Prognostic Discussion for Long-Lead Hawaiian Outlooks NWS Climate Prediction Center College Park MD 830AM EDT Thu Jun 20 2019 MONTHLY FORECAST DISCUSSION VALID JULY 2019 Sea surface temperature (SST) anomalies are around positive one to two degrees Celsius surrounding the Hawaiian Islands during the previous week. For January 2019 through May 2019, rainfall total accumulations were: - Lihue Airport 8.53 inches (54 percent of normal) - Honolulu Airport 3.08 inches (41 percent of normal) - Kahului Airport 9.50 Inches (100 percent of normal) - Hilo Airport 34.53 Inches (67 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 July 2019. This elevates the chances of above normal monthly mean air temperatures for Hawaii in July 2019. Most dynamical models predict above normal precipitation over the Hawaiian Islands during July 2019, consistent with the Canonical Correlation Analysis (CCA) forecast tool. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV Hilo A60 76.2 0.4 A40 7.1 9.5 11.4 Kahului A60 79.2 0.4 A40 0.2 0.4 0.5 Honolulu A60 81.4 0.5 A40 0.2 0.4 0.5 Lihue A60 79.2 0.4 A40 1.5 1.7 1.9 SEASONAL FORECAST DISCUSSION VALID JAS 2019 - JAS 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. Weak EL Nino conditions currently are present, and equatorial sea surface temperatures (SSTs) are above average, across most of the equatorial Pacific Ocean. Positive subsurface temperature anomalies have weakened, but still reside near the surface across the central Pacific, while negative subsurface temperature anomalies have strengthened in the western and eastern Pacific. Enhanced convection persisted over the Date Line, and low-level wind anomalies were westerly over the western tropical Pacific Ocean. Upper-level wind anomalies were easterly over the western and east-central Pacific. A weak El Nino is likely to continue through the Northern Hemisphere summer 2019 (with a 66% chance) and possibly through the fall and winter (50-55% chance). Enhanced probabilities for above normal temperatures are indicated across the Hawaiian Islands in the outlook from JAS to NDJ 2019, due to persistent above normal sea surface temperatures predicted by the NMME dynamical models, which is also supported by statistical models including the Canonical Correlation Analysis (CCA) and Constructed Analog (CA). The signal weakens at longer leads, therefore Equal Chances (EC) for above, near, or below normal temperatures are indicated for Hawaii beginning in DJF 2019-2020 and beyond. With enhanced probabilities of the continuation of an El Nino through summer, the precipitation forecast for Hawaii follows historical El Nino impacts that indicate strong correlations between El Nino and increased probabilities of below normal precipitation in winter and spring and weaker correlations between El Nino and above normal precipitation in summer, due to potential impacts from enhanced tropical cyclone activity in the central Pacific during summer El Nino conditions. Most dynamical models predict larger signals for above normal precipitation over the Hawaiian Islands during JAS to SON 2019, supported by the Constructed Analog statistical forecast of precipitation, which also are consistent with an ENSO-OCN tool that combines the impacts of El Nino and decadal climate variability. Increasing uncertainty in the tropical climate state in OND 2019 and longer leads, 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 JAS 2019 A55 76.1 0.4 A45 25.2 28.6 33.4 ASO 2019 A60 76.4 0.4 A45 26.1 28.8 33.3 SON 2019 A50 76.2 0.4 A40 24.3 30.2 40.8 OND 2019 A45 75.5 0.4 EC 28.3 34.5 42.0 NDJ 2019 A40 74.2 0.4 EC 26.4 36.6 43.0 DJF 2020 EC 72.8 0.4 EC 19.6 30.2 33.3 JFM 2020 EC 71.8 0.4 EC 22.0 32.0 44.5 FMA 2020 EC 71.7 0.4 EC 24.6 34.1 45.5 MAM 2020 EC 72.0 0.5 EC 22.5 28.4 34.0 AMJ 2020 EC 72.9 0.5 EC 21.4 23.7 29.0 MJJ 2020 EC 74.0 0.4 EC 20.2 27.5 29.1 JJA 2020 EC 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 Kahului TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JAS 2019 A50 79.0 0.4 A45 0.8 1.1 1.6 ASO 2019 A55 79.4 0.4 A45 0.8 1.6 2.5 SON 2019 A50 79.1 0.4 A40 2.1 3.3 4.8 OND 2019 A45 77.8 0.4 EC 4.2 5.3 8.1 NDJ 2019 A40 75.9 0.4 EC 5.2 7.6 9.5 DJF 2020 EC 73.8 0.4 EC 4.6 6.9 8.7 JFM 2020 EC 72.5 0.4 EC 4.2 6.2 8.2 FMA 2020 EC 72.3 0.4 EC 3.2 4.1 6.4 MAM 2020 EC 73.0 0.4 EC 2.5 3.5 4.6 AMJ 2020 EC 74.3 0.5 EC 1.2 1.6 2.2 MJJ 2020 EC 76.0 0.5 EC 0.7 1.1 1.8 JJA 2020 EC 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 Honolulu TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JAS 2019 A50 81.3 0.4 A45 1.0 1.4 1.7 ASO 2019 A55 81.7 0.4 A45 1.6 2.4 3.1 SON 2019 A50 81.4 0.4 A40 2.5 4.0 5.6 OND 2019 A45 80.0 0.4 EC 4.4 6.4 8.5 NDJ 2019 A40 77.7 0.5 EC 3.9 5.6 8.8 DJF 2020 EC 75.3 0.5 EC 3.7 5.6 8.6 JFM 2020 EC 73.9 0.4 EC 2.1 4.6 7.8 FMA 2020 EC 73.8 0.4 EC 1.9 3.2 4.7 MAM 2020 EC 74.8 0.4 EC 1.8 2.6 3.0 AMJ 2020 EC 76.3 0.4 EC 1.2 1.6 1.8 MJJ 2020 EC 78.2 0.4 EC 0.8 1.4 1.6 JJA 2020 EC 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 Lihue TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV JAS 2019 A50 79.0 0.3 A45 5.3 6.1 7.8 ASO 2019 A55 79.4 0.3 A45 6.2 7.9 8.4 SON 2019 A50 79.1 0.3 A40 9.2 10.0 11.2 OND 2019 A45 77.8 0.3 EC 9.2 11.7 15.6 NDJ 2019 A40 75.7 0.3 EC 8.6 12.1 16.9 DJF 2020 EC 73.6 0.4 EC 7.5 8.4 14.0 JFM 2020 EC 72.2 0.4 EC 6.5 8.8 13.8 FMA 2020 EC 72.1 0.5 EC 5.8 8.4 9.9 MAM 2020 EC 72.8 0.5 EC 5.3 6.6 8.0 AMJ 2020 EC 74.2 0.5 EC 4.7 5.5 6.0 MJJ 2020 EC 76.0 0.5 EC 4.9 5.4 5.9 JJA 2020 EC 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 FORECASTER: Luke He 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 Jul 18, 2019. $$