90 Day Narrative
739 FXUS05 KWBC 181231 PMD90D PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EDT THURSDAY JUL 18 2013 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS THE MAIN FACTORS THAT USUALLY INFLUENCE THE SEASONAL CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH TOGETHER COMPRISE EL NINO/SOUTHERN OSCILLATION OR ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM 3 OR MORE DECADES INTO EL NINO, NEUTRAL, AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "ENSO COMPOSITES", WHICH ARE USED AT TIMES TO SUBJECTIVELY MODIFY THE FORECAST. 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 1981-2010). 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 CONSIDERED LESS PREDICTABLE ON A SEASONAL TIMESCALE THAN ENSO. 5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE VARIABILITY AFFECTING 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 SPRING AND 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), CONSTRUCTED ANALOGUE (CA) AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS). AN EXPERIMENTAL MODEL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE, COMPRISED OF SEVERAL MODELS AND DESIGNATED NMME, MAY ALSO BE USED EXPERIMENTALLY AND SUBJECTIVELY UNTIL IT IS INCLUDED INTO THE CONSOLIDATION. AN INTERNATIONAL MODEL ENSEMBLE DESIGNATED IMME IS ALSO AVAILABLE. 9) CONSOLIDATION (CON) - AN OBJECTIVE, SKILL WEIGHTED COMBINATION 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. RECENT ATMOSPHERIC AND OCEANIC OBSERVATIONS CONTINUE TO INDICATE ENSO NEUTRAL CONDITIONS, AND THE OFFICIAL ENSO OUTLOOK IS FOR A CONTINUATION OF THE ENSO NEUTRAL STATE INTO AT LEAST THE NORTHERN HEMISPHERE AUTUMN OF 2013. THERE IS GREATER UNCERTAINTY IN THE STATE OF ENSO FROM LATE 2013 ONWARDS. THE ASO 2013 TEMPERATURE OUTLOOK INDICATES ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS MOST OF THE WESTERN CONTINENTAL U.S. STRETCHING EASTWARD ACROSS THE CENTRAL AND SOUTHERN PLAINS TO INCLUDE PARTS OF ARKANSAS AND LOUISIANA. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE NORTH SLOPE OF ALASKA AND PARTS OF THE NORTHEAST. CONFIDENCE IN THE FORECAST IS HIGHEST FOR THE REGION OF THE ROCKY MOUNTAINS FROM ARIZONA IN THE SOUTH TO THE CANADIAN BORDER IN THE NORTH. THE ASO 2013 PRECIPITATION OUTLOOK CALLS FOR ELEVATED CHANCES OF ABOVE MEDIAN PRECIPITATION IN PARTS OF THE SOUTHWEST MONSOON REGION AND FOR THE SOUTHEAST. BELOW MEDIAN PRECIPITATION AMOUNTS ARE MORE LIKELY FOR PARTS OF SOUTHERN ALASKA. IN AREAS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) IS SHOWN. 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 EQUATORIAL SST ANOMALIES CONTINUE TO BE NEAR ZERO FOR MUCH OF THE WESTERN AND CENTRAL PACIFIC IN EARLY JULY, WHILE NEGATIVE ANOMALIES INCREASED IN MAGNITUDE AND AREAL EXTENT FROM ABOUT 120W LONGITUDE TO THE SOUTH AMERICAN COAST. IN THE MOST RECENT WEEK, SST ANOMALIES IN THE NINO3.4 REGION ARE ABOUT -0.4 DEGREES CELSIUS. POSITIVE EQUATORIAL OCEAN TEMPERATURE ANOMALIES WERE OBSERVED AT DEPTHS OF APPROXIMATELY 