Objective Verification of CPC Outlooks

Michael Halpert

Climate Prediction Center

Outline

• Motivation

• Data

• Procedure

• Results

• Future Plans

Verification at CPC

Historically, CPC has verified ERF and LRF at first order stations

Forecasts made at 77 (out of 117) stations, 45 correct.Heidke Skill Score = 37.7%

Monitoring Data Sets

Temperature• ~5000 stations/day: RFC,

HADS, CADB• 0.5 x 0.5 degree resolution• 20°- 60°N, 140° - 60°W,

Conus only• Mid – Midnight window• Daily Max + Min/2• SD Quality Control check Temperature Station Locations

Monitoring Temperature

90 Day Mean/Anomaly

Precipitation Station Locations

Monitoring Data Sets

Precipitation• ~8000 stations/day: RFC,

HADS, CADB, SNOTEL, Mexican data

• 0.25 x 0.25 deg resolution• 10°- 60°N, 140° - 60°W,

Conus/Mexico• 12Z – 12Z window• QC: SD, buddy, Duplicate,

Nexrad checks

Monitoring Precipitation

2° x 2° Grid

20° - 56°N, 130° - 60°W, 232 valid points

Temperature Analysis

Procedure

Calculate means and tercile limits for all 232 grid boxes based on 1971-2000 base period

Tercile limits calculated as 0.43 SD for temperature; 33rd and 67th percentile (based on gamma) for precipitation

January – March Temperature Difference (Upper – Lower)

Procedure

• Characterize seasonal mean temperature and total precipitation as above, near, or below average.

Procedure

• Compare verification field to forecast

DJF Verification Grid DJF Forecast Grid

Seasonal OutlookDec 2005 – Feb 2006

Seasonal OutlookDec 2005 – Feb 2006

Heidke = 77, Coverage = 73%

Heidke = 82, Coverage = 64%

All Non-EC % Cov 37.6 71.0 53.0

April – June 2006 Temperature

All Non-EC % Cov 27.6 48.1 57.3

April – June 2006 Temperature

Temperature Skill ScoresGridded vs. Stations ( non-EC)

Gridded Score – 23.7 Station Score – 24.2

All Non-EC % Cov 2.6 5.9 43.6

April – June 2006 Precipitation

All Non-EC % Cov 14.9 39.7 37.5

April – June 2006 Precipitation

June 2006 TOfficial, Update, Observations OBS

UPD0.5 Lead

Off. Up. ChangeAll Stations 18.4 33.3 +14.9 Non-EC: 56.6 65.0 +8.4 % Cov: 32.5 51.3 +18.8

Off. Up. ChangeAll Stations 18.8 25.4 +6.6 Non-EC: 48.3 43.1 -5.2% Cov: 38.8 59.1 +20.3

June 2006 TOfficial, Update, Observations

OBS

UPD

0.5 Lead

Gridded verification makes tool verification simple

JJA 2006 Temperature

JJA 2006 Temperature

Official – 60

Consolidation – 58.2

January – March 1998 Temperature

Official – 37.3

Consolidation – 51.5

Temperature Heidke Skill ScoresOfficial vs. Consolidation (non-EC)

Official – 23.7

Consolidation – 27.6

Temperature Heidke Skill ScoresOfficial vs. Consolidation (all)

Official – 11.4

Consolidation – 18.4

Precipitation Heidke Skill ScoresOfficial vs. Consolidation (non-EC)

Official – 5.3

Consolidation – 12.4

Precipitation Heidke Skill ScoresOfficial vs. Consolidation (all)

Official – 1.4

Consolidation – 3.1

Future Plans

Seasonal/monthly

• Verification of tools

• Ranked Probability Skill Score

• Conversion of tools to 2x2 grid

Future Plans

Extended Range

• Verification of forecasts

• Development of 5 and 7 day data sets

• Precipitation Complications

• Verification of tools

• RPSS

• Development of tercile limits