Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
816 AM EDT Mon Mar 13 2017

Valid 00Z Tue Mar 14 2017 - 00Z Tue Mar 21 2017

The models are in good agreement and show a low level ridge in
place early this week just north of the islands. A weak inverted
trough and local sea breezes focus scattered showers mostly in the
big island and Maui. Isolated light showers are expected elsewhere.

By mid week, shortwaves in the westerlies north of the islands
cause a break in the ridge with a weak trough in the islands mid
week.  On Thu-Thu night, a trailing cold front crosses the
islands.
The front brings an uptick in showers but weak low level
convergence leads to modest coverage and amounts.

After the front passes, the low level flow is forecast to
gradually veer, starting from north
to northeast and eventually east near the end of next weekend or
early next week. Windward showers are expected with the wind
speeds greater than early in the week.  The higher speeds result
in greater lift and the model amounts are a little higher next
weekend where coastal convergence occurs. 

The location of the low-mid level ridge early next week keeps
precipitable water values low, so the chances of heavy rain are
minimal. The rising heights aloft lead to above normal
temperatures.

The models and ensembles cluster well with the pattern evolution. 
The 06z gfs lags the 06z gefs mean, ecmwf ensemble mean and
operational gfs with the timing of the low moving north of the
islands mid week.
The model come back into better than average agreement on the
strong mid level ridge building into the islands early next week.

Petersen