Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
255 AM EST Sun Dec 01 2019

Valid 00Z Mon Dec 02 2019 - 00Z Mon Dec 09 2019

Latest guidance displays better agreement with the overall
forecast for the next seven days compared to the past couple days
when meaningful spread developed for some aspects mid-late period.
 Consensus shows initial high pressure well north of the state
quickly weakening with the approach of a stronger high from the
west.  Expect the second high to reach a position similar to the
first one by around Thursday and then track southeastward.  This
evolution should promote moderate to brisk trades through most of
the week.  By next weekend the combination of the high reaching
the far eastern Pacific and a cold front coming into the picture
northwest of the islands should lead to somewhat weaker trades. 

Generally windward/mountain-focused showers will fluctuate in
coverage and intensity during the period.  Early this week there
should be a drier trend albeit with precipitable water values
remaining a little above climatology.  Then moisture will increase
mid-late week, likely peaking around Thursday or Friday ahead of a
sharpening shortwave aloft that should pass over the area Friday
and reach southeast of the islands next weekend.  Guidance is
consistent with the general signal for increased rainfall in this
time frame while ECMWF trends away from a band of very heavy
rainfall have yielded better agreement toward a more moderate
event.  Models/means indicate that shortwave passage will likely
bring precipitable water values to or slightly below normal for
next weekend.

Rausch