PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 
830 AM EST THU DEC 18 2008 
 
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. 
 
OCEANIC AND ATMOSPHERIC INDICATORS CONTINUE TO SUGGEST ENSO-NEUTRAL CONDITIONS 
PREVAILED FROM LATE NOVEMBER THROUGH EARLY DECEMBER 2008, ALTHOUGH IN RECENT 
WEEKS CONDITIONS IN THE EQUATORIAL PACIFIC OCEAN HAVE BECOME SUGGESTIVE OF LA 
NINA CONDITIONS.  SEA SURFACE TEMPERATURES (SSTS) ARE BELOW NORMAL ALONG THE 
EQUATOR THROUGHOUT MOST OF THE EASTERN PACIFIC OCEAN WITH WATER TEMPERATURES 
JUST UNDER THE SURFACE SUBSTANTIALLY BELOW NORMAL.  SST FORECASTING TOOLS ARE 
FAIRLY EVENLY SPLIT BETWEEN CONTINUING ENSO-NEUTRAL CONDITIONS AND THE 
DEVELOPMENT OF A WEAK LA NINA IN EARLY 2009.  THESE CURRENT OBSERVATIONS 
TOGETHER WITH THE SST FORECAST SUGGEST THAT THE OCEAN-ATMOSPHERE STATE WILL BE 
ON THE BOARDER LINE BETWEEN NEUTRAL AND WEAK LA NINA CONDITIONS IN THE NEXT FEW 
MONTHS. 
 
THE TEMPERATURE OUTLOOK FOR JFM 2009 CALLS FOR ABOVE AVERAGE TEMPERATURES FROM 
THE INTERIOR SOUTHWESTERN U.S. EXTENDING EASTWARD TO INCLUDE TEXAS, THE 
SOUTHERN GREAT PLAINS, AND MUCH OF THE EASTERN U.S. EXCEPT FOR THE NORTHEAST. 
BELOW NORMAL TEMPERATURES ARE FAVORED IN THE PACIFIC NORTHWEST, PORTIONS OF THE 
NORTHERN ROCKIES AND MOST OF MONTANA.  BELOW NORMAL TEMPERATURES ARE ALSO 
EXPECTED IN PARTS OF SOUTHERN ALASKA.  THIS TEMPERATURE PATTERN IS SUPPORTED BY 
A RANGE OF NUMERICAL CLIMATE MODELS AND STATISTICAL TOOLS AND IS TYPICAL OF 
TEMPERATURES ASSOCIATED WITH LA NINA.  ABOVE NORMAL TEMPERATURES ARE EXPECTED 
FOR NORTHERN ALASKA DUE TO LONG TERM TRENDS.  ELSEWHERE, EQUAL CHANCES OF 
BELOW-, NEAR-, AND ABOVE AVERAGE TEMPERATURES ARE PREDICTED. 
 
THERE IS AN ENHANCED LIKELIHOOD OF BELOW MEDIAN PRECIPITATION AMOUNTS FOR JFM 
2009 ACROSS MUCH OF THE SOUTHERN CONTIGUOUS U.S. EXCEPT FOR PORTIONS OF THE 
CENTRAL GULF OF MEXICO COAST AS INDICATED MAINLY BY CFS DYNAMICAL MODEL 
PREDICTIONS AND THE CONSOLIDATION FORECAST.  ABOVE MEDIAN PRECIPITATION AMOUNTS 
ARE EXPECTED FROM THE SOUTHERN GREAT PLAINS TO THE OHIO VALLEY, DUE TO A 
COMBINATION OF LONG TERM TRENDS, NEAR OKLAHOMA, AND CFS FORECASTS IN THE OHIO 
VALLEY. 
 
