Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
348 AM EDT Thu Mar 23 2023

Valid 00Z Fri Mar 24 2023 - 00Z Fri Mar 31 2023

Latest guidance agrees well for about the first half of the
period.  Into early Friday expect some showers to produce enhanced
rainfall as an axis of relatively high precipitable water values
extends through the state.  An associated surface trough that will
promote light winds may allow for land/sea influence on showers. 
Passage/weakening of the system to the north will lead to a modest
deep-layer ridge building northeast of the state during the
weekend and a more typical trade pattern with windward focus of
any remaining showers that should be lighter.

Another upper low/trough will approach from the northwest, with
digging northern stream energy likely to reinforce the feature
early next week.  From Monday onward guidance diverges some for
the eastward progression/extent of the upper trough along with the
associated surface front/trough plus axis of moisture and enhanced
rainfall that may move into the main islands.  The most pronounced
extreme is the 00Z GFS that strays well ahead of the other
models/means by next Wednesday-Thursday.  That run is within the
full 00Z GEFS envelope but differs so much from the overwhelming
majority of solutions that confidence in its specifics is rather
low.  That said, the multi-day trend for the current system
affecting the state ultimately gravitated closer to the eastern
GFS/GEFS side of the spread and the trailing trough/low has
adjusted somewhat eastward over the past few days.  Incorporating
the less extreme but still somewhat eastward 18Z GFS and 00Z GEFS
mean in a compromise with the 00Z ECMWF appears to be a reasonable
starting point for this part of the forecast.  This solution would
lead to increasing rainfall arriving from the west by
Tuesday-Thursday with a surface front/trough reaching into the
western-central islands and interrupting trade flow once again. 
Winds should tend to be southeasterly to southerly ahead of the
surface boundary.  

Rausch