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Lingering Heavy Rain Threat Along the Central Gulf Coast; Rain in the Pacific Northwest; Critical Fire Weather

Locally heavy rainfall may bring flash flooding along the central Gulf Coast today and Saturday from southeast Louisiana to the Florida Panhandle. A strong cold front will bring heavy rain with the arrival of cooler temperatures to the Northwest through the weekend. Widespread critical fire weather due to dry, gusty winds is forecast from the Great Basin into the northern Plains. Read More >

Utica IL Tornado

Overview Science Accounts Advancement




  (as of  the 10-year anniversary in 2014)


Preparedness & Weather Message Dissemination

While there was a tornado warning for Utica over 20 minutes prior to the tornado striking the town, there were still eight direct fatalities and one indirect fatality.  In the past decade, the NWS has worked closely with the entire weather enterprise and its emergency management and broadcast media partners, as well as team with social scientists to better understand response to weather threats and the conveying of that in NWS messages.  Much has changed in this realm since 2004, and below is a listing of some of these improvements.

  • In 2004, NWS warnings were primarily plotted and shown by entire county, even if the hazard threat was specific for a portion of the county.  This was due to many factors, including the disseminating and mapping technology in place at that time.  Specific warned areas, or polygons, from the NWS were implemented nationwide in 2007 after testing and working with communications partners.  This has helped to focus the greatest threat area and limit false alarms.  See below for how the warning would have looked different for the Granville to Utica tornadic storm of April 20, 2004.  The image to the right, or the Storm Based Warning, was what had been indicated as the highest threat area by the NWS warning forecasters on that day.

Utica Tornado Event

  • A quote from Patti S. on our Accounts page of this event was "...thinking it was just like any other of the hundred tornado warnings we've seen in our county."  While any one area is actually rarely under tornado warnings (sometimes going years without any), it was true that in 2004 all tornado warnings were basically created equal.  The entire NWS Central Region (including NWS Chicago) is now issuing Impact Based Warnings.  Within these warnings, more information about the threat level and impacts can be conveyed by NWS meteorologists, if the environment, radar, and spotter reports support as such.  For instance during the November 17th outbreak, a heightened degree of potential damage was mentioned in multiple warnings given the favored environment and radar signatures for long-lived destructive tornadoes.

  • Tornadoes on April 20, 2004 passed within two miles of Illinois Valley Community College, Kankakee Community College, and Joliet Junior College, and even directly impacted the IVCC campus.  Warnings from NWS Chicago now often mention colleges and universities, as well as other areas where there may be large groups of people, including outdoor venues. 

  • The NWS continues to work closely with emergency managers and expand its reach with community leaders and other public officials toward preparedness for severe weather.  The NWS has a program called StormReady to help prepare communities, universities, and other locations to ensure reception and communication of severe weather threats. The NWS Chicago office is very active with this program, having over 60 entities certified.  There were only a handful in 2004.

  • Severe weather information is now disseminated many ways, including our social media platforms.  Through these, YOU can be a force of nature as well and help the spread of weather safety information!
  • The major cell phone providers, FCC, FEMA, and NWS worked together to now provide Wireless Emergency Alerts.  These will alert your smart phone for Tornado and Flash Flood Warnings if your cell phone providing tower is within a warning polygon. 
  • From LaSalle County EMA...."Out of the lessons learned from the Granville/Utica Tornado, various agencies have implemented:

    - Use of agency photo identifications for its people
    - Forming and enhancing partnerships & professional relationships BEFORE a disaster 
    - Training and exercising emergency plans more often
    - Collaboration, communication, & cooperation among response partner agencies

    We've been able to test some of these things in the last 10 years with the various other disasters we've had in LaSalle County like the Streator & Dana tornadoes and historic floods."



 Computer Modeling

The April 20, 2004 proved an extremely difficult one to forecast at that time. Just a couple hours prior to the tornado and numerous others in the region, it was thought that storms may not even develop, let alone produce significant severe weather.

Meteorologists rely upon high capacity computing systems to run millions of mathematical equations every hour, on massive weather datasets. The computer models provide a visual forecast as to how a particular weather system may evolve in the future. For the most part, Numerical Weather Prediction (NWP) has kept pace with technological advancements, with the National Weather Service (NWS) leveraging these tools extensively when preparing for possible convection. One advancement of NWP that has greatly benefited forecasters has been the ability to perform retrospective analysis of significant events through the Weather Research and Forecasting (WRF) model. By ingesting past data, forecasters can simulate that event in order to gain further insight of the evolution process.

In the early 2000's NWP was limited on resolution capacity; however, this has greatly changed over recent years with newer hi-resolution models coming online and updating on a frequent basis. Forecasters now have tools that analyze mesoscale features which were once very limiting from the 1990's. Below are examples from simulations performed on the Utica Tornado through a retrospective simulation.


Simulated Radar Using 20KM DomainSimulated Radar


In addition to the above images displaying simulated reflectivity, forecasters now have the ability to display the antecedent conditions before seeing the main thunderstorms/supercells develop. Meteorologist scour these environmental parameters, in order to prepare for convective initiation.  Below are just a couple parameters forecasters use in solving the meteorological puzzle. 


Simulated Radar Using 20KM Domain Simulated Radar




In the past decade there have been several advancements in the computer processing and displaying of radar data.  The below image captures the difference in radar resolution that NWS warning forecasters have when interrogating radar data. 

Radar Resolution Improvement

In addition, the NWS radars were upgraded to dual-polarization in 2011-2013.  This advancement allowed for better detection of precipitation types, including hail.  But it also allowed for meteorologists to better detect non-meteorological echoes, including tornadic debris.  During the storm pictured above from November 17th, NWS meteorologists could tell there was a destructive tornado based on concentrated debris signatures on radar from Washington to Dana.