 
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 
 
ENSO-NEUTRAL CONDITIONS CONTINUED BETWEEN MID-NOVEMBER AND MID-DECEMBER, 2008, 
ALTHOUGH OCEANIC AND ATMOSPHERIC INDICATORS HAVE BECOME MORE SUGGESTIVE OF LA 
NINA CONDITIONS IN THE RECENT FEW WEEKS.  SSTS ALONG THE EQUATOR ARE NOW MORE 
THAN .5 DEGREES C BELOW NORMAL FROM THE DATE LINE TO ABOUT 120W LONGITUDE, WITH 
ANOMALIES GENERALLY BETWEEN 0 AND -1.0 C FROM 120W TO THE SOUTH AMERICAN COAST. 
 THE LATEST WEEKLY SST INDEX VALUES FOR THE NINO REGIONS, FROM WEST TO EAST ARE 
-0.5 IN NINO 4, -0.7 IN NINO 3.4, -0.5 IN NINO 3, AND -0.6 IN THE NINO 1+2 
REGIONS.  THE SUBSURFACE OCEANIC HEAT CONTENT ANOMALIES IN THE EASTERN PACIFIC 
OCEAN (THE AVERAGE WATER TEMPERATURES IN THE UPPER 300M) HAVE BECOME 
INCREASINGLY NEGATIVE IN THE LAST MONTH AND ARE NOW AROUND -1.0 C.  LOW-LEVEL 
EASTERLY WIND ANOMALIES COUPLED WITH WESTERLY WIND ANOMALIES AT UPPER LEVELS 
HAVE STRENGTHENED IN RECENT WEEKS AND LARGE SCALE CONVECTION CONTINUES TO BE 
ENHANCED IN THE WESTERN PACIFIC NEAR INDONESIA AND SUPPRESSED IN THE CENTRAL 
PACIFIC NEAR THE DATELINE. 
 
 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
MOST DYNAMICAL AND STATISTICAL SST FORECASTS FOR THE NINO 3.4 REGION PREDICT 
SST ANOMALIES IN THE RANGE BETWEEN -0.1 AND -0.7 C, INDICATING ENSO-NEUTRAL OR 
WEAK LA NINA CONDITIONS IN THE NEXT FEW MONTHS.  A CONSOLIDATION FORECASTS 
BASED ON THE CFS AND SEVERAL STATISTICAL TOOLS FOR THE NINO 3.4 SSTS INDICATE 
THAT NINO 3.4 SSTS WILL DIP BELOW -.5 C FOR THE EARLY PART OF 2009, BUT RETURN 
TO NEAR NORMAL VALUES SOON THERAFTER, REMAINING SOMEWHAT BELOW NORMAL THROUGH 
AT LEAST EARLY SUMMER. 
 
 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR ALL LEAD TIMES ARE BASED HEAVILY 
ON THE CONSOLIDATION FORECAST (CON), A SKILL-WEIGHTED AND CALIBRATED OBJECTIVE 
BLEND OF THE CFS, SMLR, OCN, CCA, AND ECCA FORECAST TOOLS.  OTHER TOOLS, THE 
IRI MULTI-MODEL ENSEMBLE FORECASTS BASED ON SEVERAL DYNAMIC CLIMATE MODELS, THE 
ECPC CLIMATE FORECAST, AND THE CAS TOOL ARE ALSO CONSIDERED AND USED TO ADJUST 
THE FORECAST.  THE CONSOLIDATION FORECAST IS NOT AVAILABLE FOR ALASKA, SO THE 
FORECAST THERE IS BASED ON A SUBJECTIVE COMBINATION OF CCA, CFS, OCN, AND SMLR 
FORECASTS.  LA NINA COMPOSITES WERE NOT CONSULTED FOR THIS SERIES OF FORECASTS, 
HOWEVER MOST CLIMATE MODEL PREDICTIONS PREDICT A PATTERN SIMILAR TO LA NINA 
COMPOSITES IN THE NEXT FEW SEASONS, LENDING SOME SUPPORT TO THE POSSIBILITY 
THAT THE MARGINAL LA NINA CONDITIONS IN THE TROPICAL PACIFIC MAY HAVE AN 
INFLUENCE ON NORTH AMERICAN TEMPERATURE AND PRECIPITATION, HENCE THESE MODELS 
WERE GIVEN SOME ADDITIONAL WEIGHT FROM JFM TO MAM. 
 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2009 TO JFM 2010 
 
TEMPERATURE: 
 
