Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
341 AM EDT Tue Apr 11 2023

Valid 00Z Wed Apr 12 2023 - 00Z Wed Apr 19 2023

A reasonably strong surface high to the north of Hawaii, between
35-40N latitude, will keep trade winds at breezy levels over the
next couple of days. With moisture levels now looking to be above
average and some weak instability possible due to a weak trough
overhead, showers mainly in windward areas can be expected, but
some may make it to leeward areas given the strength of the winds.
Trades are forecast to lessen some by later this week as the high
shifts east and weakens as a cold front well north of the islands
disrupts the high. A showery pattern in more moderate trades may
continue for windward and mountain areas through late week. Then
by early next week, a drying/more stable trend is possible
underneath a brief upper ridge and as winds turn to southeasterly
in response to upper and surface lows developing northwest of the
state. These lows tracking eastward toward Hawaii could bring a
wetter pattern next week as moisture is drawn north. Model
guidance shows some spread as far as the timing of increased
moisture arriving (first for the western islands), with the
GFS/GEFS indicating around Monday and the ECMWF/EC ensemble means
showing around Tuesday. Regardless, a wetter pattern is likely at
some point next week, and will continue to monitor for updates.

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