Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
823 AM EDT Mon Jun 27 2016

Valid 00Z Tue Jun 28 2016 - 00Z Tue Jul 05 2016

As a large trough lifts northeastward across the North Pacific and
a weak shortwave trough crosses the central Pacific in its wake, a
1030 mb surface anticyclone near 38N 168W will drift east
southeastward and weaken thru Wednesday before an amplifying
shortwave trough over the west central Pacific lifts northeastward
toward the northern Pacific, allowing the upper ridge over the
east central Pacific to build and amplify. This allows the surface
anticyclone to shift slightly eastward and intensify,  with a 1030
mb high near 150 W expected to build to near 1035 mb by Friday
near 38N 150 W. The surface high is then forecast to drift slowly
westward through the weekend to near 1033 mb near 38N 155W,
supported by the ensemble means for location and the operational
runs for central pressure. On Sunday into Monday, the operational
models begin to diverge on the strength and location of the
anticyclone, with the Canadian and the ECMWF farther east and
northeast closer to 150W.

Per the 06Z GFS, the precipitable water values over the state
increase slightly from 1.25 inches to near 1.5 inches by Thursday
before dropping back down to 1.25 inches over the weekend.  The
GFS does point to increase in forecast shower activity especially
over Kauai by Thursday into Friday while activity diminishes over
the next few days with the usual windward development. The 00Z
ECMWF and Canadian models have a weaker QPF signal but is similar
with drying out next weekend.


Kocin