PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THURSDAY OCT 15 2015

30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2015

THE ONGOING EL NINO IS PREDICTED TO PEAK DURING THE LATE FALL OR EARLY WINTER. 
PLEASE SEE THE ENSO DIAGNOSTIC DISCUSSION AT: 
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/ENSO_ADVISORY/ FOR A 
MORE DETAILED ANALYSIS OF SEA SURFACE TEMPERATURES ACROSS THE EQUATORIAL 
PACIFIC. THIS STRONG EL NINO IS EXPECTED TO CONTINUE TO PLAY A MAJOR ROLE IN 
CLIMATE ANOMALIES ACROSS THE FORECAST DOMAIN. THE NOVEMBER TEMPERATURE AND 
PRECIPITATION OUTLOOK IS BASED ON PATTERNS TYPICALLY ASSOCIATED WITH EL NINO 
ALONG WITH GUIDANCE FROM THE DYNAMICAL MODELS. THE MJO REMAINS WEAK AT THIS 
TIME ALTHOUGH RECENT DYNAMICAL MODELS INDICATE AN INCREASE IN THE AMPLITUDE OF 
THE MJO SIGNAL DURING LATE OCTOBER.  THE MJO IS NOT A FACTOR IN THIS NOVEMBER 
OUTLOOK BUT MAY NEED TO BE CONSIDERED FOR THE UPDATE ON OCTOBER 31. 

INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS MUCH OF THE 
CONTINENTAL U.S. AND ALASKA WHICH IS CONSISTENT WITH THE ONGOING STRONG EL 
NINO. RELATIVELY HIGH PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ACROSS THE 
EASTERN U.S. ARE A COMMON FEATURE AMONG CFS TEMPERATURES FORECASTS DATING BACK 
A WEEK AGO. HOWEVER, PROBABILITIES ARE REDUCED ACROSS THE EASTERN U.S. DUE TO 
UNCERTAINTY UPSTREAM ACROSS THE NORTH PACIFIC. THE SLIGHTLY HIGHER 
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ACROSS THE NORTH SLOPE OF ALASKA ARE 
BASED ON A VERY ROBUST TREND DURING THE PAST 15 YEARS. A SLIGHT TILT IN THE 
ODDS TOWARDS BELOW-NORMAL TEMPERATURES FORECAST ACROSS THE UPPER RIO GRANDE 
VALLEY HAS MINOR SUPPORT FROM THE CFS MODEL AND IS CONSISTENT WITH THE 
BACKGROUND CLIMATE STATE. 

CONSISTENT SIGNALS FROM DYNAMICAL MODEL GUIDANCE AND ENSO-BASED COMPOSITES OF 
PRECIPITATION SUPPORT ENHANCED ODDS OF ABOVE-MEDIAN PRECIPITATION ACROSS THE 
SOUTHWEST, SOUTHERN GREAT PLAINS, GULF COAST, AND SOUTHEAST. ABOVE-MEDIAN 
PRECIPITATION IS FAVORED ACROSS THE ALEUTIANS, SOUTHERN COAST OF ALASKA, AND 
ALASKA PANHANDLE, WHICH IS CONSISTENT WITH EL NINO. RECURVING TROPICAL CYCLONES 
ACROSS THE NORTH PACIFIC COULD ALSO ENHANCE PRECIPITATION AMOUNTS ACROSS THESE 
AREAS DURING EARLY NOVEMBER. A WEAK SIGNAL FOR BELOW-NORMAL PRECIPITATION 
EXISTS AMONG DYNAMICAL MODEL GUIDANCE ACROSS THE NORTHERN ROCKIES EXTENDING 
EAST TO THE GREAT LAKES. 

THE MAIN FACTORS THAT 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) 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 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 
VERSION 2 (CFS) AND FOR THE ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE 
FORECAST SYSTEM (GEFS).  AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL 
MULTI-MODEL ENSEMBLE (NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED.


FORECASTER: BRAD PUGH


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 SAT OCTOBER 31 2015


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

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