Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
741 AM EDT Tue May 30 2017

Valid 00Z Wed May 31 2017 - 00Z Wed Jun 07 2017

Current water vapor imagery and mid-level height fields show a
circulation east of the island chain while mid/upper-level dry air
filters in to the west of Hawai`i. General agreement exists in
lifting this cyclonic circulation to the north during the next few
days with GEFS members being a tad slower than the ECMWF
ensembles. While timing issues do exist, they do not to create any
notable impacts to the state as upper ridging starts to envelop
the Central Tropical Pacific. Such ridging will prevail through
the remainder of the period as amplified flow stays well north
into the mid-latitudes.

At the surface, high pressure to the north will gradually
strengthen by mid-week which should lead to an uptick in the
climatological trades. These are expected to persist through the
weekend as the anticyclone should maintain its presence across the
mid-latitudes. Eventually lowering heights accompanying the next
upper trough will lead to an eastward shift of this ridge by early
next week. Low-level winds are forecast to diminish in strength,
particularly over Kauai and perhaps Oahu. Some solutions even
depict winds decreasing to below 5 knots at times, most notably
the 06Z GFS. Regarding precipitation, the usual trade driven
shower activity is likely, especially during periods of
strengthening in such wind fields. Precipitable water values
throughout the forecast should generally meander between 1 to 1.25
inches with higher moisture content being suppressed toward the
Intertropical Convergence Zone.


Rubin-Oster