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FXHW40 KWBC 151231
PMDHCO
PROGNOSTIC DISCUSSION FOR LONG-LEAD HAWAIIAN OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EDT THU APR 15 2021
MONTHLY FORECAST DISCUSSION VALID MAY 2021
SEA SURFACE TEMPERATURE (SST) ANOMALIES FROM ZERO DEGREE TO NEGATIVE ONE-HALF
DEGREE CELSIUS WERE OBSERVED OVER NORTHWESTERN ISLANDS (KAUAI AND OAHU), WHILE
NEGATIVE ONE-HALF DEGREE TO NEGATIVE ONE DEGREE CELSIUS SST ANOMALIES WERE OVER
SOUTHEASTERN ISLANDS (MAUI AND BIG ISLAND) DURING THE PREVIOUS WEEK.
FOR JANUARY THROUGH MARCH 2021, RAINFALL TOTAL ACCUMULATIONS WERE:
- LIHUE AIRPORT 17.67 INCHES (153 PERCENT OF NORMAL)
- HONOLULU AIRPORT 8.98 INCHES (142 PERCENT OF NORMAL)
- KAHULUI AIRPORT 14.06 INCHES (195 PERCENT OF NORMAL)
- HILO AIRPORT 55.59 INCHES (172 PERCENT OF NORMAL)
THE NCEP CLIMATE FORECAST SYSTEM (CFS) AND OTHER CLIMATE MODELS OF THE NORTH
AMERICAN MULTI-MODEL ENSEMBLE (NMME) PREDICT ABOVE NORMAL MONTHLY MEAN AIR
TEMPERATURES FOR KAHULUI, HONOLULU AND LIHUE IN MAY 2021. EQUAL CHANCES (EC)
FOR ABOVE, NEAR, OR BELOW NORMAL PRECIPITATION ARE INDICATED BY MOST DYNAMICAL
AND STATISTICAL MODELS FOR THE HAWAIIAN ISLANDS DURING MAY 2021.
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
HILO EC 74.0 0.5 EC 4.1 7.4 8.7
KAHULUI A50 75.8 0.6 EC 0.2 0.5 0.8
HONOLULU A60 78.0 0.6 EC 0.2 0.4 0.8
LIHUE A60 75.8 0.6 EC 1.3 1.5 2.3
SEASONAL FORECAST DISCUSSION VALID MJJ 2021 - MJJ 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. LA NINA CONDITIONS ARE PRESENT
ACROSS THE PACIFIC OCEAN, WITH BELOW AVERAGE SEA SURFACE TEMPERATURES (SSTS)
FROM THE WEST-CENTRAL TO EASTERN EQUATORIAL PACIFIC OCEAN. NEGATIVE SUBSURFACE
TEMPERATURE ANOMALIES HAVE WEAKENED AND NOW ONLY REMAIN IN A LAYER CLOSE TO THE
SURFACE, WHILE A LARGE AREA OF POSITIVE SUBSURFACE TEMPERATURE ANOMALIES IN THE
WESTERN PACIFIC HAS SHIFT EASTWARD TO AROUND 110W. TROPICAL CONVECTION IS
SUPPRESSED OVER THE WESTERN AND CENTRAL PACIFIC. LOW-LEVEL EASTERLY WIND
ANOMALIES WERE OBSERVED ACROSS THE EQUATORIAL PACIFIC, WHILE UPPER-LEVEL
WESTERLY WIND ANOMALIES WERE OBSERVED OVER MOST OF THE TROPICAL PACIFIC. A
TRANSITION FROM LA NINA TO ENSO-NEUTRAL IS LIKELY IN THE NEXT MONTH OR SO, WITH
AN 80 PERCENT CHANCE OF ENSO-NEUTRAL DURING MAY-JULY 2021.
ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES ARE INDICATED OVER HILO
FROM JJA 2021 TO ASO 2021, WHILE ABOVE NORMAL TEMPERATURES ARE FORECAST OVER
HONOLULU FROM MJJ TO JJA 2021, AND OVER LIHUE FROM MJJ 2021 TO ASO 2021,
SUPPORTED BY MOST DYNAMICAL AND STATISTICAL FORECAST TOOLS.
ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION ARE LIKELY OVER THE
HAWAIIAN ISLANDS FROM SUMMER(JJA) 2021 TO OND 2021, CONSISTENT WITH MOST
DYNAMICAL MODELS. DUE TO CONSIDERABLE UNCERTAINTY IN THE PRECIPITATION
FORECASTS FROM DYNAMICAL AND STATISTICAL MODELS OVER THE HAWAIIAN ISLANDS IN
NDJ 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
MJJ 2021 EC 74.0 0.4 EC 20.2 27.5 29.1
JJA 2021 B40 75.2 0.4 B40 19.4 27.2 31.4
JAS 2021 B40 76.1 0.4 B50 25.2 28.6 33.4
ASO 2021 B40 76.4 0.4 B60 26.1 28.8 33.3
SON 2021 EC 76.2 0.4 B50 24.3 30.2 40.8
OND 2021 EC 75.5 0.4 B40 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
MAM 2022 EC 72.0 0.5 EC 22.5 28.4 34.0
AMJ 2022 EC 72.9 0.5 EC 21.4 23.7 29.0
MJJ 2022 EC 74.0 0.4 EC 20.2 27.5 29.1
KAHULUI
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
MJJ 2021 EC 76.0 0.5 EC 0.7 1.1 1.8
JJA 2021 EC 77.7 0.4 B40 0.7 1.1 1.5
JAS 2021 EC 79.0 0.4 B50 0.8 1.1 1.6
ASO 2021 EC 79.4 0.4 B60 0.8 1.6 2.5
SON 2021 EC 79.1 0.4 B50 2.1 3.3 4.8
OND 2021 EC 77.8 0.4 B40 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
MAM 2022 EC 73.0 0.4 EC 2.5 3.5 4.6
AMJ 2022 EC 74.3 0.5 EC 1.2 1.6 2.2
MJJ 2022 EC 76.0 0.5 EC 0.7 1.1 1.8
HONOLULU
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
MJJ 2021 A40 78.2 0.4 EC 0.8 1.4 1.6
JJA 2021 A40 79.9 0.4 B40 0.7 0.8 1.3
JAS 2021 EC 81.3 0.4 B50 1.0 1.4 1.7
ASO 2021 EC 81.7 0.4 B60 1.6 2.4 3.1
SON 2021 EC 81.4 0.4 B50 2.5 4.0 5.6
OND 2021 EC 80.0 0.4 B40 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
MAM 2022 EC 74.8 0.4 EC 1.8 2.6 3.0
AMJ 2022 EC 76.3 0.4 EC 1.2 1.6 1.8
MJJ 2022 EC 78.2 0.4 EC 0.8 1.4 1.6
LIHUE
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
MJJ 2021 A50 76.0 0.5 EC 4.9 5.4 5.9
JJA 2021 A45 77.7 0.4 B40 4.4 5.3 6.9
JAS 2021 A40 79.0 0.3 B50 5.3 6.1 7.8
ASO 2021 A40 79.4 0.3 B60 6.2 7.9 8.4
SON 2021 EC 79.1 0.3 B50 9.2 10.0 11.2
OND 2021 EC 77.8 0.3 B40 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
MAM 2022 EC 72.8 0.5 EC 5.3 6.6 8.0
AMJ 2022 EC 74.2 0.5 EC 4.7 5.5 6.0
MJJ 2022 EC 76.0 0.5 EC 4.9 5.4 5.9
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 MAY 20, 2021.
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