There are Cat 3 Hurricanes & EF-3 Tornadoes, But Do Winter Storms Get Categories Too???


Many people are aware of the Enhanced Fujita (EF) Scale for tornadoes.  Most also know about the Saffir-Simpson Hurricane Wind Scale.  However there is also a rating scale for Winter Storms that fewer people know about. In 2004, Paul Kocin and Louis Uccellini from the National Weather Service (Kocin and Uccellini, 2004) developed the Northeast Snowfall Impact Scale (NESIS).    Below is a description from the National Climate Data Center (NCDC) website for NESIS:

“The index differs from other meteorological indices in that it uses population information in addition to meteorological measurements. Thus NESIS gives an indication of a storm’s societal impacts. This scale was developed because of the impact Northeast snowstorms can have on the rest of the country in terms of transportation and economic impact.

NESIS scores are a function of the area affected by the snowstorm, the amount of snow, and the number of people living in the path of the storm. The diagram below illustrates how NESIS values are calculated within a geographical information system (GIS). The aerial distribution of snowfall and population information are combined in an equation that calculates a NESIS score which varies from around one for smaller storms to over ten for extreme storms. The raw score is then converted into one of the five NESIS categories. The largest NESIS values result from storms producing heavy snowfall over large areas that include major metropolitan centers. Continue reading

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Quick Web Maps – How’d you do that???


  • As a Geographic Information Systems (GIS) professional for nearly 10 years, I’m used to having people ask, “can you make a map of…”  With the increase in the use of Social Media and the use of web services to share information, it has become much easier to share the data behind the scenes.  Enter in a concept called interoperability.  For many years, the term interoperability was used when two public safety agencies (ie. police and fire) used different radio frequencies and they couldn’t talk to each other.  But as new technology has been developed, interoperability is being used more to describe:

Assembling separate but related pieces of information from different sources and/or disciplines in order to answer a common question

In this morning’s post, October snow and Online Web Maps, I put together a web map showing elevations above 3,500 feet (a snow level discussed my many meteorologists and spotters).  Let’s walk through the separate but related pieces of information and steps to the process to show how they are interoperable with one another to answer the common question “If it snows above 3,500 feet, where will the snow occur?” Continue reading

October Snow and Online Web Maps


October is finally here, and just in time we are having reports of snow in the Mid-Atlantic / Appalachian Mountains.  Earlier today, I saw a tweet  from Jim Cantore of the Weather Channel.

@jimcantore: I remain bullish on HEAVY WET #SNOW EVENT above 3500ft in WV,VA, & NC Sat nt thru Sun.More tree issue than anything

We don’t usually get snow this early, but it has been known to happen.  With that in mind, the main question comes up, “Well what is above 3500 feet???”  Enter GIS and some new functionality from ESRI’s ArcGIS Online.  In recent months, they have added the capability to load GPX tracks, Shapefiles, KML files and reference existing WMS and ESRI REST Services.  This past week, they added functionality to “Publish Maps” from ArcGIS Online.  Below is a quick map that was created in just over 2 hours using ArcGIS for Home and ArcGIS Online. Continue reading