814  
FXHW40 KWBC 191231  
PMDHCO  
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830AM EDT THU OCT 19 2017  
 
MONTHLY FORECAST DISCUSSION VALID NOVEMBER 2017  
 
SEA SURFACE TEMPERATURE (SST) ANOMALIES SURROUNDING THE HAWAIIAN ISLANDS ARE  
 
CURRENTLY BETWEEN POSITIVE ONE-HALF DEGREE AND ONE DEGREE C.  
 
FOR JANUARY 2017 THROUGH THE END OF SEPTEMBER 2017, RAINFALL TOTAL  
ACCUMULATIONS WERE:  
 
- LIHUE AIRPORT 18.42 INCHES (78 PERCENT OF NORMAL)  
 
- HONOLULU AIRPORT 15.99 INCHES (167 PERCENT OF NORMAL)  
 
- KAHULUI AIRPORT 15.16 INCHES (137 PERCENT OF NORMAL)  
 
- HILO AIRPORT 57.53 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 NOVEMBER 2017. THIS ELEVATES THE  
CHANCES OF ABOVE NORMAL MONTHLY MEAN AIR TEMPERATURES FOR THE HAWAIIAN ISLANDS  
IN NOVEMBER 2017. EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW MEDIAN  
PRECIPITATION ARE INDICATED BY DYNAMICAL MODEL FORECASTS FOR HAWAII DURING  
NOVEMBER 2017.  
 
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
HILO A60 74.4 0.4 EC 8.7 11.4 17.1  
KAHULUI A60 76.0 0.6 EC 1.2 1.8 2.6  
HONOLULU A65 77.8 0.6 EC 0.9 1.4 2.1  
LIHUE A70 75.8 0.5 EC 2.6 3.5 5.5  
 
SEASONAL FORECAST DISCUSSION VALID NDJ 2017 - NDJ 2018  
 
REFER TO THE PROGNOSTIC DISCUSSION ON LONG-LEAD SEASONAL OUTLOOKS FOR THE CONUS  
AND ALASKA, 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 REMAIN ACROSS THE  
EQUATORIAL PACIFIC OCEAN, HOWEVER RECENT CONDITIONS INDICATE AN INCREASING  
CHANCE OF THE DEVELOPMENT OF LA NINA CONDITIONS BY WINTER. CORRESPONDINGLY, A  
LA NINA WATCH WAS CONTINUED, WITH ODDS OF LA NINA AT 55-65 PERCENT DURING THE  
NORTHERN HEMISPHERE WINTER.  
 
EQUATORIAL SEA SURFACE TEMPERATURES (SSTS) WERE BELOW AVERAGE ACROSS THE  
CENTRAL AND EASTERN PACIFIC OCEAN IN THE LAST MONTH. WHILE SOME SSTS INCREASED  
NEAR 100W, NEGATIVE SUBSURFACE TEMPERATURE ANOMALIES STRENGTHENED AT DEPTH FROM  
160W TO 110W. ATMOSPHERIC CONVECTION, AS INDICATED BY OUTGOING LONGWAVE  
RADIATION ANOMALIES, WAS NEAR AVERAGE OVER THE EASTERN PACIFIC, ENHANCED OVER  
THE MARITIME CONTINENT, AND SUPPRESSED OVER THE CENTRAL PACIFIC OCEAN. THE OLR  
PATTERN IS CLOSER TO A CANONICAL LA NINA PATTERN THAN THE OLR PATTERN FROM ONE  
MONTH PRIOR. THE LOWER-LEVEL TRADE WINDS INCREASED OVER MUCH OF THE PACIFIC,  
ESPECIALLY THE CENTRAL AND WESTERN PACIFIC, WHILE UPPER-LEVEL EASTERLY WIND  
ANOMALIES INCREASED NEAR THE DATE LINE. THE NCEP CFS AND DYNAMICAL MODELS FROM  
THE NMME ARE NOW INDICATING AN INCREASED PROBABILITY OF LA NINA CONDITIONS  
DEVELOPING BY WINTER. STATISTICAL MODELS AND THE CPC NINO 3.4 SST CONSOLIDATION  
FORECAST INDICATE AN INCREASED, AS COMPARED TO LAST MONTH, BUT RELATIVELY LOWER  
PROBABILITY OF LA NINA, COMPARED TO THE NMME MODELS. IN THE OFFICIAL OUTLOOK, A  
LA NINA IS LIKELY TO DEVELOP FOR NORTHERN HEMISPHERE WINTER 2017-18.  
 
ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE INDICATED FOR HAWAII  
FROM NDJ 2017-2018 TO AMJ 2018 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 MJJ 2018 AND BEYOND.  
 
THE OUTLOOK FOR PRECIPITATION IS MUCH LESS CERTAIN THAN THE TEMPERATURE  
OUTLOOK. RECENT TRENDS IN PRECIPITATION INDICATE A DRYING DURING OCTOBER AND  
NOVEMBER, MANIFESTED BY A LATER ONSET OF WETTER CONDITIONS. THE SIGNAL WOULD BE  
ENHANCED BY A LA NINA DUE TO INCREASED TRADEWINDS FOR LEEWARD LOCATIONS AND  
REDUCED FOR WINDWARD LOCATIONS. DURING NDJ, THE DYNAMICAL MODELS INDICATE ABOVE  
NORMAL PRECIPITATION WHILE TRENDS AND STATISTICAL TOOLS SHOW BELOW AVERAGE  
PRECIPITATION AND NEAR NORMAL PRECIPITATION, RESPECTIVELY. THEREFORE THE  
OFFICIAL OUTLOOK REFLECTS THAT UNCERTAINTY WITH AN EC OUTLOOK. FOR DJF  
2017-2018, THE CONSTRUCTED ANALOG TOOL AND DYNAMICAL MODELS SLIDE TOWARD WETTER  
THAN NORMAL CONDITIONS, WHICH IS REFLECTED IN THE OUTLOOK THROUGH JFM 2018.  
DURING MAM AND AMJ, STATISTICAL TOOLS AND TRENDS INDICATE BELOW NORMAL  
PRECIPITATION, AND THAT SIGNAL IS INCLUDED IN THE OUTLOOK. DURING MJJ 2018 AND  
BEYOND, EQUAL CHANCES (EC) FOR ABOVE, NEAR, OR BELOW NORMAL PRECIPITATION ARE  
INDICATED AT ALL LOCATIONS.  
 
HILO  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
NDJ 2017 A60 74.2 0.4 EC 26.4 36.6 43.0  
DJF 2018 A55 72.8 0.4 A40 19.6 30.2 33.3  
JFM 2018 A55 71.8 0.4 A40 22.0 32.0 44.5  
FMA 2018 A50 71.7 0.4 EC 24.6 34.1 45.5  
MAM 2018 A45 72.0 0.5 B40 22.5 28.4 34.0  
AMJ 2018 A40 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  
OND 2018 EC 75.5 0.4 EC 28.3 34.5 42.0  
NDJ 2018 EC 74.2 0.4 EC 26.4 36.6 43.0  
\N KAHULUI  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
NDJ 2017 A60 75.9 0.4 EC 5.2 7.6 9.5  
DJF 2018 A55 73.8 0.4 A40 4.6 6.9 8.7  
JFM 2018 A55 72.5 0.4 A40 4.2 6.2 8.2  
FMA 2018 A50 72.3 0.4 EC 3.2 4.1 6.4  
MAM 2018 A45 73.0 0.4 B40 2.5 3.5 4.6  
AMJ 2018 A40 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  
OND 2018 EC 77.8 0.4 EC 4.2 5.3 8.1  
NDJ 2018 EC 75.9 0.4 EC 5.2 7.6 9.5  
\N HONOLULU  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
NDJ 2017 A60 77.7 0.5 EC 3.9 5.6 8.8  
DJF 2018 A60 75.3 0.5 A40 3.7 5.6 8.6  
JFM 2018 A55 73.9 0.4 A40 2.1 4.6 7.8  
FMA 2018 A50 73.8 0.4 EC 1.9 3.2 4.7  
MAM 2018 A45 74.8 0.4 B40 1.8 2.6 3.0  
AMJ 2018 A40 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  
OND 2018 EC 80.0 0.4 EC 4.4 6.4 8.5  
NDJ 2018 EC 77.7 0.5 EC 3.9 5.6 8.8  
\N LIHUE  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
NDJ 2017 A65 75.7 0.3 EC 8.6 12.1 16.9  
DJF 2018 A60 73.6 0.4 A45 7.5 8.4 14.0  
JFM 2018 A60 72.2 0.4 A40 6.5 8.8 13.8  
FMA 2018 A55 72.1 0.5 EC 5.8 8.4 9.9  
MAM 2018 A50 72.8 0.5 B40 5.3 6.6 8.0  
AMJ 2018 A45 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  
OND 2018 EC 77.8 0.3 EC 9.2 11.7 15.6  
NDJ 2018 EC 75.7 0.3 EC 8.6 12.1 16.9  
\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 NOV 16, 2017.  
 

 
 
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