PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EST THU FEB 15 2007

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

THE MAIN FACTORS WHICH USUALLY INFLUENCE SEASONAL CLIMATE INCLUDE:
1) EL NINO AND LA NINA - WHICH COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO
2) TRENDS - APPROXIMATED BY THE DIFFERENCE BETWEEN THE MOST RECENT 10-YEAR MEAN 
OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN LOCATION AND TIME 
OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY 1971-2000)
3) TROPICAL 30-60-DAY OSCILLATION - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS.
4) THE NORTH ATLANTIC OSCILLATION (NAO) AND THE PACIFIC NORTH AMERICAN (PNA) 
PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING THE 
COLD SEASONS.  THESE PHENOMENA ARE CURRENTLY KNOWN TO BE PREDICTABLE ONLY OVER 
A WEEK OR SO.
5) PERSISTENTLY DRY OR WET SOILS IN THE SUMMER AND SNOW AND ICE COVER ANOMALIES 
IN THE WINTER.  THESE FACTORS TEND TO PERSIST FOR LONG PERIODS AND ACT AS A 
KIND OF MEMORY IN THE CLIMATE SYSTEM.
6) AN OBJECTIVE CONSOLIDATION (CALLED CON IN THE TEXT) OF THE OCN, CCA, SMLR 
AND CFS FORECASTS IS USED AS A FIRST-GUESS IN PREPARING THE FORECAST MAPS.  
THIS TECHNIQUE MAKES OPTIMUM USE OF THE KNOWN SKILL OF OUR FORECAST TOOLS.

EQUATORIAL SEA SURFACE TEMPERATURES (SST) IN THE PACIFIC OCEAN REMAINED ABOVE 
THEIR LONG-TERM AVERAGE DURING THE MONTHLY PERIOD ENDING IN EARLY FEBRUARY FROM 
JUST OFF THE SOUTH AMERICAN COAST TO ABOUT 165E WITH DEPARTURES MORE THAN 1 
DEGREE C ABOVE AVERAGE OBSERVED BETWEEN 170E AND THE DATE LINE AND BETWEEN 120W 
AND 90W.  HOWEVER THESE DEPARTURES ARE SIGNIFICANTLY SMALLER THAN THOSE 
OBSERVED LAST MONTH... AS THE CURRENT EL NINO EPISODE CONTINUES TO WEAKEN.  THE 
ATMOSPHERIC INDICATORS DURING THE PAST TWO MONTHS WERE ALSO CONSISTENT WITH 
WEAKENING EL NINO CONDITIONS... AS SLIGHTLY ENHANCED LOW LEVEL EASTERLIES 
DOMINATED THE CENTRAL PACIFIC.  ANOMALOUS LARGE SCALE CONVECTIVE ACTIVITY IN 
THE CENTRAL PACIFIC OCEAN WAS CENTERED BETWEEN THE EQUATOR AND 10N.  MJO 
ACTIVITY STRENGTHENED DURING LATE DECEMBER WITH THE CONVECTIVE PHASE ACTIVE 
OVER INDONESIA DURING LATE DECEMBER... BEFORE MOVING INTO THE WEST PACIFIC 
DURING EARLY JANUARY AND WEAKENING.  CURRENTLY MJO ACTIVITY IS QUITE WEAK AND 
IS NOT EXPECTED TO IMPACT THE WANING PHASE OF THIS EL NINO.  PERHAPS MOST 
SIGNIFICANTLY... THE EQUATORIAL UPPER-OCEAN TOTAL HEAT CONTENT OF THE  PACIFIC 
OCEAN... WHICH PEAKED IN LATE NOVEMBER... HAS DECREASED RAPIDLY SINCE THEN TO A 
SLIGHTLY NEGATIVE ANOMALY IN THE MOST RECENT WEEK.

