Lesley L. Smith – Extreme California Precip

All plots preliminary.        


Extreme Precipitation in California

(CA DWR activity 6 subproject 2)

Re. OLR-based MJO index "mjoindices" from https://github.com/cghoffmann/mjoindices:

Former version of this page here

All nClimDiv daily precipitation data from A.Hoell; all ERA5 OLR daily data from M.Gehne.

Sample ERA-5 MJO (OMI) Plot November 2022 thru March 2023
where red star indicates a maximum California precip event: Jan 16, 2023

 

Re. OMI Phase frequency and extreme CA precip with MJO leads and precip lags:
7-day, 14-day accumulations:
Northern_Central California 33rd percentile (MJOs radius>1)
     
where the 7-day case included 414 nonoverlapping Nov-Mar precip-less-than-33-percentile points, 14-day case included 243 nonoverlapping Nov-Mar precip-less-than-33-percentile points;
with the Strong MJO condition reducing this to 27,39,38,22,22,37,27,40 7-day lag-0 Phase 1-8 points respectively
and 11,18,26,18,17,18,15,24 14-day lag-0 Phase 1-8 points respectively.

 
Northern_Central California 67th percentile (MJOs radius>1)
     
where the 7-day case included 292 nonoverlapping Nov-Mar precip exceedances, 14-day case included 166 nonoverlapping Nov-Mar precip exceedances,
with the Strong MJO condition reducing this to 12,19,31,29,12,31,19,24 7-day lag-0 Phase 1-8 points respectively
and 2,15,9,12,14,14,17,12 for 14-day lag-0 Phase 1-8 points respectively.

 
Southern California 33rd percentile (MJOs radius>1)
     
where the 7-day case included 418 nonoverlapping Nov-Mar precip-less-than-33-percentile points, 14-day case included 256 nonoverlapping Nov-Mar precip-less-than-33-percentile points,
with the Strong MJO condition reducing this to 28,31,38,22,21,33,34,35 7-day lag-0 Phase 1-8 points respectively
and 24,20,21,13,22,20,21,23 for 14-day lag-0 Phase 1-8 points respectively.

 
Southern California 67th percentile (MJOs radius>1)
     
where the 7-day case included 276 nonoverlapping Nov-Mar precip exceedances, 14-day case included 153 nonoverlapping Nov-Mar precip exceedances,
with the Strong MJO condition reducing this to 13,18,24,14,21,18,30,21 7-day lag-0 Phase 1-8 points respectively
and 8,7,18,9,10,12,10,15 for 14-day lag-0 Phase 1-8 points respectively.

 

Re. bandpass-filtered OLR anomaly and extreme CA precip with OLR leads and precip lags:
7-day, 14-day accumulations:
Northern_Central California 33rd percentile
     
Northern_Central California 67th percentile
     
Southern California 33rd percentile
     
Southern California 67th percentile
     

Re. 250hPa geopotential height anomaly and extreme CA precip with geopotential_height leads and precip lags:
7-day, 14-day accumulations:
Northern_Central California 33rd percentile
     
Northern_Central California 67th percentile
     
Southern California 33rd percentile
     
Southern California 67th percentile
     

Re. OMI Phase frequency and extreme CA precip with MJO leads, El Nino and precip lags:
7-day, 14-day accumulations:

Northern_Central California 33rd percentile (MJOs radius>1)
     
Corresponding lag-0 dates and OMI MJO phase data: NorthCentral El Nino 7-day   NorthCentral El Nino 14-day

Northern_Central California 67th percentile
     
Corresponding lag-0 dates and OMI MJO phase data: NorthCentral El Nino 7-day   NorthCentral El Nino 14-day

Southern California 33rd percentile (MJOs radius>1)
     
Corresponding lag-0 dates and OMI MJO phase data: South El Nino 7-day   South El Nino 14-day

Southern California 67th percentile
     
Corresponding lag-0 dates and OMI MJO phase data: South El Nino 7-day   South El Nino 14-day

Re. OMI Phase frequency and extreme CA precip with MJO leads, La Nina and precip lags:
7-day, 14-day accumulations:
Northern_Central California 33rd percentile (MJOs radius>1)
     
Corresponding lag-0 dates and OMI MJO phase data: NorthCentral La Nina 7-day   NorthCentral La Nina 14-day

Northern_Central California 67th percentile
     
Corresponding lag-0 dates and OMI MJO phase data: NorthCentral La Nina 7-day   NorthCentral La Nina 14-day

Southern California 33rd percentile (MJOs radius>1)
     
Corresponding lag-0 dates and OMI MJO phase data: South La Nina 7-day   South La Nina 14-day

Southern California 67th percentile
     
Corresponding lag-0 dates and OMI MJO phase data: South La Nina 7-day   South La Nina 14-day

Re. OMI Phase frequency and extreme CA precip with MJO leads, ENSO Neutral and precip lags:
7-day, 14-day accumulations:
Northern_Central California 33rd percentile (MJOs radius>1)
     
Northern_Central California 67th percentile
     
Southern California 33rd percentile (MJOs radius>1)
     
Southern California 67th percentile