive and an unusually large cumulonimbus SUPERCELL Thunderstorm.

Other features in Supercell Thunderstorms include:

MesoCyclone : Which is the strong rotation you can detect on Doppler radar at the center of the storm. It is usually a precursor to a tornado.


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This image provided by shows an incredible supercell thunderstorm with a mesocyclone in the middle.

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I love this graphic you can clearly see the TILT in the supercell where updrafts and downdrafts can last for a VERY long time. I thank for this picture.


Thunderstorms can bring death and destruction if you are not prepared. So it is vitally important to take precautions when thunderstorms are forecasted for your area. the national Weather Service has two criteria guidelines A Severe thunderstorm Watch and A Severe Thunderstorm Warning. A Watch means to be alert to potential severe thunderstorms to occur within 4-8 hours. And a warning means a severe thunderstorm is occurring and the time frame is 15-30 minutes.

Hazards include:

-Deadly cloud to ground lightning

– Hail

– Damaging winds

– Tornadoes

– Torrential rain and flash flooding

– tornadoes or waterspouts –  tornadoes over the water

– So remember when thunder roars GO INDOORS.

Thank you all for listening be safe when thunderstorms are forecasted for you’re area and take precautions always.

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