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Service Change Notice 13-55: Amended

National Weather Service Headquarters Washington DC

345 PM EDT Tue Sep 22 2013


TO:††††† Subscribers:

†††††††† -Family of Services

†††††††† -NOAA Weather Wire Service

†††††††† -Emergency Managers Weather Information Network

†††††††† -NOAAPORT

†††††††† Other NWS Partners and NWS employees


FROM:††† Kevin McCarthy

†††††††† Acting Director, Weather Prediction Center


SUBJECT: Amended: Application of Downscaling to WPC 5 km

††††††† Deterministic Quantitative Precipitation Forecasts

†††††††† Effective October 23, 2013


Amended to change effective date to October 23, 2013, due to significant

computer challenges


Effective October 23, 2013, at 1800 UTC, the National Centers

for Environmental Predictionís (NCEP) Weather Prediction Center

(WPC) will implement downscaling to 5 km resolution on all

deterministic quantitative precipitation forecasts. The change

is based on numerous requests and as part of continual product

improvement. The downscaling uses monthly PRISM data. Enhanced

product detail is most evident during the cool season in the

western United States, with lessor effects in the East.


No changes will be made to WMO headers. Grid file sizes will

remain comparable to current sizes.


WPC has developed graphical and gridded examples of 6-hour,

24-hour, and 168-hour deterministic downscaled QPF available at:



The Hurricane Sandy examples (sandy_) demonstrate results for a

heavy precipitation event in the eastern continental United

States. The U.S. western examples (westus_) show results for a

period of heavy precipitation at the end of November 2012 into

early December 2012.


For more information, please contact:


David Novak


College Park, MD 20740




National Service Change Notices are online at: