The experimental SPC Storm-Scale Ensemble of Opportunity (SSEO) is produced by postprocessing seven (7) deterministic convection-allowing model runs. Special emphasis is placed on hourly maximum storm-attribute fields. (Updated: November 13 2012)

Effective September 26, 2012, the SPC Thunderstorm Outlook becomes operational. Here is the Service Change Notice 12-29. (Updated: September 26 2012)

Effective September 25, 2012, the Day 3 Outlook includes general thunderstorm information. Please see Service Change Notice 12-26 for more information. (Updated: September 26 2012)

Severe Weather GIS (SVRGIS) page has been updated with preliminary January - June 2012 tornado data. Visit http://www.spc.noaa.gov/gis/svrgis/ for details. (Updated: September 21 2012)

On September 26, 2012, the SPC Thunderstorm Outlook becomes operational. Here is the Service Change Notice 12-29. (Updated: August 23 2012)

From June 5, 2012 to January 30, 2013, SPC will issue Experimental Probabilistic Fire Weather Dry Thunder and Strong Wind Outlooks for Day 3 to 8 with individual web graphics. Please read the Product Description Document (PDD) and provide feedback using this link: http://www.weather.gov/survey/nws-survey.php?code=spc38firewx. (Updated: June 5 2012)

The Rapid Refresh (RAP) model has replaced the RUC model at 12Z on May 1 2012. All references to RUC model fields in the Mesoscale Analysis, Fire Weather Analysis, and Compmap pages have been changed to indicate the RAP model provides background input to the display fields. (Updated: May 1 2012)

Severe Weather GIS (SVRGIS) page has been updated with tornadoes (1950-2011), hail/wind (1955-2011) reports converted into shapefile (.shp) format. Visit http://www.spc.noaa.gov/gis/svrgis/ for details. (Updated: Apr 9 2012)

New Meso Analysis Page has been implemented on March 27, 2012. Changes include: 1) overlay/underlay select buttons moved from the bottom to the side based on user feedback. 2) current SPC products are displayed in a hovered window at the lower-right of the page to facilitate better situational awareness as new products are issued. 3) A Trends/Forecast section has been added. This allows the user to view trends in the parameter being examined, and even project the data into the future for selected parameters. The images are viewed when you mouseover the selected past/forecast hour. Past images are of the SfcOA system, while future images are based on RUC model output. Another use for this function is to compare the SfcOA Analysis of a selected parameter to the RUC forecast for the same parameter at 00H. This may provide useful information regarding the performance of the model. (Updated: Mar 27 2012)

New SREF Page has been implemented on March 27, 2012. Go to www.spc.noaa.gov/exper/sref/index_old.html to access the legacy version. (Updated: Mar 27 2012)

The 2011 SPC Severe Weather Database files are now available for download at http://www.spc.noaa.gov/wcm/#data. (Updated: Mar 26 2012)

New Meso Analysis Page will be implemented on March 27, 2012. To preview, go to www.spc.noaa.gov/exper/mesoanalysis/new/vs4.php. Changes include: 1) overlay/underlay select buttons moved from the bottom to the side based on user feedback. 2) current SPC products are displayed in a hovered window at the lower-right of the page to facilitate better situational awareness as new products are issued. 3) A Trends/Forecast section has been added. This allows the user to view trends in the parameter being examined, and even project the data into the future for selected parameters. The images are viewed when you mouseover the selected past/forecast hour. Past images are of the SfcOA system, while future images are based on RUC model output. Another use for this function is to compare the SfcOA Analysis of a selected parameter to the RUC forecast for the same parameter at 00H. This may provide useful information regarding the performance of the model. (Updated: Mar 23 2012)

New SREF Page will be implemented on March 27, 2012. To preview, go to www.spc.noaa.gov/exper/sref/cmm_sref.php. (Updated: Mar 23 2012)

Two new RSS feeds have been added:

Click here to view a video clip on What is a Watch? (updated: Mar 8 2012)

The 2012 National Severe Weather Workshop was held March 1-3, 2012 in Norman, OK. Visit www.norman.noaa.gov/nsww/ for more details.

Starting July 8, 2011 the Storm Reports page has been updated to display both the new un-filtered reports side by side with the filtered version. For more info about the differences click here. Additionally, the links to display storm reports in Google Maps have been added.

