Prognostic Discussion for Long-Lead Hawaiian Outlooks NWS Climate Prediction Center College Park MD 830AM EDT Thu Sep 19 2019 MONTHLY FORECAST DISCUSSION VALID OCTOBER 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 August 2019, rainfall total accumulations were: - Lihue Airport 17.83 inches (83 percent of normal) - Honolulu Airport 9.06 inches (102 percent of normal) - Kahului Airport 9.96 Inches (93 percent of normal) - Hilo Airport 57.39 Inches (72 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 October 2019. Model guidance from the NMME indicates anomalies of 1-2 degrees C above normal.This elevates the chances of above normal monthly mean air temperatures for Hawaii in October 2019. Most dynamical models predict above normal precipitation over the Hawaiian Islands during October 2019, consistent with the Hawaii outlook. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV Hilo A60 75.7 0.5 A40 7.8 8.6 12.1 Kahului A60 78.2 0.4 A45 0.3 0.6 1.1 Honolulu A60 80.2 0.5 A45 0.5 1.3 1.9 Lihue A60 78.1 0.3 A45 2.5 3.3 4.2 SEASONAL FORECAST DISCUSSION VALID OND 2019 - OND 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 west of the Date Line across the equatorial Pacific Ocean and are below average in the eastern-central and eastern equatorial Pacific. Positive subsurface temperature anomalies have persisted and strengthened near the Date Line in the central equatorial Pacific, while negative subsurface temperature anomalies have expanded in the eastern equatorial Pacific. Low-level westerly wind anomalies are present over the western tropical Pacific Ocean, and upper-level winds were near average over the tropical Pacific. ENSO-neutral is likely to continue through the Northern Hemisphere autumn 2019 with probabilities exceeding 65% and winter 2019-2020 with a probabilities exceeding 55%. Enhanced probabilities for above normal temperatures are indicated across the Hawaiian Islands in the outlook from OND 2019 to AMJ 2020, due to persistent above normal sea surface temperatures predicted by the NMME dynamical models through FMA 2020, and supported by statistical models including the Canonical Correlation Analysis (CCA) and Constructed Analog (CA) through AMJ 2020. The signal weakens at longer leads, therefore Equal Chances (EC) for above, near, or below normal temperatures are indicated for Hawaii beginning in MJJ 2020 and thereafter. Most dynamical models predict likely above normal precipitation over the Hawaiian Islands during OND 2019 to DJF 2019-2020, while some statistical tools predict below normal precipitation is more likely. While continuation of ENSO-neutral conditions is most likely, enhanced probabilities of El Nino conditions would increase the likelihood of below normal precipitation across the Hawaiian Islands from NDJ 2019-2020 through MAM 2020. Above normal precipitation is indicated across Hawaii from OND 2019 through DJF 2019-2020. Increasing uncertainty in the tropical climate state in JFM 2020 and longer leads, results in 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 OND 2019 A65 75.5 0.4 A50 28.3 34.5 42.0 NDJ 2019 A65 74.2 0.4 A50 26.4 36.6 43.0 DJF 2020 A65 72.8 0.4 A50 19.6 30.2 33.3 JFM 2020 A65 71.8 0.4 A45 22.0 32.0 44.5 FMA 2020 A65 71.7 0.4 A45 24.6 34.1 45.5 MAM 2020 A65 72.0 0.5 A45 22.5 28.4 34.0 AMJ 2020 A65 72.9 0.5 A45 21.4 23.7 29.0 MJJ 2020 A65 74.0 0.4 A45 20.2 27.5 29.1 JJA 2020 A60 75.2 0.4 A45 19.4 27.2 31.4 JAS 2020 A60 76.1 0.4 A45 25.2 28.6 33.4 ASO 2020 A60 76.4 0.4 A45 26.1 28.8 33.3 SON 2020 A60 76.2 0.4 A40 24.3 30.2 40.8 OND 2020 A60 75.5 0.4 A40 28.3 34.5 42.0 Kahului TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV OND 2019 A65 77.8 0.4 A50 4.2 5.3 8.1 NDJ 2019 A65 75.9 0.4 A50 5.2 7.6 9.5 DJF 2020 A65 73.8 0.4 A50 4.6 6.9 8.7 JFM 2020 A65 72.5 0.4 A45 4.2 6.2 8.2 FMA 2020 A65 72.3 0.4 A45 3.2 4.1 6.4 MAM 2020 A65 73.0 0.4 A45 2.5 3.5 4.6 AMJ 2020 A65 74.3 0.5 A45 1.2 1.6 2.2 MJJ 2020 A65 76.0 0.5 A45 0.7 1.1 1.8 JJA 2020 A60 77.7 0.4 A45 0.7 1.1 1.5 JAS 2020 A60 79.0 0.4 A45 0.8 1.1 1.6 ASO 2020 A60 79.4 0.4 A45 0.8 1.6 2.5 SON 2020 A60 79.1 0.4 A45 2.1 3.3 4.8 OND 2020 A60 77.8 0.4 A45 4.2 5.3 8.1 Honolulu TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV OND 2019 A65 80.0 0.4 A50 4.4 6.4 8.5 NDJ 2019 A65 77.7 0.5 A50 3.9 5.6 8.8 DJF 2020 A65 75.3 0.5 A50 3.7 5.6 8.6 JFM 2020 A65 73.9 0.4 A45 2.1 4.6 7.8 FMA 2020 A65 73.8 0.4 A45 1.9 3.2 4.7 MAM 2020 A65 74.8 0.4 A45 1.8 2.6 3.0 AMJ 2020 A65 76.3 0.4 A45 1.2 1.6 1.8 MJJ 2020 A65 78.2 0.4 A45 0.8 1.4 1.6 JJA 2020 A60 79.9 0.4 A45 0.7 0.8 1.3 JAS 2020 A60 81.3 0.4 A45 1.0 1.4 1.7 ASO 2020 A60 81.7 0.4 A45 1.6 2.4 3.1 SON 2020 A60 81.4 0.4 A45 2.5 4.0 5.6 OND 2020 A60 80.0 0.4 A45 4.4 6.4 8.5 Lihue TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV OND 2019 A65 77.8 0.3 A50 9.2 11.7 15.6 NDJ 2019 A65 75.7 0.3 A50 8.6 12.1 16.9 DJF 2020 A65 73.6 0.4 A50 7.5 8.4 14.0 JFM 2020 A65 72.2 0.4 A45 6.5 8.8 13.8 FMA 2020 A65 72.1 0.5 A45 5.8 8.4 9.9 MAM 2020 A65 72.8 0.5 A45 5.3 6.6 8.0 AMJ 2020 A65 74.2 0.5 A45 4.7 5.5 6.0 MJJ 2020 A65 76.0 0.5 A45 4.9 5.4 5.9 JJA 2020 A60 77.7 0.4 A45 4.4 5.3 6.9 JAS 2020 A60 79.0 0.3 A45 5.3 6.1 7.8 ASO 2020 A60 79.4 0.3 A45 6.2 7.9 8.4 SON 2020 A60 79.1 0.3 A45 9.2 10.0 11.2 OND 2020 A60 77.8 0.3 A45 9.2 11.7 15.6 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 Oct 17, 2019. $$