PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EDT THU SEP 15 2016 30-DAY OUTLOOK DISCUSSION FOR OCTOBER 2016 A REVIEW OF TROPICAL SEASONAL AND INTRASEASONAL CLIMATE CONDITIONS DURING EARLY TO MID SEPTEMBER INDICATE CONTINUED ENSO-NEUTRAL CONDITIONS AND INCOHERENT MJO ACTIVITY. ALTHOUGH EQUATORIAL CENTRAL AND EASTERN PACIFIC SEA SURFACE TEMPERATURES (SST) ARE BELOW NORMAL ON AVERAGE, THEY REMAIN GENERALLY WEAKLY SO ACROSS SUBSTANTIAL PORTIONS OF THE BASIN. NEGATIVE ANOMALIES OF EQUATORIAL OCEAN HEAT CONTENT (OCEAN TEMPERATURE DEPARTURES TO A DEPTH OF 300 METERS) HAVE SLOWLY DECREASED SINCE MAY. ALTHOUGH SUPPRESSED CONVECTION IS INDICATED ACROSS PORTIONS OF THE CENTRAL PACIFIC, SUBSTANTIAL LOWER- AND UPPER-LEVEL WIND ANOMALIES, CONSISTENT WITH LA NINA, ARE LACKING. IN ADDITION TO THESE LATEST OBSERVATIONS, DYNAMICAL MODEL GUIDANCE OF FORECASTS OF NINO3.4 SST HAVE TRENDED TOWARD ENSO-NEUTRAL CONDITIONS FOR THE AUTUMN AND WINTER MONTHS AND THE ODDS FOR LA NINA HAVE DECREASED. THE LA NINA WATCH IS NO LONGER IN PLACE AND ENSO-NEUTRAL CONDITIONS ARE FAVORED THROUGH OCTOBER. MJO INDICES (CPC VELOCITY POTENTIAL AND RMM) INDICATE NO APPRECIABLE COHERENT MJO ACTIVITY DURING THE PAST MONTH AND FORECASTS DO NOT DEPICT CLEAR, LONG TERM STRENGTHENING AT THE CURRENT TIME AND THE MJO DID NOT PLAY A ROLE IN THE HALF-MONTH-LEAD OCTOBER OUTLOOK. THE OCTOBER 2016 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE PRIMARILY BASED ON AVAILABLE DYNAMICAL MODEL GUIDANCE, ALTHOUGH STATISTICAL BASED TOOLS WERE UTILIZED AS WELL INCLUDING THOSE TARGETING AUTUMN SEASON LONGER TERM TRENDS. COASTAL SST DEPARTURES FROM NORMAL ALSO PLAYED A ROLE IN THE OUTLOOK PRIMARILY FOR AREAS NEAR ALASKA AND NEW ENGLAND. THE OCTOBER TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES FOR MOST OF THE FORECAST DOMAIN. THERE IS NEARLY UNANIMOUS SUPPORT FOR ANOMALOUS WARMTH AS DEPICTED ON THE OUTLOOK MAP FROM THE NMME AND IMME MODEL SUITE WHICH INCLUDES THE CFS AND ECMWF MODELING SYSTEMS, AMONG SEVERAL OTHER PARTICIPANT MODELS. THE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE THE LARGEST FOR AREAS IN ALASKA, THE SOUTHWEST AND NEW ENGLAND. STRONGLY ABOVE NORMAL SSTS SURROUNDING WESTERN AND SOUTHERN ALASKA AND LONG TERM TRENDS ACROSS THE NORTH SLOPE INCREASE ODDS FOR ABOVE NORMAL TEMPERATURES IN THESE AREAS. STRONGLY POSITIVE LONG TERM TEMPERATURE TRENDS AND STATISTICAL GUIDANCE INCREASE PROBABILITIES FOR AREAS IN THE SOUTHWEST AND NEW ENGLAND. AVAILABLE WEEK 3-4 SPECIFIC MODEL GUIDANCE DOES SHOW AREAS OF FAVORED NEAR TO BELOW NORMAL TEMPERATURES AND GREATER UNCERTAINTY IN GENERAL ACROSS THE INTERIOR OF THE CONUS IN EARLY OCTOBER SO PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE LESS FOR PARTS OF THE CENTRAL AND NORTHERN PLAINS AND SOUTHEAST. MOREOVER, THIS UNCERTAINTY AND CONSIDERABLY WEAKER SIGNALS FOR ANOMALOUS WARMTH FROM THE NMME AND IMME DYNAMICAL MODEL SUITE SUPPORT EQUAL CHANCES (EC) FOR ABOVE, NEAR OR BELOW NORMAL TEMPERATURES ACROSS THE SOUTH CENTRAL PART OF THE CONUS. THERE IS HIGH UNCERTAINTY FOR THE PRECIPITATION OUTLOOK, AS IS TYPICAL FOR THIS TIME OF THE YEAR. THERE ARE SOME SIGNALS THAT CAN BE HIGHLIGHTED, HOWEVER, BASED ON THE CURRENTLY FAVORED FORECAST PATTERN. ANOMALOUS SOUTHERLY FLOW ACROSS THE GULF OF ALASKA FAVORS ABOVE MEDIAN PRECIPITATION FOR THE SOUTHERN AREAS OF ALASKA INCLUDING THE PANHANDLE REGION. DYNAMICAL MODEL GUIDANCE ACROSS TIME SCALES FAVORS BELOW-MEDIAN PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST AND INTERIOR SOUTHEAST DURING THE MONTH OF OCTOBER. ABOVE-MEDIAN PRECIPITATION FAVORED BY THE MONTHLY CFS FORECAST AND POTENTIAL TROUGHING ACROSS AREAS OF THE CENTRAL CONUS IS THE REASON FOR ENHANCED ODDS FOR ABOVE MEDIAN PRECIPITATION DEPICTED IN THE CENTRAL PLAINS. EQUAL CHANCES FOR ABOVE, NEAR OR BELOW-MEDIAN PRECIPITATION ARE INDICATED IN REMAINING AREAS. 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 OCT WILL BE ISSUED ON FRI SEPTEMBER 30 2016 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$