325  
FXHW40 KWBC 161231  
PMDHCO  
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830AM EDT THU AUG 16 2018  
 
MONTHLY FORECAST DISCUSSION VALID SEPTEMBER 2018  
 
SEA SURFACE TEMPERATURE (SST) ANOMALIES ARE CURRENTLY AROUND ZERO TO POSITIVE  
ONE-HALF DEGREE C NEAR THE HAWAIIAN ISLANDS.  
 
FOR JANUARY 2018 THROUGH THE END OF JULY 2018, RAINFALL TOTAL ACCUMULATIONS  
WERE:  
 
- LIHUE AIRPORT 29.02 INCHES (150 PERCENT OF NORMAL)  
 
- HONOLULU AIRPORT 8.57 INCHES (103 PERCENT OF NORMAL)  
 
- KAHULUI AIRPORT 13.98 INCHES (137 PERCENT OF NORMAL)  
 
- HILO AIRPORT 80.96 INCHES (116 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 ABOVE NORMAL SSTS  
AROUND THE SOUTHEASTERN HAWAIIAN ISLANDS FOR SEPTEMBER 2018. THIS ELEVATES THE  
CHANCES OF ABOVE NORMAL MONTHLY MEAN AIR TEMPERATURES FOR HAWAII IN SEPTEMBER  
2018. MOST DYNAMICAL TOOLS ALSO FAVOR ABOVE NORMAL PRECIPITATION FOR THE  
HAWAIIAN ISLANDS DURING SEPTEMBER 2018.  
 
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
HILO A65 76.4 0.5 A50 8.0 9.3 11.0  
KAHULUI A60 79.3 0.4 A50 0.1 0.2 0.5  
HONOLULU A60 81.8 0.4 A50 0.4 0.6 0.8  
LIHUE A55 79.4 0.3 A50 1.7 1.9 2.6  
 
SEASONAL FORECAST DISCUSSION VALID SON 2018 - SON 2019  
 
REFER TO THE PROGNOSTIC DISCUSSION ON LONG-LEAD SEASONAL OUTLOOKS FOR THE CONUS  
AND ALASKA FOR A DISCUSSION OF THE FORECASTS OF EQUATORIAL PACIFIC SSTS, AND  
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-TO-ABOVE AVERAGE ACROSS MOST OF THE PACIFIC OCEAN.  
POSITIVE SUBSURFACE TEMPERATURE ANOMALIES EXTENDED TO THE SURFACE IN THE  
EASTERN PACIFIC OCEAN. CONVECTION REMAINED SUPPRESSED NEAR THE DATE LINE.  
ANOMALOUS LOW-LEVEL WESTERLY WINDS WERE EVIDENT OVER THE EAST-CENTRAL TROPICAL  
PACIFIC OCEAN, WHILE UPPER-LEVEL WINDS WERE NEAR AVERAGE OVER THE EASTERN  
PACIFIC OCEAN AND NEAR THE INTERNATIONAL DATE LINE. MOST MODELS INDICATE  
ENSO-NEUTRAL TO CONTINUE AT LEAST THROUGH THE NORTHERN HEMISPHERE SUMMER 2018,  
WITH THE PROBABILITY OF EL NINO NEARING 60% DURING THE NORTHERN HEMISPHERE  
AUTUMN, INCREASING TO ABOUT 70% BY NORTHERN HEMISPHERE WINTER 2018-19.  
 
ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE INDICATED FOR HAWAII  
FROM SON 2018 TO FMA 2019 DUE TO PREDICTED ABOVE NORMAL SEA SURFACE  
TEMPERATURES ACROSS THE REGION. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW  
NORMAL TEMPERATURES ARE INDICATED AT ALL LOCATIONS FOR MAM 2019 AND BEYOND.  
 
DYNAMICAL TOOLS FAVOR ABOVE NORMAL PRECIPITATION FOR HAWAII IN SON 2018. MOST  
ENSO FORECAST MODELS PREDICT A WARM EVENT (EL NINO) BY THE NORTHERN HEMISPHERE  
AUTUMN OR WINTER 2018-19. IF CORRECT, HISTORICAL EL NINO COMPOSITES FAVOR  
INCREASED ODDS FOR DRY CONDITIONS FOR HAWAII IN WINTER AND SPRING , WHICH IS  
CONSISTENT WITH THE FORECASTS FROM THE STATISTICAL TOOLS (CONSTRUCTED ANALOG,  
CANONICAL CORRELATION ANALYSIS, AND ENSO-OCN). THERE IS CONSIDERABLE  
UNCERTAINTY ACROSS THE HAWAIIAN ISLANDS IN THE PRECIPITATION FORECAST AMONG  
AVAILABLE FORECAST TOOLS IN OND 2018, AND IN MJJ 2019 AND LONGER LEADS, SO  
EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW NORMAL PRECIPITATION ARE INDICATED.  
 
