Prognostic Discussion for Long-Lead Hawaiian Outlooks NWS Climate Prediction Center College Park MD 830AM EST Thu Dec 21 2023 MONTHLY FORECAST DISCUSSION VALID JANUARY 2024 Sea surface temperature (SST) anomalies ranged from +0.5 to +1.0 degree Celsius during the past week near the Hawaiian islands. For January through November 2023, total rainfall accumulations were: -Lihue Airport 39.07 inches (124 percent of normal) -Honolulu Airport 12.60 inches (89 percent of normal) -Kahului Airport 10.57 inches (79 percent of normal) -Hilo Airport 95.16 inches (88 percent of normal) The NCEP Climate Forecast System (CFS) and other climate models of the North American Multi-Model Ensemble (NMME) predict above average SSTs around the northwestern and central Hawaiian Islands through January 2024, and near average SSTs around the Big Island. These SSTs favor above normal temperatures for Kauai, Oahu, and Maui, and Equal Chances (EC) of below, near, and above normal temperatures for the Big Island. Elevated chances for below normal precipitation are favored for all the Hawaiian Islands in January 2024, as indicated by most dynamical model forecasts, consistent with the strong El Nino conditions over the tropical Pacific. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV Hilo EC 71.6 0.5 B60 3.1 8.9 11.8 Kahului A40 72.1 0.6 B60 1.2 2.3 2.8 Honolulu A50 73.3 0.5 B60 0.7 1.1 2.1 Lihue A60 71.8 0.7 B60 1.3 2.2 4.8 SEASONAL FORECAST DISCUSSION VALID JFM 2024 - JFM 2025 Refer to the prognostic discussion of the long-lead seasonal outlooks for the CONUS and Alaska for a description of the ENSO outlook and other climate conditions relevant to the seasonal outlook. El Nino conditions are observed over the Pacific Ocean. Equatorial SSTs are above average across the central and eastern Pacific Ocean. Positive subsurface temperature anomalies dominate most of the equatorial Pacific Ocean. Low-level wind anomalies were westerly over the eastern half of the equatorial Pacific, while upper-level wind anomalies were easterly along the equatorial Pacific. Enhanced convection and precipitation were observed around the Date Line, and extend into the eastern Pacific, while suppressed convection and precipitation were evident around Indonesia. Atmospheric and oceanic conditions over the tropical Pacific are generally consistent with El Nino conditions. El Nino is expected to continue through the Northern Hemisphere winter, with a 60% chance of transition to ENSO-neutral during April-June 2024. Above normal temperatures are forecast for the Hawaiian islands for January-February-March (JFM) 2024, including Kauai, Oahu, Maui, and the Big Island. Above normal temperatures are likely to persist through May-June-July (MJJ) 2024, supported by most NMME dynamical model inputs and consistent with persistent, large-scale forcing from a strong El Nino with decadal trends. Equal chances (EC) for above, near, or below-normal temperatures are forecast for all of Hawaii for June-July-August (JJA) and longer leads as