Tropical storm Isaac remains somewhat disorganized early this morning as it slowly marches towards the Florida keys. As has been the case much of the week, the energy for the storm is not completely aligned with the center. Until all the pieces of the system become better organized it can't really strengthen very much. Atmospheric conditions over the waters west of the Florida peninsula are forecast to become quite favorable for the storm. Once the storm reaches the Gulf of Mexico's warm water it should easily achieve hurricane strength later this weekend and early next week. Before that happens, the southwest corner and the lower Keys of Florida have the best chance for tropical storm force winds. Thereafter, most of the strongest winds from the storm will remain offshore until the storm hits the Gulf Coast next week. You can see in the image below how the wind field is predicted to move. The cone widens the further out in time we go as there is less certainty to the track and thus where the strongest winds will actually occur.
As you can see from the map above Isaac is forecast to move over the southwest part of Florida and perhaps even over Key West later Sunday and Monday. Even though the track of Isaac is a bit more certain a wobble left or right of the track is still likely. The bigger question is what part of the Gulf Coast does Isaac ultimately strike late Tuesday night and early Wednesday. Anyone from New Orleans to Panama City Florida needs to be very aware of this storm over the weekend and early next week.
What is the cone of uncertainty?
The new buzz phrase seems to be the "cone of uncertainty". If you look at the projected track of the storm or the projected wind field you will notice these predictions start at a point and then widen into a "cone" shape over time. The further out in time a prediction is made, the greater the chance for error. The cone allows meteorologists wiggle room in their predictions and also gives the public a chance to know that even if the exact track is not over their area, there is still some risk.
How big will Isaac become?
As I mentioned, Isaac is poorly organized and still a tropical storm. As the storm passes by Cuba it will then head into an area of very warm water and somewhat favorable conditions for strengthening. Meteorologists are confident the storm will grow stronger later this weekend and early next week but uncertainty remains as to how strong the storm will become. Sometimes, if conditions are favorable, storms can go from a Category 1 to a Category 3 in less than a day. Once the storm begins to get stronger Sunday and Monday we will have to watch it hour by hour as it approaches the Gulf Coast.
Why do hurricanes form?
You might wonder why these storms form in the first place. I tell my students that hurricanes are nature's way of moving excess heat from the tropics to the northern latitudes. From about June through October, the oceans in the tropics are very warm. The water temperatures must be in the 80s not only at the surface but several feet below as well. This temperature structure to the sea only happens in the warm months. As the sun evaporates the ocean water that warm moist air rises and can, if conditions are favorable, create thunderstorms. In some cases, these clusters of thunderstorms will group together and begin to rotate. The rotation can be attributed to something called the Coriolis force. The Coriolis is strongest at the poles and zero at the equator. This is why hurricanes don't happen on or within several hundred miles of the equator. (no Coriolis=no spin) Winds inside the thunderstorms stir up more ocean spray which then evaporates and continues to feed the storms. If the winds reach 39 mph, the storm is called a "tropical storm." And when the wind speeds reach 74 mph, the storm is officially a "tropical cyclone," or hurricane. Once the storm becomes a hurricane they are then categorized into 5 different levels of strength. Category 5 is the strongest and the last time one of those actually hit the United States was in 1992 when hurricane Andrew came ashore south of Miami.
Gardening tip this week
This is a great time of year to plant. I actually feel that for many plants fall is a better time to plant than it is in the spring. Since the ground stays warm well into October, roots have a good chance to become established. When you plant in the spring, much of the energy of the plant goes into making new leaves, not new roots.
If you have a tough spot that you can't seem to grow anything, check out this video and learn about some of the plants that actually thrive in hard to grow conditions.
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