Hawaii 30 & 90 Day Narrative

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.
$$