Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EST Sun Nov 03 2024

Valid 00Z Mon Nov 04 2024 - 00Z Mon Nov 11 2024

Not much has changed over the past day in the guidance, with
respect to decent agreement between now and midweek followed by
increasing model/ensemble spread for details at the surface and
aloft.  Moderate trades and windward/mountain shower focus will
prevail into the first part of this week, supported by high
pressure well to the northeast of the state.  Weak shortwave
energy approaching from the west and enhanced moisture arriving
from the east-southeast will combine to support some locally heavy
rainfall around next Monday-Tuesday with particular emphasis over
the Big Island.  Then a front should progress close to or into the
main islands from the northwest around midweek while the southern
periphery of the supporting upper trough starts to drop southward.

From Thursday onward, the ECMWF continues to be in the relative
minority with the combined depth and location of its upper low,
which is now northeast/east of the state versus over the main
islands in the 00Z ECMWF from 24 hours ago.  The 12Z ECens mean
offers support in more muted form though.  In varying ways, most
other guidance indicates that the energy aloft will be more
sheared over/just east of the main islands, with any weak upper
low possibly tracking just south of the state by the weekend as
upper ridging builds eastward to the north of the islands.  Most
of the latest machine learning model runs support the non-ECMWF
scenario in principle, so preference would go to a compromise
among non-ECMWF guidance.  This majority cluster would favor a
period of brisk northeasterly winds after midweek and more
easterly trades by next weekend, in contrast to somewhat weaker
winds in the 00Z ECMWF due to its more pronounced surface trough
arriving from the east.  Moisture/rainfall should decrease some
later in the week, with trends by next weekend dependent on
shortwave/upper low details.

Rausch