Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
722 AM EST Fri Nov 23 2018

Valid 00Z Sat Nov 24 2018 - 00Z Sat Dec 01 2018

Upper-level ridging will dominate the weather pattern across
Hawaii through much of the next week before things begin to change
by the mid to late part of next week. Surface high pressure
initially in place well northeast of the state is expected to
gradually weaken over the next several days, before redeveloping
north of the state by next Tue-Wed. Trades will respond in kind,
with weakening expected over the weekend before returning into the
20-25 kt range by next Tue-Wed. By the middle of next week, a
number of solutions continue to show an amplifying trough
developing in the westerlies to the northwest of Hawaii, with a
number of solutions continuing to suggest significant
amplification possible along with a rather deep surface cyclone.
These solutions push a cold front into the western Hawaiian
islands by next Thu-Fri. Model spread remains high, although there
seems to be a bit more confidence that this feature will undergo a
fairly significant degree of amplification, resulting in the
potential transport of tropical moisture northward. Solutions
continue to differ substantially, however, on the precise timing
of the feature and the track of the resultant surface low. The
deterministic ECMWF seems likely too fast when compared to its
mean, perhaps to the point of being an outlier. A solution more
along the lines of the GFS seems more representative of a
consensus at this point. Nonetheless, chances appear to be
increasing that rainfall may become more widespread across the
western islands by later next week as the trough amplifies and the
front approaches.

Ryan