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Meteorological Development Laboratory

December 2007 Gridded MOS Changes

On December 18, 2007, we will be making modifications to the GFS-based gridded MOS guidance for the CONUS. Based on feedback we have received from users of the gridded MOS, we will:

1) modify the mask that designates whether a gridpoint is land or water (land/water mask)
used in the analysis process
2) modify the QPF analysis scheme, and
3) remove stations from the analysis

More details are provided below.

Change 1: Modifications to Land/Water Mask

Presentation - "Creation of Gridded MOS Land Water Mask"
Summary of Land/Water Mask creation
Images for Comparison

Land/Water Mask

Land/Water Mask

Difference between
Land/Water Masks

Max Temperature
w/Operational Mask

Max Temperature
w/Proposed Mask

Min Temperature
w/Operational Mask

Min Temperature
w/Proposed Mask

2-m Temperature
w/Operational Mask

2-m Temperature
w/Proposed Mask

Change 2: Change to Precipitation Amount analysis scheme

The analysis was modified slightly because it was felt our expected value approach was too conservative. This new method results in higher precipitation amounts.

Current Precipitation AmountPrecipitation Amount with new scheme

Change 3: Removal of stations from analysis

The following list of stations will be removed from the analysis for the given elements based on user feedback indicating these stations were causing errors in the analysis.

ElementStations Removed
Max/Min TemperatureKHZY -- Ashtabula, OH
171381/CHAM1 -- Chamberlain Bridge, ME -- cooperative observer site
Dew point TemperatureKTZR -- Columbus/Bolton Field, OH
KIDI -- Stewart Field, PA
All elementsQOSA3 -- Piney Hill, AZ - mesonet site
NS006 -- O W Saddle, AZ - mesonet site

Return to Gridded MOS Page
Send questions and comments to:

National Weather Service
Office Of Science and Technology
Meteorological Development Laboratory
Statistical Modeling Branch
1325 East West Highway
Silver Spring, MD 20910
Page last modified: 9 Nov 2007
Page Author: MOS Web Team
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