532  
FXHW40 KWBC 171231  
PMDHCO  
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830AM EDT THU AUG 17 2017  
 
MONTHLY FORECAST DISCUSSION VALID SEPTEMBER 2017  
 
SEA SURFACE TEMPERATURE (SST) ANOMALIES SURROUNDING THE HAWAIIAN ISLANDS ARE  
 
CURRENTLY BETWEEN ZERO DEGREE AND POSITIVE ONE DEGREE C, WITH HIGHER ANOMALIES  
NEAR THE NORTHWEST ISLANDS.  
 
FOR JANUARY 2017 THROUGH THE END OF JULY 2017, RAINFALL TOTAL ACCUMULATIONS  
WERE:  
 
- LIHUE AIRPORT 16.39 INCHES (85 PERCENT OF NORMAL)  
 
- HONOLULU AIRPORT 14.04 INCHES (168 PERCENT OF NORMAL)  
 
- KAHULUI AIRPORT 14.84 INCHES (145 PERCENT OF NORMAL)  
 
- HILO AIRPORT 44.74 INCHES (64 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 HAWAIIAN ISLANDS TO CONTINUE FOR SEPTEMBER 2017. THIS ELEVATES THE  
CHANCES OF ABOVE-NORMAL MONTHLY MEAN AIR TEMPERATURES FOR THE HAWAIIAN ISLANDS  
IN SEPTEMBER 2017. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW MEDIAN  
PRECIPITATION ARE ALSO INDICATED BY MOST DYNAMICAL MODEL FORECASTS FOR HAWAII  
DURING SEPTEMBER 2017.  
 
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
HILO A55 76.4 0.5 EC 8.0 9.3 11.0  
KAHULUI A60 79.3 0.4 EC 0.1 0.2 0.5  
HONOLULU A65 81.8 0.4 EC 0.4 0.6 0.8  
LIHUE A65 79.4 0.3 EC 1.7 1.9 2.6  
 
SEASONAL FORECAST DISCUSSION VALID SON 2017 - SON 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 REMAIN ACROSS THE  
EQUATORIAL PACIFIC OCEAN. EQUATORIAL SEA SURFACE TEMPERATURES (SSTS) WERE NEAR  
AVERAGE OVER MOST OF THE PACIFIC OCEAN. NEGATIVE SUBSURFACE TEMPERATURE  
ANOMALIES STRENGTHENED AT DEPTH WITH MAXIMUM STRENGTH AROUND 150W. ATMOSPHERIC  
CONVECTION, AS INDICATED IN OUTGOING LONGWAVE RADIATION ANOMALIES, WAS NEAR  
AVERAGE OVER THE EASTERN HALF OF THE PACIFIC AND ENHANCED OVER THE MARITIME  
CONTINENT AND THE WESTERN PACIFIC OCEAN. THE LOWER-LEVEL TRADE WINDS WERE  
SLIGHTLY ENHANCED NEAR THE INTERNATIONAL DATE LINE, WHILE UPPER-LEVEL WINDS  
WERE NEAR AVERAGE OVER MOST OF THE TROPICAL PACIFIC OCEAN. THE NCEP CFSV2 AND  
MOST OF THE MODELS FROM THE LATEST RUNS OF THE NMME ARE NOW FAVORING THE  
CONTINUATION OF ENSO-NEUTRAL THROUGH THE REMAINDER OF 2017. IN THE OFFICIAL  
OUTLOOK, ENSO-NEUTRAL IS FAVORED THROUGH THE NORTHERN HEMISPHERE WINTER 2017-18.  
 
ENHANCED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR HAWAII  
FROM SON 2017 TO JFM 2018 DUE TO PREDICTED ANOMALOUSLY ABOVE-NORMAL SEA SURFACE  
TEMPERATURES ACROSS THE REGION. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW  
NORMAL TEMPERATURES ARE ANTICIPATED AT ALL LOCATIONS FOR FMA 2018 AND BEYOND.  
 
THERE IS HIGH UNCERTAINTY WITH THE PRECIPITATION FORECAST FROM DYNAMICAL AND  
STATISTICAL TOOLS FOR HAWAII FROM SON TO JFM 2018. EQUAL CHANCES (EC) FOR  
ABOVE, NEAR, OR BELOW MEDIAN PRECIPITATION ARE INDICATED FOR HAWAII FROM SON TO  
JFM 2018. THE CPC CONSTRUCTED ANALOG (CA) TOOL FAVORS BELOW MEDIAN  
PRECIPITATION FOR LIHUE, HONOLULU, KAHULUI, AND HILO FOR FMA TO AMJ 2018. EQUAL  
CHANCES (EC) FOR ABOVE, NEAR, OR BELOW MEDIAN PRECIPITATION ARE FORECAST FOR  
HAWAII IN MJJ 2018 AND LONGER LEADS.  
 
