PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 
830 AM EDT THU JUN 19 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. 
7) STATISTICAL FORECAST TOOLS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING 
MULTIPLE LINEAR REGRESSION (SMLR), 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. 
 
LA NINA CONTINUED TO WEAKEN DURING MAY AND EARLY JUNE 2008, AS REFLECTED BY 
CHANGES IN SEA SURFACE TEMPERATURES (SSTS) ACROSS THE EQUATORIAL PACIFIC OCEAN. 
 SSTS IN THE EAST-CENTRAL PACIFIC OCEAN REMAIN BELOW NORMAL AND ARE 
SUFFICIENTLY COOL TO MAINTAIN THE PERSISTENT ATMOSPHERIC ANOMALIES ASSOCIATED 
WITH LA NINA.  HOWEVER SSTS ALONG THE EQUATOR ARE NOW ABOVE NORMAL FROM ABOUT 
130W TO NEAR THE SOUTH AMERICAN COAST, AND THE BELOW NORMAL WATER TEMPERATURES 
IN THE CENTRAL PACIFIC ARE CONFINED TO A SHALLOW LAYER NEAR THE SURFACE. 
TOGETHER, THESE OBSERVATION SUGGEST THAT THE ENSO STATE IS CURRENTLY IN 
TRANSITION FROM LA NINA TO NEUTRAL CONDITIONS. 
 
THERE CONTINUES TO BE CONSIDERABLE DISAGREEMENT IN THE FORECAST FOR NINO 3.4 
SST ANOMALIES IN THE NEXT FEW MONTHS. THE NCEP CFS MODEL PREDICTS THAT NINO 
3.4 SST ANOMALIES WILL BECOME SLIGHTLY POSITIVE BY LATE SUMMER, FOLLOWED BY A 
GRADUAL RETURN TO NEAR ZERO ANOMALIES BY THE END OF THE YEAR WHILE THE 
STATISTICAL MODELS FOR SST RUN AT NCEP HOLD NINO 3.4 SST ANOMALIES STEADY AT 
AROUND -0.5 C. FOR THE NEXT FEW MONTHS.  A CONSENSUS OF THESE FORECASTS 
SUGGESTS NEUTRAL ENSO CONDITIONS, WITH NINO 3.4 SST ANOMALIES OF AROUND -0.3 C 
IN THE NEXT FEW SEASONS. 
 
THE TEMPERATURE OUTLOOK FOR JAS 2008 CALLS FOR ABOVE NORMAL TEMPERATURES IN THE 
SOUTHWESTERN U.S., EXTENDING NORTHWARD TO INCLUDE MUCH OF THE GREAT BASIN AND 
INTERIOR CALIFORNIA.  THIS AREA REFLECTS RECENT TEMPERATURE TRENDS, WITH 
ADDITIONAL SUPPORT FROM FORECASTS FROM STATISTICAL TOOLS.  DRY SOIL MOISTURE 
CONDITIONS IN PARTS OF CALIFORNIA CONTRIBUTED TO ANTICIPATED ABOVE NORMAL 
TEMPERATURES IN INTERIOR CALIFORNIA.  ABOVE NORMAL TEMPERATURES ARE ALSO 
EXPECTED IN THE NORTHEASTERN U.S. BASED ON THE CON TOOL.  BELOW NORMAL SSTS 
ALONG THE PACIFIC COAST OF NORTH AMERICA WILL ELEVATE CHANCES OF BELOW NORMAL 
TEMPERATURES IN ADJACENT COASTAL AREAS FROM JAS THROUGH SON. 
 
ABOVE MEDIAN PRECIPITATION IS CALLED FOR IN SOUTHERN ALASKA FROM JAS THROUGH 
SON 2008.  BELOW MEDIAN RAINFALL AMOUNTS ARE EXPECTED IN PARTS OF THE PACIFIC 
NORTHWEST FROM JJA THROUGH ASO.  ABOVE MEDIAN RAINFALL IS PREDICTED FOR 
SECTIONS OF THE NORTHEAST AND THE SOUTHEAST FROM JAS TO SON. 
 
