1 / 12

NCEP FY04 GPRA Performance

NCEP FY04 GPRA Performance. “Where America’s Climate, Weather and Ocean Services Begin”. Dr. Louis W. Uccellini Director, National Centers for Environmental Prediction February 16, 2005. GPRA Scores. NCEP responsible for 3 NWS GPRA Performance Measures. Definitions: Day 1 Threat Score.

sheera
Download Presentation

NCEP FY04 GPRA Performance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NCEP FY04 GPRAPerformance “Where America’s Climate, Weather and Ocean Services Begin” Dr. Louis W. Uccellini Director, National Centers for Environmental Prediction February 16, 2005

  2. GPRA Scores NCEP responsible for 3 NWS GPRA Performance Measures

  3. Definitions: Day 1 Threat Score • HPC forecasts of U.S. observed precipitation of 1inch or greater in the 24-hour period 6 to 30 hours into the future. • Takes into account two types of precipitation forecasting errors: the errors associated with not forecasting rainfall where it does occur and those associated with forecasting rainfall where it does not occur. • Equals the number of correct forecasts divided by the total of number of correct forecasts plus the number of wrong forecasts. • The scores vary seasonally during the year with higher values generally occurring during the fall and winter when weather systems are larger and more well-defined and lower values occurring in the spring and summer when precipitation is scattered and on a smaller scale.

  4. Definitions: US Seasonal Temperature Skill • For each three month period, seasonal outlooks for U.S. surface temperature are produced by CPC and reported as either warmer than normal, cooler than normal or, where no definite seasonal guidance can be provided, equal chance. • These forecasts are verified using a 48 month running mean of Heidke Skill scores computed for seasonal outlooks for each 3-month seasonal mean (e.g., January-February-March mean; February-March-April mean; March-April-May mean; and so on). It is calculated as follows: Heidke skill score: S = ((c-e)/(t-e)) x 100, where c = number of stations where forecast was correct and e = number of stations expected to be correct by chance alone and t = total number of stations where the forecast was made. • The Skill Score varies from -50 to +100, with +100 representing perfect forecast skill. Because of natural (and unpredictable) variability of climate regimes, the skill score can fluctuate considerably from one season to another. To reduce the natural variability, this measure is constructed after averaging Heidke skill scores for 48 consecutive individual seasons. • Since its inception, the GPRA measure has varied between a high value of 27 and a low value of 15. Much of this variability is due to the predictability of different climate regimes.

  5. TPC Atlantic 72 hr Track Forecast Errors

  6. Impact of NCEP Models on HPC Precipitation Forecasts Correlations Of HPC with: Eta: 0.99 GFS: 0.74 NGM: 0.85 1 day of QPF skill gained every 25 years

  7. Seasonal Temperature Skill Score Performance • FY02-04 skill scores have not met the GPRA goal • Initially established in the mid to late 1990s, when seasonal temperature skill scores were relative high due to strong El Nino and La Nina events.  • Meeting among CPC, CDC, OGP, COLA, and IRI held on Jan 26 to discuss the GPRA measure of Heidke seasonal temperature skill score. • Agreed this measure is too complicated and too low in interest & impact to merit further pursuit. • Recommended replacing this measure as soon as possible (FY07 ??) with a new operational GPRA climate measure, measuring skill by means of an index predicting high impact seasonal and sub-seasonal climate events, and climate driven events.

  8. Appendix

  9. 2004 - 6 months above 99.9%

  10. High impact seasonal and sub-seasonal climate or climate driven events, which might have been predicted during Dec 04-Mar 05 (for JFM – 2nd quarter of FY05) as part of a new GPRA measure: • The SE US cooler than normal for DJF as measured by temperature anomalies in key states (of interest to the energy community) • Above normal Heating Degree Days expected during DJF in the SE US as measured in key states (of interest to the energy community) • Drought in the SW US improves during DJF as measured by the March 2005 US Drought Monitor in selected states (hydro/water interests) • Drought continues or worsens in the hardest hit areas of the NW US drought as measured by the March 2005 US Drought Monitor (hydro/water interests) • Weak El Nino ENSO conditions are forecast to remain during DJF as measured by the NOAA index in Niño region 3.4 (range expected to be +0.5 to +0.8) • MJO instability will phase with long wave trough to bring “pineapple express” extreme precipitation event to CA, NV in early Jan 2005 (issued in late Dec 2004)

More Related