PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 300PM EDT WEDNESDAY OCT 31 2012 30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2012 THE UPDATED NOVEMBER OUTLOOK SHOWS A LARGE AREA OF ENHANCED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOR THE SOUTHWEST, INTERMOUNTAIN WEST AND WESTERN GREAT PLAINS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR AREAS ACROSS THE SOUTHEAST U.S. AS WELL AS THE SOUTH COAST OF ALASKA AND THE ALASKA PANHANDLE. THERE IS AN ENHANCED LIKELIHOOD FOR ABOVE NORMAL TEMPERATURES FOR THE NORTH SLOPE OF ALASKA. ABOVE-MEDIAN PRECIPITATION IS FAVORED FOR THE NORTH SLOPE OF ALASKA AS WELL AS MUCH OF THE NORTHERN TIER OF THE U.S. FROM IDAHO TO THE GREAT LAKES. THERE ARE ENHANCED CHANCES FOR BELOW-MEDIAN PRECIPITATION FOR MUCH OF THE WEST COAST, SOUTHWEST, EXTENDING INTO THE SOUTH-CENTRAL GREAT PLAINS. WHERE WEATHER AND CLIMATE SIGNALS ARE LESS CLEAR OR CONFLICTING, EQUAL CHANCES (EC) FOR ABOVE-, NEAR- OR BELOW-AVERAGE TEMPERATURE AND PRECIPITATION, ARE INDICATED. THE MONTHLY UPDATE IS ABLE TO UTILIZE SHORT- AND EXTENDED-RANGE FORECASTS FROM NUMERICAL WEATHER FORECAST MODELS IN ADDITION TO THE MORE TRADITIONAL LONGER RANGE FORECAST TOOLS. ABOVE-NORMAL TEMPERATURES REMAIN FAVORED ACROSS MUCH OF THE WESTERN U.S. AND IS ENLARGED WITH SLIGHTLY HIGHER PROBABILITIES AS SHORT- AND EXTENDED RANGE MODEL GUIDANCE ARE CONSISTENT WITH THIS AREA. UPCOMING MJO PHASES ALSO SUPPORT THE FORECAST FOR SOME NORTHERN AND EASTERN PORTIONS OF THIS AREA. THE HIGHEST PROBABILITIES ARE INDICATED ACROSS THE SOUTHWEST WHERE BOTH SHORT-, EXTENDED-RANGE TOOLS AND THE CFSV2 MONTHLY FORECAST ARE IN AGREEMENT. A EASTERN U.S. TROUGH AND BELOW NORMAL HEIGHTS FORECAST DURING APPROXIMATELY THE FIRST 10 DAYS OF NOVEMBER LEAN PROBABILITIES TOWARD THE COLD SIDE FOR PARTS OF THE SOUTHEAST. THE NAEFS AND OTHER EXTENDED RANGE FORECAST TOOLS FAVOR BELOW NORMAL TEMPERATURES IN THIS REGION. COOL CONDITIONS EARLY IN THE PERIOD FOR PARTS OF THE MID-ATLANTIC AND OHIO VALLEY MAY OFFSET A TREND TOWARD ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES IN EXTENDED RANGE FORECAST GUIDANCE AND THE CFSV2. CONSEQUENTLY, EC IS INDICATED FOR THESE AREAS. BELOW NORMAL TEMPERATURES ARE REMOVED FROM THE OUTLOOK ACROSS THE COASTAL PACIFIC NORTHWEST SINCE SHORT AND MEDIUM RANGE FORECAST GUIDANCE FAVOR ABOVE NORMAL TEMPERATURES AND SSTS HAVE WARMED. EXTENDED RANGE FORECAST GUIDANCE AND CONTINUED BELOW-NORMAL SSTS ELEVATE CHANCES FOR BELOW NORMAL TEMPERATURES ACROSS THE SOUTH COAST OF ALASKA AND THE ALASKA PANHANDLE SO THIS AREA HAS BEEN ADDED TO THE OUTLOOK. FOR PRECIPITATION, COVERAGE FOR ELEVATED CHANCES OF BELOW-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST IN THE HALF MONTH LEAD OUTLOOK HAVE BEEN REDUCED AND MAINLY ENCOMPASS THE WESTERN HALF OF OREGON. PRECIPITATION IN NORTHERN AND EASTERN AREAS OF THE ORIGINAL HIGHLIGHTED AREA LEAD TO A DESIGNATION OF EC IN THOSE AREAS IN THE UPDATE. NAEFS EXTENDED RANGE FORECAST GUIDANCE FAVOR ABOVE-MEDIAN PRECIPITATION FOR AN AREA FROM NORTHERN IDAHO TO MICHIGAN AND THE BELOW-AVERAGE PRECIPITATION AREA ACROSS THE MIDWEST IN THE HALF MONTH LEAD OUTLOOK WAS SHIFTED SOUTHWESTWARD AND JOINED WITH AN AREA STRETCHING FROM CALIFORNIA ACROSS THE SOUTHWEST, AND IS MAINLY DUE TO EXTENDED RANGE FORECAST GUIDANCE AND THE CFSV2 MONTHLY FORECAST. MJO PHASES LATER DURING THE MONTH, IF THE ACTIVITY CONTINUES, ALSO FAVOR BELOW-MEDIAN PRECIPITATION FOR MUCH OF THE WEST COAST. PREVIOUS DISCUSSION ENSO NEUTRAL CONDITIONS CONTINUED DURING THE FIRST HALF OF OCTOBER WITH EQUATORIAL SEA SURFACE TEMPERATURES (SSTS) CLOSE TO AVERAGE ACROSS MUCH OF THE WESTERN AND CENTRAL PACIFIC. POSITIVE ANOMALIES GREATER +0.5 DEGREES C ARE EVIDENT IN A