Climate Prediction Center - Seasonal Outlook

Prognostic Discussion for Long-Lead Hawaiian Outlooks 
NWS Climate Prediction Center College Park MD 
830AM EDT Thu Jul 18 2019 
 
MONTHLY FORECAST DISCUSSION VALID AUGUST 2019 
 
Sea surface temperature (SST) anomalies are around positive one half to about one and one half degrees Celsius surrounding the Hawaiian Islands during the previous week. 
 
For January 2019 through June 2019, rainfall total accumulations were: 
 
- Lihue Airport 14.32 inches (82 percent of normal) 
- Honolulu Airport 8.76 inches (112 percent of normal) 
- Kahului Airport 9.53 Inches (98 percent of normal) 
- Hilo Airport 38.43 Inches (65 percent of normal) 
 
The NCEP Climate Forecast System (CFS) and other climate models of the North American Multi-Model Ensemble (NMME) predict above normal SSTs around the Hawaiian Islands for August 2019. Model guidance from NMME and IMME indicate anomalies of 1-2 degrees C above normal.This elevates the chances of above normal monthly mean air temperatures for Hawaii in August 2019. Most dynamical models  predict above normal precipitation over the Hawaiian Islands during August 2019, with some statistical tools indicating near or below average rains, especially for Lihue. The statistical tools outlooks for ENSO are at odds with the dynamical model outlooks and the official outlook from CPC and IRI, so the statistical tools are discounted this month.
 
 
 





  TEMPERATURE   PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 Hilo  A65  76.6  0.4  A45  7.6  8.4  10.3
 Kahului  A65  79.8  0.4  A45  0.3  0.5  0.6
 Honolulu  A65  82.1  0.4  A45  0.1  0.2  0.4
 Lihue  A65  79.7  0.4  A40  1.4  1.8  2.5
 
 
SEASONAL FORECAST DISCUSSION VALID ASO 2019 - ASO 2020 
 
Refer to the prognostic discussion of the long-lead seasonal outlooks for the CONUS and Alaska for a discussion of the ENSO outlook and other climate conditions relevant to the seasonal outlook, including details on the current state of the atmosphere and ocean. Weak El Nino conditions are present, with a transition to ENSO neutral expected in the next month or two. A mixture of above and below normal sea surface temperatures (SSTs) are present from 140W to the coast of South America, with warmer than average temperatures in the central Pacific. In the subsurface, a swath of colder than average water is present from 130E to 140W, from 100-200 meters below the surface. Low-level wind anomalies were near average over the tropical Pacific Ocean, and upper-level wind anomalies were westerly over the far eastern Pacific. 
 
The statistical tool outlooks for ENSO are at odds with the dynamical model outlooks and the official outlook from CPC and IRI, so the statistical tools are discounted this month. That results in a relatively heavy weighting of the dynamical models  from the NMME and IMME suites. Those models generally predict above normal temperatures, and the outlook here reflects those outputs, though the official outlook is slightly more conservative in the early leads. Through the winter, the consolidation depicts uncertainty between near and above normal temperatures, so equal chances is indicated from JFM to MAM 2020. From AMJ to ASO 2020, trends  slightly favor above normal temperatures. 
 
The precipitation outlook reflects the dynamical model output and a transition to ENSO neutral during early autumn. During transition to ENSO neutral, relationships from SSTs to precipitation weaken quickly, and intraseasonal variability is likely to dominate. Dynamical models  (NMME) tilt toward above normal precipitation with some statistical tools on the drier side, compared to the dynamical models . The official outlook is between the two sets of tools. Trade winds are likely to return to normal levels as the calendar advances through 2019, which could lead to locally drier conditions on leeward sections of the islands, though the overall climate scale circulations still favor above normal precipitation as the most likely single category. The human With the predicted ENSO neutral state later in the year, a return to climatological conditions necessitates an equal chances forecast for later in 2019.
 
