Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
709 AM EST Fri Feb 06 2015

Valid 00Z Sat Feb 07 2015 - 00Z Sat Feb 14 2015

Today (Fri) lingering moisture is departing from the Big Island
along with a leading front while a weak front immediately upstream
may bring a few showers to the islands into Sat.  Breezy northwest
winds behind these fronts will slacken and turn northerly on Sat
with the approach of a trailing weak surface high.

Departure of this high and approach of a fairly strong cold front
will support strengthening southwesterly winds early next week
with frontal passage expected to occur in the Mon-Tue time frame. 
One band of enhanced rainfall is possible with the front as
precipitable water values are forecast to be at least 1.25-1.50
inches.  There is still some debate as to the northwestward extent
of a leading band of deep moisture/rainfall lifting from the
southeast toward the Big Island.  ECMWF runs are still bringing
this southeastern band farther northwest than the GFS.  The latter
has been showing a gradual trend toward the ECMWF scenario and
still shows somewhat greater southeastward amplitude versus
consensus with the trough aloft, so leaning more toward the ECMWF
forecast seems reasonable. 

Passage of this front will bring a drying trend and another period
of brisk northwesterly winds Tue-Wed, followed on Thu by weak
winds and showers that may have more of a land/sea breeze focus
with passage of a very weak surface high.

Forecast confidence rapidly declines by next Fri as guidance
disagrees over the existence/timing of a possible wave tracking to
the northwest of the islands.  GFS/CMC runs are rather strong with
such a wave while the 00z GEFS mean has a wave but is much slower.
 The ECMWF/ECMWF mean/CMC mean merely show a front but at least
the ECMWF is similar with the idea of a significant increase in
deep moisture.  Low amplitude of southern stream flow seems to
recommend weaker strength than the GFS if such a wave were to
evolve.

Rausch