Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
238 AM EDT Thu Apr 09 2020

Valid 00Z Fri Apr 10 2020 - 00Z Fri Apr 17 2020

The weakened remnants of a cold front are expected to drift
eastward across the state through the end of the week. PWs of 1.2
to 1.4 in. will be focused in the vicinity of the boundary, which
should be sufficient for scattered showers. Light low-level flow
should favor mauka areas for shower activity. Over the weekend,
models/ensembles show general agreement that another shortwave
should separate from the Pacific northern stream and amplify as it
moves southeast toward Hawaii, with likely development of another
closed upper-level low north of the state, and the approach of
another cold front. Deterministic guidance has come into much
better agreement on this feature over the past couple days, and a
general blend of model guidance should represent the feature well,
including any relatively minor differences in frontal timing and
intensity of low pressure north of Hawaii. Guidance continues to
suggest that the axis of deepest moisture associated with this
feature may remain primarily east of Hawaii, with the Big Island
perhaps having the best prospect for more significant showers over
the weekend and into next week as the front likely stalls in the
vicinity. By the middle of next week, as the upper-level system
moves away from the state, ensemble show consensus that
upper-level ridging from the west central Pacific should begin to
build east toward/across Hawaii, with heights gradually rising.
This, along with a surface high building north of the state,
should allow for a resumption of a somewhat more typical trade
wind pattern for Hawaii. Guidance shows relatively light (10-15
kt) trades to begin next week, gradually increasing through the
week, perhaps reaching 20 kt and becoming gustier by mid-week.
Gradual advection of somewhat drier air should keep windward
showers relatively sparse by the middle of next week.

Ryan