Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
716 AM EST Sat Dec 03 2016

Valid 00Z Sun Dec 04 2016 - 00Z Sun Dec 11 2016

...Continued Heavy Rainfall Pattern for Hawai'i...

...Guidance and Uncertainty Assessment...

Weakening upper low over the region will soon be replaced by a
digging shortwave along 165W. This will pull additional moisture
through the central/eastern islands late Sunday into Monday. The
00Z ECMWF/Canadian remain on the slower side with this incoming
shortwave (briefly closing off) while the 00Z UKMET and 06Z-00Z
GFS (and parallel 00Z GFS) were quicker. Ensemble means generally
followed their parent model. A slower solution would infer greater
rainfall potential. The ECMWF/Canadian are not unreasonably slow
as there are many ECMWF ensemble members slower than the
deterministic run and some GEFS members as slow as the ECMWF.
Preference lies in between the two camps, but hedging toward a
slower solution.

By next week, models are still unsure how to handle the next
digging trough and perhaps closed low along 170W. Ensembles
suggest something in between the 06Z GFS (farther southwest and
slower) and the 00Z ECMWF (farther north and a bit quicker). 


...Weather Highlights/Threats...

Waves of rainfall over the next several days will be dependent
upon the evolution of the upper trough/low Sunday into Monday,
though the central/eastern islands have the best chance of heavier
rain. By the middle/end of next week, much more uncertainty in QPF
is seen over the region due to differences in the evolution of the
upstream troughing. Moisture connection to the ITCZ appears to
remain into next weekend.


Fracasso