Climate Prediction Center - Seasonal Outlook

Prognostic Discussion for Long-Lead Hawaiian Outlooks 
NWS Climate Prediction Center College Park MD 
830AM EST Thu Dec 17 2020 
 
MONTHLY FORECAST DISCUSSION VALID JANUARY 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 November 2020, rainfall total accumulations were: 
 
- Lihue Airport 40.88 inches (128 percent of normal) 
- Honolulu Airport 13.31 inches (96 percent of normal) 
- Kahului Airport 11.22 Inches (77 percent of normal) 
- Hilo Airport 107.04 Inches (93 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 January 2021. This elevates the chances of above normal monthly mean air temperatures for Hawaii in January 2021. Most dynamical models  indicate an increased chance of above normal precipitation over the Hawaiian Islands during January 2021, as is typical of La Nina. 
 
 
 





  TEMPERATURE   PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 Hilo  A70  71.6  0.5  A60  3.1  8.9  11.8
 Kahului  A70  72.1  0.6  A60  1.2  2.3  2.8
 Honolulu  A70  73.3  0.5  A60  0.7  1.1  2.1
 Lihue  A75  71.8  0.7  A60  1.3  2.2  4.8
 
 
SEASONAL FORECAST DISCUSSION VALID JFM 2021 - JFM 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 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 a probability of about 95 percent, into spring 2021 (about 65 percent chance during March-April-May), 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 JFM to JJA 2021, consistent with predicted persistence of above normal sea surface temperatures in the NMME dynamical model forecasts through MJJ 2021, and supported by statistical models including the Constructed Analog (CA) and Optimum Climate Normals (OCN) through JJA 2021. Above normal temperature forecasts for Hawaii through MAM 2021 are also consistent with the impacts of a continued La Nina. 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 JAS 2021 and thereafter. 
 
Most dynamical models , and a statistical model combining the impacts of the predicted ENSO state and decadal climate trends , predict likely above normal precipitation from JFM through AMJ 2021, consistent with negative SST anomalies across the eastern equatorial Pacific Ocean and continuing La Nina conditions through the Northern Hemisphere winter and spring. Due to considerable uncertainty in the precipitation forecasts from dynamical and statistical models over the Hawaiian Islands in MJJ 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
 JFM 2021  A65  71.8  0.4  A65  22.0  32.0  44.5
 FMA 2021  A60  71.7  0.4  A60  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   EC  20.2  27.5  29.1
 JJA 2021  A40  75.2  0.4   EC  19.4  27.2  31.4
 JAS 2021   EC  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
 

















 Kahului
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 JFM 2021  A65  72.5  0.4  A65  4.2  6.2  8.2 
 FMA 2021  A60  72.3  0.4  A60  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   EC  0.7  1.1  1.8 
 JJA 2021  A40  77.7  0.4   EC  0.7  1.1  1.5 
 JAS 2021   EC  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 
 

















 Honolulu
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 JFM 2021  A65  73.9  0.4  A65  2.1  4.6  7.8 
 FMA 2021  A60  73.8  0.4  A60  1.9  3.2  4.7 
 MAM 2021  A55  74.8  0.4  A50  1.8  2.6  3.0 
 AMJ 2021  A50  76.3  0.4  A40  1.2  1.6  1.8 
 MJJ 2021  A45  78.2  0.4   EC  0.8  1.4  1.6 
 JJA 2021  A40  79.9  0.4   EC  0.7  0.8  1.3 
 JAS 2021   EC  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 
 

















 Lihue
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 JFM 2021  A70  72.2  0.4  A65  6.5  8.8  13.8
 FMA 2021  A65  72.1  0.5  A60  5.8  8.4  9.9 
 MAM 2021  A55  72.8  0.5  A50  5.3  6.6  8.0 
 AMJ 2021  A50  74.2  0.5  A40  4.7  5.5  6.0 
 MJJ 2021  A45  76.0  0.5   EC  4.9  5.4  5.9 
 JJA 2021  A40  77.7  0.4   EC  4.4  5.3  6.9 
 JAS 2021   EC  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
 

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 Jan 21, 2021.
 
 
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