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Hawaii Extended Forecast Discussion
(Latest Discussion - Issued 1214Z Nov 24, 2017)
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Abbreviations and acronyms used in this product

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
714 AM EST Fri Nov 24 2017

Valid 00Z Sat Nov 25 2017 - 00Z Sat Dec 02 2017

...Heavy rain possible next week over the Big Island and perhaps

Upper high to the northwest of Hawai'i will weaken and move
westward in the short term, allowing troughing to settle over the
region over the region. The sfc high to the northwest of the
region will be reinforced this weekend and slide southeastward
then eastward along 33N next week which will maintain breezy/windy
trades into next week. Light to scattered windward/mauka showers
are expected with only some spillover to leeward areas possible as
the overall air mass remains dry.

Next week, the trough or weakly closed low will continue to push
westward, allowing moisture from the ITCZ to creep northward. This
will increase rain coverage from southeast to northwest over the
island chain. The GFS/ECMWF have wavered on how much to increase
precipitable water values but the latest 00Z ECMWF was more in
line with the multi-center ensemble mean whereas the GFS showed
lower PW values. In addition, the 00Z GEFS M-Climate QPF
percentiles were at the 99th percentile very near the southeast
islands next Wed-Fri, so the potential remains for at least some
modest to locally heavy rain next week, especially over the Big
Island and Maui.