Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
816 AM EDT Mon Mar 11 2019

Valid 00Z Tue Mar 12 2019 - 00Z Tue Mar 19 2019

A couple areas of high pressure at the surface will remain north
of Hawaii through midweek before shifting east by Wed night-Thu. A
mid/upper-level weakness evident across the eastern Hawaiian
Islands this morning is forecast to slowly drift eastward through
the next few days. Sensible weather impacts of this feature on the
state are relatively minimal, with PWs around 1 inch, resulting in
relatively sparse shower activity. Trades are forecast to
gradually weaken through midweek as the pressure gradient across
the region weakens. Models/ensembles continue to show broad
consensus that a larger scale upper trough should amplify across
the north central Pacific Fri-Sun, pushing a cold front southward
across Hawaii by Sat night. Deterministic model solutions show
some relatively small timing differences with respect to the
frontal passage, but the 00Z ECMWF was very close to the center of
the consensus. The GFS appeared to be on the faster side of the
spread. Moisture accompanying the front will be rather sparse,
with only a modest increase in showers expected along the
boundary. Additionally, while the strongest height falls, cold
advection in the wake of the front should generally remain north
of the state, a period of gusty north to northwesterly winds is
likely. By Monday, a surface high should once again rebuild just
north of Hawaii with upper ridging west of Hawaii expanding east
across the state. This will bring a return to more typical
conditions and 10-20 kt trades. Subsidence associated with the
ridge will dry the air mass further, with PWs dropping well below
1 inch by early next week.


Ryan