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NOUS41 KWBC 221225

Service Change Notice 17-20
National Weather Service Headquarters Silver Spring MD
825 AM EST Wed Feb 22 2017

To: Subscribers:
 -NOAA Weather Wire Service
 -Emergency Managers Weather Information Network
 Other NWS partners and NWS employees

From: David Novak
 Director, Weather Prediction Center

Subject: Upgrade to WPC Probabilistic Quantitative Precipitation
 Forecasts over CONUS effective May 10, 2017

Effective Wednesday, May 10, 2017, beginning with the 1800
Coordinated Universal Time (UTC) issuance, the National Centers
for Environmental Prediction (NCEP) Weather Prediction Center
(WPC) will change the Probabilistic Quantitative Precipitation
Forecast (PQPF) products as follows:

- Upgrade all products from the 5-km resolution NDFD grid to a
2.5-km resolution grid which fully covers the Northwest River
Forecast Center basin
- Provide additional probabilistic grids describing the
distribution standard deviation and the 5th, 25th, 75th and 95th
percentile values of the cumulative distribution function
- Issue the 6-, 24- and 72-hour accumulation grids four times
per day

All products will be disseminated on the Satellite Broadcast
Network (SBN), NOAAPORT, and an ftp server in GRIB2 format.

Test grids for the 2.5-km products will be available in GRIB2
format with WMO headers on or about Wednesday, February 22,
2017, on the WPC ftp server:

Upon implementation on May 10, 2017, the 2.5-km grids will be
available via ftp at:

The new 2.5-km resolution data will replace the 5-km products
and reuse the existing 5-km WMO headers. Additional headers will
be allocated to accommodate the new probabilistic grids. A
listing of the WMO headers affected by this change notice is
provided at the URL below:

For questions regarding the implementation please contact:
James A. Nelson
WPC/College Park, Maryland

National Service Change Notices are online at: is the U.S. government's official web portal to all federal, state and local government web resources and services.