Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
721 AM EST Sat Feb 03 2018

Valid 00Z Sun Feb 04 2018 - 00Z Sun Feb 11 2018

...Locally heavy rain for northwest islands through the weekend
then through the rest of the islands early next week...

Very deep troughing near the Dateline (500mb height anomalies
around -3 standard deviations) will move eastward over the
weekend, driving a surface cold front through the region starting
early Monday over Kauai and Ni'ihau. The models have trended
toward a bit slower frontal passage owing to a stronger upper
shortwave (possibly closing off) and a couple surface waves (even
up through 850-800mb) forming along the cold front and lifting
northeastward. With available moisture well above average
(1.50-1.75" precipitable water) the heavy rain threat will
translate eastward through the island chain Monday-Tuesday and
maybe into early Wednesday. Models/ensembles show the cold front
exiting past the Big Island late Wednesday or early Thursday as
the upper trough finally swings through. Northwesterly upper flow
will follow in the wake of the FROPA as surface winds veer to
northwesterly behind the front then northerly to northeasterly. A
showery and breezy pattern for the islands will follow later next
week into next weekend with the upper low and surface front east
of the region. GFS/ECMWF blended solution should suffice through
the period given the shifts in the guidance over the past 24-48
hours. 


Fracasso