Mean, Median, and Extreme Date of first 32F Temperature
Conterminous United States

Statistic: 30-year mean/median/extreme date of first 32F temperature in Autumn 
Time period: 1961-1990
Time interval: annual
Spatial format: grid
Data format: ARC/Info ASCII GRID

 Projection: Geographic
Spatial resolution: 1.25 arc-minutes (~2 km)
Spatial Extent: Conterminous United States
Units: Julian days
Date created: August 2000
Methods: Statistical derivation from mean minimum temperature, mapped with the PRISM modeling system, and Gaussian filter resolution enhancement. See FGDC-compliant metadata for details. 

Examples 
 
Mean date of first 32F temperature in Autumn
Features
  • Reviewed and approved by the US National Climatic Data Center 
  • Incorporates topographic effects on temperature 
  • Includes coastal and lake effects on temperature 
  • Accounts for temperature inversions on coasts and in inland valleys 
  • Uses upper-air temperature data to capture high-elevation patterns 
  • Consistent treatment and spatial quality control of station data 
  • Consistent coverage across all state boundaries 
  • "Universal" geographic (latitude/longitude) projection allows conversion to any other coordinate system 
  • Data format allows for easy import into ESRI's GIS products, as well as MAPINFO and Intergraph's GeoMedia 
Data used in analysis
  • 5,141 National Weather Service stations for date of last 32F in Spring 
  • 6,420 stations for minimum temperature
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