Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
321 AM EST Tue Jan 28 2020

Valid 00Z Wed Jan 29 2020 - 00Z Wed Feb 05 2020

A relatively drier air mass across the state into the middle of
the week should result in fairly sparse windward shower activity.
Light to moderate trades should persist through midweek with a
ridge of high pressure north of Hawaii. Models show consensus that
a cold front should approach Hawaii by late in the week as a
shortwave amplifies across the north central Pacific.
Model/ensemble agreement remains good, with the cold front likely
to move into the western Hawaiian Islands Thu night or Fri
morning, and then moving east across the state through Fri
night/Sat. As the primary upper wave moves east, the trailing
front across Hawaii may begin to stall across the eastern islands
by the weekend.  Some component of the upper-level wave appears
likely to cut off and drift southward across Hawaii over the
weekend, potentially bringing a period of somewhat greater
instability across the state. Trades should see some disruption
ahead of the front, with low-level flow becoming initially lighter
and veering to a more southeasterly direction. There remains some
potential for a very brief period of northeasterly flow behind the
front (particularly across the western islands) before the front
begins to wash out and trades gradually resume. Deeper moisture
along the front is also likely, with guidance showing PWs
increasing into the 1.2-1.5 inch range, increasing the potential
for more widespread shower activity across the state in
association with the front through the weekend (especially across
the western islands), perhaps lingering into early next week as
the front washes out over the state. High pressure should pass
north of Hawaii through early next week, with models showing a
similar scenario unfolding with another front approaching toward
the middle of next week.

Ryan