THE AVERAGE OF SSTS IN THE NINO 3.4 REGION - A BOX BOUNDED BY 120W AND 170W AND 
BY 5N AND 5S - IS OFTEN USED AS AN INDICATOR OF THE STRENGTH OF AN EL NINO 
EVENT.  SSTS IN THIS REGION PEAKED AT A LITTLE MORE 1 DEGREE C ABOVE NORMAL... 
BEFORE DECREASING TO NEAR 1 DEG C IN EARLY JANUARY AND TO ABOUT 0.4 DEG C IN 
EARLY FEBRUARY.  NEARLY ALL PREDICTION TOOLS INDICATE THAT SST ANOMALIES IN THE 
NINO 3.4 REGION WILL CONTINUE TO DECREASE DURING THE NEXT FEW MONTHS... 
ALTHOUGH AT VARYING SPEEDS.  THUS WEAK EL NINO CONDITIONS ARE ANTICIPATED FOR 
ONLY THE NEXT FEW WEEKS... AND ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO BE IN 
PLACE BY EARLY IN THE MARCH-MAY 2007 SEASON.  THEREFORE THIS EVENT IS EXPECTED 
TO HAVE THE POTENTIAL TO IMPACT THE CLIMATE OF THE UNITED STATES FOR ONLY THE 
EARLY PART OF THE SPRING SEASON... AFTER WHICH LITTLE OR NO EFFECT IS 
ANTICIPATED.  A CONSENSUS OF STATISTICAL AND COUPLED DYNAMICAL CLIMATE MODELS 
SUGGESTS THAT THERE IS EVEN A POSSIBLILITY THAT BY SOMETIME IN THE SUMMER 
CONDITIONS COULD BE IN WEAK LA NINA TERRITORY... BUT IT IS TOO EARLY TO PUT 
MUCH CONFIDENCE IN THIS YET. 

THE TEMPERATURE OUTLOOK FOR MAR-APR-MAY (MAM) 2007 CALLS FOR WARMER THAN NORMAL 
CONDITIONS OVER MOST OF THE WESTERN THIRD OF THE NATION... INCLUDING MUCH OF 
ALASKA... WITH SOME WARMTH EXTENDING ACROSS THE NORTHERN BORDER STATES AS FAR 
AS THE UPPER MISSISSIPPI VALLEY.  ELSEWHERE THERE ARE EQUAL CHANCES OF 
WARMER-THAN- ... COOLER-THAN- ... OR NEAR-NORMAL TEMPERATURES... AS THE 
CIRCCULATION PATTERN IS INDICATED TO BECOME MORE PROGRESSIVE AND THE CURRENT 
COLD WEATHER OVER THE NORTHEAST IS NOT EXPECTED TO LAST INTO MARCH.

BELOW MEDIAN PRECIPITATION IS EXPECTED FOR MAM 2007 IN THE WESTERN AND CENTRAL 
GULF COAST REGION.  THE CHANCES FOR ABOVE MEDIAN PRECIPITATION ARE ELEVATED 
OVER SOUTHERN PARTS OF THE ROCKIES AND HIGH PLAINS DUE TO EXPECTATIONS THAT THE 
ACTIVE SUBTROPICAL JET STREAM USUALLY ASSOCIATED WITH EL NINO CONDITIONS THAT 
HAS FINALLY PUT IN A WEAK APPEARANCE WILL NOT PERSIST VERY LONG INTO THE 
SPRING.  ONGOING FAILURE OF THIS FEATURE TO BRING SIGNIFICANT RAINFALL INTO 
SOUTHERN CALIFORNIA LEADS TO A FORECAST OF BELOW MEDIAN PRECIPITATION IN THE 
FAR SOUTHWEST.  ELSEWHERE THERE ARE EQUAL CHANCES OF ABOVE-... BELOW-... OR 
NEAR-MEDIAN PRECIPITATION DURING MAM.  

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK
NOTE: FOR GRAPHICAL DISPLAYS OF THE FORECAST TOOLS DISCUSSED BELOW SEE:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/90DAY/TOOLS/BRIEFING