climate signals weaken thereafter with decreasing chances of a continuing, significant El Nino and uncertainty increases. Below normal precipitation is forecast throughout the Hawaiian Islands in January-February-March (JFM) 2024 through May-June-July (MJJ) 2024. This is supported by most dynamical models of the NMME and statistical tools. The forecast is consistent with prediction of a strong El Nino event over the tropical Pacific and typical impacts to precipitation over Hawaii. Equal chances (EC) for above, near, or below-normal precipitation are forecast for all of Hawaii for summer (JJA) 2024 and longer leads as climate signals weaken with decreasing chances of a continuation of El Nino. Hilo TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JFM 2024 A40 71.8 0.4 B70 22.0 32.0 44.5 FMA 2024 A40 71.7 0.4 B70 24.6 34.1 45.5 MAM 2024 A40 72.0 0.5 B60 22.5 28.4 34.0 AMJ 2024 A40 72.9 0.5 B50 21.4 23.7 29.0 MJJ 2024 A40 74.0 0.4 B40 20.2 27.5 29.1 JJA 2024 EC 75.2 0.4 EC 19.4 27.2 31.4 JAS 2024 EC 76.1 0.4 EC 25.2 28.6 33.4 ASO 2024 EC 76.4 0.4 EC 26.1 28.8 33.3 SON 2024 EC 76.2 0.4 EC 24.3 30.2 40.8 OND 2024 EC 75.5 0.4 EC 28.3 34.5 42.0 NDJ 2024 EC 74.2 0.4 EC 26.4 36.6 43.0 DJF 2025 EC 72.8 0.4 EC 19.6 30.2 33.3 JFM 2025 EC 71.8 0.4 EC 22.0 32.0 44.5 Kahului TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JFM 2024 A50 72.5 0.4 B70 4.2 6.2 8.2 FMA 2024 A50 72.3 0.4 B70 3.2 4.1 6.4 MAM 2024 A50 73.0 0.4 B60 2.5 3.5 4.6 AMJ 2024 A45 74.3 0.5 B50 1.2 1.6 2.2 MJJ 2024 A40 76.0 0.5 B40 0.7 1.1 1.8 JJA 2024 EC 77.7 0.4 EC 0.7 1.1 1.5 JAS 2024 EC 79.0 0.4 EC 0.8 1.1 1.6 ASO 2024 EC 79.4 0.4 EC 0.8 1.6 2.5 SON 2024 EC 79.1 0.4 EC 2.1 3.3 4.8 OND 2024 EC 77.8 0.4 EC 4.2 5.3 8.1 NDJ 2024 EC 75.9 0.4 EC 5.2 7.6 9.5 DJF 2025 EC 73.8 0.4 EC 4.6 6.9 8.7 JFM 2025 EC 72.5 0.4 EC 4.2 6.2 8.2 Honolulu TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JFM 2024 A60 73.9 0.4 B70 2.1 4.6 7.8 FMA 2024 A60 73.8 0.4 B70 1.9 3.2 4.7 MAM 2024 A55 74.8 0.4 B60 1.8 2.6 3.0 AMJ 2024 A45 76.3 0.4 B50 1.2 1.6 1.8 MJJ 2024 A40 78.2 0.4 B40 0.8 1.4 1.6 JJA 2024 EC 79.9 0.4 EC 0.7 0.8 1.3 JAS 2024 EC 81.3 0.4 EC 1.0 1.4 1.7 ASO 2024 EC 81.7 0.4 EC 1.6 2.4 3.1 SON 2024 EC 81.4 0.4 EC 2.5 4.0 5.6 OND 2024 EC 80.0 0.4 EC 4.4 6.4 8.5 NDJ 2024 EC 77.7 0.5 EC 3.9 5.6 8.8 DJF 2025 EC 75.3 0.5 EC 3.7 5.6 8.6 JFM 2025 EC 73.9 0.4 EC 2.1 4.6 7.8 Lihue TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JFM 2024 A60 72.2 0.4 B70 6.5 8.8 13.8 FMA 2024 A60 72.1 0.5 B70 5.8 8.4 9.9 MAM 2024 A55 72.8 0.5 B60 5.3 6.6 8.0 AMJ 2024 A45 74.2 0.5 B50 4.7 5.5 6.0 MJJ 2024 A40 76.0 0.5 B40 4.9 5.4 5.9 JJA 2024 EC 77.7 0.4 EC 4.4 5.3 6.9 JAS 2024 EC 79.0 0.3 EC 5.3 6.1 7.8 ASO 2024 EC 79.4 0.3 EC 6.2 7.9 8.4 SON 2024 EC 79.1 0.3 EC 9.2 10.0 11.2 OND 2024 EC 77.8 0.3 EC 9.2 11.7 15.6 NDJ 2024 EC 75.7 0.3 EC 8.6 12.1 16.9 DJF 2025 EC 73.6 0.4 EC 7.5 8.4 14.0 JFM 2025 EC 72.2 0.4 EC 6.5 8.8 13.8 FORECASTER: Luke He Anomalies are based on the 1991-2020 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 Jan 18, 2024. $$