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Temp5.7 C
RH46 %
WindN 10 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

847
FXHW60 PHFO 112003
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1003 AM HST Thu Aug 11 2022

.SYNOPSIS...
Strong trade winds will continue through much of today due to
high pressure to the north and a tropical disturbance passing
south of the islands. The trade winds will gradually ease Friday
and Saturday becoming land and sea breezes early next week. With
limited moisture and a stable atmosphere, little total rainfall is
anticipated.

&&

.DISCUSSION...
A 1030 mb far to the north northeast and a tropical disturbance
southwest of the state will drive fresh to locally strong trade
winds today. Winds or gusts could approach advisory levels in
exposed areas, mainly around the Big Island and Maui County, but
overall wind speeds will be on the downward trend today as the
tropical disturbance advances westward. Visible satellite shows
scattered, thin cirrus clouds on the northern periphery of the
disturbance. Low clouds moving in with the trades are and will
continue to focus over windward slopes today. Soundings from 12Z
show a strong inversion at 5-6 kft indicating stable atmospheric
conditions. Radar shows very little precipitation across the
state.

CIMSS MIMIC layer precipitable waters imagery reveals a
much drier upstream airmass extending from about 150W to the West
Coast and reaching as far south as 15N, so no major sources of
moisture are expected to impact the islands in the coming days.
The high in the East Pacific will be forced southward by an
intruding low pressure system and weaken tonight and Friday,
resulting in a weakening of the trade winds across Hawaii Friday
and Saturday.

By early next week, trades become light as the associated remnant front
approaches and stalls well north of the the islands. At this
time, it appears winds may be light enough for island-scale land
and sea breezes to be the dominant weather pattern. Continued dry
and stable conditions will limit cloud cover and showers into the
middle of next week.

&&

.AVIATION...
Gusty trade winds will continue over the islands into this
evening, as an area of high pressure remains well north-northeast
of the state. Limited moisture will generate mainly VFR
conditions through early Friday, while showers affect mainly
windward and mauka sections. Some MVFR cigs will occasionally
drift across windward areas this morning, continuing the need for
AIRMET Sierra due to tempo mountain obscurations for windward
areas of the Big Island. However the latest satellite trends
suggests MVFR cigs should diminish by this afternoon as dry flow
continues to stream in from the northeast.

AIRMET Tango remains in effect for low-level mechanical
turbulence leeward of mountains due to windy trades. These
turbulent conditions will continue across the islands this
afternoon.

&&

.MARINE...
The low-level pressure gradient between high pressure centered
far NE of the islands and a tropical disturbance passing well SW
of the islands is supporting fresh to strong trade winds. A Small
Craft Advisory (SCA) remains in effect for a large portion of the
coastal waters. The disturbance will move steadily WNW away from
the area over the next couple of days while the high weakens and
moves S. Trade wind speeds are expected to be on the decline for
most of the forecast period, although this is expected to be a
gradual process. Winds should be below SCA speeds in all zones by
late this weekend, with gentle to moderate trade winds prevailing
statewide early next week.

Little in the way of surf is expected into next week. Small,
long-period S swell is expected over the next couple of days, as
well as a relatively short-period SE swell, supporting surf near
or below seasonal averages along S facing shores. Choppy surf
along E facing shores will gradually diminish as the trade winds
ease the next couple of days.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 6 PM HST this evening for Niihau-Kauai
Leeward-Oahu South Shore-Waianae Coast-Oahu North Shore-Central
Oahu-Waianae Mountains-Molokai Leeward-Lanai Makai-Lanai Mauka-
Kahoolawe-Maui Leeward West-Maui Central Valley-Leeward
Haleakala-Kona-South Big Island-Kohala-Big Island Interior.

Small Craft Advisory until 6 PM HST Friday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

Small Craft Advisory until 6 PM HST this evening for Kauai
Northwest Waters-Kauai Leeward Waters-Kauai Channel-Oahu Leeward
Waters-Kaiwi Channel-Maui County Windward Waters-Maui County
Leeward Waters-Big Island Windward Waters.


&&

$$


DISCUSSION...Foster
AVIATION...SWR
MARINE...Birchard

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office