A friend asks . . . Mark, when will Spring finally arrive in Maryland, and when will Spring start where you live? Well, here is the answer:
Spring Casting ( Real Time Spring Mapping )
Near real-time predictions of the start of spring have wide applicability for tracking the start of the season across the continent.
The Extended Spring Indices (SI-x) are statistical models that scientists have developed to predict the “start of spring” at a particular location. Using historical observations of the timing of leaf-out and bloom in cloned lilacs and honeysuckle and daily observations from nearby weather stations, scientists have been able to determine the weather conditions that precede general spring leaf-out for a wide range of plants. Like many other deciduous plants in temperate systems, these plants put on their leaves as temperatures warm in late winter and early spring.
The accumulation of warm days (or hours) can be calculated from weather data, in any year, to predict when spring started. Using the SI-x predictive models, scientists can look at how much the start of spring has varied from one year to the next at a particular location, and whether recent years are dramatically different from the past or not. The models can also be used to forecast when selected plants might bloom or put on leaves in future years.
Click for animated progression of Spring.
Researchers have used daily gridded weather data, generated from observations at weather stations, to predict the start of early spring (first leaf date index), at every location in the United States, as shown in the map above for leaf out in 2015. Grid cells are shaded as temperatures become warm enough for plant leaf buds to burst (hold control and refresh the page to see the latest weekly animation, and click on the map to animate).
Source Article from the National Phenology Network (NPN): https://www.usanpn.org/springcast