Prognostic Discussion for Long-Lead Hawaiian Outlooks NWS Climate Prediction Center College Park MD 830AM EDT Thu Oct 19 2023 MONTHLY FORECAST DISCUSSION VALID NOVEMBER 2023 Sea surface temperature (SST) anomalies near zero degree Celsius were observed over the Hawaiian islands (Kauai, Oahu, Maui and the Big Island) during the previous week. For January through September 2023, rainfall total accumulations were: -Lihue Airport 32.67 inches (135 percent of normal) -Honolulu Airport 9.88 inches (94 percent of normal) -Kahului Airport 9.59 inches (89 percent of normal) -Hilo Airport 82.34 inches (98 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 northwestern Hawaiian Islands through November 2023, and near-average SSTs near southeastern Hawaiian Islands. Therefore, Equal Chances (EC) of below, near, and above-normal temperatures are predicted for the Big Island in November 2023, while above-normal temperatures are forecast for Kauai, Oahu and Maui. Enhanced chances for below-normal precipitation are predicted for all the Hawaiian Islands in November 2023, as indicated by dynamical model forecasts, consistent with the El Niño conditions over the tropical Pacific. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV Hilo EC 74.4 0.4 B55 8.7 11.4 17.1 Kahului A40 76.0 0.6 B55 1.2 1.8 2.6 Honolulu A50 77.8 0.6 B55 0.9 1.4 2.1 Lihue A60 75.8 0.5 B55 2.6 3.5 5.5 SEASONAL FORECAST DISCUSSION VALID NDJ 2023 - NDJ 2024 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 Niño 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. Positive subsurface temperature anomalies weakened around 130W-120W, with negative anomalies emerging at depths of 50-150m. Low-level wind anomalies were weak and westerly over the western equatorial Pacific. Upper-level wind anomalies were cross equatorial over the eastern tropical Pacific, and weak over the central Pacific. Enhanced convection and precipitation were observed over the western Pacific and extend north of the equator into the eastern Pacific Ocean. Atmospheric and oceanic conditions over the tropical Pacific are generally consistent with El Niño conditions. There is a greater than 80% chance that El Niño will continue through the Northern Hemisphere Spring. Above normal temperatures are forecast for northwestern islands of Hawaii for November-December-January (NDJ) 2023, including Kauai, Oahu and Maui. Above normal temperatures are likely to persist through March-April-May (MAM) 2024 for Oahu, Kauai and Maui. Equal chances (EC) for above, near, or below-normal temperatures are forecast over the Big Island of Hawaii for all seasons, as dynamical models predict near-normal temperatures in early leads and statistical models show weaker signals. Equal chances (EC) for above, near, or below-normal temperatures are forecast for all of Hawaii for April-May-Jun (AMJ) and longer leads as climate signals weaken and uncertainty increases. Below normal precipitation is forecast throughout the Hawaiian Islands in November-December-January (NDJ) 2023 through March-April-May (MAM) 2024. This is supported by most dynamical models of the NMME, and to some extent the constructed analog (CA) statistical model. The forecast is consistent with prediction of a likely strong El Niño event over the tropical Pacific through next spring and typical impacts to precipitation over Hawaii. Equal chances (EC) for above, near, or below-normal precipitation are forecast for all of Hawaii for April-May-June (AMJ) 2024 and longer leads as climate signals weaken with decreasing chances of a continuation of El Niño. Hilo TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV NDJ 2023 EC 74.2 0.4 B60 26.4 36.6 43.0 DJF 2024 EC 72.8 0.4 B70 19.6 30.2 33.3 JFM 2024 EC 71.8 0.4 B70 22.0 32.0 44.5 FMA 2024 EC 71.7 0.4 B50 24.6 34.1 45.5 MAM 2024 EC 72.0 0.5 B40 22.5 28.4 34.0 AMJ 2024 EC 72.9 0.5 EC 21.4 23.7 29.0 MJJ 2024 EC 74.0 0.4 EC 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 Kahului TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV NDJ 2023 A40 75.9 0.4 B60 5.2 7.6 9.5 DJF 2024 A40 73.8 0.4 B70 4.6 6.9 8.7 JFM 2024 A40 72.5 0.4 B70 4.2 6.2 8.2 FMA 2024 A40 72.3 0.4 B50 3.2 4.1 6.4 MAM 2024 A40 73.0 0.4 B40 2.5 3.5 4.6 AMJ 2024 EC 74.3 0.5 EC 1.2 1.6 2.2 MJJ 2024 EC 76.0 0.5 EC 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 Honolulu TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV NDJ 2023 A50 77.7 0.5 B60 3.9 5.6 8.8 DJF 2024 A50 75.3 0.5 B70 3.7 5.6 8.6 JFM 2024 A45 73.9 0.4 B70 2.1 4.6 7.8 FMA 2024 A40 73.8 0.4 B50 1.9 3.2 4.7 MAM 2024 A40 74.8 0.4 B40 1.8 2.6 3.0 AMJ 2024 EC 76.3 0.4 EC 1.2 1.6 1.8 MJJ 2024 EC 78.2 0.4 EC 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 Lihue TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV NDJ 2023 A50 75.7 0.3 B60 8.6 12.1 16.9 DJF 2024 A50 73.6 0.4 B70 7.5 8.4 14.0 JFM 2024 A45 72.2 0.4 B70 6.5 8.8 13.8 FMA 2024 A40 72.1 0.5 B50 5.8 8.4 9.9 MAM 2024 A40 72.8 0.5 B40 5.3 6.6 8.0 AMJ 2024 EC 74.2 0.5 EC 4.7 5.5 6.0 MJJ 2024 EC 76.0 0.5 EC 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 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 Nov 16, 2023. $$