Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
809 AM EDT Thu Jul 13 2017

Valid 00Z Fri Jul 14 2017 - 00Z Fri Jul 21 2017

The general synoptic pattern features amplified flow within the
mid-latitudes as broad ridging extends across the central Pacific.
Across the subtropics, an upper low west of the Hawai`ian islands
will continue to move toward the International Dateline while
elongated troughing extends over a vast majority of the
subtropical eastern Pacific. The lead feature embedded in this
region of lower heights should meander northeast of Hawai`i but
generally be of no consequence to the region. By the weekend, a
positively-tilted upper trough sits over the state with this
feature shifting west of the islands by early/mid-next week.
Beyond this period, what is currently Tropical Storm Fernanda will
be somewhere southeast of the region.

At the surface, persistent ridging to the north will continue to
favor an active period of moderate trade winds. By Monday, the
anticyclone generally breaks into two with a pair of surface highs
setting up to either side over the mid-latitudes. This subtle
weakening in the pressure gradient will lead to a slight reduction
in the strength of the trades next week. Looking at precipitation,
scattered light showers are currently falling across the region.
However, this is occurring in an environment with decreasing
precipitable water values, on the order of 0.50 inches lower than
the previous day. Within the active period of trades, expect the
usual daily threats for windward showers with local orographics
helping augment rainfall amounts.


Rubin-Oster