JJA Mean Precipitation

OBS NCEP

MM5 WRF

Regional simulations driven by NCEP/NCAR global reanalysis for 25 years at 50 km spatial resolution

JJA Precipitation Anomaly (1993 minus 1988)

OBS NCEP

MM5 WRF

DJF Mean Precipitation

OBS NCEP

MM5 WRF

Cold Season Variability

Columbia River Basin

0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

DJf

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

California

0

1

2

3

4

5

6

7

8

9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

DJF

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 9980 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

Great Basin

0

0.5

1

1.5

2

2.5

3

3.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

DJF

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

Ohio Basin

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

DJF

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

ACC ~ 0.90 ACC ~ 0.94

ACC ~ 0.92 ACC ~ 0.30

ACC ~ 0.60 in NCEP

WRF and MM5 have similar skill in capturing cold season variability

Warm Season Variability

Ohio Basin

0

1

2

3

4

5

6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

JJA

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

Columbia River Basin

0

0.5

1

1.5

2

2.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

JJA

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

California

0

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

JJA

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

Upper Mississippi Basin

0

1

2

3

4

5

6

7

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

JJA

Pre

cip

itat

ion

(m

m/d

ay)

OBS

MM5

WRF

ACC ~ 0.80 ACC ~ 0.60

ACC ~ 0.3 - 0.8ACC ~ 0.3 - 0.4

ACC ~ 0.60 in NCEPACC ~ 0.17 in NCEP

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

Larger differences between WRF and MM5 skill in capturing warm season variability; differences traced to new vs old KF scheme