Originally posted by DogsRule!
It's certainly not the worst of the worst...last August, after only 15 minutes of INTENSE rain that came out of NOWHERE (THAT is the Florida summer--unpredictable rain).
The only thing predictible about Florida weather is that with a few exceptions (hurricanes, fronts, etc.) the weather will always be unpredictable. The safe thing to assume is that rain and/or thunderstorms will happen just about every afternoon in the summertime.
Anybody care to guess why all of the rainfall?
The answer is by the very location of WDW itself. As most of you should know, central Florida has two major bodies of water (Gulf of Mexico to the west, Atlantic Ocean to the east), and each of them are about an hour away from WDW. As a result pretty much all of Florida has an atmosphere that is chuck full of moisture 24/7. There's just a neverending stream of moisture from groundwater evaporation on the ground and from the oceans nearby.
Now that the atmosphere is full of moisture, why does it only seem to rain in the afternoon and evening? Why won't it rain like that in the morning?
There can at times be thunderstorms and large amounts of rainfall during the morning. However, the vast majority of those cases are from organized storms systems such as fronts (warm, cold, stationary and occluded) and the occasional hurricane. It is rare for an individual storm cell to go from nothing to everything during the morning hours.
The main reason for the storms to develop in the afternoon is from one of Florida's most famous features --- good ol' Florida sunshine. In order for clouds to develop it is important for the moisture to rise up into the atmosphere and condense. One way is to force it up by ground terrain such as forcing it up mountains. Since there are no mountains in Florida, the air has to be risen by another means --- sunshine and daytime heating. An important thing to remember is that the atmosphere is heated from below, that is, from the ground up. Basically, the sunshine heats up the ground to high temperatures, much of the heat is reflected off the ground into the sky, and the heated air molecules rise up into the atmosphere. The molecules then rise up, condense, become saturated with moisture, collide with other molecules, eventually form clouds, and ultimately gain enough mass to fall back onto the earth as rain.
What about those pop-up thunderstorms and periods of heavy rainfall?
This process is kinda technical, so here goes nothing! During the overnight and morning hours the atmosphere basically "settles down", and a layer of air will form at some point (usually pretty low) overhead. This layer is called the
CAP, and it's critical to the development of these storms. The CAP basically prevents the atmosphere from rising, and it's pretty much why you won't see many (if any) low to mid-level clouds in Florida during the summer. In order to break through the CAP, the air is going to need
a lot of energy. This energy is called
CAPE, and is pretty much a measure of potential energy at that point in the atmosphere. CAPE is simply a combination of moisture and heat, so the more moisture and hotter the atmosphere, then the more CAPE is available.
An important thing is that the CAP cannot be too strong or too weak. If it's too strong then the air molecules will not break through the barrier and the storms will never develop. Too weak and the air molecules will break through too early, and it won't have enough energy built up to actually form the thunderstorms.
The storms usually develop between 3 and 6 pm because that's when the maximum temperatures occur during the day. By that time of day the air is heated to a maximum and is already full of moisture. At that time the CAPE will be near its peak and should easily be able to break though the CAP. Once it breaks through the air rises very rapidly and quickly develop into storms. With lots of energy, very large storm clouds can develop, and those large clouds are the ones mainly responsible for heavy rainfall, thunder, lightning and hail. These storms are so powerful that they can literally develop in a matter of minutes (usually 20-30). The good thing is that these storms usually don't last for long, and most are usually gone from the area within an hour to two.
As always, whenever in Florida (or anywhere in the southeast for that matter) be ready to head for cover during the afternoon during the summertime as you never know exactly when or where these storms will develop.
Any questions?
