Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
220 AM EDT Sun Oct 17 2021

Valid 00Z Mon Oct 18 2021 - 00Z Mon Oct 25 2021

Surface high pressure centered near 35-40 degrees north will begin
to break down some as a col develops within this ridge early in
the week.  This will be the result of a strong storm system
passing well to the north with a weakening cold front approaching
a few hundred miles north of the Islands, and a second
front/trough following behind it for mid-week.  The surface high
is expected to rebuild near 30-35 degrees north for the end of the
week.  Aloft, a weak upper level disturbance will likely track
westward across the state through Monday, and potentially another
weak upper feature passing south of the state late in the week. 
There is good agreement among the ECENS and GEFS means on the
evolution of the overall weather pattern.

The features noted above are not expected to have much of an
impact in terms of rainfall, with mainly dry conditions for
leeward areas and trade wind showers for east-facing terrain.  The
heaviest rainfall should remain well south of the Islands.  Steady
easterly trades through the weekend are expected to abate some by
Tuesday/Wednesday as the col develops and the pressure gradient
weakens, and then increase again by next Friday/Saturday as the
surface high becomes more firmly established. 

Hamrick