On July 6, 2011 SPC created the official Facebook page. Please click on the Facebook icon on the left side menu or click on this link.

On April 19, 2011 SPC began issuing the Experimental Probabilistic Day 3-8 Fire Weather Outlooks. Please read the Product Description Document (PDD) and provide feedback using this link: http://www.weather.gov/survey/nws-survey.php?code=spc38firewx.

Severe Weather GIS (SVRGIS) page has been updated with tornadoes (1950-2010), hail/wind (1955-2010) reports converted into shapefile (.shp) format. Visit http://www.spc.noaa.gov/gis/svrgis/ for details.

NCEP is pleased to announce the first edition of NCEP's online Newsletter, which will appear on a quarterly basis. The newsletter, suggested as a result of a review of NCEP conducted by the University Corporation of Atmospheric Research (UCAR), will be distributed to NCEP customers and partners to keep them apprised of the breadth of NCEP activities. The newsletter can be accessed via a link from NCEP's homepage <http://www.ncep.noaa.gov/>, as well as from links from each of the NCEP Centers.

Beginning March 15, 2011, the SPC will provide multimedia weather briefings on an experimental basis for most Moderate and all High Risk severe weather days during the Day 1 period. As a supplement to the Public Severe Weather Outlook (PWO), these once-per-day recorded briefings will be available during the early morning hours (approximately 6:00-10:30 am Central) on the SPC website.

On March 8, 2011, the SPC removed space/time filtering on incoming National Weather Service (NWS) Local Storm Reports (LSRs). This filtering had been used by SPC in an attempt to reduce duplicate reports and limit artificially inflated initial estimates of severe weather events when many reports arrived for the same event. Space/time filtering is no longer being applied to decoded NWS LSRs and this approach is consistent with NWS storm-based verification methods. However, identical reports should still be removed from SPC logs and should not appear on the preliminary maps and lists.

SPC has switched to the new NOAA WOC web farms mid January 2011. Please do NOT use w1.spc.woc.noaa.gov or w2.spc.woc.noaa.gov for SPC web pages. Please clear your browser cache if your browser still redirects www.spc.noaa.gov to either w1 or w2.

The 2011 National Severe Weather Workshop is scheduled for March 3-5, 2011 in Norman, OK. Visit http://www.norman.noaa.gov/nsww/ for details. Visit here for early registration until January 10, 2011.

The Experimental Thunderstorm Outlooks product will continue to be issued through winter. Please click here for the Product Description Document (PDD). Please click here to take the survey. Public comment period ends on September 30, 2011.

The Mesoscale Analysis page has been substantially redesigned. Several additions and improvements have been added, such as image overlays, larger images, and fixed sector areas that permanently cover the entire contiguous United States. For more information, visit the Mesoscale Analysis Page, or download a MPEG4 video clip here. (5.8MB)

The Storm Prediction Center is one of the initial participants in the NWS experimental email updates service. The SPC products available with email updates are: Tornado/Severe Thunderstorm Watches and Watch Status updates, Mesoscale Discussions, Day 1, 2, 3 and 4-8 Convective Outlooks, Day 1, 2 and 3-8 Fire Weather Outlooks. More info.

Effective Tuesday March 23, 2010, the SPC began issuing fire weather products during the daylight hours. Click here for more details.

SPC Mesoscale Analysis Page has been extensively revised! Several additions and improvements have been added, such as image overlays, larger images, and fixed sector areas that permanently cover the entire contiguous United States. This new format is expected to replace the existing set of pages on April 13, 2010.

Starting January 5, 2010, the daily storm report summaries will record 1 inch and greater diameter hail, as well as severe thunderstorm wind and tornado reports. Please see this link for more information.

Public Severe Weather Outlooks for nighttime tornado potential will be issued December 1 through March 31. More information here.

Day 4-8 Convective Outlook NDFD grid becomes operational December 1, 2009. Click here for the Product Description Document. Click here for the Technical Implementation Notice 09-38.

Mesoscale Discussions for significant short range winter weather events will be issued on a scheduled basis (four times a day around 00, 06, 12 and 18 UTC) from December 1 through February 28.

Experimental Enhanced Thunderstorm Outlooks have been suspended on December 1, 2009 and will resume March 1, 2010.

