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Tropical Atlantic Headquaters

This graphic highlights any tropical depressions, storms, or hurricanes that the NHC is issuing advisories on as well as invests or other weather systems discussed in the Tropical Weather Outlook (TWO) and the Tropical Weather Discussion.

Tropical Weather Outlook Tropical Weather Discussion

Enhanced TInfrared View Of The Atlantic Basin

(Click image to animate)

This graphic shows the GFS forecast for sea level pressure and wind vectors out to 48 hours.

12 Hour 24 Hour 36 Hour 48 Hour NHC 24 hour surface forecast showing sea level pressure, tropical waves, and current systems.

This image shows the latest SSTs. The red boundary separates the temperatures above and below 26 C, the temperature needed to support tropical cyclone development. (Click image to animate)

Another view of Atlantic Sea Surface Temperatures (Depth of 26 C Isotherm) In addition to warm SSTs of over 26 C, these warm temperatures need to have a depth of around 50 meters in order for a tropical cyclone to sustain itself. This image shows the depth of the 26 C isotherm.

Wind Shear Analysis (Click images for larger version)

Wind shear is a change in wind velocity (speed and/or direction) with height. Shear can rip a tropical cyclone apart or keep one from forming by preventing the convection from building. The following images show the latest wind shear and the shear tendency - whether it is increasing or decreasing.

Shear Tendency

Upper Level Divergence

Upper level divergence is when the air in the upper levels of the atmosphere is moving away from a common area. It can induce sustained updrafts and therefore provide the exhaust system for a tropical cyclone, allowing it to strengthen.

Lower Level Convergence

Lower level convergence is when the air in the lower levels of the atmosphere is coming together in a relatively small area - the opposite of divergence. Eventually, there is nowhere for the air to go but up.

                Forecast Models Computer models help show us the possibilities of how various weather sysems, such as tropical cyclones, may interact with each other. They take initial conditions and show us predictions based on the laws of physics and atmospheric equations. Each model has its own biases and shortcomings as well as its strengths. It is important to take all of this into account when using the models. Computer models are a powerful tool, but should not be used by themselves.                          FSU's Tropical Model Page                         PSU's Tropical Model Page
              NCEP's Model Page
                            ARL's Model Animations Page                                            CSU's Tropical Cyclone Model Guidance
                     Steering Layers The steering winds in the atmosphere can help us determine the path and speed of a tropical cyclone. One rule of thumb says that the cyclone will move in the direction of the steering currents, but at about half the speed. However, the steering layer we need to look at is based on how deep the tropical cyclone is. We can determine this from the minimum pressure and then use the appropriate image below.                         Steering Layer (MSLP 1000-1010mb)

Steering Layer (MSLP 990-999mb)

Steering Layer (MSLP 970-989mb)

Steering Layer (MSLP 950-969mb)

Steering Layer (MSLP 940-949mb)

Steering Layer (MSLP 940mb or less)