PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 
830 AM EDT THU JUN 18 2009 
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS 
 
THE MAIN FACTORS WHICH USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE: 
1) EL NINO AND LA NINA - WHICH COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO. 
2) TRENDS - APPROXIMATED BY THE OCN TOOL AS 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) THE TROPICAL 30-60 DAY OSCILLATION - SOMETIMES CALLED MADDEN JULIAN 
OSCILLATION (MJO) - 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) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE 
VARIABILITY AFFECTING BOTH THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN 
REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO. 
6) 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. 
THE MAIN FORECAST TOOLS ARE AS FOLLOWS: 
7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING 
MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA 
(ECCA). 
8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). 
9) AN OBJECTIVE CONSOLIDATION (ABBREVIATED CON IN THE TEXT) OF THE OCN, CCA, 
SMLR, ECCA, 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. 
 
SEA SURFACE TEMPERATURES (SSTS) IN THE EASTERN AND CENTRAL EQUATORIAL PACIFIC 
OCEAN HAVE TRANSITIONED FROM BELOW NORMAL JUST A FEW MONTHS AGO TO ABOUT 0.5 
DEGREES C ABOVE NORMAL IN THE RECENT TWO WEEKS.  SSTS IN THIS REGION OF THE 
PACIFIC OCEAN ARE A RELIABLE ENSO INDICATOR AND SHOW A TRANSITION FROM LA NINA 
CONDITIONS EARLY IN THE YEAR TO NEUTRAL CONDITIONS IN MAY.  THE CONTINUED 
INCREASE IN SST ANOMALIES IN THIS REGION IN EARLY JUNE IS A STRONG INDICATION 
THAT EL NINO CONDITIONS ARE LIKELY TO DEVELOP WITHIN THE NEXT FEW MONTHS. 
WATER TEMPERATURES ARE WELL ABOVE NORMAL IN THE UPPER 200 METERS OF THE 
TROPICAL PACIFIC OCEAN, MAKING IT LIKELY THAT ABOVE NORMAL SSTS WILL CONTINUE 
INTO THE SUMMER.  THE CFS MODEL CORRECTLY ANTICIPATED THIS RAPID TRANSITION IN 
ITS FORECASTS FOR THE LAST FEW MONTHS, AND ITS CURRENT FORECAST SHOWS A 
CONTINUED INCREASE IN SST ANOMALIES IN THE COMING FEW MONTHS, SUGGESTING THAT 
MODERATE EL NINO CONDITIONS MAY SOON DEVELOP AND CONTINUE THROUGH THE END OF 
THE YEAR.  THE OUTLOOKS FOR TEMPERATURE AND PRECIPITATION FROM OND 2009 TO MAM 
2010 ARE HEAVILY INFLUENCED BY THE POSSIBILITY OF EL NINO.  IT IS STILL A BIT 
EARLY TO PREDICT THE EL NINO STRENGTH FOR THE WINTER MONTHS, WHEN ITS INFLUENCE 
ON U.S. CLIMATE IS STRONGEST.  THE EVOLUTION OF SSTS IN THE EQUATORIAL PACIFIC 
IN THE COMING MONTHS WILL BE CRITICAL TO WINTERTIME FORECAST IN THE U.S. 
 
THE TEMPERATURE OUTLOOK FOR JAS 2009 CALLS FOR AN ENHANCED LIKELIHOOD OF BELOW 
NORMAL TEMPERATURES FOR PORTIONS OF THE LOWER AND MIDDLE MISSISSIPPI VALLEY, 
DUE MAINLY TO THE INFLUENCE OF INITIALLY WET SOIL MOISTURE CONDITIONS IN THE 
AREA.  ABOVE NORMAL TEMPERATURES ARE FAVORED FROM THE ROCKY MOUNTAINS WESTWARD, 
EXCEPT ALONG THE PACIFIC COAST.  ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED IN 
INTERIOR SECTIONS OF SOUTHERN ALASKA.  ELSEWHERE, EQUAL CHANCES OF BELOW, NEAR, 
AND ABOVE NORMAL TEMPERATURES ARE PREDICTED. 
 
