# Presentation: 424699

## Current ENSO Status and its Downscaled Effects on Winter Weather Across the Lower Missouri River Valley 

**Mark O’Malley**
**WFO Pleasant Hill**
**Kansas City Chapter of the AMS**
**   ****December 4, 2006**

**Ni****ño Indices: Recent Evolution**

**The latest weekly SST anomalies are positive (between +0.8 ****o****C and +1.2 ****o****C) in all of the Niño regions****. **

## 17 September-14 October 2006

**Average SST Departures in the Tropical Pacific**

## NOAA Operational Definitions for El Niño and La Niña

**NOAA Operational Definitions for El Niño and La Niña**

_**El Niño:**_** characterized by a *****positive*****  ONI greater than or equal to +0.5 °C.**
_**La Niña:**_** characterized by a *****negative***** ONI less than or equal to ****-****0.5 °C.**
**To be classified as a full-fledged El ****Ni****ño or La ****Ni****ña episode these thresholds must be exceeded for a period of at least 5 consecutive months.**

## Recent Evolution of Equatorial Pacific SST Departures

**Time**

**During September 2005- January 2006 SST anomalies decreased and below-average temperatures developed throughout most of the central and eastern equatorial Pacific. **
**In February 2006 positive SST anomalies developed in the extreme eastern equatorial Pacific, similar to what occurred during the La Niña** **years** **1999, 2000 and 2001****.**
**Since May 2006, positive SST anomalies have increased across the equatorial Pacific between 160E and the South American coast.**

**Recent Evolution of Equatorial Pacific SST Departures**

## Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m/s)

**Weaker-than-average easterlies (orange/red shading). **
**Stronger-than-average easterlies (blue shading).**

**Low-level easterly winds have averaged weaker than normal over the western equatorial Pacific between 130E and 170E.  **
**Since July, anomalous westerly winds have also dominated the east-central equatorial Pacific. **

**Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m/s)**

## Subsurface Conditions in the Equatorial Pacific

**Subsurface Conditions in the Equatorial Pacific**

**Time**

**Most recent pentad analysis**

** ****During August-September 2006 ****positive subsurface temperature anomalies were observed throughout the equatorial Pacific. A pattern of basin-wide positive subsurface temperature departures is usually observed prior to and in the early stages of El Ni****ño.**
** ****The most recent analysis shows positive anomalies, between the surface and 200 m depth, across most of the equatorial Pacific. **

## Outgoing Longwave Radiation (OLR) Anomalies

**Wetter-than-average conditions (blue shading)**

**Drier-than-average conditions (orange/red shading)**

**Since early August, suppressed convection has been persistent over the eastern Indian Ocean and Indonesia. **
**Recently, enhanced convection has developed over the western tropical Pacific.**

**Outgoing Longwave Radiation (OLR) Anomalies**

**The pattern of anomalous OLR over the equatorial Pacific during the last 30 days reflects the early stages of El Niño.**

## SST Outlook: NCEP CFS  22 October 2006

**SST Outlook: NCEP CFS****  22 October 2006**

- The CFS ensemble mean (blue line) indicates El Niño conditions through NH spring 2007.

## Typical US El Nino Temperature Probabilities 

**Typical US El Nino Temperature Probabilities **

- Trend Adjusted for general warming in the past 10 years

- Enhanced Probability the DJF temperature will fall within the Above, Below, or Near Normal category

## Typical US El Nino Precipitation Probabilities 

**Typical US El Nino Precipitation Probabilities **

- Trend Adjusted for precipitation trends in the past 15 years

- Enhanced Probability the DJF precipitation will fall within the Above, Below, or Near Normal category

## US JFM Temp. Departures (oC) for ranges of the ONI

- El Niño

**All ****episodes**

**Weak**

**Moderate/**
**Strong**

**US JFM Temp. Departures (oC) for ranges of the ONI**

## US JFM Precip. Departures (mm) for ranges of the ONI

**US JFM Precip. Departures (mm) for ranges of the ONI**

**All ****episodes**

**Weak**

**Moderate/**
**Strong**

- El Niño

## CFS Forecast US temperature departures (oC)

**CFS Forecast US temperature departures (****o****C)**

## CFS Forecast US precipitation departures (mm)

**CFS Forecast US precipitation departures (mm)**

## U. S. Seasonal OutlooksDecember 2006-February 2007

**U. S. Seasonal Outlooks****December 2006-February 2007**

**Temperature**

**Precipitation**

**Outlooks combine ****long-term trends**** ****and**** ****soil-moisture effects, with**** typical ****ENSO cycle impacts, when appropriate.**

## Local 3 Month Temperature Outlook Dec 2006-Feb 2007

**Local 3 Month Temperature Outlook Dec 2006-Feb 2007**

- Local Kansas City Temperatures Outlook based on historical comparison of local temperatures with Climate Division temperature probabilities. Initialized from CPC DJF temperature outlook.

## Historical Composite of Kansas City Temperatures for DJF

**Historical Composite of Kansas City Temperatures for DJF**

- No Statistical Significance based on the number of occurrences.

## Historical Composite of Kansas City Temperatures for AMJ

**Historical Composite of Kansas City Temperatures for AMJ**

- Here, there exists Statistical Significance, however tells us very little whether Spring temperatures will be Above or Below Average

## Historical Composite of Kansas City Precipitation for OND

**Historical Composite of Kansas City Precipitation for OND**

- Good Statistical Significance indicating very little chance of above average precipitation for the remainder of the calendar year.

## Historical Composite of Kansas City Precipitation for AMJ

**Historical Composite of Kansas City Precipitation for AMJ**

- No Statistical Significance based on the number of occurrences.

## Possible Analog years based on ONI index trend

**Possible Analog years based on ONI index trend**

## Average Temperatures for Analog Years versus 30-year averages

**Average Temperatures for Analog Years versus 30-year averages**

## Total Precipitation for Analog Years versus 30-year averages

**Total Precipitation for Analog Years versus 30-year averages**

## Total Snowfall for Analog Years versus 30-year averages

**Total Snowfall for Analog Years versus 30-year averages**

## Summary

**Summary**

** ****The recent atmospheric circulation and precipitation patterns indicate weak El Niño conditions already present in the tropical Pacific Ocean.**
** ****SST anomalies are between +0.8 ****o****C and +1.2 ****o****C in all of the Niño regions. **
** ****Based on recent trends and a majority of the statistical and dynamic coupled model forecasts, El Ni****ñ****o conditions should intensify during the next several months and will likely continue through at least April-May 2007.**

## Summary

**Summary**

** ****Based mainly on past 10 year temperature trends, there exists a better than normal chance that winter temperatures in western Missouri will be above average.**
** ****Historical composites from Kansas City indicate a better chance of average to below average precipitation for the remainder of the calendar year.**
** ****Based on past El Nino events, the stronger the ENSO signal, the better chance for warmer and wetter conditions across the Lower Missouri River Valley during the winter months.**