North Atlantic ITCZ is Stronger; Tropical Disturbance Forming
08/08/2022, 10:09 am EDTTropical Upper Troposphere Trough Continues to Protect Western North Atlantic Basin from Tropical Activity
08/09/2022, 10:19 am EDTHighlight: Tropical Disturbance 97L forms.
Fig. 1: Formation of Tropical Disturbance 97L is indicated this afternoon in the far eastern tropical North Atlantic basin.
Discussion: Tropical Disturbance 97L has formed in the outer tropical North Atlantic basin (Fig. 1). 97L has gained clarity today and may be a little farther west than indicated by NOAA/NHC. The preliminary 5-day forecast by Climate Impact Company (CIC) indicates west to west-northwest travel almost to the far northeast Caribbean Sea and likelihood of intensification to a tropical storm. 97L is embedded within a strengthening ITCZ which implies above normal convection associated with this system. Upper shear is light and the ocean surface is in the 82-83F range which is certainly sufficient to allow for intensification. However, there are some obstacles ahead. Based on the preliminary forecast track, this system will cross over cooler waters while navigating the central tropical North Atlantic which could inhibit development. Additionally, an upper shear axis associated with an elongated tropical upper tropospheric trough (TUTT) is across the northeast Caribbean Sea and if still present would also prevent this system from strengthening and also causing a northwest turn. The CIC strengthening forecast is based mostly on climatology of systems in this location with above normal strength at their onset and the prevailing opinion of tropical cyclone model tracks and intensity (Fig. 2-3).
Fig. 2: Tropical cyclone models forecast tracks for Tropical Disturbance 97L.
Fig. 3: Tropical cyclone models forecast intensity for Tropical Disturbance 97L.