Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
258 AM EST Sun Feb 18 2024

Valid 00Z Mon Feb 19 2024 - 00Z Mon Feb 26 2024

After a cold frontal passage a day or two ago, relatively cool and
dry air prevails over Hawaii with northeasterly winds. A surface
high currently northwest of the state will continue tracking
eastward through the early part of the week and then southeast,
ending up east of Hawaii by midweek. The high to the north will
help cause winds to continue to veer to a more typical easterly
direction, starting out breezy early week and decreasing to more
moderate levels Tuesday-Wednesday as the high weakens and shifts
positions. Drier than normal precipitable water values are likely
to remain in place through the first half of the week, but a few
light showers may affect favored windward and mountain areas under
easterly flow.

By the latter half of the week, trades look to strengthen and
possibly veer a bit more with some southerly component to the
winds. This is in response to another surface high well north of
the state while upper and surface lows develop well west of the
islands. Model guidance varies with how close the surface
low/frontal system edge toward the state by late week. The
ECMWF/CMC bring the moisture plume just ahead/east of the cold
front and spread heavy rainfall amounts close to the northwestern
islands, while the GFS stays well west, and ensemble members vary
but the ensemble means generally follow their parent models.
Confidence is low at this point but the forecast will continue to
be monitored. Slightly more predictable is that the atmosphere
should gradually moisten into late week while a weak west-east
front may push through the state slowly.

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