THE CHANCE OF BELOW MEDIAN PRECIPITATION IS ENHANCED FOR JAS 2009 FOR PARTS OF 
THE PACIFIC NORTHWEST INTO THE NORTHERN ROCKY MOUNTAINS.  ABOVE MEDIAN 
PRECIPITATION AMOUNTS ARE FAVORED FROM PARTS OF THE SOUTHWESTERN U.S. TO 
SOUTHERN WYOMING.  ABOVE MEDIAN PRECIPITATION AMOUNTS ARE FAVORED FOR FLORIDA 
AND ALSO IN NEW ENGLAND.  ELSEWHERE, EQUAL CHANCES OF BELOW, NEAR, AND ABOVE 
MEDIAN PRECIPITATION ARE PREDICTED. 
 
 
 
BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS 
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 
 
SSTS IN THE EAST-CENTRAL EQUATORIAL PACIFIC CURRENTLY AVERAGE AROUND 0.5 
DEGREES C ABOVE NORMAL, AND ANOMALIES HAVE INCREASED MARKEDLY IN THE PAST FEW 
MONTHS.  THE HEAT CONTENT IN THE UPPER 300 METERS OF THE CENTRAL AND EASTERN 
PACIFIC ALONG THE EQUATOR HAS ALSO INCREASED MARKEDLY IN THE LAST FEW MONTHS 
AND NOW AVERAGES CLOSE TO 1 DEGREE C ABOVE NORMAL.  SST ANOMALIES IN THE NINO 
3.4 REGION AVERAGED JUST UNDER .5 DEGREES C IN THE FIRST HALF OF JUNE. 
 
ATMOSPHERIC CONDITIONS OVER THE EQUATORIAL PACIFIC OCEAN DURING MAY WERE 
CONSISTENT WITH ENSO NEUTRAL CONDITIONS.  LOW LEVEL WINDS WERE NEAR NORMAL NEAR 
THE EQUATOR OVER THE CENTRAL PACIFIC, AND ATMOSPHERIC CONVECTION OVER THE 
CENTRAL EQUATORIAL PACIFIC HAS RETURNED TO NEAR NORMAL VALUES AFTER HAVING BEEN 
SUPRESSED FOR MOST OF THE PAST YEAR IN THE LA NINA EVENT. 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
THE TRANSITION OF SST ANOMALIES FROM BELOW TO ABOVE NORMAL WAS PREDICTED BY 
MOST DYNAMICAL SST PREDICTION MODELS FOR THE PAST FEW MONTHS, WITH STATISTICAL 
PREDICTION TOOLS LAGGING BEHIND IN THEIR CONTINUATION OF NEAR TO BELOW NORMAL 
SSTS.  THE MOST RECENT DYNAMICAL SST FORECASTS FROM THE CFS AND OTHER MODELS 
PREDICT SST ANOMALIES OF BETWEEN .5 AND 2 DEGREES C BY LATE SUMMER. FORECASTS 
FROM THE STATISTICAL MODELS ARE NOW CONSIDERABLY WARMER THAN THEIR FORECASTS 
LAST MONTH, ALTHOUGH MOST STILL LAG BEHIND THE DYNAMIC MODELS IN THEIR 
PREDICTION OF ANOMALIES RANGING FROM 0 TO .5 DEGREES C BY LATE SUMMMER.  THE 
CPC CONSOLIDATION NINO 3.4 SST ANOMALY FORECAST INDICATES THE SST ANOMALIES 
WILL REACH THE CRITICAL THRESHOLD FOR EL NINO CONDITIONS OF .5 DEGREES C OR 
GREATER BY SON, AND CONTINUE AT THAT LEVEL THROUGH EARLY 2010.  SINCE THE 
DYNAMICAL MODELS HAVE PERFORMED CONSISTENTLY BETTER THAN THE STATISTICAL MODELS 
THIS SPRING, AND SINCE WEEKLY SST ANOMALIES IN ALL FOUR NINO REGIONS ARE 
ALREADY .5 DEGREES OR GREATER, IT IS QUITE LIKELY THAT SSTS IN THE NINO 3.4 
REGION WILL BE ABOVE .5 DEGREES C FROM JULY 2009 THROUGH AT LEAST EARLY 2010, 
AND THE CONDITIONS WILL BE FAVORABLE FOR THE ONSET OF EL NINO CONDITIONS IN THE 
NEXT FEW MONTHS. 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR JAS THROUGH SON 2009 ARE BASED 
PRIMARILY ON THE CONSOLIDATION FORECAST (CON), A SKILL-WEIGHTED AND CALIBRATED 
PROBABILISTIC FORECAST DERIVED FROM THE CFS, SMLR, OCN, CCA, AND ECCA FORECAST 
TOOLS.  OUTLOOKS BETWEEN OND 2009 AND MAM 2010 REFLECT THE LIKELY ONSET OF 
MODERATE EL NINO CONDITIONS IN THE NEXT FEW MONTHS.  THE CFS FORECAST AGREES 
WELL WITH THE EL NINO COMPOSITES FROM OND THROUGH ITS FINAL LEAD TIME OF DJF 
AND WAS USED TOGETHER WITH EL NINO COMPOSITES FOR THE PRECIPITATION FORECAST 
FOR THESE SEASONS.  THE TEMPERATURE FORECAST WAS ADJUSTED FROM THE CFS AND ENSO 
COMPOSITES ON THE BASIS OF TRENDS AS INDICATED BY THE OCN TOOL AND THE CON. 
THE FORECASTS FROM JFM TO MAM 2010 ARE BASED ON EL NINO COMPOSITES, WITH THE 
TEMPERATURE OUTLOOK ADJUSTED BY TRENDS.  THE OUTLOOKS FOR AMJ TO JAS 2010 ARE 
BASED ON THE CON FORECASTS. 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2009 TO JAS 2010 
 
