Latest results in the precipitation verification over Northern Italy

1. Latest results in the precipitation verification over Northern Italy Elena Oberto, Marco Turco, Paolo Bertolotto (*) ARPA Piemonte, Torino, Italy

2. Comparative precipitation verification • • LM-DWD, aLMo, LAMI over Northern Italy • LAMI vs. LAMI prog prec over Piedmont Objectives • Verification over NI: • Seasonal daily cycle and seasonal statistical indices over 47 basins: 00/12 UTC run, forecast time: +24, +48, 6h diurnal cycle • Seasonal statistical indices over mountain/plain basins • Seasonal statistical indices over western/eastern basins • LAMI study: • LAMI vs. LAMI with prog. Prec verification: performance comparison over Piedmont basins from August 2004 to July 2005 • Seasonal statistical indices and cumulated precipitation maps • Application to a foehn case study.

3. Piedmont: percentage valid data (August 2004-July 2005) Eastern Italian basins Mountain Italian basins Plain Italian basins Western Italian basins

4. 5 mm Seasonal trend over NI: run00

5. 10 mm Seasonal trend over Northern Italy- run00

6. 5 mm Seasonal trend over NI: run12

7. 10 mm

8. 10 mm Seasonal trend over Northern Italy: different performance over plain and mountainous areas

9. 10 mm Seasonal trend over Northern Italy: different performance over western and eastern areas

10. Seasonal daily cycle over NI

11. General worsening during last seasons, exp. DJF’05: • there is an increasing in QPF (due to the introduction of prog. cloud ice scheme?), BUT  • DJF ’04 ~ 400 events > 10mm/24h on the average • DJF ’05 ~ 150 events > 10mm/24h on the average 110 on the East, 40 on the West • 1) How many does an halved statistics affect the results interpretation? • 2) How much is more difficult to estimate quantitatively the precipitation • during a particularly dry winter with respect to a “normal” winter? • The role of soil moisture analisys during summer seasons seems to be decisive in term of QPF (better BIAS index for LM-DWD in JJA) but not in term of capability to localize and predict accurately the precipitation pattern (ETS very low) • Big differences in term of BIAS between mountainous and plain areas: we obtain a greater overestimation on the mountain, except for LAMI in DJF’05: only LAMI runs without prog. prec.: to investigate the behaviour of prognostic precipitation during very dry season. • Different trend on the West and East areas: • aLMo general increasing in QPF, but much greater overestimation on Western areas • LK-DWD general increasing in QPF during last seasons, slightly greater overestimation on Western areas • LAMI behaviour similar to the other version, but not for DJF’05: big overestimation on the East where we have the greater majority of precipitation cases. Remarks

12. LAMI study • “PROGNOSTIC PRECIPITATION” version (lam00) vs. STANDARD (nud00) • Domain study: Piedmont basins (with Ticino raingauges) • Period study: August 2004-July 2005

13. Aug’04/Jul’05 BIAS and ETS: Forecast time D+2 The error bars indicates 2.5th and 97.5th percentiles of resampled distribution, applied to the "reference" model. Lam00  prog prec version Nud00  standard version

14. Aug’04/Jul’05 HRR and FAR: Forecast time D+2 Lam00  prog prec version Nud00  standard version

15. SON ‘04 BIAS and ETS: Forecast time D+2 Lam00  prog prec version Nud00  standard version

16. SON ‘04 HRR and FAR: Forecast time D+2 Lam00  prog prec version Nud00  standard version

17. November 2004 LAMI prognostic rain scheme observed LAMI “standard”

18. DJF ‘05 BIAS and ETS: Forecast time D+2 Lam00  prog prec version Nud00  standard version

19. DJF ‘05 HRR and FAR: Forecast time D+2 Lam00  prog prec version Nud00  standard version

20. Case study during a strong foehn event: 21-22 Jan’05 LAMI prognostic rain scheme Observed LAMI “standard”

21. MAM ‘05 BIAS and ETS: Forecast time D+2 Lam00  prog prec version Nud00  standard version

22. MAM ‘05 HRR and FAR: Forecast time D+2 Lam00  prog prec version Nud00  standard version

23. Seasonal comparison LAMI vs. LAMI prog Scale (mm)

24. Remarks • Aug’04-Jul’05  globally for high thresholds the BIAS is significantly reduced • Seasonal trend: the BIAS reduction is noticeable during wet season and for moderate/strong precipitation • The prognostic scheme seems to not solve completely the underestimation downwind but it reduces the overestimation upwind • DJF ’05  slightly worsening of LAMI prog., particularly over north-western alpine chain, that represents in this case the “downwind side” (north-western flux as prevailing synoptic situation)!