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 
 
LA NINA CONTINUED TO WEAKEN DURING MAY 2008, AS REFLECTED BY CHANGES IN SEA 
SURFACE TEMPERATURES (SSTS) ACROSS THE EQUATORIAL PACIFIC OCEAN.  SSTS IN THE 
EAST-CENTRAL PACIFIC OCEAN REMAIN BELOW NORMAL AND ARE SUFFICIENTLY COOL TO 
MAINTAIN THE PERSISTENT ATMOSPHERIC ANOMALIES ASSOCIATED WITH LA NINA. 
CONVECTION CONTINUES TO BE SUPRESSED IN THE CENTRAL EQUATORIAL PACIFIC OCEAN, 
WITH ENHANCED LOW LEVEL EASTERLY WINDS AND ENHANCED UPPER LEVEL WESTERLIES OVER 
THE TROPICAL PACIFIC REGION.  SSTS ALONG THE EQUATOR ARE NOW ABOVE NORMAL FROM 
ABOUT 130W TO NEAR THE SOUTH AMERICAN COAST.  SST ANOMALIES IN EARLY JUNE ARE 
-.6 , -.4, +.2 AND +.5 DEGREES C IN THE NINO 4, NINO 3.4, NINO 3, AND NINO 1+2 
REGIONS, RESPECTIVELY. WATER TEMPERATURES IN THE UPPER 300 M OF THE CENTRAL 
PACIFIC OCEAN NEAR THE EQUATOR HAVE INCREASED DRAMATICALLY SINCE FEBRUARY AND 
ARE NOW SLIGHTLY ABOVE NORMAL, SO BELOW NORMAL OCEAN TEMPERATURES ARE NOW 
CONFINED TO A SHALLOW LAYER NEAR THE SURFACE.  TOGETHER, THESE OBSERVATION 
SUGGEST THAT THE ENSO STATE IS CURRENTLY IN TRANSITION FROM LA NINA TO ENSO 
NEUTRAL CONDITIONS. 
 
 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
MOST RECENT DYNAMICAL AND STATISTICAL SST FORECASTS FOR THE NINO 3.4 REGION 
INDICATE THAT THE LATE SUMMER AND EARLY FALL SSTS WILL RANGE BETWEEN -0.5 AND 
+0.5 C, INDICATING ENSO-NEUTRAL CONDITIONS.  THE NCEP CFS CONTINUES TO BE ONE 
OF THE WARMEST MODELS, PREDICTING NINO 3.4 ANOMALIES OF +0.5 C BY THE AUGUST, 
HOWEVER SST ANOMALIES PREDICTED BY THE CFS GRADUALLY DECREASE PAST AUGUST AND 
REACH NEAR ZERO ANOMALIES BY DECEMBER.  STATISTICAL SST FORECASTS RUN AT NCEP 
KEEP NINO 3.4 SSTS STEADY AT AROUND -0.5 C THROUGH THE END OF THE YEAR.  A 
CONSOLIDATION OF THESE FORECASTS SUGGESTS THAT NINO 3.4 SST ANOMALIES MAY PEAK 
IN LATE SUMMER AT AROUND -0.3 C, THEN DECREASE TO AROUND -0.6 BY NDJ BEFORE 
RETURNING TO NEAR ZERO BY AMJ 2009.  TAKING THE SPREAD IN MODEL PREDICTIONS 
INTO ACCOUNT, AND CONSIDERING CURRENT OBSERVATIONS AND SST FORECASTS FROM 
MODELS RUN AT OTHER CENTERS THAT ARE NOT INCLUDED IN THE CONSOLIDATION 
FORECAST, ENSO NEUTRAL CONDITIONS ARE EXPECTED WITH NINO 3.4 SSTS EXPECTED TO 
BE WITHIN 0.5 DEGREES OF NORMAL THROUGH EARLY SPRING 2009. 
 