100-250 METERS BELOW THE SURFACE FOR MUCH OF THE WESTERN AND CENTRAL PACIFIC AND NEARER THE SURFACE FOR PARTS OF THE CENTRAL AND EASTERN PACIFIC TO ABOUT 100W. LOW-LEVEL AND UPPER-LEVEL WINDS REMAINED NEAR AVERAGE ACROSS THE EQUATORIAL PACIFIC. TROPICAL CONVECTION CONTINUES TO BE ENHANCED OVER THE AREA OF THE MARITIME CONTINENT AND SUPPRESSED ALONG THE EQUATOR OVER THE CENTRAL AND EASTERN PACIFIC. THESE OCEANIC AND ATMOSPHERIC CONDITIONS REFLECT THE ENSO NEUTRAL STATE. PROGNOSTIC DISCUSSION OF SST FORECASTS ENSO NEUTRAL CONDITIONS ARE EXPECTED TO CONTINUE INTO AT LEAST THE NORTHERN HEMISPHERE AUTUMN OF 2013. THE CPC CONSOLIDATION OF NINO3.4 SST FORECASTS PREDICTS ANOMALIES LIKELY RANGING FROM 0.0 TO -0.5 DEGREES C THROUGH THE REMAINDER OF 2013 AND INTO 2014. THE RANGE OF MOST DYNAMICAL AND STATISTICAL MODEL FORECASTS INCLUDED IN THE IRI PLUME, NMME AND IMME REMAINS FROM -0.5 TO +0.5 DEGREES C INTO AUTUMN OF 2013. THE SPREAD OF NINO3.4 SST FORECASTS INCLUDING STATISTICAL AND DYNAMICAL MODELS CONTINUES TO BE HIGH, REFLECTING GREATER UNCERTAINTY IN THE ENSO OUTLOOK THAN TYPICAL FOR THIS TIME OF YEAR. OVERALL, FORECASTS FAVOR A CONTINUATION OF THE ENSO NEUTRAL STATE INTO AUTUMN, AND ENSO NEUTRAL CONTINUES TO BE SLIGHTLY FAVORED INTO THE WINTER. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS THE TEMPERATURE AND PRECIPITATION OUTLOOKS WERE MADE CONSIDERING ENSO NEUTRAL CONDITIONS TO BE MOST LIKELY THROUGH EARLY 2014. THE FORECASTS FROM ASO THROUGH DJF 2013-14 WERE BASED ON A COMBINATION OF STATISTICAL TOOLS AND DYNAMICAL MODEL GUIDANCE INCLUDING THE CFS, THE NMME AND THE IMME. INITIAL SOIL MOISTURE CONDITIONS PLAYED A ROLE IN THE OUTLOOKS DURING ASO 2013. THE CONSOLIDATION AND DECADAL TRENDS FROM THE OCN WERE CONSIDERED IN THE FORECASTS STARTING IN ASO 2013 THROUGH ASO 2014. DECADAL CLIMATE TRENDS WERE THE PRIMARY SOURCE OF PREDICTABILITY FOR THE FORECASTS AFTER JFM 2014. PROGNOSTIC DISCUSSION OF OUTLOOKS - ASO 2013 TO ASO 2014 TEMPERATURE THE SEASONAL TEMPERATURE OUTLOOK FOR ASO 2013 INDICATES ELEVATED CHANCES OF ABOVE-NORMAL TEMPERATURES FOR MOST OF THE WESTERN CONUS, THE SOUTHERN ALASKAN PANHANDLE, THE SOUTHERN GREAT PLAINS, THE WESTERN LOWER MISSISSIPPI VALLEY, EASTERN PARTS OF THE NORTHEAST AND MID-ATLANTIC STATES, AND THE NORTH SLOPE OF ALASKA. THE HIGHEST PROBABILITIES ARE ALONG THE ROCKY MOUNTAINS AND THE NORTH SLOPE OF ALASKA. THESE FORECASTS ARE BASED PRIMARILY ON DYNAMICAL MODEL GUIDANCE FROM THE CFS, NMME AND IMME. ANOMALOUSLY WET INITIAL SOIL MOISTURE CONDITIONS AND RECENT FORECASTS FROM DYNAMICAL MODELS INDICATE NEAR OR BELOW AVERAGE TEMPERATURES OVER MUCH OF THE EASTERN U.S. ALONG WITH ABOVE MEDIAN PRECIPITATION. CONFLICTING SIGNALS FOR ABOVE NORMAL TEMPERATURES FROM DECADAL TRENDS LEADS TO AN EQUAL CHANCES FORECAST FOR THIS REGION. THE NORTH SLOPE OF ALASKA IS MORE LIKELY TO EXPERIENCE ABOVE NORMAL TEMPERATURES FOR ASO THROUGH OND 2013 DUE TO SIGNIFICANT POSITIVE DECADAL TEMPERATURE TRENDS, RELATED TO A REDUCTION IN