NDFDClimate: A Computer Application for the National Digital Forecast Database

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NDFDClimate A Computer Application for the
National Digital Forecast Database

• Christopher Mello
• WFO Cleveland

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NDFDClimate

• NDFDClimate is a computer application that
  creates images of forecast and climatological
  parameters for the U.S. from two different
  digital data sets.
• NDFD (National Digital Forecast Database)
  weather forecast grids produced by the NWS and
  PRISM data (Parameter-elevation Regressions on
  Independent Slopes Model), an expert system that
  uses point climatological temperature data and a
  digital elevation model (DEM) to generate gridded
  estimates of climate parameters.

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PRISM DataParameter-elevation Regressions on
Independent Slopes Model

• PRISM system determines climate elements (temp,
  or rainfall) values at grid cells by calculating
  linear regression relationships between the
  climate element and elevation
• Each grid cell estimate is determined from a
  separate multiple linear regression using data
  from nearby climate stations
• Each station in the regression is weighted based
  on five factors distance, elevation, vertical
  layer (helps identify temp inversions in high
  mountain valleys), topographic orientation,
  coastal proximity

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PRISM DataParameter-elevation Regressions on
Independent Slopes Model

• Temperature data from PRISM consist of daily
  maximum and minimum temp fields for 1971 2000
  at 5 km resolution
• PRISM derived daily normal max min temperature
  grids were compared to official data from the
  NCDC for CLE, TOL, ERI, YNG, SYR, RIC, GSP
• Each site had a MAE near 0.25 F for both max and
  min temp with the highest daily error lt 1 F

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NDFD DataNational Digital Forecast Database

• NDFD consists of digital forecast data that are
  produced by the WFOs across the U.S. and merged
  into a single image or file for each parameter
  and projection.
• Forecast grids are produced for Days 1-7 with 5
  km resolution
• NDFD grids include max and min temp, POP, temp,
  water equivalent, snow amount

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NDFDClimate

• NDFDClimate uses the GRADS software to create
  images that utilize information from both the
  NDFD and PRISM data
• GRADS has the ability to add, subtract, or
  manipulate fields using many formulas. Users can
  specify the domain and contour interval of images.

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NDFDClimate

• NDFDClimate produces temperature anomaly grids by
  subtracting NDFD grids from PRISM derived daily
  climate grids
• NDFDClimate combines some NDFD fields to generate
  5 day totals of heating and cooling degree days
  and 60 hour QPF

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NDFD Low Temp Fcst
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Normal Low Temp 0909
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Min Temp Anomaly 0909
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Max Temp Anomaly
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NDFD 5day Total CDD F
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NDFDClimate Uses

• Processes NDFD data for users with 5 day HDD
  CDD totals temp changes
• Educate users on current temperatures anomalies
  where point data may be inadequate

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NDFDClimate

• References
• Berman, F., A. Chien, K. Cooper, J. Dogarra, I.
  Foster, D. Gannon, L. Johnson, K. Kennedy, C.
  Kesselman, J. Mellor-Crummey, D. Reed, L.
  Torczon, and R. Wolski., 2002. The GRADS Project
  Software Support for High-Level Grid Application
  Development. International Journal of High
  Performance Computing Applications, 15 327-344.
• Daly, C., R.P. Neilson, and D. L. Phillips,
  1994. A Statistical-Topographic Model for
  Mapping Climatological Precipitation over
  Mountainous Terrain. J. Appl. Meteor., 33,
  140-158