Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
830 PM HST Friday Jul 31 2015
moderate trades will continue through the rest of the weekend and
into Monday. Showers will increase as remnant moisture associated
with former tropical depression 8e reach the islands during the next
couple of days. The forecast for next week will be highly dependent
on the eventual track of Hurricane Guillermo.
high pressure centered far north of the main Hawaiian islands is
keeping a moderate trade wind pattern across the area with trade
showers moving over most windward areas. The showers should get more
active later tonight and through Sat as moisture associated with the
remnants of tropical depression 8e reach the east half of the island
chain. Best chances of rain reside over windward Big Island areas
Sat afternoon and evening. The area of moisture will spread across
the rest of the islands on sun...still with best chances of rain
over windward areas. The trades will remain strong enough to push
some of the larger showers into leeward locations at times.
Model data show the trades gradually decreasing early next week as
Hurricane Guillermo moves closer to the state from the east. At 5 PM
HST...Guillermo was located about 1330 miles east-southeast of Hilo...and is
expected to enter the central Pacific waters Sat morning. The
tropical cyclone will then bring a disruption of the trades...but
it is too early to have a Concrete idea of specific impacts for the
islands. Thus...will continue to carry the inherited forecast trend
of increasing cloud cover and showers for the second half of next
week and wait for future model runs before making any significant
changes to the forecast.
Regardless of the outcome of Hurricane Guillermo...it is a great
reminder to get prepared if you have not done so already. The
central Pacific is off to a fast start this season and August is
historically the most active month of the year for tropical
high pressure north of the state and a series of low pressure systems S
of the islands will keep a breezy east to NE trade wind flow in place
through Saturday. As a result...clouds and showers will focus
primarily across mountain and north through east sections of the islands.
Occasional brief MVFR ceilings will be possible at phli and phto through
middle morning Saturday...with higher probabilities of MVFR ceilings
expected at phto late Saturday afternoon into Saturday evening as
moisture associated with the remnant low of tropical depression 8e
moves over The Big Island.
Airmet Tango remains in effect for moderate low level turb over and
S through west of the mountains...and these conditions are expected to
continue through Saturday. Airmet Sierra may be needed for mountain
obscuration later tonight across portions of the islands.
a Small Craft Advisory remains in effect for typically windy areas
around Maui and The Big Island. Hurricane Guillermo is located far
east southeast of the state moving toward the west northwest.
Although the track and intensity of the tropical cyclone remains
uncertain so far in the future...adverse effects for Hawaiian
coastal waters next week can not be ruled out.
Advisory level surf along east facing shores of The Big Island is
likely as early as Sunday.
Small Craft Advisory until 6 am HST Sunday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island leeward waters-Big
Island southeast waters.