THE TEMPERATURE OUTLOOK FOR JFM 2009 CALLS FOR ABOVE AVERAGE TEMPERATURES FROM 
THE INTERIOR SOUTHWESTERN U.S. EXTENDING EASTWARD TO INCLUDE TEXAS, THE 
SOUTHERN GREAT PLAINS, AND MUCH OF THE EASTERN U.S. EXCEPT FOR THE NORTHEAST. 
BELOW NORMAL TEMPERATURES ARE EXPECTED IN THE PACIFIC NORTHWEST, PORTIONS OF 
THE NORTHERN ROCKIES, MOST OF MONTANA, AND ALSO IN SOUTHERN ALASKA.  THIS 
TEMPERATURE PATTERN IS SUPPORTED BY A RANGE OF NUMERICAL MODELS AND STATISTICAL 
TOOLS AND IS TYPICAL OF LA NINA WINTERS.  ABOVE NORMAL TEMPERATURES ARE 
EXPECTED FOR NORTHERN ALASKA DUE TO LONG TERM TRENDS.  THERE IS A WIDE 
CONSENSUS AMONG CLIMATE MODELS THAT BELOW NORMAL TEMPERATURES WILL CONTINUE 
INTO FMA 2009 IN THE PACIFIC NORTHWEST.  OTHERWISE, TEMPERATURES FOR OUTLOOKS 
FROM FMA 2009 THROUGH JFM 2010 ARE MAINLY FROM LONG TERM TRENDS ADJUSTED TO 
SOME EXTENT BY WEAK SIGNALS FROM THE VARIOUS OTHER TOOLS USED IN THE 
CONSOLIDATION FORECAST. 
 
 
PRECIPITATION: 
 
THERE IS WIDE CONSENSUS FOR BELOW MEDIAN PRECIPITATION AMOUNTS OVER MUCH OF THE 
SOUTHERN CONUS WITH GREATEST CONFIDENCE NEAR WESTERN TEXAS AND IN FLORIDA. 
THERE IS SOME SUPPORT FROM LONG TERM TRENDS FOR ABOVE MEDIAN PRECIPITATION NEAR 
OKLAHOMA.  THIS AREA WAS ADJUSTED ON THE BASIS OF CFS FORECASTS WHICH FAVORED 
DRY CONDITIONS OVER TEXAS AND ABOVE MEDIAN PRECIPITATION AMOUNTS FROM THE 
MIDDLE MISSISSIPPI VALLEY TO OHIO.  DRY CONDITIONS CONTINUE OVER THE SOUTHEAST 
AND SOUTHERN ROCKIES INTO FMA 2009, DUE MAINLY TO OCN AND CFS FORECASTS.  THE 
CFS FAVORS BELOW MEDIAN PRECIPITATION IN THE SOUTHERN AND CENTRAL ROCKIES FOR 
MAM AND AMJ 2009.  BY MJJ 2009 ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION 
APPEAR IN PARTS OF THE NORTHERN GREAT BASIN AND THEN IN THE PACIFIC NORTHWEST 
BY JJA THROUGH ASO, PRIMARILY REFLECTING LONG TERM TRENDS.  THE ABOVE MEDIAN 
PRECIPITATION AMOUNTS FOR COASTAL AREAS IN THE SOUTHEAST IN JAS THROUGH SON ARE 
RELATED TO INCREASED TROPICAL ACTIVITY DURING RECENT YEARS.  THE CONSOLIDATION 
FORECAST INDICATES ABOVE MEDIAN PRECIPITATION FOR PARTS OF THE NORTHEASTERN 
CONUS FOR ASO AND SON 2009.  SIGNALS FOR DJF AND JFM 2009-2010 REFLECT TRENDS. 
THE PRECIPITATION OUTLOOK FOR ALASKA FOR ALL SEASONS IS LEFT AT CLIMATOLOGICAL 
PROBABILITIES, WITH NO STRONG TRENDS IN PRECIPITATION EVIDENT DURING ANY SEASON. 
 
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 JAN 15 2009 
 
1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 
FORECAST RELEASE. 
 
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