PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 300PM EDT SATURDAY OCT 31 2015 30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2015 THE UPDATED MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS FOR NOVEMBER 2015 ARE BASED PRIMARILY ON THE LATEST DYNAMICAL MODEL GUIDANCE, WEATHER PREDICTION CENTER (WPC) TEMPERATURE AND PRECIPITATION FORECASTS DURING THE FIRST WEEK OF NOVEMBER, THE CPC 6-10/8-14 DAY TEMPERATURE AND PRECIPITATION OUTLOOKS, AND CPC'S EXPERIMENTAL WEEKS 3-4 TEMPERATURE AND PRECIPITATION OUTLOOKS. ALTHOUGH THE MJO BECAME MORE COHERENT DURING LATE OCTOBER, IT IS NOT EXPECTED TO PLAY A MAJOR ROLE WITH THE ONGOING, STRONG EL NINO REMAINING THE MORE DOMINANT MODE OF CLIMATE VARIABILITY. THE UPDATED MONTHLY TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES ACROSS THE NORTH-CENTRAL AND EASTERN U.S. HIGHER PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ACROSS THE GREAT LAKES ARE BASED ON THE PREDICTION OF LARGE POSITIVE ANOMALIES DURING THE FIRST WEEK OF THE MONTH, A GFS FORECAST OF A POSITIVE ARCTIC OSCILLATION INDEX, AND A VERY CONSISTENT SIGNAL FOR ABOVE-NORMAL TEMPERATURES FROM THE CFS MODEL DATING BACK TO MID-OCTOBER. SINCE TROPICAL CYCLONE ACTIVITY WANED DURING LATE OCTOBER ACROSS THE WEST PACIFIC, RECURVING TYPHOONS ARE NOT EXPECTED TO AFFECT THE LONGWAVE PATTERN DOWNSTREAM OVER NORTH AMERICA. BELOW-NORMAL TEMPERATURES ARE FAVORED ACROSS PARTS OF THE GREAT BASIN AND SOUTHWEST DUE TO BELOW-NORMAL TEMPERATURES EXPECTED EARLY IN NOVEMBER UNDER AN AMPLIFIED UPPER-LEVEL TROUGH, AND A CONTINUED SIGNAL FOR BELOW-NORMAL TEMPERATURES IN CPC'S 8-14 DAY OUTLOOK AND CPC'S EXPERIMENTAL WEEKS 3-4 TEMPERATURE OUTLOOKS. FRESH SNOW COVER EXPECTED AT THE BEGINNING OF THE MONTH ALSO FAVORS BELOW-NORMAL TEMPERATURES FOR PARTS OF THE GREAT BASIN. THEREFORE, A TWO CATEGORY CHANGE IN THE TEMPERATURE OUTLOOK RELEASED ON OCTOBER 15 IS NECESSARY. SEA SURFACE TEMPERATURES (SSTS) REMAIN ABOVE-NORMAL ALONG THE WEST COAST WHICH FAVORS ABOVE-NORMAL TEMPERATURES FOR THIS REGION. EL NINO TEMPERATURE COMPOSITES AND ABOVE-NORMAL SSTS INCREASE CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF ALASKA. THE CFS MODEL CONTINUES TO DEPICT ENHANCED ODDS FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE SOUTHEAST, LOWER MISSISSIPPI VALLEY, AND PARTS OF THE SOUTHWEST. A NOTABLE CHANGE IN THE PRECIPITATION OUTLOOK COMPARED TO THE 0.5 LEAD RELEASED ON OCTOBER 15 IS THE REDUCTION OF BELOW-MEDIAN PRECIPITATION FAVORED FOR THE NORTHERN ROCKIES AND NORTHERN GREAT PLAINS AND A NORTHWARD EXPANSION OF ABOVE-MEDIAN PRECIPITATION ACROSS THE ROCKIES. THESE CHANGES ARE DUE TO THE AMPLIFIED TROUGH EARLY IN NOVEMBER ALONG WITH CONSISTENT PRECIPITATION FORECASTS FROM THE SHORT RANGE MODELS. DOWNSTREAM OF THE WESTERN U.S. TROUGH, ANOTHER ROUND OF HEAVY RAINFALL IS EXPECTED ACROSS THE SOUTHERN GREAT PLAINS EARLY IN NOVEMBER. THEREFORE, FORECAST CONFIDENCE IS HIGHEST FOR ABOVE-MEDIAN PRECIPITATION FOR EASTERN OKLAHOMA AND NORTH TEXAS. MOST TOOLS AND THE PREDICTED LONGWAVE PATTERN DURING EARLY TO MID-NOVEMBER OVER NORTH AMERICA SUPPORT A SLIGHT TILT IN THE ODDS FOR BELOW-MEDIAN PRECIPITATION FOR NEW ENGLAND. SIMILAR TO MID-OCTOBER, THE CFS MODEL CONTINUES TO INDICATE A WEAK PRECIPITATION SIGNAL ALONG THE WEST COAST. ABOVE-MEDIAN PRECIPITATION IS EXPECTED TO ACCOMPANY ABOVE-NORMAL TEMPERATURES ACROSS THE ALEUTIANS, SOUTHWEST ALASKA, AND SOUTHERN COASTAL AREAS OF ALASKA. ----------- PREVIOUS MESSAGE (FROM OCTOBER 15) IS SHOWN BELOW ------------ 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. THE NEXT MONTHLY OUTLOOK...FOR DEC ... WILL BE ISSUED ON THU NOV 19 2015 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$