Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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FXHW40 KWBC 191231
PMDHCO
Prognostic Discussion for Long-Lead Hawaiian Outlooks
NWS Climate Prediction Center College Park MD
830AM EDT Thu Sep 19 2024
MONTHLY FORECAST DISCUSSION VALID OCTOBER 2024
Sea-surface temperatures (SSTs) near the Hawaiian islands of Kauai, Oahu, and
Maui, have warmed during the past few weeks to slightly above average, while
SSTs surrounding the Big Island remain close to the 30-year climatological
average.
From January through August 2024, rainfall total accumulations were:
Lihue Airport 23.18 inches (105 percent of average)
Honolulu Airport 9.71 inches (101 percent of average)
Kahului Airport 10.79 inches (105 percent of average)
Hilo Airport 68.22 inches (91 percent of average)
The NCEP Climate Forecast System (CFS) and other climate models of the North
American Multi-Model Ensemble (NMME) generally predict near average SSTs around
the Hawaiian Islands through October 2024, with the exceptions of the IMME and
GFDL-SPEAR models which predict an SST anomaly pattern similar to current
observations. Given the fact that ocean temperatures typically change very
slowly over time, it was decided to go with the IMME and GFDL-SPEAR solutions
which agree with current SST observations. Based primarily on the expected
persistence of the current SST anomaly pattern, surface temperatures are
slightly favored to be above normal for Kauai, Oahu, and Maui, and Equal
Chances (EC) of below, near, and above normal for the Big Island through
October. For the October 2024 precipitation outlook, below normal precipitation
probabilities are elevated for all of the island chain, as indicated by most
dynamical model forecasts, and consistent with a transition from ENSO-neutral
to La Nia conditions over the tropical Pacific in the near future.
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
Hilo EC 75.7 0.5 B50 7.8 8.6 12.1
Kahului A40 78.2 0.4 B45 0.3 0.6 1.1
Honolulu A40 80.2 0.5 B40 0.5 1.3 1.9
Lihue A40 78.1 0.3 B40 2.5 3.3 4.2
SEASONAL FORECAST DISCUSSION VALID OND 2024 - OND 2025
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. ENSO-neutral conditions continue
to be observed over the Pacific Ocean throughout August. Equatorial SSTs are
near average throughout most of the Pacific Ocean. Negative subsurface
temperature anomalies remain at depth in the central and eastern Pacific Ocean,
with positive subsurface temperature anomalies over the western Pacific Ocean.
Low-level easterly wind anomalies were observed over most of the equatorial
Pacific, while upper-level easterly wind anomalies were observed over the
east-central Pacific. Convection was slightly enhanced over parts of Indonesia
and was near average near the Date Line. Collectively, the coupled
ocean-atmosphere system reflected ENSO-neutral. Though the onset of La Nia
has been delayed from initial projections, it is still favored to emerge in
September-October-November (SON) 2024 with a 71% chance, and is expected to
persist through January-February-March (JFM) 2025.
Enhanced probabilities favoring above normal temperatures are indicated for the
Hawaiian islands (Kauai, Oahu, Maui, and the Big Island) in OND
(October-November-December) 2024, consistent with most dynamical model
forecasts from the NMME and C3S. Above normal temperatures are favored to
continue throughout FMA 2025 in association with the expected La Nia, peaking
in or around JFM 2025. The forecast signal weakens at longer leads, therefore
EC is indicated for Hawaii beginning in MAM 2025 and extending through longer
leads.
For precipitation, OND 2024 is forecast to be a season of transition for the
Hawaiian archipelago, with EC favored. From NDJ 2024 through FMA 2025, elevated
probabilities for above normal precipitation are supported by most of the
dynamical models and some of the statistical models. Cold season La Nias
often accentuate the usual trade wind pattern of the lower latitudes, and
typically bring increased precipitation to windward locations and increased
dryness to leeward locations. The primary exception to this involves the
development of Kona Lows, which frequently bring increased rainfall to both
windward and leeward sites. Thereafter, beginning in MAM 2025 and extending
through longer leads, the forecast signal decreases, leaving EC as the most
likely outcome.
