455 
FXHW60 PHFO 011344
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
344 AM HST Sat Apr 1 2023

.SYNOPSIS...
Considerable high cloud cover will keep skies mostly cloudy
through the weekend. Rather dry weather will continue over the 
eastern end of the state today and tonight, while scattered 
showers continue and a few thunderstorms remain possible over the
western islands. An afternoon thunderstorm may develop on the Big
Island as well. A disturbance aloft will develop over the state on
Sunday, increasing showers and bringing the potential for a few 
thunderstorms to the entire island chain. Moderate to breezy 
trade winds and more typical trade wind weather will then return
Monday and linger through late next week.

&&

.DISCUSSION...
Currently at the surface, a trough of low pressure is located 175
miles northwest of Kauai, while a 1027 mb high is centered around
1500 miles north-northeast of Honolulu. Light winds prevail over 
the western islands, while moderate trades persist over the 
eastern end of the state. Infrared satellite imagery shows mostly 
cloudy skies across the state. Radar imagery shows scattered 
showers over Kauai, a few showers showers affecting the Big 
Island, and very little if any shower activity over Oahu and Maui
County at the moment. Main short term focus revolves around trade
wind trends and thunder chances during the next couple days.

The trough of low pressure will remain nearly stationary northwest
of Kauai today and tonight, with little change to the winds 
expected. The trough will then slowly shift west and further away 
from the islands Sunday and Sunday night as high pressure builds 
to the distant northeast, allowing moderate to locally breezy 
trade winds to build back across the entire island chain. A ridge 
of high pressure will then settle in several hundred miles to the 
north and northeast of the state next week, keeping moderate to 
breezy trade winds in place across the island chain.

As for the remaining weather details, little change in the overall
weather pattern is expected through tonight, with shower coverage
remaining the highest over Kauai. Shower coverage will be less 
over Oahu during this time, but not as dry as over Maui County and
the Big Island where fairly dry weather will continue. The 
airmass will remain unstable over the western end of the state, so
a slight chance of thunderstorms will need to be included in the 
forecast from Oahu westward. A thunderstorm or two could pop over
the Big Island slopes this afternoon as well. A disturbance aloft
will develop over the state Sunday, bringing the potential for 
some heavier showers and even a few thunderstorms to the entire 
island chain. Considerable cloudiness will continue statewide 
through the weekend. The most unstable airmass appears to slide 
south of the state by daybreak Monday, allowing a more typical 
trade wind pattern featuring mainly windward and mauka showers to 
settle in and linger through the end of the work week.

&&

.AVIATION...
The active pattern with showers and the potential for isolated 
thunderstorms will continue this weekend due to an upper 
disturbance and surface trough lingering to the northwest. Low- 
level flow will remain out of the east-southeast, which will 
translate to the localized land/sea breeze regime holding for 
Oahu and Kauai. Although the bulk of the shower activity will 
remain focused over the western end of the state this morning, 
much of the state could get into the mix later today through the 
end of the weekend as deep moisture pools northward ahead of the 
upper trough.

AIRMET Sierra remains in effect for mountain obscuration for 
Kauai and Oahu due to low clouds and showers. This may be lifted
for Oahu later this morning if conditions continue to improve. 

AIRMET Tango remains in effect for tempo moderate turbulence in 
the layer FL200-FL400.

&&

.MARINE...
Weak ridging over the state, with a stationary trough west of 
Kauai, is resulting in generally moderate areawide southeasterlies
that are veering more southerly around Kauai. The trough is 
forecast to remain nearly stationary through the day before it 
drifts slowly westward into early next week. This will allow 
trades to return over the near and offshore waters through the 
remainder of the week. Winds across the eastern end of the state 
will remain strong enough to continue a Small Craft Advisory (SCA)
for the windier areas around Big Island. Upper level troughing 
northwest of the area, along with convergence ahead of the surface
trough, will create enough instability to support thunderstorm 
activity over the coastal waters from Oahu westward through the 
weekend. Thunderstorm activity may expand into more eastern waters
Sunday as a new low aloft develops over the state. 

The ongoing small northwest (320 degree) swell will slowly decline 
through Saturday. A small northeast swell will fill in tonight,
peak Saturday and then level out through early next week. There 
are no other significant North Pacific swells that will affect the 
islands through late next week. Moderate to fresh trades upstream
of the state will continue to produce choppy surf conditions along
eastern exposures through next week. Small background energy from
different southerly directions will continue to hold small surf 
in along south-facing shores for the foreseeable future.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Sunday for Maui County 
Windward Waters-Maalaea Bay-Pailolo Channel-Alenuihaha Channel-
Big Island Windward Waters-Big Island Leeward Waters-Big Island 
Southeast Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Gibbs
MARINE...Blood