PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EDT THU APR 20 2017 MONTHLY FORECAST DISCUSSION VALID MAY 2017 SEA SURFACE TEMPERATURE (SST) ANOMALIES SURROUNDING THE HAWAIIAN ISLANDS ARE CURRENTLY FROM POSITIVE ONE-HALF DEGREE TO TWO DEGREES. THIS IS WARMER THAN LAST MONTH. FOR JANUARY 2017 THROUGH THE END OF MARCH 2017, RAINFALL TOTAL ACCUMULATIONS WERE: - LIHUE AIRPORT 10.73 INCHES (93 PERCENT OF NORMAL) - HONOLULU AIRPORT 10.08 INCHES (159 PERCENT OF NORMAL) - KAHULUI AIRPORT 6.62 INCHES (92 PERCENT OF NORMAL) - HILO AIRPORT 21.89 INCHES (68 PERCENT OF NORMAL) THE NCEP CLIMATE FORECAST SYSTEM (CFS) AND OTHER CLIMATE MODELS RUN AS A PART OF THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) PREDICT NEAR TO ABOVE NORMAL SSTS AROUND THE HAWAIIAN ISLANDS. THIS ELEVATES THE CHANCES OF ABOVE-NORMAL MONTHLY MEAN AIR TEMPERATURES FOR THE HAWAIIAN ISLANDS IN MAY 2017. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW MEDIAN PRECIPITATION ARE ALSO INDICATED BY MOST DYNAMICAL MODEL FORECASTS FOR HAWAII DURING MAY 2017. TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV HILO A55 74.0 0.5 EC 4.1 7.4 8.7 KAHULUI A55 75.8 0.6 EC 0.2 0.5 0.8 HONOLULU A55 78.0 0.6 EC 0.2 0.4 0.8 LIHUE A55 75.8 0.6 EC 1.3 1.5 2.3 SEASONAL FORECAST DISCUSSION VALID MJJ 2017 - MJJ 2018 REFER TO THE PROGNOSTIC DISCUSSION ON LONG-LEAD SEASONAL OUTLOOKS FOR THE CONUS AND ALASKA, AND DISCUSSION OF THE FORECASTS OF EQUATORIAL PACIFIC SSTS, FOR THE GENERAL BACKGROUND FOR THE SEASONAL FORECAST, 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 NEAR AVERAGE IN THE CENTRAL PACIFIC OCEAN, WHILE ABOVE AVERAGE SSTS ARE PRESENT IN THE EASTERN PACIFIC OCEAN AND ALONG 20N IN THE PACIFIC BASIN. SUBSURFACE (DOWN TO 150 METERS) TEMPERATURES HAVE DECREASED IN THE EAST-CENTRAL PACIFIC DURING RECENT WEEKS, WHILE INCREASING NEAR THE DATE LINE AND THE COAST OF SOUTH AMERICA. CONVECTION REMAINED ENHANCED OVER MOST OF THE MARITIME CONTINENT WHILE BEING SUPPRESSED OVER THE CENTRAL TROPICAL PACIFIC AND MUCH OF THE OFF-EQUATORIAL NORTHERN PACIFIC THAT LIES EAST OF THE DATE LINE. ENSO-NEUTRAL CONDITIONS ARE FAVORED TO CONTINUE THROUGH AT LEAST THE NORTHERN HEMISPHERE SPRING 2017, WITH INCREASING CHANCES FOR EL NINO DEVELOPMENT BY LATE SUMMER AND FALL. ENHANCED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR HAWAII FROM MJJ 2017 TO ASO 2017 DUE TO PREDICTED ANOMALOUSLY ABOVE-NORMAL SEA SURFACE TEMPERATURES ACROSS THE REGION. THE CPC CONSTRUCTED ANALOG (CA) TOOL ALSO FAVORS NEAR TO ABOVE NORMAL TEMPERATURES, WITH ODDS INCREASING FROM SOUTH TO NORTH, AND ANOMALIES RATHER SMALL IN MAGNITUDE. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW NORMAL TEMPERATURES ARE ANTICIPATED AT ALL LOCATIONS FOR SON 2017 AND BEYOND. THE NMME FAVORS ABOVE MEDIAN PRECIPITATION FOR MUCH THE BOREAL SUMMER. THE CPC CONSTRUCTED ANALOG (CA) TOOL FAVORS BELOW MEDIAN RAINFALL FOR EACH OF THE NEXT 12 SEASONS. THE OUTLOOK FAVORS THE DYNAMICAL GUIDANCE FOR THE FIRST LEAD, IN THE REGIONS WHERE THE SIGNAL IS STRONGEST. SOME DYNAMICAL MODELS PREDICT A WARM EVENT (EL NINO) BY THE NORTHERN HEMISPHERE AUTUMN, CONTINUING INTO WINTER 2017-18. IF CORRECT, HISTORICAL EL NINO COMPOSITES FAVOR INCREASED ODDS FOR DRY CONDITIONS FOR HAWAII IN WINTER, WHICH IS CONSISTENT WITH THE FORECAST FROM THE CA TOOL. THE MIDDLE LEADS