Hilo
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2024 A40 75.5 0.4 EC 28.3 34.5 42.0
NDJ 2024 A40 74.2 0.4 A45 26.4 36.6 43.0
DJF 2025 A40 72.8 0.4 A55 19.6 30.2 33.3
JFM 2025 A40 71.8 0.4 A55 22.0 32.0 44.5
FMA 2025 A40 71.7 0.4 A45 24.6 34.1 45.5
MAM 2025 EC 72.0 0.5 EC 22.5 28.4 34.0
AMJ 2025 EC 72.9 0.5 EC 21.4 23.7 29.0
MJJ 2025 EC 74.0 0.4 EC 20.2 27.5 29.1
JJA 2025 EC 75.2 0.4 EC 19.4 27.2 31.4
JAS 2025 EC 76.1 0.4 EC 25.2 28.6 33.4
ASO 2025 EC 76.4 0.4 EC 26.1 28.8 33.3
SON 2025 EC 76.2 0.4 EC 24.3 30.2 40.8
OND 2025 EC 75.5 0.4 EC 28.3 34.5 42.0
Kahului
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2024 A45 77.8 0.4 EC 4.2 5.3 8.1
NDJ 2024 A45 75.9 0.4 A40 5.2 7.6 9.5
DJF 2025 A45 73.8 0.4 A45 4.6 6.9 8.7
JFM 2025 A45 72.5 0.4 A45 4.2 6.2 8.2
FMA 2025 A45 72.3 0.4 A40 3.2 4.1 6.4
MAM 2025 EC 73.0 0.4 EC 2.5 3.5 4.6
AMJ 2025 EC 74.3 0.5 EC 1.2 1.6 2.2
MJJ 2025 EC 76.0 0.5 EC 0.7 1.1 1.8
JJA 2025 EC 77.7 0.4 EC 0.7 1.1 1.5
JAS 2025 EC 79.0 0.4 EC 0.8 1.1 1.6
ASO 2025 EC 79.4 0.4 EC 0.8 1.6 2.5
SON 2025 EC 79.1 0.4 EC 2.1 3.3 4.8
OND 2025 EC 77.8 0.4 EC 4.2 5.3 8.1
Honolulu
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2024 A45 80.0 0.4 EC 4.4 6.4 8.5
NDJ 2024 A50 77.7 0.5 A40 3.9 5.6 8.8
DJF 2025 A50 75.3 0.5 A45 3.7 5.6 8.6
JFM 2025 A50 73.9 0.4 A45 2.1 4.6 7.8
FMA 2025 A50 73.8 0.4 A40 1.9 3.2 4.7
MAM 2025 EC 74.8 0.4 EC 1.8 2.6 3.0
AMJ 2025 EC 76.3 0.4 EC 1.2 1.6 1.8
MJJ 2025 EC 78.2 0.4 EC 0.8 1.4 1.6
JJA 2025 EC 79.9 0.4 EC 0.7 0.8 1.3
JAS 2025 EC 81.3 0.4 EC 1.0 1.4 1.7
ASO 2025 EC 81.7 0.4 EC 1.6 2.4 3.1
SON 2025 EC 81.4 0.4 EC 2.5 4.0 5.6
OND 2025 EC 80.0 0.4 EC 4.4 6.4 8.5
Lihue
TEMPERATURE PRECIPITATION
FCST AVE LIM FCST BLW MEDIAN ABV
OND 2024 A45 77.8 0.3 EC 9.2 11.7 15.6
NDJ 2024 A50 75.7 0.3 A45 8.6 12.1 16.9
DJF 2025 A50 73.6 0.4 A55 7.5 8.4 14.0
JFM 2025 A50 72.2 0.4 A55 6.5 8.8 13.8
FMA 2025 A50 72.1 0.5 A45 5.8 8.4 9.9
MAM 2025 EC 72.8 0.5 EC 5.3 6.6 8.0
AMJ 2025 EC 74.2 0.5 EC 4.7 5.5 6.0
MJJ 2025 EC 76.0 0.5 EC 4.9 5.4 5.9
JJA 2025 EC 77.7 0.4 EC 4.4 5.3 6.9
JAS 2025 EC 79.0 0.3 EC 5.3 6.1 7.8
ASO 2025 EC 79.4 0.3 EC 6.2 7.9 8.4
SON 2025 EC 79.1 0.3 EC 9.2 10.0 11.2
OND 2025 EC 77.8 0.3 EC 9.2 11.7 15.6
FORECASTER: Anthony Artusa
Anomalies are based on the 1991-2020 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 Oct 17, 2024.
$$