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. $$