HILO  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2017 A65 76.2 0.4 EC 24.3 30.2 40.8  
OND 2017 A60 75.5 0.4 EC 28.3 34.5 42.0  
NDJ 2017 A60 74.2 0.4 EC 26.4 36.6 43.0  
DJF 2018 A55 72.8 0.4 EC 19.6 30.2 33.3  
JFM 2018 A45 71.8 0.4 EC 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 B40 22.5 28.4 34.0  
AMJ 2018 EC 72.9 0.5 B40 21.4 23.7 29.0  
MJJ 2018 EC 74.0 0.4 EC 20.2 27.5 29.1  
JJA 2018 EC 75.2 0.4 EC 19.4 27.2 31.4  
JAS 2018 EC 76.1 0.4 EC 25.2 28.6 33.4  
ASO 2018 EC 76.4 0.4 EC 26.1 28.8 33.3  
SON 2018 EC 76.2 0.4 EC 24.3 30.2 40.8  
\N KAHULUI  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2017 A65 79.1 0.4 EC 2.1 3.3 4.8  
OND 2017 A60 77.8 0.4 EC 4.2 5.3 8.1  
NDJ 2017 A60 75.9 0.4 EC 5.2 7.6 9.5  
DJF 2018 A55 73.8 0.4 EC 4.6 6.9 8.7  
JFM 2018 A45 72.5 0.4 EC 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 B40 2.5 3.5 4.6  
AMJ 2018 EC 74.3 0.5 B40 1.2 1.6 2.2  
MJJ 2018 EC 76.0 0.5 EC 0.7 1.1 1.8  
JJA 2018 EC 77.7 0.4 EC 0.7 1.1 1.5  
JAS 2018 EC 79.0 0.4 EC 0.8 1.1 1.6  
ASO 2018 EC 79.4 0.4 EC 0.8 1.6 2.5  
SON 2018 EC 79.1 0.4 EC 2.1 3.3 4.8  
\N HONOLULU  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2017 A70 81.4 0.4 EC 2.5 4.0 5.6  
OND 2017 A65 80.0 0.4 EC 4.4 6.4 8.5  
NDJ 2017 A60 77.7 0.5 EC 3.9 5.6 8.8  
DJF 2018 A55 75.3 0.5 EC 3.7 5.6 8.6  
JFM 2018 A45 73.9 0.4 EC 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 B40 1.8 2.6 3.0  
AMJ 2018 EC 76.3 0.4 B40 1.2 1.6 1.8  
MJJ 2018 EC 78.2 0.4 EC 0.8 1.4 1.6  
JJA 2018 EC 79.9 0.4 EC 0.7 0.8 1.3  
JAS 2018 EC 81.3 0.4 EC 1.0 1.4 1.7  
ASO 2018 EC 81.7 0.4 EC 1.6 2.4 3.1  
SON 2018 EC 81.4 0.4 EC 2.5 4.0 5.6  
\N LIHUE  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
SON 2017 A70 79.1 0.3 EC 9.2 10.0 11.2  
OND 2017 A65 77.8 0.3 EC 9.2 11.7 15.6  
NDJ 2017 A65 75.7 0.3 EC 8.6 12.1 16.9  
DJF 2018 A60 73.6 0.4 EC 7.5 8.4 14.0  
JFM 2018 A50 72.2 0.4 EC 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 B40 5.3 6.6 8.0  
AMJ 2018 EC 74.2 0.5 B40 4.7 5.5 6.0  
MJJ 2018 EC 76.0 0.5 EC 4.9 5.4 5.9  
JJA 2018 EC 77.7 0.4 EC 4.4 5.3 6.9  
JAS 2018 EC 79.0 0.3 EC 5.3 6.1 7.8  
ASO 2018 EC 79.4 0.3 EC 6.2 7.9 8.4  
SON 2018 EC 79.1 0.3 EC 9.2 10.0 11.2  
\NFORECASTER: LUKE HE  
 
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 SEP 21, 2017.  
 

 
 
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