Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
820 AM EDT Sun Mar 10 2019

Valid 00Z Mon Mar 11 2019 - 00Z Mon Mar 18 2019

A relatively benign weather pattern is expected to persist across
Hawaii through much of the upcoming week. Surface high pressure
will remain centered north of the state through early in the week,
keeping brisk 20-30 kt trades initially in place. Trades will
begin to weaken by Tue as the surface high slides east and a cold
front washes out well north of the state. PWs will hover near or
just above 1 inch through the week, supporting some scattered
shower activity. In general, models show agreement on the broad
pattern with the strongest westerly flow remaining well north of
Hawaii through much of the week, with Hawaii on the eastern
periphery of a strong upper ridge across the west central Pacific.
By next weekend, model/ensemble guidance suggest the likely
development of a more substantial upper-level trough across the
north central Pacific. Consensus among deterministic solutions has
improved a bit since yesterday, with most solutions now showing a
shortwave amplifying north of Hawaii on Sat, and a closed upper
low developing by Sun as the trough passes well north of Hawaii.
This scenario would likely push a stronger cold front southward in
the direction of Hawaii, as shown by the ECMWF and GFS. Moisture
availability appears to remain rather limited, so while some
increase in shower activity would likely accompany the front next
weekend, the primary impacts would likely be a period of gusty
northwest winds behind the front on Sunday. Given the time frame,
still expect deterministic solutions to vary somewhat with respect
to this feature over the coming days. Ensemble means continue to
lend at least moderate confidence to this scenario, however.


Ryan