ATMOSPHERIC CONDITIONS RELATED TO LA NINA OFTEN PERSIST FOR A FEW MONTHS AFTER 
SSTS RETURN TO ENSO-NEUTRAL CONDITIONS.  THUS RESIDUAL LA NINA IMPACTS MAY HAVE 
A SLIGHT POSITIVE IMPACT ON HURRICANE ACTIVITY IN THE ATLANTIC AND SLIGHTLY 
SUPPRESS HURRICANE ACTIVITY IN THE EASTERN PACIFIC IN THE UPCOMMING SEASON, 
HOWEVER GIVEN THAT ENSO IS EXPECTED TO TRANSITION TO NEUTRAL CONDITIONS BY LATE 
SUMMER, ITS INFLUENCE IS NOT EXPECTED TO BE STRONG.  THE CURRENT SST FORECAST 
REMAINS CONSISTENT WITH THOSE AVAILABLE AT THE TIME THE NOAA HURRICANE OUTLOOK 
WAS RELEASED IN EARLY JUNE (SEE THE NOAA 2008 HURRICANE SEASON OUTLOOK 
DISCUSSION FOR MORE INFORMATION). 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR ALL LEAD TIMES ARE BASED ON THE 
CONSOLIDATION (CON), A SKILL-WEIGHTED AND CALIBRATED OBJECTIVE BLEND OF THE 
CFS, CCA, SMLR, OCN, AND ECCA FORECAST TOOLS.  THE CON TOOL IS NOT AVAILABLE 
FOR ALASKA, SO THE FORECAST THERE IS BASED MOSTLY ON OCN, CCA, SMLR AND THE 
CFS.  ENSO IS NOT EXPECTED TO HAVE AN IMPACT ON THIS SET OF FORECASTS, ASIDE 
FROM THE RESIDUAL EFFECTS OF THIS PAST WINTERS LA NINA, WHICH INCLUDE THE 
INITIAL SOIL MOISTURE PATTERN OVER THE U.S., AND BELOW NORMAL SSTS IN PACIFIC 
ADJACENT NORTH AMERICA. 
 
THE TEMPERATURE AND PRECIPITATION FORECAST FOR ALL LEADS IS BASED ON THE 5-TOOL 
CON FORECAST.  LOCAL FACTORS ALSO AFFECT THE FIRST SEVERAL LEADS OF THE 
TEMPERATURE FORECAST.  THESE INCLUDE COLD SST ANOMALIES IN THE EASTERN NORTH 
PACIFIC ALONG THE WEST COAST OF NORTH AMERICA AND SOUTH OF ALASKA, AMPLE SOIL 
MOISTURE IN THE CENTRAL U.S., AND DRY SOIL MOISTURE CONDITIONS IN CALIFORNIA. 
THE CFS DROPS OUT OF THE CON AFTER LEAD 6 (DJF), AND ONLY STATISTICAL TOOLS 
(OCN, CCA, SMLR, ECCA) CONTRIBUTE TO CON AFTER THAT. 
 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - JAS 2008 TO JAS 2009 
 
TEMPERATURE: 
 
THE OUTLOOK FOR JAS 2008 CALLS FOR ABOVE NORMAL TEMPERATURES IN THE 
SOUTHWESTERN U.S., EXTENDING NORTHWARD TO INCLUDE MUCH OF THE GREAT BASIN AND 
INTERIOR CALIFORNIA.  THIS AREA REFLECTS OCN, CCA, AND THE IRI MULTI-MODEL 
ENSEMBLE FORECASTS.  DRY SOIL MOISTURE CONDITIONS IN PARTS OF CALIFORNIA 
CONTRIBUTED TO ANTICIPATED ABOVE NORMAL TEMPERATURES IN INTERIOR CALIFORNIA. 
ABOVE NORMAL TEMPERATURES ARE ALSO EXPECTED IN THE NORTHEASTERN U.S. BASED ON 
THE CONSOLIDATION FORECAST.  BELOW NORMAL SSTS IN THE ALONG THE PACIFIC COAST 
OF NORTH AMERICA WILL ELEVATE CHANCES OF BELOW NORMAL TEMPERATURES IN ADJACENT 
COASTAL AREAS FROM JAS THROUGH SON. 
 
