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452 Precipitation

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Bias scores for the (a) 1.33- and (b) 4-km model simulations for 1400 UTC 13 Dec ... Hurricane Isabel Reflectivity at Landfall. Radar Composite. 18 Sep 2003 1700 Z ... – PowerPoint PPT presentation

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Title: 452 Precipitation


1
452 Precipitation
2
Northwest Weather Terrain Ocean Influence
3
Annual Precipitation
4
SW Olympic Slopes-Hoh Rain Forest 150-170
inches yr-1
5
Sequim roughly 15 inches per year. .
6
Puget Sound Convergence Zone
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Bias scores for the (a) 1.33- and (b) 4-km model
simulations for 1400 UTC 13 Dec 2001 through 0800
UTC 14 Dec 2001.
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Human Versus Objective Skill for Precipitation
Forecasts NWS Offices Around the US
17
Prob. Of Precip. Cool Season(0000/1200 UTC
Cycles Combined)
18
Brier Scores for Precipitation for all stations
for the entire study period.
19
Brier Score for all stations, 1 August 2003 1
August 2004. 3-day smoothing is performed on the
data.
20
Precipitation
Brier Score for all stations, 1 August 2003 1
August 2004, sorted by geographic region.
21
Reliability diagrams for period 1 (a), period 2
(b), period 3 (c) and period 4 (d).
22
Rain Psychology
More than a day out.Human Forecasters Tend to
Overpredict 10-30 --exaggerating the threat of
rain when it is not likely. Its probably not
going to rainbut I will throw in 10-30 anyway
to cover myself And underpredict rain when it
is fairly definite. Well it looks like it will
rainbut I am unsureso I will knock down the
probabilities to 60-80 to cover myself
23
Humans Help with Heavier Precipitation
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Convective Precipitation
  • Need at least 2-4 km resolution to get most
    convection even half right.
  • If grid spacing is more coarse must have cumulus
    parameterization--Kain-Fritsch is used for MM5.
  • Convection is least skillful precipitation in
    virtually all models.
  • High resolution models can potentially give a
    heads on type of precipitation a day ahead
    (squall line, supercell, etc.)

31
Real-time WRF 4 km BAMEX Forecast
Valid 6/10/03 12Z
Composite NEXRAD Radar
4 km BAMEX forecast 36 h Reflectivity
4 km BAMEX forecast 12 h Reflectivity
32
Real-time 12 h WRF Reflectivity Forecast
Valid 6/10/03 12Z
Composite NEXRAD Radar
4 km BAMEX forecast
10 km BAMEX forecast
22 km CONUS forecast
33
Hurricane Isabel Reflectivity at Landfall
18 Sep 2003 1700 Z
41 h forecast from 4 km WRF
Radar Composite
34
The End
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