TEMPERATURE: 
 
THE TEMPERATURE OUTLOOK FOR JAS 2009 FAVORS ABOVE NORMAL TEMPERATURES FOR MOST 
OF THE WESTERN U.S., EXCEPT ALONG THE IMMEDIATE WEST COAST AS INDICATED BY THE 
CONSOLIDATION FORECAST TOOL.  THIS AREA IS MOSTLY DUE TO RECENT TEMPERATURE 
TRENDS.  BELOW NORMAL TEMPERATURES ARE INDICATED IN PARTS OF THE CENTRAL CONUS 
BY A NUMBER OF FORECAST TOOLS.  INTIALLY WET SOIL MOISTURE CONDITIONS PLAY A 
PART IN REDUCING TEMPERATURES IN THIS AREA ACCORDING TO THE SMLR TOOL, AND ARE 
LIKELY A FACTOR IN THE CFS MODEL FORECAST AS WELL.  THE ABOVE NORMAL 
TEMPERATURES INDICATED ON LAST MONTHS OUTLOOK FOR JAS IN NEW ENGLAND HAVE BEEN 
REMOVED DUE TO CONTRADICTING INDICATIONS FROM THE CFS SURFACE TEMPERATURE AND 
UPPER LEVEL CIRCULATION FORECAST.  ABOVE NORMAL TEMPERATURES IN ALASKA ARE 
FAVORED BY CCA AND SMLR FORECASTS IN INTERIOR PORTIONS, WITH CONFLICTING 
SIGNALS ON THE COASTAL AREAS LEADING TO A FORECAST OF EQUAL CHANCES. 
 