ARCTIC OCEAN SEA ICE COVER DURING RECENT YEARS FOR THE SPRING THROUGH AUTUMN SEASONS. FROM AUTUMN 2013 THROUGH WINTER, CHANCES FOR ABOVE NORMAL TEMPERATURES ARE INCREASED FOR THE GREAT LAKES REGION. THE PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE INCREASED ACROSS THE GREAT PLAINS AND MUCH OF THE EASTERN U.S. BEGINNING IN OND 2013 FOLLOWING DYNAMICAL MODEL FORECASTS FROM THE NMME AND IMME AND LONG-TERM TEMPERATURE TRENDS. AFTER THE WINTER SEASONS, ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES BEGIN TO DECREASE IN AREAL EXTENT FOR MUCH OF THE CENTRAL AND EASTERN U.S. AS THE PREDICTABILITY OF THIS POSITIVE TEMPERATURE TREND DECREASES, AS INDICATED BY THE CONSOLIDATION. ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE INDICATED FOR THE PACIFIC NORTHWEST IN FMA AND MAM 2014 FOLLOWING DECADAL TEMPERATURE TRENDS. ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE FORECAST FOR SOUTHERN ALASKA IN OND AND NDJ 2013, FOLLOWING DYNAMICAL MODEL GUIDANCE OF THE CFS AND NMME. IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF BELOW, NEAR AND ABOVE NORMAL SEASONAL MEAN TEMPERATURES ARE INDICATED. PRECIPITATION THE ASO 2013 PRECIPITATION OUTLOOK INDICATES AN ENHANCED LIKELIHOOD OF ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE SOUTHEASTERN U.S. AND PARTS OF THE SOUTHWEST MONSOON REGION. ENHANCED PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE INDICATED FOR MUCH OF SOUTHERN ALASKA IN ASO 2013, CONTINUING THROUGH OND 2013. THESE FORECASTS ARE PRIMARILY BASED ON DYNAMICAL MODEL GUIDANCE FROM THE NMME AND IMME. CONSIDERATION FOR THE PREDICTION OF AN ABOVE-AVERAGE ATLANTIC TROPICAL STORM SEASON, LARGELY CONSISTENT WITH DECADAL TRENDS, ARE ALSO CONSIDERED IN THE OUTLOOK FOR ABOVE MEDIAN PRECIPITATION IN THE SOUTHEAST. A CONSENSUS OF FORECASTS FROM THE CFS, NMME AND IMME MODELS FAVORS ABOVE-MEDIAN PRECIPITATION IN THE SOUTHWEST MONSOON REGION PRIMARILY DUE TO GREATER THAN MEDIAN PRECIPITATION IN THE MONTH OF AUGUST. DYNAMICAL MODEL GUIDANCE IS ALSO THE SOURCE OF INFORMATION INDICATING ENHANCED CHANCES OF ABOVE MEDIAN PRECIPITATION IN NORTHERN PARTS OF THE PACIFIC NORTHWEST IN SON THROUGH NDJ 2013. DECADAL TRENDS FOR BELOW MEDIAN PRECIPITATION APPEAR IN THE SOUTHEAST FOR NDJ 2013 THROUGH JFM 2014 AND IN THE PACIFIC NORTHWEST FOR JJA AND JAS 2014. IN AREAS WITHOUT SUBSTANTIAL AND RELIABLE CLIMATE SIGNALS, EQUAL CHANCES OF BELOW, NEAR AND ABOVE MEDIAN SEASONAL TOTAL PRECIPITATION AMOUNTS ARE INDICATED. FORECASTER: DAN COLLINS THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING THE WORLD METEROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3 COMPLETE DECADES AS THE CLIMATIC REFERENCE PERIOD. THE PROBABILITY ANOMALIES FOR TEMPERATURE AND PRECIPITATION BASED ON THESE NEW NORMALS BETTER REPRESENT SHORTER TERM CLIMATIC ANOMALIES THAN THE FORECASTS BASED ON OLDER NORMALS. 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 AUG 15 2013 1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 FORECAST RELEASE. $$