Drought in Hawaii, November 5 to 30, 2019

Area Forecast Discussion
National Weather Service Honolulu HI
840 PM HST Mon Nov 4 2019

.SYNOPSIS...
Light winds will continue through Tuesday, with trade winds making a
brief return Wednesday and Thursday before diminishing again by the
end of the week. A passing disturbance in the upper atmosphere will
bring increasing high clouds, and some instability, Tuesday into
Wednesday. This may allow a few heavy showers to develop over Kauai
and Oahu Tuesday afternoon. The returning trade winds will bring
clouds and a few showers to windward areas, but the chance of heavy
showers will diminish. A front approaching the area this weekend may
bring the potential for unsettled weather.

&&

.DISCUSSION...
Currently, moisture associated with a stalled and dissipating front
is draped over Kauai and adjacent waters, with broken to overcast
stable to showery low clouds noted on satellite and radar. Although
showers along the boundary are not particularly heavy or widespread,
an isolated thunderstorm briefly fired on the outer edges of the
coastal waters N of Oahu earlier this evening. A surface ridge
extends NE from windward waters NE of Maui and the Big Island, and
the associated stability and light winds are maintaining a quiet
weather regime over the islands from Oahu to the Big Island,
although some of the frontal moisture is lurking over Oahu's leeward
waters. Winds are light statewide, and favor an ESE direction,
except W of the frontal boundary, where low-level winds are from the
NNE. A sharpening trough aloft is rapidly approaching the islands
from the NW, with water vapor imagery highlighting its axis near 26N
176W, as well as an area of associated broken to overcast high
clouds.

Although the island forecast is seasonably dynamic through the next
week, the short term forecast expects little significant change
through early Tuesday. Land breezes will clear skies over land
statewide, except on Kauai, where clouds and spotty showers will
likely linger through the night as the frontal boundary drifts NW.
The approaching trough aloft may bring some increase in instability
Tuesday, but guidance indicates the frontal moisture will lift N of
Kauai, while a different area of moisture moves up over Kauai and
Oahu from the SSW. With light winds persisting due to the nearby
surface ridge, afternoon sea breezes may help to trigger a few heavy
showers over Kauai and Oahu. Depending on how things evolve
overnight, isolated thunderstorms may need to be added to the
forecast. The trough aloft is expected to bring a period of broken
to overcast high clouds starting Tuesday afternoon, clearing the
islands from NW to SE Wednesday and Wednesday night as a strong
ridge aloft builds over the area from the W.

The aforementioned ridge aloft will linger over the area into the
weekend, keeping the island atmosphere very stable as trade winds
return briefly. A surface high to the NW will begin to make itself
felt in the islands late Tuesday through Thursday as the surface
front dissipates, leading to light to moderate NE trade winds.
Guidance indicates that some of the moisture associated with the
dissipated front will move back over the islands with the weakly
convergent trade winds, bringing passing windward clouds and
showers, despite the strong stability.

The high will dissipate Thursday night and Friday, leading to a
collapse of the trade winds once again. An approaching trough aloft
will push the ridge aloft S of the islands, while also driving a
surface front toward the area from the NW, increasing the potential
for unsettled weather next weekend as winds weaken, and potentially
turn southerly.

&&

.AVIATION...
Winds will remain light across the island chain through Tuesday as a
stalled dissipating front persists over the western end of the
state. Most showers, with their accompanying brief to TEMPO MVFR
conditions of lower ceilings and visibilities, will affect Kauai and
Oahu, especially in the afternoon and early evening hours Tuesday.
VFR will prevail overall, however, around the islands.

An AIRMET for mountain obscuration is currently in effect for Kauai.

&&

.MARINE...
A stationary front over the western islands will slowly dissipate
through Tuesday, keeping mainly light winds in place across the
marine area. High pressure building northwest of the state will
bring a brief return of trade winds Wednesday and Thursday. A new
front approaching from the northwest will weaken the winds again
Friday through the weekend. Winds are expected to remain below Small
Craft Advisory (SCA) levels during the next 7 days.

A High Surf Advisory remains in effect for most north and west
facing shores of the smaller islands through 6 AM Tuesday. A SCA
also remains in effect for the marine zones exposed to this
northwest swell, which also runs through 6 AM Tuesday. Based on
upstream buoy observations, only a slow gradual decline in the surf
is expected, and as a result the HSA and SCA may need to be extended
through the day Tuesday. This swell is then expected to continue to
slowly subside through rest of the work week. A new moderate to
large northwest swell is expected to arrive late in the weekend into
early next week.

A couple overlapping southerly swells are expected Friday through
early next week, with the potential for advisory level surf not out
of the question during the weekend. East shore surf will remain well
below seasonal levels during the next 7 days.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Tuesday for North and West facing
shores of Niihau Kauai Oahu and Molokai and for North facing shores
of Maui.

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

&&

DISCUSSION...Birchard
AVIATION...Kinel
MARINE...Jelsema