HILO  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2018 A65 76.2 0.4 A40 24.3 30.2 40.8  
OND 2018 A65 75.5 0.4 EC 28.3 34.5 42.0  
NDJ 2018 A60 74.2 0.4 B55 26.4 36.6 43.0  
DJF 2019 A60 72.8 0.4 B65 19.6 30.2 33.3  
JFM 2019 A50 71.8 0.4 B65 22.0 32.0 44.5  
FMA 2019 A40 71.7 0.4 B60 24.6 34.1 45.5  
MAM 2019 EC 72.0 0.5 B50 22.5 28.4 34.0  
AMJ 2019 EC 72.9 0.5 B40 21.4 23.7 29.0  
MJJ 2019 EC 74.0 0.4 EC 20.2 27.5 29.1  
JJA 2019 EC 75.2 0.4 EC 19.4 27.2 31.4  
JAS 2019 EC 76.1 0.4 EC 25.2 28.6 33.4  
ASO 2019 EC 76.4 0.4 EC 26.1 28.8 33.3  
SON 2019 EC 76.2 0.4 EC 24.3 30.2 40.8  
KAHULUI  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2018 A65 79.1 0.4 A40 2.1 3.3 4.8  
OND 2018 A65 77.8 0.4 EC 4.2 5.3 8.1  
NDJ 2018 A60 75.9 0.4 B55 5.2 7.6 9.5  
DJF 2019 A60 73.8 0.4 B65 4.6 6.9 8.7  
JFM 2019 A50 72.5 0.4 B65 4.2 6.2 8.2  
FMA 2019 A40 72.3 0.4 B60 3.2 4.1 6.4  
MAM 2019 EC 73.0 0.4 B50 2.5 3.5 4.6  
AMJ 2019 EC 74.3 0.5 B40 1.2 1.6 2.2  
MJJ 2019 EC 76.0 0.5 EC 0.7 1.1 1.8  
JJA 2019 EC 77.7 0.4 EC 0.7 1.1 1.5  
JAS 2019 EC 79.0 0.4 EC 0.8 1.1 1.6  
ASO 2019 EC 79.4 0.4 EC 0.8 1.6 2.5  
SON 2019 EC 79.1 0.4 EC 2.1 3.3 4.8  
HONOLULU  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2018 A60 81.4 0.4 A40 2.5 4.0 5.6  
OND 2018 A60 80.0 0.4 EC 4.4 6.4 8.5  
NDJ 2018 A55 77.7 0.5 B55 3.9 5.6 8.8  
DJF 2019 A55 75.3 0.5 B65 3.7 5.6 8.6  
JFM 2019 A45 73.9 0.4 B65 2.1 4.6 7.8  
FMA 2019 A40 73.8 0.4 B60 1.9 3.2 4.7  
MAM 2019 EC 74.8 0.4 B50 1.8 2.6 3.0  
AMJ 2019 EC 76.3 0.4 B40 1.2 1.6 1.8  
MJJ 2019 EC 78.2 0.4 EC 0.8 1.4 1.6  
JJA 2019 EC 79.9 0.4 EC 0.7 0.8 1.3  
JAS 2019 EC 81.3 0.4 EC 1.0 1.4 1.7  
ASO 2019 EC 81.7 0.4 EC 1.6 2.4 3.1  
SON 2019 EC 81.4 0.4 EC 2.5 4.0 5.6  
LIHUE  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2018 A55 79.1 0.3 A40 9.2 10.0 11.2  
OND 2018 A55 77.8 0.3 EC 9.2 11.7 15.6  
NDJ 2018 A50 75.7 0.3 B55 8.6 12.1 16.9  
DJF 2019 A50 73.6 0.4 B65 7.5 8.4 14.0  
JFM 2019 A45 72.2 0.4 B65 6.5 8.8 13.8  
FMA 2019 A40 72.1 0.5 B60 5.8 8.4 9.9  
MAM 2019 EC 72.8 0.5 B60 5.3 6.6 8.0  
AMJ 2019 EC 74.2 0.5 B40 4.7 5.5 6.0  
MJJ 2019 EC 76.0 0.5 EC 4.9 5.4 5.9  
JJA 2019 EC 77.7 0.4 EC 4.4 5.3 6.9  
JAS 2019 EC 79.0 0.3 EC 5.3 6.1 7.8  
ASO 2019 EC 79.4 0.3 EC 6.2 7.9 8.4  
SON 2019 EC 79.1 0.3 EC 9.2 10.0 11.2  
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 SEP 20, 2018.  
 

 
 
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