Severe Weather GIS (SVRGIS) page has been updated with tornadoes (1950-2008), hail/wind (1955-2008) reports converted into shapefile (.shp) format. Visit http://www.spc.noaa.gov/gis/svrgis/ for details.

2010 National Severe Weather Workshop is scheduled for March 4-6, 2010 in Norman, OK. Visit http://www.norman.noaa.gov/nsww/ for details.

Experimental Enhanced Resolution Thunderstorm Outlooks product was suspended on February 27, 2009 for further development and refinement. This experimental product is now available to the general public on May 5, 2009. Please click here for a description of the revised outlook product. Click here for the Product Description Document (PDD).

Experimental Enhanced Resolution Thunderstorm Outlooks were suspended on February 27, 2009. Please visit here for a description of the revised outlook product.

2009 National Severe Weather Workshop is scheduled for March 5-7, 2009 in Norman, OK. Visit http://www.norman.noaa.gov/nsww2009/ for details.

MD LAT/LON points format changed effective 10/21/2008. The change standardizes the format for LAT/LON data within SPC products.

Click here then click on the FNUS38 KWNS PFWF38 link close to the bottom of the page to see the LAT/LON points product for Day 3-8 Fire Weather Outlook. (effective May 20, 2008)

Click here then click on the WWUS48 PTSD48 link to see the LAT/LON points product for Day 4-8 Convective Outlook. (effective March 25, 2008)

2008 National Severe Weather Workshop is scheduled for March 6-8, 2008 in Norman, Oklahoma. Visit http://www.norman.noaa.gov/ nsww2008/ for details.

Click here to see the SPC Preliminary Severe Weather Database Summary.

The day 3-8 fire weather outlook became an official product June 12, 2007.

The day 4-8 convective outlooks became an official product March 22, 2007.

2007 National Severe Weather Workshop is scheduled for March 1-3, 2007. Visit http://www.norman.noaa.gov/nsww2007/ for details.

The SPC has updated the Short-Range Ensemble (SREF) guidance page.

Go to http://www.wdtb.noaa.gov/courses/EF-scale/index.html for more information regarding EF-Scale training by the WDTB.

Mesoscale Analysis now has 6 sectors.

PNS announcement for new Convective Watch Hazard Probabilities Product in effect on April 25, 2006.

PNS announcement for new Fire Weather Outlook Areal Outline Products in effect on May 2, 2006.

SPC Historical Storm Report Archives page has been created/reorganized March, 2006.

SPC Product & Report Archives page has been reorganized March, 2006.

SPC Probabilistic Outlook information page has been updated on February 24, 2006.

Enhanced Fujita Scale Page is available here.

Information regarding changes to the SPC probabilistic convective outlooks (in effect on Feb. 14th, 2006) is available here.

2006 National Severe Weather Workshop is scheduled for March 2, 3 and 4, 2006. Visit http://www.norman.noaa.gov/nsww2006/ for details.

PNS announcement for Lat/Lon addition to SAW and removal from SEL in effect on Feb 14, 2006.

PNS announcement regarding removal of areal description relative to anchor points in SWODY[1-2] in effect on Feb 14, 2006.

The day 4-8 severe thunderstorm outlooks are experimental and opened to the public from October 3, 2005 for comments through July 28, 2006. Product Definition Document (PDD) in HTML or MS-Word. Please send your comments for this product to spc.feedback@noaa.gov.

The 2005 National Severe Weather Workshop was held March 3-5, 2005. Workshop presentations can be found at http://www.spc.noaa.gov/misc/NSWW05/.

The National Weather Service is undertaking research on how satisfied customers are with the weather products and services provided to the general public. We would appreciate your feedback by completing the survey. Click on http://www.cfigroup.net/NOAANWS2005 to begin the survey.

Monitor the number of tornadoes during the year compared to normal and other years at www.spc.noaa.gov/climo/torn/monthlytornstats.html.

Short-Range Ensemble Forecast (SREF) based on postprocessing the 15 member NCEP SREF plus the 3-hour time lagged, operational (12 km grid spacing) NCEP Eta for a total of 16 members, is now available.

May 4, 2003 tornado outbreak links.

Updated: December 20, 2012