Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
330 am HST Thursday Oct 8 2015
light to moderate trades will prevail over the main Hawaiian
islands into the weekend. However...a couple of low level troughs
will bring a boost in showers to parts of the island chain over the
weekend. A front is expected to drop down on the islands about
Tuesday of next week.
upon further examination...a small low level trough likely from an
front that nudged just east of The Big Island a day or two ago...is
currently located off the Kona coast noted as a mass of clouds on
satellite imagery. There are a few embedded showers but mostly consist
of middle level clouds with tops about 11k feet. The models are tracking it
toward the northwest or in the direction of Kauai. It is slated to
pick up some low level moisture while on its way there...and in the
process graze Oahu with a few showers tonight and early Friday morning.
It is expected to give Kauai some wet weather on Friday and Friday night
before easing west of Kauai County Saturday.
As one trough falls apart...another one reaches The Big Island. This
trough is once associated with T.C. Oho which got left behind as oho
ran off toward the NE. It is noted on satellite imagery as a line
with a few towering cumulus clouds located 475 miles southeast of The
Big Island. It will be heading toward The Big Island later today...
being carried westward by the trade winds. The European model (ecmwf) /ec/ and GFS
models difffer on its timing. The ec is faster and touches all the
islands...while the GFS solution has it affecting primarily The
Big Island Saturday through Sunday...before easing off to the
northwest north of Molokai on Monday. Some minor but critical
differences. We would like to have the models come to a more unify
solution. These two models do concur in bringing in a front reaching
Kauai Tuesday afternoon.
In the mean time...the trades are light enough during the next
couple of days where some afternoon clouds and an isolated showers
may form over the leeward areas of the smaller islands particularly
Kauai and Oahu. Otherwise...a background light to moderate NE wind
flow will rule the islands into Saturday. Do expect a few trade
showers to move in with this flow affecting the windward and
mountain areas. This second trough is more identifiable where low
level winds east of the axis are from the east and southeast.
VFR will prevail over most areas through the day...with only
brief MVFR conditions possible over windward...Mauka...and
interior areas of each Isle in lower ceilings and light showers.
Conditions have improved over The Big Island...so the airmet
for mountain obscuration along north through east sections of
the Isle has been cancelled.
nothing much on the marine front. There are no marine warnings in
effect...and none is expected into the weekend.
Surfwise...a small to moderate north-northwest swell is expected
to fill in over the weekend. A long period south-southwest swell will bring
increased surf to south shores through the weekend...but staying
below advisory levels. A small west swell is possible over the
weekend as well.
Discussion and marine...lau