The Monthly Sea Level Pressure Records and Their Use in Messaging

The Weather Prediction Center (WPC) maintains a repository of maps that track monthly high and low sea level pressure records over North America dating back into the 1870s. These products can indicate when in the calendar year extreme weather is more likely (e.g. unusually strong arctic highs or deep extratropical cyclones, tropical cyclones and their remnants). Preferred tracks for major storms stand out in the monthly low sea level pressure extreme maps across the continent. The records can be used, in conjunction with standardized anomalies, to determine the rarity of such events for any month of the year, and can aid in the determination if storms during the medium range period – 3-7 days – are plausible or implausible. The maps can be used to create a storm history for National Weather Service (NWS) County Warning Areas, as was done by the Wilmington, NC forecast office. The monthly pressure records maps were embraced by climatologists across the Plains/Midwest during the record high pressure event of January 7, 2015, and are being used to help determine state pressure records, in coordination with state climatologists and NCEI, as was done in Colorado in the wake of the March 2019 cyclone.

The Monthly Sea Level Pressure website: https://www.wpc.ncep.noaa.gov/research/roth/SLPrecords.html