FXHW60 PHFO 090226 CCA
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
425 PM HST Sun Dec 8 2024

.SYNOPSIS...
Light to moderate easterly trades will gradually strengthen into 
the breezy to strong range by midweek as high pressure strengthens
to the north, with brief passing showers favoring windward and 
mountain areas. An upper level low passing just south of the 
islands may enhance rainfall coverage over the eastern half of the
state Friday into the weekend, with trades gradually subsiding 
into the moderate to breezy range. 

&&

.DISCUSSION...
Current visible satellite imagery and surface observations show
some low clouds moving into windward areas on the light to 
moderate trades and additional cloud build up over leeward 
interiors with sea breeze activity this afternoon. As an 
approaching front dissipates and high pressure builds to our 
north, trades will gradually strengthen tonight through mid week.
The latest model guidance suggests that the strongest winds 
speeds will impact the state Wednesday into Thursday as trades 
become breezy to strong, with Wind Advisory conditions possible 
for the typical windier areas. Wind speeds at the Big Island 
summits are expected to jump up to warning levels as early as 
tomorrow morning as an upper level jet streak dives down over the 
area. As such, a High Wind Warning has been issued for the summits
starting tomorrow at 6 AM HST. 

Fairly dry and stable conditions will persist for the first
half of the week before a combination of upper level dynamics and
low level moisture edging up from the tropics begin to increase
the rain chances for windward areas across the eastern end of the
state. Model guidance continues to show an upper level low 
pinching off from the main trough southeast of the island chain 
and then retrograding westward, potentially bringing increased 
instability that could help to enhance trade wind showers across 
the Big Island. However, there are still some model discrepancies 
concerning that upper level feature, so forecast confidence on 
potential impacts (mostly rainfall potential) is on the lower side
for now. Stay tuned for forecast updates. 

&&

.AVIATION...
VFR conditions will dominate as trade winds gradually strengthen 
through Monday. Somewhat dry weather will persist, with only 
isolated areas of MVFR conditions in -SHRA along terrain, mainly
on windward Big Island and Kauai. With trades on the rise, AIRMET
Tango for tempo moderate low level turbulence over and downwind 
of terrain could be needed as early as Monday.

An upper level trough and an accompanying jet stream will develop
just north then east of the islands tonight and Monday. The jet 
stream may produce moderate to severe turbulence above FL250 just 
northeast of the islands tonight, while AIRMET Tango for moderate 
turbulence aloft will likely be needed over the state after 
midnight.

&&

.MARINE...
Easterly trade winds will strengthen to moderate to locally 
strong overnight. A Small Craft Advisory (SCA) has been issued
to address the freshening winds. Initially, SCA conditions should 
be limited to the windier waters around Maui County and the
Big Island, but by Tuesday, the advisory will likely need to be 
expanded to include most Hawaiian waters due to the combination of
stronger winds and building seas. SCA conditions are expected 
within Hawaiian coastal waters throughout the coming week and 
possibly beyond. 

A series of overlapping north-northwest swells are expected to push 
surf heights to near advisory levels on Monday and Tuesday. A 
gradual downward trend is expected to follow, but surf along north
and west facing shores could remain elevated through the weekend.

Surf along south-facing shores will remain up through Monday due 
to an out-of-season south swell, which will gradually subside 
Tuesday. Seasonal conditions will return around midweek with a 
mix of smaller southeast and south-southwest swells. 

Surf along east-facing shores will increase through midweek due to 
strengthening trade winds both locally and upstream of the Islands. 

&&

.FIRE WEATHER...
Critical fire weather conditions are not anticipated this evening 
as wind speeds and relative humidity values aren't anticipated to 
approach critical levels. For the rest of the week, the main 
concern will be the strengthening trades, which current model 
guidance suggests will peak around Wednesday, likely exceeding 
critical thresholds. Relative humidity values look to be the 
limiting factor next week, but could still drop below 50 percent 
during the windier periods. 

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 AM to 6 PM HST Monday for Big Island 
Summits.

Small Craft Advisory from midnight tonight to 6 PM HST Wednesday 
for Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island 
Leeward Waters-Big Island Southeast Waters.

&&

$$

DISCUSSION/FIRE WEATHER...Farris
AVIATION...Wroe
MARINE...Bedal