CPC Extended Range Forecasts Ed O Lenic NOAA-NWS-Climate Prediction

CPC Extended Range Forecasts Ed O’Lenic NOAA-NWS-Climate Prediction Center Camp Springs, Maryland ed. olenic@noaa. gov 301 -763 -8000, ext 7528

Outline – over-view Outline - overview • Weather versus climate • Current status of CPC’s forecast system • Schematic of the forecast system/process • Outlook schedules/formats/tools/process • Verification • Threats, heat wave, wind chill products

WEATHER vs. CLIMATE • Wildly oscillating curve = daily “weather” • Smooth curve = 30 year mean (climatology) Subtracting the climatology and performing a 31 -day running mean reveals the low-frequency signal or short-term climate variations we are trying to predict.

CPC Forecast system schematic

Forecast Process Schematic Dynamical model forecasts/multimodel ensembles Recent observations Historical observations. . Verifications/Statistical tools Downscaling, Analogs, Composites WEB PAGES/AUTOMATED DATABASES Peer-reviews of the forecast tools and of the penultimate forecast via web/telephone conference with partners and through local discussions (map discussions, sanity check, conference calls, etc…) Forecaster-created or automated products Dissemination to public

Z 500 die off

Six-to-Ten Day and Week 2 Outlooks

6 -10 DAY/WEEK 2 OUTLOOK SCHEDULE/LEADS • Each day, CPC prepares and disseminates outlooks for 6 -10 days (lead time of 5 days) and week 2 (days 8 -14, lead time of 7 days). • Each of these outlooks is accompanied by forecast maps of – 1) 500 mb height and 500 mb height anomalies over the Northern Hemisphere, forecast maps of – 2) surface temperature and – 3) precipitation for the continental U. S. and Alaska and a single bulletin, FEUS 40, giving a prognostic discussion for both forecasts and a table of stateby-state forecasts for each forecast. • On Monday through Friday, including holidays, the outlooks are prepared by a forecaster who draws the maps, writes the bulletin and composes the table. • On Saturday and Sunday only automated versions of the maps and the tables are disseminated.

6 -10 day/week 2 Outlook Categories, Probabilities 6 -10 day/week 2 outlooks are prepared for 5 -day/7 -day average temperature and total accumulated precipitation category. Three categories are used (terciles). These are BELOW-, NEAR- and ABOVE-normal, for temperature, and BELOW-, NEAR- and ABOVE-median for precipitation. The contours on the maps depict the TOTAL probability of the occurrence of the indicated category. Contours of the climatological normals are also shown.

Recent Changes to Procedures • • • From 3 times/week to daily in October 2000 Automated weekend forecasts from October 2000 Percent probability format from October 2000 Alaska and week 2 added October 2000 Automated wind-chill product introduced Nov 2001 Bias-corrected precipitation forecast tool and other improvements added in the fall of 2001

6 -10 day/week 2 process schematic Multi-model ensemble R 9: 00 AM Weighted average of model 500 h. Pa height Downscale: get surface weather from 500 mb height via analogs, regression, neural network. R Forecaster formulates maps of predicted T, P, PMD bulletin Disseminate via web, AWIPS, FOS 3 -4 PM R = Forecaster reconciliation of tools required

Forecast Maps and Bulletins Each day, between 3 and 4 PM Eastern Time, CPC issues a set of 6 -10 day and week 2 outlooks. These are formulated by a forecaster (Monday through Friday) and are automated on weekends. There are two 500 mb height maps, two surface maps and a single bulletin. Sample 6 -10 day outlook 500 mb height and anomaly forecast map from CPC web page.

Sample 6 -10 day average T outlook

Sample 6 -10 day P outlook Sample 6 -10 day 5 -day total precipitation outlook from CPC web page.

6 -10 day/week 2 Forecast Tools Examples of the variety of tools used in preparing the 6 -10 Day and week 2 outlooks. These forecast tools consist of: 1. Statistical: Klein, Neural Network, analogs, teleconnections, calibrated MRF precipitation 2. Dynamical: hr. MRF, MRF ensembles, ECMWF, d. AVA, CDC calibrated MRF

A Simple Calibration Scheme 23 years of daily forecasts (1 forecast/day) out to week 2, October 1978 -present (MRF T 62) Climatology of model: mean, standard deviation, error variance Operations: Run a 15 -member ensemble in real-time using the same model as is used to create the archive. Ensemble mean for 8 -14 days Calculate anomalies using the 23 -year model climatology (bias corrected) Assume the mean week 2 spread is determined by the error variance of the 23 -years of forecasts.

Uncalibrated forecasts reliability

Calibrated forecasts reliability

ECMWF upper-air height forecasts, analog

MRF Ensemble upper-airheight forecasts, analog

Official 6 -10 day 500 h. Pa forecast

Teleconnections (TC) Definition: Composite of those maps, for a calendar month, with largest + (top 10%) or – (bottom 10%) 500 h. Pa height at a specified space point from 1950 -1999 (~150 maps). Forecasters compute TC on the major anomaly centers (base points) of 500 h. Pa forecast maps. If there is a strong relationship between the base point centered at the largest anomaly, and distant points, the TC map will display large correlation values at the base point and at the distant centers. If there is no strong historical relationship, only the correlations at the base point will be large. Weak TC indicate the pattern is probably transient and not as likely to be well predicted by the model as would a persistent (strong TC) pattern.

Teleconnection on 500 h. Pa weighted mean anomaly center at 140 W/53 N(-)

Composite of observed T, P anomalies associated with teleconnection on - 500 h. Pa anomaly at 53 N 140 W

T prediction analog maps

Week 2 forecast tools from CDC

MRF Precipitation Bias Correction: Week 2

Z 500 d+8 skill

Z 500 d+11 skill

T 850 d+8 skill

T 850 d+11 skill

Official 8 -14 day T, P forecast The final forecasts of temperature and precipitation. The forecasters reasoning is given in the bulletin (next slide).

6 -10 day Monthly Average Skill Scores

U. S. Hazards Assessment

Definitions of Threats Listed at left are the nominal definitions of threats. Because prior conditions play a role in the impact of anomalies on the level of threat, the definitions listed are only guidelines, to be used along with knowledge of prior conditions, by the forecaster in assigning threats. Research is required to objectively determine thresholds for threats at a large number of locations.

New medium range automated products CPC and MDL have collaborated to create new MOS-based products which are produced and disseminated automatically. Heat index outlooks for 6 -10 and 8 -14 days Wind-chill outlooks for 6 -10 days Average temperature outlooks for 6 -10 days

Excessive Heat Outlooks

Excessive Heat probabilities

Wind-chill Outlooks

Average T Outlook

The End