PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THURSDAY OCT 18 2012

30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2012

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.



AN UPDATED MONTHLY OUTLOOK... FOR NOV WILL BE ISSUED ON WED OCTOBER 31 2012


THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.

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