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

THE MOST RECENT MONTHLY MEAN SSTS IN THE EQUATORIAL PACIFIC ARE MORE THAN 0.5 
DEG C ABOVE NORMAL FROM ABOUT 165E TO NEAR THE SOUTH AMERICAN COAST...WITH 
DEPARTURES OF MORE THAN +1.0 DEG C OBSERVED BETWEEN 170E AND THE DATE LINE AND 
ALSO FROM 90W TO ABOUT 120W.  SSTS HAVE CONTINUED TO DECREASE RAPIDLY AND THE 
MOST RECENT WEEKLY MEAN ENDING ON 07 FEB 2007 SHOWS AN AREA OF BELOW NORMAL 
SSTS ON THE EQUATOR BETWEEN ABOUT 120W AND 150W... WITH POSITIVE DEPARTURES OF 
MORE THAN 1 DEG C REMIANING ONLY BETWEEN 165E TO 175E AND BETWEEN 85W AND 100W. 
THE LOW LEVEL EASTERLY WINDS (AT 850 MB) IN THE TROPICAL PACIFIC HAVE REMAINED 
NEAR OR SLIGHTLY STRONGER THAN NORMAL DURING THE PAST TWO MONTHS AFTER HAVING 
BEEN GENERALLY WEAKER THAN NORMAL ACROSS MUCH OF THE CENTRAL AND EASTERN 
EQUATORIAL PACIFIC BETWEEN JULY AND NOVEMBER.  THE UPPER OCEAN HEAT CONTENT IN 
THE EQUATORIAL PACIFIC HAS RECENTLY FALLEN TO SLIGHTLY BELOW THE LONG-TERM 
AVERAGE.  CONVECTIVE ACTIVITY IN THE CENTRAL EQUATORIAL PACIFIC HAS BEEN 
SLIGHTLY ENHANCED ON THE EQUATOR DURING THE PAST MONTH... BUT MORE 
SIGNIFICANTLY ENHANCED BETWEEN THE EQUATOR AND 10N. DURING THE MOST RECENT 
WEEK... MOST OF THE ENHANCED CONVECTIVE ACTIVITY HAS BEEN CONFINED TO AREAS 
WEST OF THE DATE LINE.  MADDEN-JULIAN OSCILLATION (MJO)ACTIVITY STRENGTHENED 
DURING LATE DECEMBER AND EARLY JANUARY... ENHANCING CONVECTION OVER INDONESIA 
AND THEN THE WESTERN PACIFIC... BEFORE EVENTUALLY MOVING TO THE CENTRAL PACIFIC 
WHILE WEAKENING.  THE SOI INDEX WAS SLIGHTLY NEGATIVE DURING DECEMBER AFTER 
TURNING SLIGHTLY POSITIVE DURING NOVEMBER.  HOWEVER... THE MEAN SEA LEVEL 
PRESSURE HAS BEEN GENERALLY ABOVE NORMAL AT DARWIN SINCE MAY 2006... WHICH IS 
PROBABLY A BETTER INDICATOR OF THE WEAK TO MODERATE EL NINO THAT IS NOW RAPIDLY 
WEAKENING.

PROGNOSTIC DISCUSSION OF SST FORECASTS

ALL PREDICTION TOOLS FOR NINO 3.4 SST ANOMALIES INDICATE THAT THE CURRENT EL 
NINO HAS PASSED ITS PEAK AND THE DECLINE IN SST ANOMALIES FIRST SEEN IN LATE 
DECEMBER/EARLY JANUARY HAS CONTINUED AT AN ACCELERATED RATE.  THE MAIN 
DISAGREEMENT AMONG THE VARIOUS MODEL SOLUTIONS IS THE SPEED WITH WHICH SST 
ANOMALIES WILL CONTINUE TO DECREASE AND WHETHER THE DEPARTURES REMAIN WARM... 
AS THE CCA PREDICTS... APPROACH ZERO... SIMILAR TO THE CONSENSUS... OR EVEN 
BECOME SIGNIFICANTLY COLD... AS IN THE CFS MODEL.  THE NCEP CONSOLIDATION SHOWS 
THAT NINO 3.4 IS PREDICTED TO BE ONLY +0.3 DEG C BY MAM... WHICH IS 0.2 DEG C 
LESS THAN THE CONSOLIDATION MADE LAST MONTH FOR THAT SEASON.  FORECAST VALUES 
REMAIN JUST SLIGHTLY ABOVE ZERO THROUGHOUT 2007... BUT WITH A HIGH DEGREE OF  
UNCERTAINTY.  SOME SOLUTIONS FROM MODELS RUN IN OTHER CENTERS DO NOT SHOW SUCH 
A RAPID RETURN TO NEUTRAL CONDITIONS... BUT ON THE AVERAGE THEY DO SHOW A MORE 
RAPID DEMISE OF EL NINO THAN THEY DID LAST MONTH.  

