Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
356 AM EDT Wed Oct 02 2024

Valid 00Z Thu Oct 03 2024 - 00Z Thu Oct 10 2024

Today's guidance is consistent with the general pattern evolution
at the surface but has made some additional changes aloft.
Consensus still shows moderate trades with primarily
mountain/windward shower focus through Thursday. Then there should
be a period of lighter trades Friday through the weekend as fronts
weaken high pressure to the north and upper troughing develops
overhead.  This may allow for sea/land breezes to affect the
distribution of rainfall late week during Friday-Sunday.  Trades
should rebound to moderate speeds Monday-Wednesday with a return
of windward shower focus as high pressure to the north
strengthens.  The 00Z ECMWF has an extraneous mid-latitude system
that breaks the ridge again toward midweek but still shows
increasing trades.

As for flow aloft, recent guidance has been quite diverse and
variable from run to run.  Today's notable shift versus 24 hours
ago is toward the axis of the forecast upper trough (with possible
embedded low) staying over or very close to the main islands into
next Tuesday or Wednesday versus being aligned somewhat farther
east.  On the positive side, the models and ensembles look more
similar for their details than they have in previous days and the
latest machine learning models also cluster in line with the
dynamical guidance.  This helps to increase confidence relative to
previous days but recent history suggests further change is
possible.  The current consensus forecast aloft could promote some
enhancement to showers from the weekend into next week, with most
guidance showing relatively higher precipitable water values
around the weekend.

Rausch