Prognostic Discussion for Long-Lead Hawaiian Outlooks NWS Climate Prediction Center College Park MD 830AM EST Thu Nov 21 2019 MONTHLY FORECAST DISCUSSION VALID DECEMBER 2019 Sea surface temperature (SST) anomalies are about positive one to two degrees Celsius surrounding the Hawaiian Islands during the previous week. For January 2019 through October 2019, rainfall total accumulations were: - Lihue Airport 26.46 inches (97 percent of normal) - Honolulu Airport 12.34 inches (108 percent of normal) - Kahului Airport 10.38 Inches (85 percent of normal) - Hilo Airport 79.35 Inches (80 percent of normal) The NCEP Climate Forecast System (CFS) and other climate models of the North American Multi-Model Ensemble (NMME) predict above normal SSTs around the Hawaiian Islands for December 2019. Model guidance from the NMME indicates anomalies of 1-2 degrees C above normal are expected to continue. This elevates the chances of above normal monthly mean air temperatures for Hawaii in December 2019. Equal chances (EC) of above, near or below normal precipitation is indicated over the Hawaiian Islands during December 2019, as dynamical model predictions of precipitation for the month vary widely. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV Hilo A65 72.5 0.4 EC 6.8 10.2 13.6 Kahului A65 73.5 0.5 EC 1.9 2.7 3.4 Honolulu A65 74.9 0.6 EC 0.8 1.3 3.8 Lihue A65 73.3 0.5 EC 1.8 3.2 5.5 SEASONAL FORECAST DISCUSSION VALID DJF 2019 - DJF 2020 Refer to the prognostic discussion of the long-lead seasonal outlooks for the CONUS and Alaska for a discussion of the ENSO outlook and other climate conditions relevant to the seasonal outlook, including details on the current state of the atmosphere and ocean. ENSO-neutral conditions currently are present across the equatorial Pacific Ocean. Equatorial sea surface temperatures (SSTs) are above average across most of Pacific Ocean and are below average in parts of the eastern Pacific. Positive subsurface temperature anomalies have strengthened and moved eastward from the central Pacific to the eastern Pacific, while negative subsurface temperature anomalies have strengthened in the central Pacific. Low-level cross-equatorial wind anomalies are observed over the eastern equatorial Pacific Ocean, and upper-level westerly wind anomalies are present over the eastern Pacific. ENSO-neutral is likely to continue through the Northern Hemisphere winter 2019-2020 with probabilities about 70% and through spring 2020 with probabilities exceeding 60%. Enhanced probabilities for above normal temperatures are indicated across the Hawaiian Islands in the outlook from DJF 2019-2020 to AMJ 2020, due to predicted persistence of above normal sea surface temperatures in the NMME dynamical model forecasts, and supported by statistical models including the Constructed Analog (CA) and Optimum Climate Normals (OCN) through JJA 2020. The signal weakens at longer leads, therefore Equal Chances (EC) for above, near or below normal temperatures are indicated for Hawaii in JAS 2020 and thereafter. Most dynamical models from the NMME predict greater probabilities for above normal precipitation over the Hawaiian Islands from DJF 2019-2020 through AMJ 2020, though some statistical tools such as the CA indicate below normal is more likely in the central islands during this period. Stronger signals for above normal are indicated by the NMME over the northwestern islands in DJF 2019-2020 through FMA 2020. Increasing