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

THE OUTLOOKS FOR MAM 2007 THROUGH JJA 2007 ARE BASED ON THE CONSOLIDATION 
TOOL... WHICH IS A SKILL-WEIGHTED OBJECTIVE BLEND OF CFS... CCA... SMLR... AND 
OCN.  SST ANOMALIES WERE CONSIDERED FOR COASTAL CALIFORNIA.  THE CAS TOOL WAS 
ALSO CONSIDERED FOR THE EARLY LEADS... AS WE ARE APPORACHING THE TIME WHEN IT 
HAS THE GREATEST A PRIORI SKILL... FOR FORECASTS INITIATED IN THE SPRING.  
SIGNALS FROM EL NINO COMPOSITIES WERE NOT WEIGHTED MUCH EVEN IN FORECASTS FOR 
MAM... AS MOST TOOLS SHOW THAT EL NINO... WHICH IS ALREADY WEAK... WILL FADE 
AWAY DURING MAM... AND ANY INFLUENCES WOULD MOST LIKELY BE EARLY IN THE SEASON. 
THE OUTLOOKS FOR JAS 2007 THROUGH MAM 2008 LARGELY REFLECT TRENDS.  TEMPERATURE 
TRENDS ARE POSITIVE AND SUBSTANTIAL FOR THE SOUTHWESTERN U.S. DURING MOST OF 
THE YEAR AND OVER MUCH OF THE COUNTRY IN THE WINTER... AND ARE WEAKEST IN THE 
FALL.  PRECIPITATION TRENDS APPEAR ONLY IN SCATTERED AREAS AND ARE WEAK. WET 
CONDITIONS ARE INDICATED IN SOUTHERN FLORIDA FOR THE LATE SUMMER AND EARLY FALL 
SEASONS... REFLECTING THE MULTI-DECADAL CYCLE IN ATLANTIC TROPICAL ACTIVITY... 
BUT SHOULD NOT BE INTERPRETEED AS AN INDICATION OF HURRICANE STRIKE 
PROBABILITIES.  FORECASTS OF DRY CONDTIONS ALONG THE GULF COAST FOR LATE WINTER 
AND SPRING 2008 REFLECT WEAK BUT CONSISTENT TRENDS... AND WOULD HAVE ADDITIONAL 
SUPPORT IF LA NINA CONDITIONS DEVELOP BY THAT TIME.   

PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2007 TO MAM 2008

TEMPERATURE:

THE TEMPERATURE OUTLOOK FOR MAM 2007 CALLS FOR ELEVATED CHANCES OF ABOVE NORMAL 
SEASONAL AVERAGE TEMPERATURE OVER MUCH OF THE WESTERN THIRD OF THE NATION... AS 
WELL AS NORTHERN PARTS OF THE GREAT PLAINS AND NORTHWESTERN ALASKA.  BELOW 
NORMAL SSTS OFF THE COAST AND THE POSSIBILITY OF AN ACTIVE SOUTHERN STORM TRACK 
DURING THE EARLY PART OF THE SEASON ARE EXPECTED TO REDUCE TEMPERATURES ALONG 
MUCH OF COASTAL CALIFORNIA.  OUTLOOKS FOR AMJ THROUGH JJA 2007 ARE BASED  
PRIMARILY ON THE CONSOLIDATION TOOL WHICH IS OFTEN DOMINATED BY THE TREND... 
ALTHOUGH THE CFS MODEL IS AN IMPORTANT COMPONTENT DURING THESE EARLY LEADS.  
CAS AND MODELS FROM OTHER CENTERS WERE ALSO CONSIDERED AND USED TO SOMEWHAT 
ENLARGE AREAS AND PROBABILITIES SHOWING EXPECTED ABOVE NORMAL TEMPERATURES WHEN 
THEY AGREED WITH THE CON TOOL.  BEGINNING WITH JAS 2007 AND CONTINUING THROUGH 
MAM 2008... FORECASTS FOR BOTH THE CONUS AND ALASKA WERE BASED ON THE CON 
TOOL... WHICH IS DOMINATED BY LONG-TERM TRENDS. 

