Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
725 AM EST Fri Feb 02 2018

Valid 00Z Sat Feb 03 2018 - 00Z Sat Feb 10 2018

...Heavy rain threat for Kauai and Oahu through the weekend...

Very deep troughing near the Dateline (500mb height anomalies
around -4 standard deviations) will move eastward this weekend.
This will drive a surface cold front through the region on Monday
with northwesterly upper flow behind it by Thursday. Surface winds
will veer to northwesterly behind the front then northerly to
northeasterly Tuesday and beyond.

Through the weekend, old surface boundaries (moisture axes) to the
northwest of the region will maintain a moist southerly to
southeasterly flow and the continued risk of modest to locally
heavier rain for Oahu/Kauai/Ni'ihau. Precipitable water values
will be in excess of 1.50-1.75 inches or +2 to +3 standard
deviations. The models and ensembles were in good agreement
through the period as the front approaches the northwesternmost
islands early Monday. This will push the rain to the southeast
through the rest of the region on Tuesday and then to the east of
the Big Island on Wednesday. The ensemble consensus slowly takes
the upper trough eastward later in the week, maintaining a showery
and breezy pattern for the islands with precipitable water
anomalies below average.


Fracasso