1. The North American Monsoon System: Recent Evolution and Current Status Update prepared by Climate Prediction Center / NCEP 27 August 2013

2. Outline Recent Evolution and Current Conditions Summary Climatology

3. Rainfall Patterns: Last 7 Days Within the NAM domain, slightly below-average rainfall over northwestern Mexico and near-average rainfall over southwestern U.S. have been observed during the past week.

4. Rainfall Patterns: Last 30 Days Rainfall accumulations over the past 30 days are below-average for northwestern Mexico and near-average for southwestern U.S.

5. Recent Evolution: Rainfall

6. NCEP/GFS Forecast Near-average rainfall over southwest U.S. during the next two weeks; However, the northwestern Mexico is expected to continue the drier-than-average condition during the next week.

7. Summary Within the NAM domain, slightly below-average rainfall over northwestern Mexico and near-average rainfall over southwestern U.S. have been observed during the past week. Rainfall accumulations over the past 30 days are below-average for northwestern Mexico and near- average for southwestern U.S. NCEP GFS forecasts indicate near-average rainfall over southwest U.S. during the next two weeks; However, the northwestern Mexico is expected to continue the drier-than-average condition during the next week.

8. Climatology MONSOON ONSET June 5 June 6 June 8June 7 June 14 June 17June 16 June 23 June 27June 25June 29 July 3July 6July 11 July 7July 8July 13 July 9July 13July 14 June 10June 11 June 22June 21 Higgins, R. W., Y. Chen and A. V. Douglas, 1999: Interannual Variability of the North American Warm Season Precipitation Regime. J. Clim, 17, 653-680

9. Precipitation Climatology