PRECIPITATION:

THE PRECIPITATION OUTLOOKS FOR MAM 2007 CALL FOR GREATER THAN AVERAGE CHANCES 
OF ABOVE-MEDIAN PRECIPITATION FOR PART OF WEST TEXAS... NEW MEXICO... AND 
COLORADO... WHERE RESIDUAL EFFECTS OF EL NINO ARE MOST LIKELY TO LINGER.  DUE 
TO THE MORE RAPID DEMISE OF THE EL NINO EVENT THAN WAS EXPECTED LAST MONTH... 
FORECASTS FOR ABOVE MEDIAN PRECIPITATION IN CALIFORNIA... ARIZONA... THE LOWER 
RIO GRANDE VALLEY... AND THE SOUTHEAST WERE REMOVED.  NEARLY ALL TOOLS NOW 
INDICATE THAT BELOW-MEDIAN PRECIPITATION IS LIKELY DURING MAM FOR PARTS OF THE 
INTERIOR SOUTHWEST AND THE WESTERN AND CENTRAL GULF COAST REGION... WHILE THE 
RAPID WEAKENING OF EL NINO PROMPTED THE REMOVAL OF DRIER THAN AVERAGE IN THE 
OHIO VALLEY.  FOR AMJ 2007 AND BEYOND... THE PRECIPITATION OUTLOOK MAINLY 
REFLECTS WEAK TRENDS... FOR RELATIVELY WET CONDITIONS IN PARTS OF THE PACIFIC 
NORTHWEST DURING AMJ AND MJJ... AND RELATIVE DRYNESS OVER PARTS OF THE GREAT 
BASIN FOR AMJ THROUGH JJA... EXPANDING FURTHER TO THE NORTH AND WEST DURING JAS 
AND ASO.  ABOVE MEDIAN RAINFALL IS EXPECTED OVER MUCH OF THE FLORIDA PENINSULA 
DURING JAS AND ASO DUE TO THE LONG-TERM INTERDECADAL CYCLE IN ATLANTIC TROPICAL 
STORM ACTIVITY... BUT THIS SHOULD NOT BE INTERPRETED AS A FORECAST FOR ABOVE 
AVERAGE HURRICANE STRIKE PROBABILITIES AS EASTERLY WAVES AND WEAK SYSTEMS 
NORMALLY CONTRIUBTE THE BULK OF WARM SEASON RAINFALL IN THIS AREA.  THE 
PRECIPITIATION PROBABILITIES FOR WINTER 2007-08 AND THE FOLLOWING SPRING 
PRIMARILY REFLECT ONLY CLIMATOLOGY BECAUSE OF A WIDE SCATTER IN THE ENSO 
FORECAST FOR NEXT WINTER.  HOWEVER... THERE ARE SOME WEAK BUT CONSISTENT 
INDICATIONS FROM CON... PRIMARILY DUE TO TREND... THAT IT COULD BE DRY ALONG 
PARTS OF THE EAST AND CENTRAL GULF COAST FROM LATE WINTER INTO SPRING 2008. 

NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).

FORECASTER: A J. WAGNER

STARTING WITH THE SEASONAL OUTLOOK RELEASED IN FEBRUARY, 2006, THE GLOSSARY OF 
TERMS WILL NO LONGER APPEAR WITH THIS MESSAGE.
INSTEAD, TERMS THAT ARE IN THE GLOSSARY WILL BE LINKED TO THEIR DEFINITION.

FOR A DESCRIPTION OF THE STANDARD FORECAST TOOLS - THEIR SKILL - AND THE
FORECAST FORMAT PLEASE SEE OUR WEB PAGE AT
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/90DAY/DISC.HTML
(USE LOWER CASE LETTERS)

INFORMATION ON THE FORMULATION AND SKILL OF THE CAS FORECASTS MAY BE FOUND AT:
HTTP://WWW.CPC.NCEP.NOAA.GOV/SOILMST/FORECASTS.HTML (USE LOWERCASE LETTERS)

NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF
THEIR VALID PERIOD.  WITHIN ANY GIVEN VALID PERIOD OBSERVATIONS AND SHORT
AND MEDIUM RANGE FORECASTS SHOULD BE CONSULTED.

THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT
MONTH ON THU MAR 15 2007.

1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001
FORECAST RELEASE

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