449  
FXHW40 KWBC 211333  
PMDHCO  
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830AM EST THU JAN 21 2021  
 
MONTHLY FORECAST DISCUSSION VALID FEBRUARY 2021  
 
POSITIVE SEA SURFACE TEMPERATURE (SST) ANOMALIES FROM GREATER THAN POSITIVE  
ONE-HALF DEGREE TO GREATER THAN ONE DEGREE CELSIUS WERE OBSERVED IN THE  
VICINITY OF THE HAWAIIAN ISLANDS DURING THE LAST SEVERAL WEEKS.  
 
FOR JANUARY THROUGH DECEMBER 2020, RAINFALL TOTAL ACCUMULATIONS WERE:  
 
- LIHUE AIRPORT 42.93 INCHES (116 PERCENT OF NORMAL)  
 
- HONOLULU AIRPORT 13.62 INCHES (80 PERCENT OF NORMAL)  
 
- KAHULUI AIRPORT 11.40 INCHES (64 PERCENT OF NORMAL)  
 
- HILO AIRPORT 121.77 INCHES (96 PERCENT OF NORMAL)  
 
THE NCEP CLIMATE FORECAST SYSTEM (CFS) AND OTHER CLIMATE MODELS OF THE NORTH  
AMERICAN MULTI-MODEL ENSEMBLE (NMME) PREDICT ABOVE AVERAGE SSTS AROUND THE  
HAWAIIAN ISLANDS THROUGH FEBRUARY 2021. THIS ELEVATES THE CHANCES OF ABOVE  
NORMAL MONTHLY MEAN AIR TEMPERATURES FOR HAWAII IN FEBRUARY 2021. MOST  
DYNAMICAL MODELS INDICATE AN INCREASED CHANCE OF ABOVE NORMAL PRECIPITATION  
OVER THE HAWAIIAN ISLANDS DURING FEBRUARY 2021, AS IS TYPICAL DURING LA NINA.  
 
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
HILO A65 71.4 0.5 A60 5.0 8.4 11.1  
KAHULUI A70 71.9 0.6 A60 0.9 1.1 1.8  
HONOLULU A70 73.3 0.5 A60 0.7 1.0 1.4  
LIHUE A75 71.7 0.6 A60 1.3 1.8 4.0  
 
SEASONAL FORECAST DISCUSSION VALID FMA 2021 - FMA 2022  
 
REFER TO THE PROGNOSTIC DISCUSSION OF THE LONG-LEAD SEASONAL OUTLOOKS FOR THE  
CONUS AND ALASKA FOR A DESCRIPTION OF THE ENSO OUTLOOK AND OTHER CLIMATE  
CONDITIONS RELEVANT TO THE SEASONAL OUTLOOK. THE OBSERVED TROPICAL PACIFIC  
ATMOSPHERE AND OCEAN CONDITIONS ARE CONSISTENT WITH THE ONGOING LA NINA, WITH  
BELOW AVERAGE SEA SURFACE TEMPERATURES (SSTS) ACROSS THE CENTRAL AND EASTERN  
EQUATORIAL PACIFIC OCEAN AND ABOVE AVERAGE SSTS IN THE WESTERN EQUATORIAL  
PACIFIC OCEAN FROM THE MARITIME CONTINENT TO 160 E LATITUDE. NEGATIVE  
SUBSURFACE TEMPERATURE ANOMALIES PERSIST FROM THE SURFACE TO DEPTHS OF 100 TO  
200 METERS IN THE CENTRAL AND EASTERN PACIFIC OCEAN, AND POSITIVE SUBSURFACE  
TEMPERATURE ANOMALIES PERSIST IN THE WESTERN PACIFIC OCEAN AND AT DEPTH NEAR  
THE DATE LINE. TROPICAL CONVECTION IS SUPPRESSED FROM THE WESTERN TO THE  
CENTRAL PACIFIC OCEAN. LOW-LEVEL EASTERLY WIND ANOMALIES WERE OBSERVED FROM THE  
WESTERN TO THE EAST-CENTRAL PACIFIC OCEAN, WHILE UPPER-LEVEL WESTERLY WIND  
ANOMALIES WERE OBSERVED OVER MOST OF THE EQUATORIAL PACIFIC OCEAN. LA NINA  
CONDITIONS ARE LIKELY TO CONTINUE THROUGH NORTHERN HEMISPHERE WINTER, WITH AN  
APPROXIMATED PROBABILITY OF 78 PERCENT FOR FMA 2021, AND TRANSITION TO NEUTRAL  
CONDITIONS IN AMJ 2021 (WITH A PROBABILITY EXCEEDING 50 PERCENT).  
 
ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE INDICATED ACROSS THE  
HAWAIIAN ISLANDS IN THE OUTLOOK FROM FMA TO JAS 2021, CONSISTENT WITH PREDICTED  
PERSISTENCE OF ABOVE NORMAL SEA SURFACE TEMPERATURES IN THE NMME DYNAMICAL  
MODEL FORECASTS THROUGH JJA 2021, AND SUPPORTED BY STATISTICAL MODELS THAT RELY  
ON DECADAL TEMPERATURE TRENDS, INCLUDING THE CONSTRUCTED ANALOG (CA) AND  
OPTIMUM CLIMATE NORMALS (OCN), THROUGH JAS 2021. PROBABILITIES OF ABOVE NORMAL  
TEMPERATURES ARE GREATER FOR THE NORTHWESTERN ISLANDS AND LOWER FOR THE  
SOUTHEASTERN ISLANDS, CONSISTENT WITH DYNAMICAL MODELS AND CANONICAL LA NINA  
SST PATTERNS. ABOVE NORMAL TEMPERATURE FORECASTS FOR HAWAII THROUGH AMJ 2021  
ARE ALSO CONSISTENT WITH THE IMPACTS OF A CONTINUED LA NINA, AND LARGELY DUE TO  
DECADAL TEMPERATURE TRENDS FOR MJJ THROUGH JAS 2021. CLIMATE FORCING SIGNALS,  
INCLUDING ENSO, WEAKEN AT LONGER LEADS, SUCH THAT EQUAL CHANCES (EC) FOR ABOVE,  
NEAR OR BELOW NORMAL TEMPERATURES ARE INDICATED FOR HAWAII IN ASO 2021 AND  
THEREAFTER.  
 
MOST DYNAMICAL MODELS PREDICT LIKELY ABOVE NORMAL PRECIPITATION FROM FMA  
THROUGH MJJ 2021, WITH GREATER PROBABILITIES FOR THE NORTHWESTERN ISLANDS AND  
LOWER PROBABILITIES FOR THE SOUTHEASTERN ISLANDS. THIS PRECIPITATION PATTERN IS  
CONSISTENT WITH NEGATIVE SST ANOMALIES ACROSS THE EASTERN EQUATORIAL PACIFIC  
OCEAN AND CONTINUING LA NINA CONDITIONS THROUGH THE NORTHERN HEMISPHERE WINTER  
AND POSSIBLY SPRING. DUE TO CONSIDERABLE UNCERTAINTY IN THE PRECIPITATION  
FORECASTS FROM DYNAMICAL AND STATISTICAL MODELS OVER THE HAWAIIAN ISLANDS IN  
JJA 2021 AND LONGER LEADS, EQUAL CHANCES (EC) FOR ABOVE, NEAR OR BELOW NORMAL  
PRECIPITATION ARE INDICATED.  
 
