INDIANA – The National Weather Service Indianapolis office is implementing new Winter Storm Watch/Warning criteria for heavy snow this upcoming season.
Effective immediately, the National Weather Service Indianapolis Forecast Office will implement new Winter Storm Watch/Warning Criteria for Heavy Snow across its County Warning Area of responsibility. This is part of a national effort to remove non-meteorological discontinuities across County Warning Areas and to better align watch/warning snowfall criteria to the local climatology of the region.
Historically NWS Indy’s snowfall criteria were partitioned into different 12-hour and 24-hour criteria. The new criteria will no longer be dependent on the time frame of the snowfall, allowing for a more event-driven approach to messaging. This new method maintains and encourages the ability to issue or withhold watches and warnings in anticipation of expected impacts or lack thereof.
The new Winter Storm Watch/Warning Criteria for Heavy Snow will be the following: 5 inches of snowfall during a winter storm event.
This criteria will be different for other NWS offices that serve Indiana. A criteria of 6 inches will be used across the northern third of Indiana and 4 inches will be used across far south and southeast Indiana.
Other hazard criteria used for Winter Storm Watch/Warning issuances will remain the same at this time. Any combination of hazards with reduced criteria or increased impacts can also result in the issuance of a Winter Storm Watch or Warning.
A map of the criteria across the entire Contiguous United States can be found at this link: www.weather.gov/snow-criteria.
There will be no changes to the Winter Weather Advisory snowfall criteria.
