# Presentation: 649980

## Automated public forecast production from the Canadian ensemble prediction system (CEPS)P. Bourgouin, R. Verret, B. Archambault, S. Beauregard, J.Hodgson, B. Denis, Y. Zhu, C. Landry, N. Gagnon                                   Meteorological Service of Canada (MSC)

**Automated public forecast production from the ****Canadian ensemble prediction system (CEPS)**_**P. Bourgouin**_**, R. Verret, B. Archambault, S. Beauregard, J.Hodgson, ****B. Denis, Y. Zhu, C. Landry, N. Gagnon****                                   ****Meteorological Service of Canada**** (MSC)**

## Background

- Extended public forecasts actually cover days 3 to 5. MSC wants to improve the service provided to Canadians by extending the range to day 7.
**Constraints**
- - Should become operational as soons as possible.
-  → Smooth integration into the actual MSC operational system
- 	→ use of a deterministic terminology
- 	→ automated forecasts
- - A probabilistic version will be tested in the future.

## Canadian EPS (CEPS)

- Members:
- 20+1 members:
- GEM 0.9° L28 (~100 km resolution).
- 16-day integration.
- Twice a day (00 and 12 UTC).
- Simulation of initial condition uncertainties:
- Perturbed ensemble Kalman filter data assimilation.
- Simulation of model uncertainties:
- A multi-model approach, each member having its own physics parameterization.
- Stochastic perturbations added to tendencies in the parameterized physical processes.

## Forecasts using a Scenario Approach

- Important forecast parameters (POP, temperature, cloud cover) are produced by a Perfect Prog (PP) technique on each members.
- Members are separated into two groups based on their POP being above or below a threshold.
- If a group has twice as many members as the other one, forecast parameters will be the average values associated with members from that larger group.
- If a group does not have twice as many members, parameters will be simply averaged over all members.

**Forecasts using a Scenario Approach**

## Verifications

- _2 periods – 120 stations across Canada_
- 	- winter-spring: 		22 february to 22 april 2008
- 	- summer:		01 may to 29 july 2008
- _The different systems_:
_**EPS-based**_
-     - E-30 Scenario with a 30% threshold 		D1-10, 	PP
-     - E-50 Scénario with a 50% threshold 		D1-10, 	PP
-     - E-ALL all members,				D1-10, 	PP
_**Deterministic**_
-     - GLB-OFF 					D1-5,    PP (TT UMOS)
-     - GLB-240 					D1-10, 	PP
_**Climatology**_
-     - CLIM

**Verifications**

## Temperature (1)

**Temperature (1)**

## Temperature (2)

**Temperature (2)**

## Summary for temperature

-  EPS-based systems:
-  give useful information for D6-7,
-  improve upon deterministic forecasts from D6 in
-   winter and from D4 in summer,
-  no significant difference between different EPS
-   systems.

**Summary for temperature**

## Probability of precipitation – Brier skill score

**Probability of precipitation – Brier skill score**

## Probability of precipitation - ROC

**Probability of precipitation - ROC**

## Probability of precipitation 

**Conditional verification on an active period**

- A precipitation event is detected if an accumulation of 0.2mm or
- more is reported (diagnosed) at the station between 06AM and
- 06PM local time.
- The threshold of 0.2mm is very low for long-range forecasts. At these
- ranges, emphasis should be put on more significant events.
- A conditional verification was performed on a selection of dates where
- significant precipitation amounts were reported at D6. The conditional
- verification includes 11 different dates during the 22 February-22 April
- period for 13 stations. A date was included when amounts of the
- order of 5mm were reported at several stations over eastern Canada.

## Probability of precipitation – Active period

## Flip-Flop Index (FFI)

-  A threshold is used to discriminate between ‘dry’ and ‘wet’ forecasts. A threshold of 30% is used since precipitation is not mentioned for POP lower than this value.
-  A flip-flop is detected if successive forecasts crosses the threshold twice. 		20% - 40% - 10% → flip-flop
- 		20% - 40% - 30% → no flip-flop
-  The flip-flop frequency is:
-    	F = (number of flip-flop / total number of case) * 100%
-  The flip-flop amplitude is the mean of the differences between the 3 consecutive values:
- 	20% - 40% - 10% → amplitude = 25

**Flip-Flop Index (FFI)**

## FLIP-FLOP Index

**FLIP-FLOP Index**

## Summary for Probability of Precipitation (POP)

- → Limited ability from all systems to forecast POP for a 0.2mm threshold after D5.
- →  EPS-based forecasts are more reliable and less sharp.
- →  However, EPS and deterministic systems show more skill than climatology for significant events.

**Summary for Probability of Precipitation (POP)**

## Cloud cover

**Cloud cover**

## Cloud cover

-  EPS systems produce the best forecasts at D6-7.
-  EPS systems under-forecast the cloudy category (7-10).
-  Little difference between EPS versions.

**Cloud cover**

## Verification summary at D6-7

- - Useful information.
- - EPS versions perform better than deterministic one.
- - Little difference between EPS versions.
**POP**
- - Little information after D5 with a threshold at 0.2mm but
-  better results when significant amounts were observed.
- - EPS versions perform better than the deterministic one.
- - E-ALL performs a little better than other EPS versions.
- - EPS versions less subject to flip-flop.

**Verification summary at D6-7**

## Conclusion

-  EPS-based systems produce useful information
-   for public forecasts at D6-7.
-  The scenario approach does not perform better
-   than the simple ‘all-members’ approach. This could
-   be related to the method to generate POPs
-  (threshold, PP, time period).
-  The EPS- ‘all-members’ version will be
-   implemented this fall.

## Future improvements

-  Use of a sampling technique to produce POP and
-   cloud cover.
-  Use of an higher accumulation threshold for POP at
-    long range.
-  Produce more verifications for higher precipitation
-   amounts.
-  Use of NCEP members (NAEFS).
-  Develop a probabilistic terminology.

**Future improvements**