NOUS41 KWBC 101546 AAA
PNSWSH

SERVICE CHANGE NOTICE 08-56 AMENDED
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1045 AM EST WED DEC 10 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:  AMENDED: EL NINO SOUTHERN OSCILLATION /ENSO/ 
          ALERTS...AS NEEDED...IN THE ENSO DIAGNOSTIC 
          DISCUSSION POSTPONED UNTIL FEBRUARY 5 2009

REFER TO: SERVICE CHANGE NOTICE 08-56 SENT ON 
          SEPTEMBER 24 2008

AMENDED TO POSTPONE EFFECTIVE DATE FOR THIS CHANGE FROM 
DECEMBER 11 2008 TO FEBRUARY 5 2009 FOR TECHNICAL REASONS.

STARTING ON THURSDAY FEBRUARY 5 2009...THE NWS CLIMATE 
PREDICTION CENTER /CPC/ WILL INCLUDE AN ENSO ALERT FOR AN  
EL NINO OR LA NINA...AS NEEDED...IN THE BEGINNING SECTION OF 
THE MONTHLY ENSO DIAGNOSTIC DISCUSSION. AN ENSO ALERT WILL 
BE A WATCH... ADVISORY...OR FINAL ADVISORY /I.E. END OF AN 
EL NINO OR LA NINA/. 
	
THE ENSO DIAGNOSTIC DISCUSSION HAS ALWAYS INDICATED THE 
EXPECTED OCCURRENCE /OR LACK OF OCCURRENCE/ OF EL NINO OR 
LA NINA FOR THE NEXT THREE MONTHS. WITH SIGNIFICANT IMPACTS 
IN VARIOUS AREAS OF THE UNITED STATES OFTEN ASSOCIATED WITH 
CLIMATE VARIABILITY PATTERNS RELATED TO EL NINO AND 
LA NINA...CPC WILL NOW USE AN ALERT TO HIGHLIGHT WHEN 
EL NINO OR LA NINA IS EXPECTED TO DEVELOP...CONTINUE OR END. 

1. AN ENSO WATCH WILL BE ISSUED WHEN A TRANSITION TO EL NINO 
   OR LA NINA CONDITIONS IS EXPECTED IN THE NEXT 3 MONTHS.

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

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

CPC DEFINES EL NINO /OR LA NINA/ CONDITIONS AS EXISTING WHEN:

A ONE-MONTH POSITIVE /NEGATIVE/ SST ANOMALY IN THE NINO 3.4 
REGION OF 0.5C /-0.5C/ OR GREATER /LESS/ IS OBSERVED AND IS 
EXPECTED TO PERSIST FOR AT LEAST 3 CONSECUTIVE MONTHS AND
AN ATMOSPHERIC RESPONSE TYPICALLY ASSOCIATED WITH EL NINO 
/LA NINA/ IS OBSERVED OVER THE EQUATORIAL PACIFIC REGION AS 
PER EL NINO/LA NINA DOCUMENTATION ON THE FOLLOWING CPC WEB 
PAGE: /USE LOWER CASE/

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

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

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

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

THE WARNING TERM WILL NOT BE USED IN THE ENSO ALERT SYSTEM 
SINCE WARNINGS ALMOST ALWAYS HAVE A NET NEGATIVE CONNOTATION 
FOR IMPACTS FROM SHORT-TERM WEATHER EVENTS. SINCE ENSO 
EVENTS HAVE A MORE NEUTRAL NET EFFECT THROUGH BOTH POSITIVE 
AND NEGATIVE IMPACTS FROM ENSO RELATED CLIMATE VARIABILITY 
PATTERNS...AN ADVISORY IS MORE APPROPRIATE FOR ENSO ALERTS. 

ALL OTHER INFORMATION IN THE ENSO DIAGNOSTIC DISCUSSION WILL 
CONTINUE TO BE ISSUED. CPC WILL CONTINUE TO ADDRESS CURRENT 
OCEANIC AND ATMOSPHERIC CONDITIONS IN THE PACIFIC AND 
RELATED CLIMATE VARIABILITY PATTERNS INCLUDING:

-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 NATIONAL NOTICES ARE ONLINE AT /USE LOWERCASE/

  HTTP://WWW.WEATHER/GOV/OS/NOTIF.HTM  

$$
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