NOAA 2020 North Atlantic Hurricane Outlook

Warmer Than Normal Ocean Surface Lead To Frequent and More Powerful Tropical Cyclones This Season
05/19/2020, 10:44 am EDT
Why La Nina Could Be Stronger
05/29/2020, 8:31 am EDT
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NOAA 2020 North Atlantic basin tropical cyclone season outlook

 Tropical StormsHurricanesIntense HurricanesACE Index
30-Year Normal13.87.33.1114
NOAA Normal1263 

 Table 1: Summary of tropical cyclone season forecasts from Colorado State University, Climate Impact Company, Tropical Storm Risk/U.K. and NOAA/NHC. The NOAA/NHC forecast is issued today. All other forecasts are from early April and updated in early June. The NOAA Normal is a 50-year climatology.

Discussion: NOAA/NHC issues their 2020 North Atlantic basin tropical cyclone activity forecast. The outlook indicates above normal activity similar to forecasts issued in early April by other leading (market) providers. The more active than normal forecast is based on neutral ENSO or possibly a La Nina developing during the season (Fig. 1). In recent weeks the upper ocean heat in the equatorial East Pacific is lowered sharply and a strong indicator that La Nina is brewing (Fig. 2). The above normal seasonal activity forecast also recognizes the persistent anomalous warmth of the North Atlantic basin tropics and subtropics (Fig. 3) forecast to warm further during the season. Tropical cyclones passing over much warmer than normal water will cause rapid intensification. Finally, the seasonal outlook also recognizes a wet tropical Africa Monsoon which implies above normal number of tropical waves moving into the North Atlantic tropics (Fig. 4).

Fig. 1: The NCEP CFS V2 ENSO phase forecast model indicates La Nina by August.

Fig. 2: The subsurface equatorial East Pacific is cooling rapidly and a leading diagnostic of La Nina ahead.

Fig. 3: The North Atlantic basin tropics and subtropics are currently warmer than normal. Global SSTA models indicate additional warming during TC season.

Fig. 4: Tropical Africa is forecast wetter than normal for JUL/AUG/SEP indicating above normal number of tropical waves entering the North Atlantic basin.