Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
809 AM EDT Mon Mar 12 2018

Valid 00Z Tue Mar 13 2018 - 00Z Tue Mar 20 2018

...Heavy rain threat this week...

Potent high pressure now northwest of the state bridges to the
north of the islands over the next few days to support moderate to
strong trade flow underneath. To the southwest of Hawai'i,
sharpening mid-level energy and an associated weak surface
low/inverted trough now west-southwest of the state should
meanwhile lift slowly northeastward toward Hawai'i. Guidance
spread is improving for this scenario and a preferred composite
would allow a surge of deep moisture and precipitation into the
islands with mean precipitable water values rising to around 2
inches (~3+ standard deviations). This would fuel an increasingly
wet period Tuesday to Thursday with moderate to heavy rainfall. By
Friday, a models/ensembles show another upper trough or closed low
near 25N/180 which should allow heights over Hawai'i to rise,
helping to diminish the heavy rain threat. Southeasterly flow will
persist through the weekend into early next week with scattered
showers as precipitable water values slowly fall to under 1.5
inches.

Schichtel