 
















 Hilo
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 ASO 2019  A65  76.4  0.4  A50  26.1  28.8  33.3
 SON 2019  A60  76.2  0.4  A45  24.3  30.2  40.8
 OND 2019  A55  75.5  0.4  A40  28.3  34.5  42.0
 NDJ 2019  A50  74.2  0.4  A40  26.4  36.6  43.0
 DJF 2020  A45  72.8  0.4   EC  19.6  30.2  33.3
 JFM 2020   EC  71.8  0.4   EC  22.0  32.0  44.5
 FMA 2020   EC  71.7  0.4   EC  24.6  34.1  45.5
 MAM 2020   EC  72.0  0.5   EC  22.5  28.4  34.0
 AMJ 2020  A40  72.9  0.5   EC  21.4  23.7  29.0
 MJJ 2020  A40  74.0  0.4   EC  20.2  27.5  29.1
 JJA 2020  A45  75.2  0.4   EC  19.4  27.2  31.4
 JAS 2020  A40  76.1  0.4   EC  25.2  28.6  33.4
 ASO 2020  A40  76.4  0.4   EC  26.1  28.8  33.3
 

















 Kahului
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 ASO 2019  A65  79.4  0.4  A50  0.8  1.6  2.5 
 SON 2019  A60  79.1  0.4  A45  2.1  3.3  4.8 
 OND 2019  A55  77.8  0.4  A40  4.2  5.3  8.1 
 NDJ 2019  A50  75.9  0.4  A40  5.2  7.6  9.5 
 DJF 2020  A45  73.8  0.4   EC  4.6  6.9  8.7 
 JFM 2020   EC  72.5  0.4   EC  4.2  6.2  8.2 
 FMA 2020   EC  72.3  0.4   EC  3.2  4.1  6.4 
 MAM 2020   EC  73.0  0.4   EC  2.5  3.5  4.6 
 AMJ 2020  A40  74.3  0.5   EC  1.2  1.6  2.2 
 MJJ 2020  A40  76.0  0.5   EC  0.7  1.1  1.8 
 JJA 2020  A45  77.7  0.4   EC  0.7  1.1  1.5 
 JAS 2020  A40  79.0  0.4   EC  0.8  1.1  1.6 
 ASO 2020  A40  79.4  0.4   EC  0.8  1.6  2.5 
 

















 Honolulu
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 ASO 2019  A65  81.7  0.4  A45  1.6  2.4  3.1 
 SON 2019  A60  81.4  0.4  A45  2.5  4.0  5.6 
 OND 2019  A50  80.0  0.4  A40  4.4  6.4  8.5 
 NDJ 2019  A45  77.7  0.5  A40  3.9  5.6  8.8 
 DJF 2020  A40  75.3  0.5   EC  3.7  5.6  8.6 
 JFM 2020   EC  73.9  0.4   EC  2.1  4.6  7.8 
 FMA 2020   EC  73.8  0.4   EC  1.9  3.2  4.7 
 MAM 2020   EC  74.8  0.4   EC  1.8  2.6  3.0 
 AMJ 2020  A40  76.3  0.4   EC  1.2  1.6  1.8 
 MJJ 2020  A40  78.2  0.4   EC  0.8  1.4  1.6 
 JJA 2020  A45  79.9  0.4   EC  0.7  0.8  1.3 
 JAS 2020  A40  81.3  0.4   EC  1.0  1.4  1.7 
 ASO 2020  A40  81.7  0.4   EC  1.6  2.4  3.1 
 

















 Lihue
  TEMPERATURE  PRECIPITATION
    FCST  AVE  LIM  FCST  BLW  MEDIAN  ABV
 ASO 2019  A65  79.4  0.3  A45  6.2  7.9  8.4 
 SON 2019  A60  79.1  0.3  A45  9.2  10.0  11.2
 OND 2019  A50  77.8  0.3  A40  9.2  11.7  15.6
 NDJ 2019  A45  75.7  0.3   EC  8.6  12.1  16.9
 DJF 2020  A40  73.6  0.4   EC  7.5  8.4  14.0
 JFM 2020   EC  72.2  0.4   EC  6.5  8.8  13.8
 FMA 2020   EC  72.1  0.5   EC  5.8  8.4  9.9 
 MAM 2020   EC  72.8  0.5   EC  5.3  6.6  8.0 
 AMJ 2020  A40  74.2  0.5   EC  4.7  5.5  6.0 
 MJJ 2020  A40  76.0  0.5   EC  4.9  5.4  5.9 
 JJA 2020  A40  77.7  0.4   EC  4.4  5.3  6.9 
 JAS 2020  A40  79.0  0.3   EC  5.3  6.1  7.8 
 ASO 2020  A40  79.4  0.3   EC  6.2  7.9  8.4 
 

FORECASTER: Matthew Rosencrans 
 
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 Aug 15, 2019.
 
 
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