Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 AM EST Fri Nov 25 2022

Valid 00Z Sat Nov 26 2022 - 00Z Sat Dec 03 2022

Guidance agrees fairly well with the overall forecast evolution
through the first part of next week.  Flow around an initial
deep-layer low northeast of the state will support relatively dry
conditions into the weekend.  Strong northeasterly winds should
trend noticeably weaker by Saturday, possibly allowing for some
land/sea breeze influence on shower activity during the weekend. 
Consensus shows a pronounced northward surge of tropical moisture
and energy aloft by around late Sunday through Tuesday, with
precipitable water values possibly reaching at least 2.0 inches at
some locations (00Z GFS higher than the 00Z ECMWF).  Standardized
anomalies in the GFS/ECMWF and their means reach plus 2.5-4. 
Guidance generally agrees on a heavy rainfall threat but with
typical spread for the specifics.  Enough southeasterly background
flow may exist at low levels to provide the best enhancement over
favored terrain on the Big Island.

By mid-late week the guidance diverges regarding the depth of
upper troughing forecast to be aligned just west of the main
islands, though the 00Z GFS/ECMWF offer better agreement on a
frontal boundary that approaches but does not reach the western
islands late in the week.  The GFS/GEFS mean depict deeper upper
troughing than other guidance, leading to a rebound of
moisture/rainfall over the state late in the week.  This contrasts
with weaker majority that would yield less extreme precipitable
water values and lower rainfall totals.  An intermediate solution
looks best at this time, given the wet GFS/GEFS being in the
minority but the 12Z ECMWF mean holding onto more moisture than
the operational 00Z ECMWF run and the approaching late week front
potentially getting close enough to support a rebound of moisture
to some extent.

Rausch