THE TEMPERATURE OUTLOOK FOR ASO THROUGH OND ARE MAINLY BASED ON THE CON 
FORECAST.  FROM NDJ 2009/10 THROUGH FMA 2010 THE TEMPERATURE FORECAST WAS 
SUBSTANTIALLY REVISED FROM LAST MONTHS FORECASTS FOR THE CORRESPONDING SEASONS 
DUE TO INCREASED CONFIDENCE THAT EL NINO WILL INFLUENCE THE WINTERTIME 
CIRCULATION.  TEMPERATURES IN EL NINO WINTERS TEND TO BE BELOW NORMAL OVER MUCH 
OF THE SOUTHERN CONUS, PARTIALLY COUNTERACTING TRENDS FOR WARMER WINTER 
TEMPERATURES IN THE SOUTHWEST, AND ENTIRELY COUNTERACTING TRENDS IN THE 
SOUTHEAST.  CONFIDENCE IN ABOVE NORMAL TEMPERATURES OVER THE NORTHERN GREAT 
PLAINS AND IN ALASKA IS INCREASED DUE TO ENSO TELECONNECTIONS. 
 
REMAINING FORECAST LEADS FROM AMJ 2010 THROUGH JAS 2010 ARE BASED ON THE 
CONSOLIDATION FORECAST AND LARGELY REFLECT TEMPERATURE TRENDS. 
 
PRECIPITATION: 
 
THE PRECIPITATION OUTLOOKS FOR JAS THROUGH SON 2009 ARE BASED PRIMARILY ON THE 
CONSOLIDATION FORECAST, AND INDICATE INCREASED CHANCES OF ABOVE MEDIAN 
PRECIPITATION AMOUNTS OVER PARTS OF THE CENTRAL AND SOUTHERN ROCKY MOUNTAINS 
AND THE SOUTHWEST, BASED MOSTLY ON FORECASTS FROM THE CFS AND ECCA.  THE AREA 
OF THE TREND-RELATED DRY FORECAST FOR THE PACIFIC NORTHWEST HAS BEEN REDUCED 
FROM THAT INDICATED IN PREVIOUS OUTLOOKS DUE TO AMPLE PRECIPITATION AND 
FAVORABLE SOIL MOISTURE CONDITIONS IN JUNE IN PARTS OF THE NORTHERN GREAT 
BASIN.  THE CON FORECAST CONTINUES TO SHOW INCREASED CHANCES FOR ABOVE MEDIAN 
PRECIPITATION AMOUNTS IN NEW ENGLAND AND ALSO IN FLORIDA.  THE CHANCE OF ABOVE 
MEDIAN PRECIPITATION AMOUNTS FROM ASO TO OND IS ENHANCED ALONG THE SOUTH COAST 
OF ALASKA AND IS BASED ON INDICATIONS FROM THE CFS.  EL NINO PRECIPITATION 
COMPOSITES WERE USED TOGETHER WITH THE CFS FORECAST FROM OND 2009 THROUGH MAM 
2010.  THESE INDICATE INCREASED CHANCES OF ABOVE MEDIAN PRECIPITATION FOR THE 
SOUTHERN CONUS, BEGINING IN CENTRAL SECTIONS OF THE REGION IN OND, EXPANDING TO 
MAXIMUM COVERAGE IN LATE WINTER, AND THEN DIMINISHING IN AREA BY MAM.  BELOW 
MEDIAN PRECIPITATION IS FAVORED IN EL NINO WINTERS FOR THE PACIFIC NORTHWEST 
AND PARTS OF THE OHIO AND TENNESSEE RIVER VALLEYS.  THERE ARE NO CLEAR SIGNALS 
FOR PRECIPITATION FROM AMJ TO JJA 2010, RESULTING IN A FORECAST FOR EQUAL 
CHANCES FOR BELOW, NEAR, OR ABOVE MEDIAN PRECIPITATION AMOUNTS NATIONWIDE.  A 
TREND-RELATED SIGNAL FOR ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION IN THE 
PACIFIC NORTHWEST, AND ABOVE MEDIAN PRECIPITATION FOR FLORIDA APPEARS IN THE 
OUTLOOK FOR JAS 2010. 
 
NOTE - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). 
 
FORECASTER: DAVID UNGER 
 
FOR A DESCRIPTION OF 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 FORMATION OF 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 JUL 16 2009 
 
1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 
FORECAST RELEASE. 
 
$$