Atlantic Hurricane Season First Look for April 2021 by Dr. Ryan Truchelut – issued 9 April 2021 Key Points WeatherTiger’s first look at the…
Articles by Ryan Truchelut
WeatherTiger’s first look at the 2021 hurricane season is for a 35-40% chance of a near normal year, with a 30-35% chance of below normal and 30% chance of above normal cumulative activity. The median of our forecast for 100% of average hurricane season activity, or around 15 named storms, seven hurricanes and three major hurricanes.
A La Nina event is quickly weakening in the Pacific, and an upcoming westerly wind burst is likely to restore ENSO neutral conditions by early May. Our ENSO Whisperer April output forecasts that cool-neutral conditions are most likely to persist into the summer months, but redevelopment of a weak La Nina or emergence of a weak El Nino are both realistic possibilities based on both our modeling and current conditions in the Pacific.
A moderate La Nina is ongoing in the Pacific. While the conditions in the Northern Hemisphere do not reflect the typical Nina winter, the ocean-atmosphere feedback cycles in the global Tropics are well established. WeatherTiger’s ENSO Whisperer January output is mostly unchanged from the previous several runs.
The 2020 hurricane season dramatically underscored the rising vulnerabilities of the United States’ increasingly crowded coasts. Phenomena like early- and late-season activity in defiance of climatology, head-spinning rapid intensification through to landfall, and extreme flooding from stalled and slow-moving storms, all with minimal historical precedent, became numbingly normal. Still, despite ripping up the record books, this season somehow avoided the absolute worst-case scenarios for most of the U.S. coastline.
Fall Hurricane Outlook for Late September 2020 by Dr. Ryan Truchelut – issued 23 September 2020 Key Points WeatherTiger’s outlook for the fall months…
WeatherTiger’s first look at winter 2020-2021 is for a cool and typically snowy winter in the Northern Plains and Great Lakes, and warmer and drier conditions in the U.S. southern tier and Eastern Seaboard.
The Pacific has cooled slightly since April, with more rapid cooling beneath the surface indicative of trends into summer. Overall, global circulation patterns continue to reflect ENSO neutral conditions, albeit with a stronger than normal subtropical jet in the eastern Pacific. WeatherTiger’s ENSO Whisperer output for May is a bit more hedged than last month’s on the potential for late summer or fall La Niña development. Our model suggests that observed cooling will persist into mid-summer, followed by an extended period of cool-neutral anomalies.
Spring 2020 begins with much of the central U.S. growing region experiencing saturated soils due to excessive precipitation over the last 12 months. These extreme initial conditions raise the specter of another year of delayed or prevented planting across much of the central and eastern U.S., as characterized spring 2019. Widespread planting delays occur when extreme spring precipitation meets existing soil saturation. In our view, the Delta and Deep South are most at risk for delayed planting, with some possibility of localized delays in the eastern and southern Ohio Valley. These regions are most likely to see continued above normal rainfall through May.
The Pacific has changed little in March and early April, warm-neutral anomalies remaining in place. Overall, global circulation patterns continue to reflect ENSO neutral conditions, with a slight lingering tilt towards Nino-ish influences as reflected by a strong subtropical jet.