California and Nevada Drought is extreme to exceptional

Severe to Exceptional Drought conditions continue 94% of California in severe to exceptional (D2-D4) drought conditions (one year ago the coverage was 100%). Over Nevada the D2-D4 area covers 87% of the state (one year ago the coverage was also 87%). Drought Monitor May 19, 2015

It’s been dry for 3 years : the percent of average precipitation from late May shows much of the west below normal (100%). Much of California is below 70% of normal and much of Nevada is below 90% of normal.

The Northern Sierra Precipitation 8-station index is at 74% of normal.

How warm has it been? May 2014-May 2015 was the warmest period on record ( ) for maximum (left) and minimum (right) average statewide temperatures for extreme western states. Other states in the west were much above average.

May 1 st : California state conditions For 2003 (left) to 2015 (right) this graph shows the percent of average for snowpack (open bars), precipitation (hatched bars), runoff (black bars) and reservoir storage (line with triangles) shows the lowest snowpack (2% of average) and lowest reservoir storage (65% of normal) From California Department of Water Resources Bulletin 120 for May 2015

Sacramento River Basin: wet and dry periods Large (blue) and small (red) amounts of precipitation over the past century aggregated over periods of one month to 3 years (y-axis)

NOAA releases a service assessment on the California Drought The principal purpose of this report is for NOAA to identify resource management decisions that were affected by the current drought in California and to assess the use and effectiveness of forecasts, indices, monitoring data, and services that are available to decision makers and stakeholders Find a copy of this report at:

Sea Surface Temperatures have been above normal off the west coast and over the equatorial Pacific for the past week, for the past month, and for the past season

CPC/IRI Probabilistic ENSO Outlook Updated: 14 May 2015 The chance of El Niño is approximately 80-90% through 2015.

IRI/CPC Pacific Niño 3.4 SST Model Outlook Figure provided by the International Research Institute (IRI) for Climate and Society (updated 19 May 2015). Almost all of the models indicate Niño 3.4 SST anomalies will remain greater than or equal to +0.5C through the end of However, there is a large amount of spread in the potential strength of El Niño.

SST Outlook: NCEP CFS.v2 Forecast (PDF corrected) Issued: 26 May 2015 The CFS.v2 ensemble mean (black dashed line) predicts El Niño through DJF

U. S. Seasonal Outlooks PrecipitationTemperature June – August 2015 The seasonal outlooks combine the effects of long-term trends, soil moisture, and, when appropriate, ENSO.