NOUS41 KWBC 241425
PNSWSH

SERVICE CHANGE NOTICE 08-56
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1025 AM EDT WED SEP 24 2008 

TO:       SUBSCRIBERS:
          -FAMILY OF SERVICES
          -NOAA WEATHER WIRE SERVICE
          -EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
          OTHER NWS PARTNERS...AND NWS EMPLOYEES

FROM:     AHSHA N. TRIBBLE 
          CHIEF...CLIMATE SERVICES DIVISION  
          OFFICE OF CLIMATE...WATER AND WEATHER SERVICES

SUBJECT:  NEW EL NIŅO SOUTHERN OSCILLATION /ENSO/ ALERTS
          TO BE INCLUDED AS NEEDED IN THE ENSO DIAGNOSTIC 
          DISCUSSION: EFFECTIVE DECEMBER 11 2008.

STARTING ON THURSDAY DECEMBER 11 2008...THE NWS CLIMATE 
PREDICTION CENTER /CPC/ WILL INCLUDE AN ENSO ALERT FOR AN  
EL NIŅO OR LA NIŅA... AS NEEDED...IN THE FRONT SECTION OF 
THE MONTHLY ENSO DIAGNOSTIC DISCUSSION. AN ENSO ALERT WILL 
BE A WATCH... ADVISORY...OR FINAL ADVISORY /I.E. END OF AN 
EL NIŅO OR A LA NIŅA/. 
	
THE ENSO DIAGNOSTIC DISCUSSION HAS ALWAYS INDICATED THE 
EXPECTED OCCURRENCE /OR LACK OF OCCURRENCE/ OF EL NIŅO OR  
LA NIŅA FOR THE NEXT THREE MONTHS. BECAUSE EL NIŅO OR  
LA NIŅA MAY AFFECT CLIMATE VARIABILITY PATTERNS THAT COULD 
SIGNIFICANTLY IMPACT VARIOUS AREAS OF THE UNITED 
STATES...CPC WILL NOW USE AN ALERT SYSTEM TO HIGHLIGHT WHEN 
EL NIŅO OR LA NIŅA IS EXPECTED TO DEVELOP...CONTINUE OR END. 

1. AN ENSO WATCH WILL BE ISSUED WHEN A TRANSITION TO EL NIŅO 
   OR LA NIŅA CONDITIONS IS ANTICIPATED WITHIN THE NEXT 
   THREE MONTHS.

2. AN ENSO ADVISORY WILL BE ISSUED WHEN EL NIŅO OR LA NIŅA
   CONDITIONS ARE ALREADY OBSERVED AND EXPECTED TO CONTINUE.

3. AN ENSO FINAL ADVISORY WILL BE ISSUED WHEN EITHER EL NIŅO
   OR LA NIŅA CONDITIONS HAVE ENDED.

CPC DEFINES EL NIŅO OR LA NIŅA CONDITIONS AS EXISTING WHEN:

A ONE-MONTH POSITIVE /NEGATIVE/ SEA SURFACE TEMPERATURE 
ANOMALY OF 0.5C /-0.5C/ OR GREATER /LESS/ IS OBSERVED IN THE 
NIŅO 3.4 REGION OF THE EQUATORIAL CENTRAL PACIFIC OCEAN /5N-
5S AND 120W-170W/ AND IS EXPECTED TO PERSIST FOR AT LEAST 
THREE CONSECUTIVE MONTHS...AND

AN ATMOSPHERIC RESPONSE TYPICALLY ASSOCIATED WITH EL NIŅO 
/LA NIŅA/ IS OBSERVED OVER THE EQUATORIAL PACIFIC REGION AS 
PER EL NIŅO/LA NIŅA DOCUMENTATION ON THE FOLLOWING CPC WEB 
PAGE: /USE LOWER CASE/

HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/
ENSOCYCLE/ENSO_CYCLE.SHTML     

CPC USUALLY ISSUES THE MONTHLY ENSO DIAGNOSTICS DISCUSSION 
ON THE THURSDAY FROM THE 5TH TO THE 11TH OF THE MONTH...AT 
AROUND 9:00 A.M. EASTERN LOCAL TIME. WITH ADVANCE NOTICE... 
CPC MAY CHANGE THE ISSUANCE DATE /E.G. DUE TO HOLIDAYS/. THE 
PRODUCT IS ISSUED UNDER THE FOLLOWING:

WMO HEADING - FXUS24 KWNC     AWIPS ID - PMDENS 
  
ON THE INTERNET AT /USE LOWER CASE/:

HTTP://WWW.CPC.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/
ENSO_ADVISORY/

THE TERM WARNING WILL NOT BE USED IN THE ENSO ALERT SYSTEM 
BECAUSE WARNINGS ALMOST ALWAYS HAVE A NEGATIVE CONNOTATION. 
BECAUSE ENSO EVENTS RESULT IN POSITIVE AND NEGATIVE IMPACTS 
RELATED TO CLIMATE VARIABILITY PATTERNS...AN ADVISORY IS 
MORE APPROPRIATE. 

CPC WILL CONTINUE TO ISSUE ALL OTHER INFORMATION IN THE ENSO 
DIAGNOSTIC DISCUSSION. CPC WILL CONTINUE TO ADDRESS CURRENT 
OCEANIC AND ATMOSPHERIC CONDITIONS IN THE PACIFIC AND 
RELATED CLIMATE VARIABILITY PATTERNS. THIS INCLUDES THE 
FOLLOWING:

  ANALYSIS OF CURRENT AND RECENT PATTERNS IN SURFACE AND  
  SUBSURFACE WATER TEMPERATURE ANOMALIES IN THE TROPICAL
  PACIFIC

  RELATED ANALYSES SUCH AS RAINFALL...OUTGOING LONG WAVE 
  RADIATION...ETC. 

  INFLUENCING FACTORS SUCH AS MADDEN-JULIAN OSCILLATIONS
  ...KELVIN WAVES...ETC.

  STATISTICAL AND COUPLED MODEL PREDICTIONS. 

FOR ADDITIONAL INFORMATION ON ENSO ALERT POLICY AND THE ENSO 
DIAGNOSTIC DISCUSSION...CONTACT 

  MICHAEL S. HALPERT
  NWS CLIMATE PREDICTION CENTER - W/NP5
  5200 AUTH RD
  CAMP SPRINGS MD 20746
  301-763-8000 EXT 7535

NWS SERVICE CHANGE NOTICES ARE ONLINE AT:
  
  HTTP://WWW.WEATHER.GOV/OS/NOTIF.HTM  

$$
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