Public Information Statement
Issued by NWS National HQ
Issued by NWS National HQ
108 NOUS41 KWBC 141945 PNSWSH Public Information Statement 24-72 National Weather Service Headquarters Silver Spring MD 245 PM EST Thu Nov 14 2024 To: Subscribers: -NOAA Weather Wire Service -Emergency Managers Weather Information Network -NOAAPort Other NWS Partners, Users and Employees From: Stephen Bieda III, Ph.D., Chief Severe, Fire, Public, and Winter Weather Services Branch Subject: Soliciting Comments through October 31, 2025 on the Experimental Probabilistic Precipitation Portal (PPP) The National Weather Service (NWS) is soliciting comments on the experimental PPP through October 31, 2025. The PPP is a website designed and maintained by the Weather Prediction Center (WPC) to be the centralized location of all NWS Probabilistic Winter Precipitation Forecast (PWPF) and Probabilistic Quantitative Precipitation Forecast (PQPF) information. PWPF graphics are created by the PPP across the contiguous United States (CONUS) and will also be displayed on the CONUS NWS Weather Forecast Office`s (WFO`s) local winter forecast page. A Public Information Statement regarding the availability of PQPF forecasts on the local WFO QPF and PQPF webpages will be issued at a later date. The PPP can be accessed here: https://www.wpc.ncep.noaa.gov/Prob_Precip Links to the respective WFO local winter forecast pages can be found here: https://www.weather.gov/prob-snow/ The winter portion of the PPP subsumes two other ongoing NWS experiments: the Experimental Probabilistic National Digital Forecast Database (NDFD) Snow Grids and also the PWPF Experiment. The winter portion of the PPP produces 10% and 90% exceedance percentiles, representing a Low End Amount (a 90% chance of higher snowfall) and a High End Amount (a 10% chance of higher snowfall) to complement the existing NWS deterministic snowfall forecasts (expected amount). Narrow ranges between the minimum and maximum snowfall totals indicate high forecast certainty, while large ranges between minimum and maximum totals indicate low forecast certainty. These two percentile values are sent as grids to NDFD. Grids are valid for 24-, 48- and 72-hour periods out to 72 hours from 0000 Coordinated Universal Time (UTC) Day 1 beginning with the 2200 UTC issuance. They are valid for 24-, 48- and 72-hour periods out to 72 hours from 1200 UTC Day 1 beginning with the 1100 UTC issuance. The Probabilistic Snow Grids are updated once per hour. The expected amount is the deterministic NDFD forecast. The PPP will also allow a forecaster to show the expected amount as a range of two values (the 25th to 75th percentile amounts) in an Impact-based Decision Support Services (IDSS) graphic. The PPP also produces the probability of exceeding the following amounts of snow (in inches): 0.1, 1, 2, 4, 8, 12, and 18. The experimental grids are available for download in gridded binary version two (GRIB2) format via both https: and ftp: from the NWS Telecommunications Gateway FTP (TGFTP) server. For CONUS: tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow24e10.bin tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow24e90.bin tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow48e10.bin tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow48e90.bin tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow72e10.bin tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.conus/V P.001-003/ds.snow72e90.bin Extensible Markup Language (XML) access: https:/digital.mdl.nws.noaa.gov/xml/ Visualization of these data will be available on the NDFD map viewer at: https://digital.weather.gov/ For additional information, please see the PPP Service Description Document (SDD) at: https://nsdesk.servicenowservices.com/api/g_noa/nwspc/res2/76dcd 1a897b596548881bb7de053af15 Users are encouraged to provide feedback on the PPP through the NWS survey at: https://www.surveymonkey.com/r/ExpPPP_2024 For additional comments/questions, please contact: Eric Guillot Winter Weather Program Manager National Weather Service Headquarters Silver Spring, MD eric.guillot@noaa.gov Kimberly McMahon Public Weather Program Manager National Weather Service Headquarters Silver Spring, MD public.program@noaa.gov James Nelson Chief, Development and Training Branch Weather Prediction Center College Park, MD james.nelson@noaa.gov For general questions regarding NDFD data, please email: nws.ndfd@noaa.gov For technical questions regarding NDFD data, please contact: Dana Strom Meteorological Development Laboratory Digital Forecast Services Branch National Weather Service Headquarters Silver Spring, MD dana.strom@noaa.gov National Public Information Statements are online at: https://www.weather.gov/notification/