Univ of AZ WRF Model Verification

Method• NCEP Stage IV data used for precipitation verification

– Stage IV is composite of rain fall observations and radar estimates– Data has a resolution of 4km– http://www.emc.ncep.noaa.gov/mmb/ylin/pcpanl/stage4/

• Nearest neighbor is used to move stage iv data to model data to observation site

• Verification was performed on 12 hour accumulations at various forecast hours– For the 24 hr model forecast, verified the amount of precipitation

accumulated for the 12 hr period ending at the time the 24 hour forecast is valid (i.e. for a 24 hr fcst from a 15 Nov 00Z model run, verify the precipitation that fell during the period 15 Nov 12Z – 16 Nov 00Z

• Statistics generated for several precipitation thresholds: >1mm, >6.25mm(.25in), >12.5mm(.5in),>25mm(1in)

Nov 25 12Z Model RunWRF 5.4 km

• On the following displays, the solid color is the model forecast• Dots and other symbols are the Stage IV precipitation observations

– The color and shape of observations symbols represent the amount of precipitation accumulated in a 12 hour period ending at the forecast valid time

• Statistics calculated for data displayed in the image

Model Run: 20081125 12ZForecast: 18hrAccumulation Period: 20081125 18Z –20081126 06Z

Model Run: 20081125 12ZForecast: 24hrAccumulation Period: 20081126 00Z –20081126 12Z

Model Run: 20081125 12ZForecast: 36hrAccumulation Period: 20081126 12Z –20081127 00Z

Model Run: 20081125 12ZForecast: 30hrAccumulation Period: 20081126 06Z –20081126 18Z

Model Run: 20081125 12ZForecast: 48hrAccumulation Period: 20081127 00Z –20081127 12Z

Model Run: 20081125 12ZForecast: 42hrAccumulation Period: 20081126 18Z –20081127 06Z

Nov 25 12Z Model RunWRF 1.8 km

Model Run: 20081125 12ZForecast: 18hrAccumulation Period: 20081125 18Z –20081126 06Z

Model Run: 20081125 12ZForecast: 24hrAccumulation Period: 20081126 00Z –20081126 12Z

Model Run: 20081125 12ZForecast: 30hrAccumulation Period: 20081125 06Z –20081126 18Z

Model Run: 20081125 12ZForecast: 36hrAccumulation Period: 20081126 12Z –20081127 00Z

Model Run: 20081125 12ZForecast: 42hrAccumulation Period: 20081126 18Z –20081127 06Z

Domain Verification

• Period of verification is from 15 Oct – 28 Nov 2008

• During this period there were two major precipitation events over the area of interest

• Not sure why the 30hr forecast shows higher skill compared to other forecasts– Probably due to the limited number of forecasts

with precipitation for period