WxNotify depends heavily on the NOAA Weather Wire Service (NWWS)
to receive alerts from the National Weather Service. Without it, WxNotify could not exist. Using open-source software
, WxNotify maintains a constant, 24x7x365 connection to NWWS, so any alerts that are issued by the National Weather Service are instantly downloaded, processed, and distributed within seconds of their retrieval.
After a "product" (e.g. warning, watch, statement, forecast, etc.) is received by WxNotify from NWWS, custom software determines various information about it; such as its type, what locations are affected, when it expires, etc. From this information, WxNotify then determines who the product should be sent to.
Before October 1st, 2007, all "short-fuse
" weather warnings (tornado, severe thunderstorm, and flash flood) were issued by the National Weather Service for entire counties at a time. After many years of people being warned for severe weather in another parts of the county that didn't affect them, the NWS came up with a more efficient method for issuing warnings. Now, when a short-fuse warning is issued, it is only for that part of the storm and where it's expected to go before it is no longer considered to be severe. The area is usually much smaller than the entire county (or counties). You may have seen a representation of this on TV or the Internet, with the warned areas resembling a cone or some other shape. This is called the "warning polygon", which is basically just a set of connected latitude and longitude points.
WxNotify takes advantage of this "storm-based" warning method and therefore will only send a notification alert for short-fuse warnings if your specific location (based on a latitude/longitude pair) lies within the warning polygon.
Either way, you will only be alerted for short-fuse warnings that affect only you!
Other non-life threatening watches, warnings, & advisories, and other products, such as Hazardous Weather Outlooks
will use your county when determining your location.Go here to read more information about storm-based warnings