Prognostic Meteorological Discussion
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FXHW01 KWNH 251226
PMDHI

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
726 AM EST Sun Feb 25 2018

Valid 00Z Mon Feb 26 2018 - 00Z Mon Mar 5 2018

The active weather pattern that has been present over Hawaii and
the adjacent waters over the past couple of days with numerous
showers and storms is expected to abate during the short range
forecast period.  The inverted surface trough and upper level low
northwest of the state will weaken and lift to the north.  A
strong surface high will become established between Hawaii and
California going into the early part of the upcoming week with
steady easterly trade winds expected with periods of mainly
orographically forced showers, with the axis of greatest QPF
centered near 165W over the open waters of the Pacific.

The models and ensembles are in decent agreement on the synoptic
scale pattern over the Hawaii domain going into the second half of
the forecast period for the end of the week and into the weekend.
A hint of an omega block flow pattern over the central Pacific is
indicated in the guidance, with the main ridge axis situated
generally near 150W with upper level troughs to the southwest and
southeast of the upper level high.  The EC mean is slightly more
amplified with the upper level ridge than the GEFS mean, with both
solutions breaking down the ridge by next Sunday.  Another weak
upper low will likely form near 170W by Friday according to both
the GEFS and EC means.  This may once again advect deeper moisture
northward across the westernmost part of the Islands for the end
of the week.  No cold fronts are expected to approach the Islands
over the next 7 days.

D. Hamrick

$$




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