Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
351 am HST Sat Mar 15 2014
a weakening front will pass through the Hawaiian islands today.
Strong high pressure will build into the state behind the front
later today through Sunday...ushering in very windy conditions.
A High Wind Warning has been issued across much of the state for
late this afternoon through Sunday. More typical trade wind
weather returns for next week.
persistent shower activity has continued to focus on windward
Maui through the night...with activity increasing across windward
Oahu recently as well. The 12z Hilo sounding reflected showers
at the station...but the Lihue sounding also showed a rising
and weakening inversion as a weak frontal boundary moves into
that area. Also notable in the Lihue sounding was the increasing
low level flow...with winds up to 29 knots at 1000 feet. Surface
observation also show increasing winds across Kauai...and winds are
starting to increase across the western tip of Oahu as well.
The main weather issue for today through Sunday continues to be
the expected strong/gusty winds. The latest model data remains
consistent with previous runs...moving a strong surface high
eastward along 35n...with the high center passing north of Hawaii
on Sunday. This will spread a band of strong northeast winds from
west to east across the state this afternoon and early this
evening...with strong winds then continuing overnight through
Sunday. Model soundings continue to depict strong low level
inversions developing at least across western sections...and cross
sections show good subsidence across the area as well. These
factors should produce very strong winds across many leeward slope
areas. Strong winds are likely in favored funneling areas such as
the Maui Central Valley and Lanai as well. The strongest winds
appear likely to occur tonight into Sunday morning.
Have upgraded the previous watch to a High Wind Warning...and
included the Kauai mountains in the warning as well. A Wind
Advisory has been posted for all zones not included in the
warning...except for Haleakala Summit and The Big Island summits.
Residents and visitors with outdoor plans from late this
afternoon through Sunday should expect strong winds and potential
issues with powerlines...roofs...and broken tree branches.
Otherwise...would expect enhanced showers to continue affecting
windward sections of Maui and The Big Island through the weekend.
Windward Haleakala and the hamakua coast may be particularly
impacted by persistent rains...as model data suggests that
considerable low/middle level moisture could remain trapped in those
areas. Expected available moisture/forcing does not appear
sufficient to warrant a Flood Watch at this point...but would not
be surprised to see a number of flood advisories in those areas
during the next couple of days. Drier conditions should prevail
across Oahu and Kauai...with just scattered showers windward and
isolated showers leeward.
Early next week...the surface high will migrate further northeast
of the state...while a weak middle level trough lingers from around
30n 145w southwestward across The Big Island. These developments
will reduce the pressure gradient across Hawaii...allowing
moderate trades to resume. The proximity of the middle level trough
and ample low level moisture should continue to produce a rather
wet trade pattern across windward portions of Maui and The Big
Island. Somewhat drier conditions should continue across Oahu and
periods of MVFR ceiling/visible in clouds/rain showers will affect the windward
terminals of all islands today as a weak front advances down the
chain...bringing more clouds and showers to the area. As
such...airmet Montana obscure will probably continue for most islands due to
clouds and showers. Elsewhere mainly VFR conditions will
prevail...though clouds and showers may reach the Lee areas at
times under the strong winds...especially over the smaller islands
resulting in brief MVFR ceiling/visible in clouds/rain showers as well.
Stronger trade winds have already reached Kauai earlier this morning
and will spread down the island chain through the day. In
fact...winds are still expected to strengthen a bit later today.
Therefore airmet Tango for turb over S and west of the mountains will
continue as well. The sustained surface winds may become strong
enough to warrant the issuance of a significant meteorological information for severe turb over the
area later today.
northwest swell energy in the 15 second range has increased
considerably at Waimea buoy during the night. This northwest swell in
combination with building north-northeast short period swell should produce
high surf on north facing shores today through Sunday...with
surf just reaching criteria on west facing shores...including
the Kona coast of The Big Island. The increasing northeast winds
will bring building high surf and rough conditions to east facing
shores as well today through Sunday.
A Gale Warning is in effect for the channels between the islands...
and for other areas around Kauai and The Big Island. Very strong
northeasterly winds are anticipated for these areas from this
afternoon through Sunday...making for hazardous boating
conditions. A Small Craft Advisory is posted for those marine
areas not included in the Gale Warning.
High Wind Warning from 4 PM this afternoon to 6 PM HST Sunday
for Niihau-Kauai-Oahu South Shore-Waianae coast-Oahu koolau-
Olomana-central Oahu-Waianae mountains-Molokai leeward-Lanai-
Kahoolawe-Maui leeward west-Maui Central Valley-leeward
Haleakala-Kona-Big Island north and east-kohala.
High surf advisory until 6 PM HST Sunday for Niihau-Kauai
leeward-Waianae coast-Oahu North Shore-Molokai leeward-Kona.
Wind Advisory from 4 PM this afternoon to 6 PM HST Sunday for
Oahu North Shore-Molokai windward-Maui windward west-windward
Haleakala-south Big Island-Big Island interior.
High surf advisory until 6 am HST Monday for Kauai windward-Oahu
koolau-Olomana-Molokai windward-Maui windward west-windward
Haleakala-Big Island north and east.
Gale Warning until 6 am HST Monday for Kauai northwest waters-
Kauai leeward waters-Kauai Channel-Kaiwi Channel-Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island windward waters-
Big Island leeward waters-Big Island southeast waters.
Small Craft Advisory until 6 am HST Monday for Kauai windward
waters-Oahu windward waters-Oahu leeward waters-Maui County
windward waters-Maui County leeward waters.