REFLECT THE UNCERTAINTY IMPLIED BY THE DISAGREEMENT IN THE DYNAMICAL MODELS AND THE CA TOOL. THE LATTER PORTIONS OF THE OUTLOOK REFLECT THE CONSISTENCY AMONG THE CA AND IMPLICATIONS OF DYNAMICAL MODEL OUTLOOKS FAVORING EL NINO. HILO TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV MJJ 2017 A60 74.0 0.4 EC 20.2 27.5 29.1 JJA 2017 A0 75.2 0.4 EC 19.4 27.2 31.4 JAS 2017 A45 76.1 0.4 EC 25.2 28.6 33.4 ASO 2017 A45 76.4 0.4 EC 26.1 28.8 33.3 SON 2017 EC 76.2 0.4 EC 24.3 30.2 40.8 OND 2017 EC 75.5 0.4 EC 28.3 34.5 42.0 NDJ 2017 EC 74.2 0.4 B40 26.4 36.6 43.0 DJF 2018 EC 72.8 0.4 B40 19.6 30.2 33.3 JFM 2018 EC 71.8 0.4 B40 22.0 32.0 44.5 FMA 2018 EC 71.7 0.4 B40 24.6 34.1 45.5 MAM 2018 EC 72.0 0.5 EC 22.5 28.4 34.0 AMJ 2018 EC 72.9 0.5 EC 21.4 23.7 29.0 MJJ 2018 EC 74.0 0.4 EC 20.2 27.5 29.1 \N KAHULUI TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV MJJ 2017 A60 76.0 0.5 EC 0.7 1.1 1.8 JJA 2017 A55 77.7 0.4 EC 0.7 1.1 1.5 JAS 2017 A45 79.0 0.4 EC 0.8 1.1 1.6 ASO 2017 A45 79.4 0.4 EC 0.8 1.6 2.5 SON 2017 EC 79.1 0.4 EC 2.1 3.3 4.8 OND 2017 EC 77.8 0.4 EC 4.2 5.3 8.1 NDJ 2017 EC 75.9 0.4 B40 5.2 7.6 9.5 DJF 2018 EC 73.8 0.4 B40 4.6 6.9 8.7 JFM 2018 EC 72.5 0.4 B40 4.2 6.2 8.2 FMA 2018 EC 72.3 0.4 B40 3.2 4.1 6.4 MAM 2018 EC 73.0 0.4 EC 2.5 3.5 4.6 AMJ 2018 EC 74.3 0.5 EC 1.2 1.6 2.2 MJJ 2018 EC 76.0 0.5 EC 0.7 1.1 1.8 \N HONOLULU TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV MJJ 2017 A60 78.2 0.4 A40 0.8 1.4 1.6 JJA 2017 A55 79.9 0.4 EC 0.7 0.8 1.3 JAS 2017 A50 81.3 0.4 EC 1.0 1.4 1.7 ASO 2017 A45 81.7 0.4 EC 1.6 2.4 3.1 SON 2017 EC 81.4 0.4 EC 2.5 4.0 5.6 OND 2017 EC 80.0 0.4 EC 4.4 6.4 8.5 NDJ 2017 EC 77.7 0.5 B40 3.9 5.6 8.8 DJF 2018 EC 75.3 0.5 B40 3.7 5.6 8.6 JFM 2018 EC 73.9 0.4 B40 2.1 4.6 7.8 FMA 2018 EC 73.8 0.4 B40 1.9 3.2 4.7 MAM 2018 EC 74.8 0.4 EC 1.8 2.6 3.0 AMJ 2018 EC 76.3 0.4 EC 1.2 1.6 1.8 MJJ 2018 EC 78.2 0.4 EC 0.8 1.4 1.6 \N LIHUE TEMPERATURE PRECIPITATION FCST AVE LIM FCST BLW MEDIAN ABV MJJ 2017 A60 76.0 0.5 A40 4.9 5.4 5.9 JJA 2017 A60 77.7 0.4 EC 4.4 5.3 6.9 JAS 2017 A50 79.0 0.3 EC 5.3 6.1 7.8 ASO 2017 A50 79.4 0.3 EC 6.2 7.9 8.4 SON 2017 EC 79.1 0.3 EC 9.2 10.0 11.2 OND 2017 EC 77.8 0.3 EC 9.2 11.7 15.6 NDJ 2017 EC 75.7 0.3 B4 8.6 12.1 16.9 DJF 2018 EC 73.6 0.4 B40 7.5 8.4 14.0 JFM 2018 EC 72.2 0.4 B40 6.5 8.8 13.8 FMA 2018 EC 72.1 0.5 B40 5.8 8.4 9.9 MAM 2018 EC 72.8 0.5 EC 5.3 6.6 8.0 AMJ 2018 EC 74.2 0.5 EC 4.7 5.5 6.0 MJJ 2018 EC 76.0 0.5 EC 4.9 5.4 5.9 \NFORECASTER: MATTHEW ROSENCRANS ANOMALIES BASED ON 1981-2010 MEANS CLARIFICATION: EC INDICATES EQUAL CHANCES THAT THE CLIMATE WILL FALL INTO ANY ONE OF THE THREE RANGES OR CATEGORIES WHOSE BOUNDARIES ARE SPECIFIED IN THE TABLES ABOVE. A FORECAST SPECIFICATION OF EC MEANS THERE IS NO PARTICULAR TILT OF THE ODDS TOWARD ABOVE-NORMAL OR BELOW-NORMAL CONDITIONS IN THE OUTLOOK. FOR EXAMPLE A40 MEANS A 40% CHANCE THAT TEMPERATURE OR PRECIPITATION WILL BE IN THE ABOVE CLASS, B40 MEANS A 40% PROBABILITY THAT TEMPERATURE OR PRECIPITATION WILL BE IN THE BELOW CLASS, AND N35 MEANS A 35% PROBABILITY THAT TEMPERATURE OR 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 THEIR VALID PERIODS. WITHIN ANY VALID PERIOD OBSERVATIONS AND SHORTER RANGE FORECASTS SHOULD BE CONSULTED. ALSO - THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT MONTH ON THU MAY 18, 2017. $$