1. A computerized method of offering for purchase, positions predicting a future first hurricane landstrike resulting from a substantially continuous ongoing natural process culminating in a future first hurricane landstrike, comprising: providing a computer graphical user interface having first and second portions; providing a database containing 1) a map of geographical areas corresponding to the positions to be offered for purchase, the geographical areas being at least one of the coastal and the inland type, 2) strike probabilities of future first hurricane landstrikes for the geographical areas; and 3) offer prices for purchasing positions predicting future first hurricane landstrikes in respective geographical areas, that are based at least in part on respective strike probabilities; and 4) current severity of the continuous ongoing natural process; displaying the map in the first portion of the graphical user interface with user selectable portions corresponding to the geographical areas of the map; during the substantially continuous ongoing natural process, electronically obtaining updated data providing the basis for electronic calculations of strike probabilities of a future first hurricane landstrike for the geographical areas and updated current severity of the continuous ongoing natural process; and in response to a user selecting a user selectable portion and thereby indicating a geographical area for selection, displaying in the second portion of the graphical user interface, an offer price, electronically updated in substantially real time so as to be based at least in part on an updated strike probability and the current severity of the continuous ongoing natural process, for purchasing a position predicting the future first hurricane landstrike in the indicated geographical area.