FEW AREAS IN THE WESTERN AND CENTRAL PACIFIC WITH BELOW NORMAL SSTS NOW EVIDENT ACROSS THE EASTERN PACIFIC EAST OF 120W WITH SOME AREAS SHOWING ANOMALIES NEAR OR LARGER THAN -1.5 DEGREES C. EL NINO COMPOSITES WERE NOT CONSIDERED IN THE MONTHLY OUTLOOK. THE NOVEMBER TEMPERATURE OUTLOOK INDICATES ENHANCED CHANCES FOR ABOVE-NORMAL MEAN TEMPERATURES FOR MUCH OF THE CENTRAL AND SOUTHERN ROCKIES, SOUTHWEST AND PARTS OF THE CENTRAL AND SOUTHERN PLAINS. THE PRIMARY RATIONALE FOR THIS AREA IS CONSISTENT INDICATORS IN CLIMATE FORECAST MODELS AS PART OF THE NATIONAL MULTI MODEL ENSEMBLE (NMME), INCLUDING THE CFS VERSION 2. OTHER MORE TRADITIONAL EMPIRICAL FORECAST TOOLS SUCH AS THE CCA AND OCN ALSO INDICATE A TILT IN THE ODDS TOWARD ABOVE NORMAL IN SOME OF THESE AREAS. SINCE LONGER RANGE CLIMATE SIGNALS ARE GENERALLY WEAK, PROBABILITIES ARE LOW FOR THIS AREA. BELOW NORMAL SSTS AND FORECASTS AS PART OF THE NMME FAVOR BELOW NORMAL TEMPERATURES FOR AREAS ACROSS THE COASTAL PACIFIC NORTHWEST. THERE IS ALSO AN ENHANCED LIKELIHOOD FOR ABOVE NORMAL TEMPERATURES FOR A SMALL AREA ACROSS THE COASTAL AREAS OF SOUTHERN CALIFORNIA RELATED TO RECENT ABOVE NORMAL SSTS IN THIS REGION. REVIEW OF RECENT TEMPERATURE ANOMALIES FOR COASTAL STATIONS IN THIS AREA SHOW THIS TENDENCY OVER THE PAST 30 TO 90 DAYS. THE MOST CONFIDENT PORTION OF THE TEMPERATURE FORECAST IS FOR ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES FOR NORTHERN AND CENTRAL ALASKA WHERE ABOVE NORMAL SSTS CONTINUE AND THERE IS A HIGH DEGREE OF AGREEMENT AMONG NMME CLIMATE FORECAST MODELS. THE HIGHEST PROBABILITIES ARE ALONG THE NORTH SLOPE WHERE OPEN WATERS ARE MOST LIKELY TO HAVE THE GREATEST IMPACT. THE NOVEMBER PRECIPITATION OUTLOOK HIGHLIGHTS TWO AREAS FOR BELOW-MEDIAN TOTAL MONTHLY PRECIPITATION, ONE ACROSS THE PACIFIC NORTHWEST AND SOUTHERN ALASKA PANHANDLE AND ANOTHER SITUATED IN THE MIDWEST. BOTH OF THESE REGIONS ARE PRIMARILY SUPPORTED BY THE CFS VERSION 2, BUT THESE AREAS ARE ALSO SUPPORTED BY EMPIRICAL FORECASTS FROM THE CCA, SMLR AND OCN. MORE OPEN WATERS AND STRONG AGREEMENT AMONG CLIMATE FORECAST MODELS FAVOR ABOVE-MEDIAN PRECIPITATION FOR NORTHERN ALASKA IN NOVEMBER. THE MAIN FACTORS WHICH USUALLY INFLUENCE THE MONTHLY CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH COMPRISE ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM THREE OR MORE DECADES INTO EL NINO, NEUTRAL AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "COMPOSITES" AND 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 - CALLED THE MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE ARCTIC OSCILLATION (AO), THE SIMILAR NORTH ATLANTIC OSCILLATION (NAO), AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING BOREAL WINTER AND ARE GENERALLY CONSIDERED TO HAVE LOW PREDICTABILITY. 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) PERSISTANTLY 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 MODELS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOG (CA), AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM (CFS) AND FOR ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS). THE UPGRADED VERSION OF THE CFS (CFSV2) BECAME OPERATIONAL IN LATE MARCH OF 2011. BOTH VERSIONS OF CFS ARE CURRENTLY RUN IN PARALLEL. AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE (NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED. FORECASTER: JON GOTTSCHALCK THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING THE WORLD METEOROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3 COMPLETE DECADES AS THE CLIMATE 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. THE NEXT MONTHLY OUTLOOK...FOR DEC ... WILL BE ISSUED ON THU NOV 15 2012 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$