Science and Technology Seminar

Confidence Interval Forecasts for NCEP/HPC QPF

Using Short Range Ensemble Forecasts

Jung-Sun Im

Hydrometeorological Prediction Center

National Centers for Environmental Prediction

(Current affiliation: Meteorological Development Laboratory)

The Hydrometeorological Prediction Center (HPC) at the National Centers for Environmental Prediction (NCEP) has produced a suite of deterministic quantitative precipitation forecasts (QPFs) for over 40 years. While the operational forecasts have proven to be useful in their present form, they offer no information concerning the uncertainties of individual forecasts. Many users (including RFCs) have expressed a need for an objective way of assessing the likely success of a particular forecast. To accommodate their needs, HPC developed a methodology to quantify the uncertainty in manually produced 6-h HPC QPF using NCEP short-range ensemble forecasts (SREFs). The basic concept of this approach is the same as the traditional spread-error skill. However, the performance of the previous work was limited to providing only deterministic outputs of the error estimates. Our research advances upon previous work by applying confidence interval (CI) statistics, which makes it possible to produce probabilistic error forecasts as well as deterministic error forecasts. Details of this CI methodology and the usefulness of the CI forecasts will be presented in this seminar.

Wed., Feb. 21, 2007

2:00-3:00 P.M.

SSMC#2, Room 10246

NOAA/NCEP/HPC QPF CI Forecasts

HPC QPF

HPC QPF_95% CI forecast

AE forecast

AE_95% CI forecast

(Contact: Bob Glahn at (310) 713-1768)