THE TEMPERATURE FORECASTS FOR OND 2008 AND BEYOND PRIMARILY REFLECT TEMPERATURE 
TRENDS AND INDICATES THE AREA OF ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES 
WILL GRADUALLY EXPAND TO INCLUDE MOST OF THE COUNTRY BY DJF 2008-2009 EXCEPT 
FOR THE AREAS IN THE FAR WEST.  SIGNALS FOR ENHANCED CHANCES OF ABOVE NORMAL 
TEMPERATURES WEAKEN IN THE TRANSITION SEASONS, SO THE AREA OF ABOVE NORMAL 
DIMINISHES WITH LEAD TIME IN THE SPRING, REACHING A MINIMUM IN MAM WHEN ONLY 
THE SOUTHWESTERN U.S. AND THE GREAT BASIN SHOW ELEVATED CHANCES OF ABOVE NORMAL 
TEMPERATURES.  THE AREA OF EXPECTED ABOVE NORMAL TEMPERATURES THEN GRADUALLY 
EXPANDS AS THE SUMMER SEASON APPROACHES. OCN INDICATES ELEVATED CHANCES OF 
ABOVE NORMAL TEMPERATURES WILL COVER MUCH OF ALASKA FROM AMJ TO JAS 2009. 
 
 
 
 
 
PRECIPITATION: 
 
ABOVE MEDIAN PRECIPITATION IS CALLED FOR IN SOUTHERN ALASKA FROM JAS THROUGH 
SON 2008 DUE MANLY TO SMLR.  BELOW MEDIAN RAINFALL AMOUNTS ARE EXPECTED IN 
SECTIONS OF THE NORTHWESTERN CONUS FROM JJA THROUGH ASO FROM THE CCA OCN. 
ABOVE MEDIAN RAINFALL IS PREDICTED FOR SECTIONS OF THE NORTHEAST AND THE 
SOUTHEAST FORM JAS TO SON DUE MOSTLY TO SMLR COMBINED WITH WEAK TRENDS.  THERE 
IS A TENDENCY FOR ABOVE MEDIAN PRECIPITATION FROM THE OHIO VALLEY TO NEW YORK, 
FROM NDJ 2008/2009 TO JFM 2009, DUE MAINLY TO WEAK SIGNALS FROM OCN AND THE 
CFS.  BELOW MEDIAN PRECIPITATION AMOUNTS ARE EXPECTED FOR PARTS OF THE 
SOUTHEASTERN CONUS FROM NDJ 2008-2009 TO MAM 2009 WITH ALL TOOLS CONTRIBUTING. 
THERE ARE CONSISTENT SIGNALS AMONG THE TOOLS FOR BELOW-MEDIAN PRECIPITATION IN 
THE NORTHERN ROCKIES FROM JFM-FMA 2009.  AN AREA OF EXPECTED BELOW MEDIAN 
PRECIPITATION AMOUNTS FORECAST FOR PARTS OF THE CENTRAL ROCKIES IN AMJ 2009 IS 
BASED ON THE CON TOOL.  THIS AREA GRADUALLY SHIFTS TOWARD THE PACIFIC NORTHWEST 
BY JAS 2009 WHERE IT IS SUPPORTED BY STRONG INDICATIONS FROM BOTH CCA AND OCN. 
THERE ARE SOME WEAK INDICATIONS FOR ABOVE MEDIAN PRECIPITATION IN PARTS OF 
TEXAS FROM MJJ TO JJA 2009, AND IN NEW ENGLAND FROM AMJ TO JAS 2009. 
 
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 17 2008 
 
1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17, 2001 
FORECAST RELEASE. 
 
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