Monitoring Tropical Wave And Latest On TD 4

Tropical Depression 4 has weakened and is no longer a tropical cyclone according to the National Hurricane Center (NHC). The system is now an open wave, but still has convection associated with the wave. The appearance on visible satellite imagery is not impressive at the moment, and Firsthand Weather is not expecting tropical cyclone development with this system for now.

Visible Satellite Imagery (Remnants of TD 4)

The next wave worth monitoring is is off of the western African coast. This wave is supported by numerical guidance to potentially undergo tropical development this upcoming week.

Visible Satellite Imagery (New Tropical Wave)

So why is this tropical wave seeing support from numerical guidance? The wave is in an environment that is conducive for slow tropical cyclone development. The latest vorticity map shows the tropical wave is beginning to show some environmental spin. This is needed for tropicalgenesis.

Current 850mp Vorticity Map (University of Wisconsin)

The latest numerical guidance is indicating this vocticity will continue to increase and become more symmetrical with time as the wave moves towards the WNW. The latest GFS (12Z) shows the environmental spin becoming well-defined by Wednesday.

Future (Wednesday) 850mp Vorticity Map (Tropical Tidbits)

This looks plausible based on the current atmospheric conditions the wave is encountering. The wave is in a moist environment with low environmental shear. Numerical guidance indicates the environmental will remain relatively favorable for organization over the next several days.

Current Environmental Wind Shear Map (University of Wisconsin)

Saharan Air Layer Map (University of Wisconsin)

As the tropical wave moves towards the WNW, the system needs to be monitored as tropical cyclone development is plausible. The general WNW motion is likely due to the strong ridge north of the system. This would potentially place the Lesser Antilles in a favorable geographical area to see impacts by the upcoming weekend. The latest GFS (12Z) shows the wave developing into a tropical cyclone, impacting the islands, and moving into the Caribbean by the weekend.

Future (Saturday) 850mp Vorticity Map (Tropical Tidbits)

It is too early to determine the strength and final movement of this system, but Firsthand Weather will continue to monitor this evolving forecast. Keep checking back for updates.

  • ChrisArc

    On New Years Eve there was a
    temperature inversion over Bee Bee Arkansas, which made sounds louder and
    travel further. The event happened at night when the birds are normally
    roosting in the trees because the Black Birds cannot see well in the dark.


    Eyewitnesses said that they heard
    several loud bangs and then the sound of thousands of wings flapping, as the
    birds were scared from the trees. All it really took was a few of the birds to
    get startled and their warning calls could get the whole flock of close to
    million birds flying and crashing into trees, houses, cars… The flock of
    birds showed up on the weather radar taking off in more than one wave. Test was
    done on the birds after the event and they showed that they died from blunt
    force trauma. Everybody knew the birds were roosting in the area so they did
    not come from miles away.