HILO  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
FMA 2021 A60 71.7 0.4 A55 24.6 34.1 45.5  
MAM 2021 A55 72.0 0.5 A50 22.5 28.4 34.0  
AMJ 2021 A50 72.9 0.5 A40 21.4 23.7 29.0  
MJJ 2021 A45 74.0 0.4 A40 20.2 27.5 29.1  
JJA 2021 A40 75.2 0.4 EC 19.4 27.2 31.4  
JAS 2021 A40 76.1 0.4 EC 25.2 28.6 33.4  
ASO 2021 EC 76.4 0.4 EC 26.1 28.8 33.3  
SON 2021 EC 76.2 0.4 EC 24.3 30.2 40.8  
OND 2021 EC 75.5 0.4 EC 28.3 34.5 42.0  
NDJ 2021 EC 74.2 0.4 EC 26.4 36.6 43.0  
DJF 2022 EC 72.8 0.4 EC 19.6 30.2 33.3  
JFM 2022 EC 71.8 0.4 EC 22.0 32.0 44.5  
FMA 2022 EC 71.7 0.4 EC 24.6 34.1 45.5  
KAHULUI  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
FMA 2021 A60 72.3 0.4 A55 3.2 4.1 6.4  
MAM 2021 A55 73.0 0.4 A50 2.5 3.5 4.6  
AMJ 2021 A50 74.3 0.5 A40 1.2 1.6 2.2  
MJJ 2021 A45 76.0 0.5 A40 0.7 1.1 1.8  
JJA 2021 A40 77.7 0.4 EC 0.7 1.1 1.5  
JAS 2021 A40 79.0 0.4 EC 0.8 1.1 1.6  
ASO 2021 EC 79.4 0.4 EC 0.8 1.6 2.5  
SON 2021 EC 79.1 0.4 EC 2.1 3.3 4.8  
OND 2021 EC 77.8 0.4 EC 4.2 5.3 8.1  
NDJ 2021 EC 75.9 0.4 EC 5.2 7.6 9.5  
DJF 2022 EC 73.8 0.4 EC 4.6 6.9 8.7  
JFM 2022 EC 72.5 0.4 EC 4.2 6.2 8.2  
FMA 2022 EC 72.3 0.4 EC 3.2 4.1 6.4  
HONOLULU  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
FMA 2021 A65 73.8 0.4 A60 1.9 3.2 4.7  
MAM 2021 A60 74.8 0.4 A55 1.8 2.6 3.0  
AMJ 2021 A55 76.3 0.4 A45 1.2 1.6 1.8  
MJJ 2021 A50 78.2 0.4 A40 0.8 1.4 1.6  
JJA 2021 A40 79.9 0.4 EC 0.7 0.8 1.3  
JAS 2021 A40 81.3 0.4 EC 1.0 1.4 1.7  
ASO 2021 EC 81.7 0.4 EC 1.6 2.4 3.1  
SON 2021 EC 81.4 0.4 EC 2.5 4.0 5.6  
OND 2021 EC 80.0 0.4 EC 4.4 6.4 8.5  
NDJ 2021 EC 77.7 0.5 EC 3.9 5.6 8.8  
DJF 2022 EC 75.3 0.5 EC 3.7 5.6 8.6  
JFM 2022 EC 73.9 0.4 EC 2.1 4.6 7.8  
FMA 2022 EC 73.8 0.4 EC 1.9 3.2 4.7  
LIHUE  
TEMPERATURE PRECIPITATION  
FCST AVE LIM FCST BLW MEDIAN ABV  
FMA 2021 A65 72.1 0.5 A60 5.8 8.4 9.9  
MAM 2021 A60 72.8 0.5 A55 5.3 6.6 8.0  
AMJ 2021 A55 74.2 0.5 A45 4.7 5.5 6.0  
MJJ 2021 A50 76.0 0.5 A40 4.9 5.4 5.9  
JJA 2021 A40 77.7 0.4 EC 4.4 5.3 6.9  
JAS 2021 A40 79.0 0.3 EC 5.3 6.1 7.8  
ASO 2021 EC 79.4 0.3 EC 6.2 7.9 8.4  
SON 2021 EC 79.1 0.3 EC 9.2 10.0 11.2  
OND 2021 EC 77.8 0.3 EC 9.2 11.7 15.6  
NDJ 2021 EC 75.7 0.3 EC 8.6 12.1 16.9  
DJF 2022 EC 73.6 0.4 EC 7.5 8.4 14.0  
JFM 2022 EC 72.2 0.4 EC 6.5 8.8 13.8  
FMA 2022 EC 72.1 0.5 EC 5.8 8.4 9.9  
FORECASTER: DAN COLLINS  
 
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 FEB 18, 2021.  
 

 
 
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