Forecast and Early Alert Model Based on Nine Viral Pandemics Originating in South-Central China, 1889-2020

South-central China is identified as the origin of repeated outbreaks of lethal diseases that have infected humans locally, and in some cases, spread worldwide. A cursory overview of web media describes the region invariably as a `disease incubator', a `hotspot for novel diseases', and `ground zero for a future pandemic'. These also point to the urgent need for well-structured monitoring, forecast, and early response as a means of prevention.

We examine evidence on the origin and timing of nine lethal viral disease outbreaks centered on south-central China, 1889-2020 and relate these to the recurring pattern evident in local meteorological data and in global climate indicators.

A distinctive deep drought and air temperature drop is evident 10-18 months prior to the inception of outbreaks, followed at disease onset, by unusually high rainfall and temperature -- as measured across 17 geographic locales. Statistical tests indicate the identified pattern is both consistent and differs significantly from a random selection of non-outbreak years. The likely mechanism is northeasterly cold, dry air intrusions from Siberia and/or the Tibetan Plateau. These show Lagrangian vorticity; upon reaching the coast, cold intrusions interact strongly with warm moist air over East China Sea, typically resulting in heavy rainfall over one or more population centers inland.

The Covid-19 Wuhan outbreak is preceded by and concurrent with an extended (12-18 months) severe drought and unusually high temperatures. All outbreaks coincide with solar troughs, except SARS which occurs at solar peak.

Of 12 atmospheric and oceanic modes examined to date, four show good potential for significant correlation and prediction; namely, the TPI (new Tripole Index for the Interdecadal Pacific Oscillation), Pacific ACE (Accumulated Cyclone Energy index), AOI (Arctic Oscillation Index), and GBI (Greenland Blocking Index).

Environmental correlates to outbreaks in China have rarely been addressed. A proposal is in progress for more detailed research. The goal is an in-situ monitoring and response network using outbreak prediction, forecast, and early alert.

Keywords: recurrent viral pandemics, climatic drivers, monitoring network, forecast, early alert, Covid-19.