uncertainty in the tropical climate state in MJJ 2020 and thereafter leads to an indication of equal chances (EC) for above, near or below normal precipitation for Hawaii. Hilo TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV DJF 2020 A65 72.8 0.4 A40 19.6 30.2 33.3 JFM 2020 A60 71.8 0.4 A40 22.0 32.0 44.5 FMA 2020 A55 71.7 0.4 A40 24.6 34.1 45.5 MAM 2020 A45 72.0 0.5 A40 22.5 28.4 34.0 AMJ 2020 A45 72.9 0.5 A40 21.4 23.7 29.0 MJJ 2020 A40 74.0 0.4 EC 20.2 27.5 29.1 JJA 2020 A40 75.2 0.4 EC 19.4 27.2 31.4 JAS 2020 EC 76.1 0.4 EC 25.2 28.6 33.4 ASO 2020 EC 76.4 0.4 EC 26.1 28.8 33.3 SON 2020 EC 76.2 0.4 EC 24.3 30.2 40.8 OND 2020 EC 75.5 0.4 EC 28.3 34.5 42.0 NDJ 2020 EC 74.2 0.4 EC 26.4 36.6 43.0 DJF 2021 EC 72.8 0.4 EC 19.6 30.2 33.3 Kahului TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV DJF 2020 A65 73.8 0.4 A40 4.6 6.9 8.7 JFM 2020 A55 72.5 0.4 A45 4.2 6.2 8.2 FMA 2020 A50 72.3 0.4 A45 3.2 4.1 6.4 MAM 2020 A45 73.0 0.4 A40 2.5 3.5 4.6 AMJ 2020 A40 74.3 0.5 A40 1.2 1.6 2.2 MJJ 2020 A40 76.0 0.5 EC 0.7 1.1 1.8 JJA 2020 A40 77.7 0.4 EC 0.7 1.1 1.5 JAS 2020 EC 79.0 0.4 EC 0.8 1.1 1.6 ASO 2020 EC 79.4 0.4 EC 0.8 1.6 2.5 SON 2020 EC 79.1 0.4 EC 2.1 3.3 4.8 OND 2020 EC 77.8 0.4 EC 4.2 5.3 8.1 NDJ 2020 EC 75.9 0.4 EC 5.2 7.6 9.5 DJF 2021 EC 73.8 0.4 EC 4.6 6.9 8.7 Honolulu TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV DJF 2020 A65 75.3 0.5 A40 3.7 5.6 8.6 JFM 2020 A55 73.9 0.4 A50 2.1 4.6 7.8 FMA 2020 A50 73.8 0.4 A45 1.9 3.2 4.7 MAM 2020 A45 74.8 0.4 A40 1.8 2.6 3.0 AMJ 2020 A40 76.3 0.4 A40 1.2 1.6 1.8 MJJ 2020 A40 78.2 0.4 EC 0.8 1.4 1.6 JJA 2020 A40 79.9 0.4 EC 0.7 0.8 1.3 JAS 2020 EC 81.3 0.4 EC 1.0 1.4 1.7 ASO 2020 EC 81.7 0.4 EC 1.6 2.4 3.1 SON 2020 EC 81.4 0.4 EC 2.5 4.0 5.6 OND 2020 EC 80.0 0.4 EC 4.4 6.4 8.5 NDJ 2020 EC 77.7 0.5 EC 3.9 5.6 8.8 DJF 2021 EC 75.3 0.5 EC 3.7 5.6 8.6 Lihue TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV DJF 2020 A65 73.6 0.4 A45 7.5 8.4 14.0 JFM 2020 A60 72.2 0.4 A50 6.5 8.8 13.8 FMA 2020 A55 72.1 0.5 A45 5.8 8.4 9.9 MAM 2020 A50 72.8 0.5 A40 5.3 6.6 8.0 AMJ 2020 A45 74.2 0.5 A40 4.7 5.5 6.0 MJJ 2020 A40 76.0 0.5 EC 4.9 5.4 5.9 JJA 2020 A40 77.7 0.4 EC 4.4 5.3 6.9 JAS 2020 EC 79.0 0.3 EC 5.3 6.1 7.8 ASO 2020 EC 79.4 0.3 EC 6.2 7.9 8.4 SON 2020 EC 79.1 0.3 EC 9.2 10.0 11.2 OND 2020 EC 77.8 0.3 EC 9.2 11.7 15.6 NDJ 2020 EC 75.7 0.3 EC 8.6 12.1 16.9 DJF 2021 EC 73.6 0.4 EC 7.5 8.4 14.0 FORECASTER: Dan Collins Anomalies are based on the 1981-2010 means. CLARIFICATION: EC indicated equal chances that the predicted parameter will fall into any one of the three categories, whose boundaries are specific in the tables above. A forecast specification of EC means there is no particulate tilt of the odds toward above normal or below normal conditions in the outlook. For example A40 means a 40% chance that the average temperature or total precipitation will be in the above normal class, B40 means a 40% chance that the average temperature or total precipitation will be in the below normal class, and N35 means a 35% probability that the average temperature or total precipitation will be in the near normal class. When EC is specified, all categories are equally likely. NOTE - These outlooks are intended for use prior to the start of the valid periods. Within any valid period, observations and shorter range forecasts should be consulted. Also, this set of outlooks will be superseded by the issuances of the new set net month, on Thu Dec 19, 2019. $$