Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
812 AM EDT Mon Apr 08 2019

Valid 00Z Tue Apr 09 2019 - 00Z Tue Apr 16 2019

...Heavy rain possible later this week into the weekend...

Weak front currently across Kauai will dissipate over the next few
days as precipitable water values oscillate around 1.25 inches.
Trades will increase
through the week and showers will be light to modest through
Wednesday. Models and ensembles show an upper low developing to
the east of the area (east of 150W) on Tuesday that is forecast to
retrograde westward as upper ridging bridges atop the upper low
from the Dateline in the tropics to the mid-latitudes. Consensus
takes the low over the eastern islands Friday and then stalls is
for the next few days, perhaps into next week. Ensemble spread of
the 500mb heights was relatively low for a 7-day lead time, but
differences lied in how much moisture to wrap back into the area
from the deep tropics. Regardless, expect an increase in rainfall
to the entire region later this week with the biggest focus on at
least the Big Island and Maui starting around Thursday. Locally
heavy rain with embedded convection for parts of the island chain
is possible given the setup and influx of moisture.


Fracasso