Wind Advisory 7, NWS Honolulu, HI

325 
WWHW70 PHFO 281333
NPWHFO

URGENT - WEATHER MESSAGE
National Weather Service Honolulu HI
333 AM HST Fri Feb 28 2020

HIZ024>027-281445-
/O.CAN.PHFO.WI.Y.0007.000000T0000Z-200228T1600Z/
South Big Island-Big Island North and East-Kohala-
Big Island Interior-
Including the cities of South Point, Pahala, Hilo, Volcano, 
Honokaa, Kamuela, Waikoloa, Bradshaw Field, 
and Saddle Road Above 5000 feet
333 AM HST Fri Feb 28 2020

...WIND ADVISORY IS CANCELLED...

Winds have decreased below advisory threshold. The Wind Advisory 
is therefore cancelled.

$$

Powell

Area Forecast Discussion
National Weather Service Honolulu HI
937 AM HST Thu Feb 27 2020

.SYNOPSIS...
A stable and breezy trade wind flow will continue to focus modest
rainfall along windward slopes today. High pressure will
strengthen northeast of the state on Friday, likely boosting
trades further through the weekend. An upper low will drift over
the islands during this time, leading to an increase in showers,
some possibly heavy with a slight chance of thunderstorms. Wet
conditions may persist into early next week.

&&

.DISCUSSION...
The stable and breezy trade wind flow will remain relatively
unchanged today. A broad surface ridge and surface high far north
of the state will slowly consolidate, leading to little change in
the strength of the trade winds. Trades will be at borderline
Wind Advisory strength this afternoon and evening over portions of
the Big Island, mainly in the Kohala Districts where wind gusts
in excess of 40 mph are expected. These strong gusts will be
induced, in part, due to a ridge aloft that is maintaining stable
conditions with a strong inversion around 6,500 to 7,000 ft.
Precipitable water within the stable trade wind flow remains just
below seasonal normal, resulting in modest windward showers that
will briefly spread to leeward areas this morning. Dew points are
holding in the upper 50s to lower 60s, which is maintaining a
somewhat cool feel under the breezy trades.

On Friday through Sunday, trade winds will likely increase. The
above mentioned surface high will strengthen to around 1040 mb as
it becomes parked about 1,300 miles north-northeast of the state.
A high of this strength and at that position would normally
ensure that trades would ramp up significantly. However, there is
some uncertainty, as a mid to upper level low currently east of
the state approaches on Friday and drifts overhead during the
weekend. This feature will likely weaken the local surface
pressure gradient and keep the strongest trade winds to the
northeast of the islands. However, it still appears that we will
see an increase in trades, possibly requiring a Wind Advisory some
time this weekend.

An increase in shower activity is due late Friday through the
weekend. As the mid to upper level low moves overhead, low level
moisture will not change substantially, but exceptionally cold
temperatures aloft will produce unstable conditions that will
likely generate spotty showers, some briefly heavy, and perhaps a
few thunderstorms. Rainfall will continue to be focused along
windward slopes, but the gusty trades will easily push fast-
moving, briefly heavy showers across leeward areas. By Friday
night, freezing levels will drop unusually low to around 9,000 to
10,000 ft, bringing chances for snow and/or freezing rain as
showers pass over the high summits of the Big Island and possibly
Haleakala on Maui.

Wet conditions may linger into early next week. The GFS and ECMWF
show the mid level low dissipating and lifting northward on
Monday, while an associated surface trough is pulled over the
islands from the east. Trades should drop and may shift out of the
southeast if the trough is strong enough. Moisture convergence on
the east side of the trough could lead to another period of wet
weather for some windward areas.

&&

.AVIATION...
A strong surface high located far northeast of the main Hawaiian
Islands will maintain gusty northeast to east trade winds through
early Friday morning. As a result, AIRMET TANGO remains in effect
for moderate low-level turbulence south through west of the higher
terrain on all the islands below 100.

The robust low-level trade wind flow will also continue to transport
low clouds with embedded showers into northeast facing sections
of the islands through this afternoon, producing brief periods of
MVFR conditions. Otherwise, expect VFR conditions to prevail during
the daylight hours across most of the state. By later tonight and
early Friday, low cloud and shower coverage may increase, thereby
causing MVFR conditions to become more widespread over the higher
terrain and northeast facing slopes, possibly enough to require
issuance of AIRMET Sierra for mountain obscuration over some
islands.

&&

.MARINE...
A high far northeast of the area is producing strong to near gale
force easterly trade winds over Hawaiian coastal waters. A Small
Craft Advisory (SCA) is in effect for all coastal waters through
the weekend. Winds are expected to be strongest from Friday night
into Sunday as the high builds to near 1040 mb. A low aloft is
expected to induce troughing at the surface near the islands which
will keep the winds from becoming even stronger. The low will
bring a chance of thunderstorms from Friday through the weekend.

The WW3 model shows a new northwest swell arriving today. The
swell has been slow building at the NOAA buoys northwest of
Kauai, but the swell is expected to rise high enough to produce
near the High Surf Advisory (HSA) threshold tonight. Surf will
slowly build along east facing shores as the trade winds
strengthen. A HSA for east facing shores will likely be needed
over the weekend, and it is possible the surf could reach warning
levels along east facing shores.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Sunday for all Hawaiian
waters-

&&

DISCUSSION...Wroe
AVIATION...TS
MARINE...Donaldson