671 
FXHW60 PHFO 071338
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
338 AM HST Fri Oct 7 2022

.SYNOPSIS...
A large low pressure system will linger far north of the Hawaiian
Islands well into next week, weakening the high pressure ridge 
north of the islands, and keeping the trade winds light through 
Thursday. Sea breezes will develop each afternoon with brief 
afternoon to evening showers. A cold front approaching the islands
from the north will stall out before reaching Kauai and fade away
on Sunday and Monday. An unstable tropical moisture plume will be
drawn northward over the islands producing a wet and unstable 
weather pattern over the state from Monday onward with enhanced 
showers forecast across the island chain.

&&

.DISCUSSION...
The satellite imagery this morning shows a weakening cold front 
stalling out just north of Kauai. This system will have little 
impact on island weather. Elsewhere cloud tops are building south 
of the Big Island, as a low level trough pulls up deeper tropical 
moisture as it passes south of the state over the next few days. 
Some of this tropical moisture will be drawn up into Hawaii and 
enhance shower activity through the first half of next week. High 
level cirrus clouds are passing over the state, these clouds are 
associated with the subtropical jet stream over the region.

A complex low pressure system far north of the state will drift
south towards the islands and become cut off from the main polar
front jet stream. The weak cold front currently stalling north of
the island chain will fade away today and then be replaced by 
another weakening front, forecast to stall north of the state 
from Sunday to Monday. The larger cut off low will anchor roughly
1000 miles north of the Hawaiian Islands this weekend. This low 
will weaken the ridge north of the islands extending our light to 
moderate trade wind flow, and draw up additional tropical 
moisture across the islands through much of next week.

Weather conditions through Sunday will remain in a light trade 
wind and sea breeze pattern. Hot and humid conditions will be the 
rule with more variable wind direction trends. Clouds and passing 
showers may develop over windward areas through the overnight and 
early morning hours, then in the afternoon to early evening these 
clouds and showers will transition to leeward and island interior 
areas due to sea breeze wind convergence and heating. A low level 
trough (shown on 700 mb streamlines) currently passing south of 
the islands will likely enhance shower activity through this 
weekend over all islands in Maui and Hawaii Counties. Isolated 
thunderstorms are also possible over the higher elevations of the 
Big Island into the weekend.

Longer range weather conditions from Monday through next Thursday
remain wet and unstable as the cut off low north of the state
draws up tropical moisture into the island chain. Our long range 
guidance continues to vary a bit on the island by island impacts 
this far out in the forecast cycle. However, wet trends remain a 
likely outcome for all islands with the highest enhancement to
clouds and showers expected over the northwestern islands from Kauai
to Molokai. More details will be added to this extended range 
forecast in the next few days as the forecast time period gets 
closer and our confidence grows. Stay tuned for weather forecast 
updates as next week's weather pattern will likely evolve over 
time.

&&

.AVIATION...
A weak front located just north of the main Hawaiian Islands will
continue to cause the background trade wind flow to weaken today.
This will likely allow local afternoon sea breezes and nighttime 
land breezes to develop over each of the individual islands 
through Saturday. The weak low-level trade wind flow will 
continue to bring some low clouds and showers into the windward 
sides of the central islands this morning. This is likely 
producing periods of MVFR conditions due to broken to locally 
overcast low clouds and scattered showers over windward sections 
of Maui and Molokai. As a result, AIRMET Sierra remains in effect
for mountain obscuration for the higher terrain on Maui and 
Molokai. This AIRMET may be cancelled later this morning if 
conditions improve. Elsewhere, brief periods of MVFR conditions 
are possible along the windward sides of the remaining islands, 
but VFR conditions will likely prevail over most areas through 
this morning. 

By this afternoon, the development of afternoon sea breezes will 
likely cause an increase of leeward and interior clouds and 
showers. Increasing instability could also enhance the intensity 
of these showers in some locations, such as the leeward Big 
Island. A slight chance of thunderstorms has been added to 
forecast for the upslope sections of the leeward Big Island this 
afternoon. This may produce periods of MVFR conditions over some 
leeward and interior sections of the island chain later today. 
After sunset, expect downslope winds to clear out most of the 
residual cloud cover and showers over leeward areas by late this 
evening. 

&&

.MARINE...
Ridges positioned both north and east of Hawaii from two different
high pressure systems will result gentle to locally moderate 
trade winds through today. Winds will weaken becoming light and 
variable this weekend as an approaching low and cold front from 
the north forces the ridges away from the islands. Winds will veer
southeast Monday and Tuesday as the front dissipates near Kauai 
and the low lifts away to the north allowing the ridge to nose 
back in from the east. Wind waves will be small around the islands
until southeasterlies strengthen early next week.

The new north swell is currently filling in at the Hanalei and 
Waimea Bay near shore buoys. Surf will continue to build along 
north facing shores today to near or just below High Surf Advisory
levels and hold through the weekend before dropping early next 
week. Surf along east facing shores will be small due to 
diminished wind swell, except for some select east facing shores 
exposed to the north swell wrap.

A small, long period south swell will fill in throughout the day
today, peak over the weekend before slowly subsiding early next 
week and bring near to slightly below summer average surf to south
facing shores. Another similar sized south swell may arrive 
around the middle of next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Bohlin
AVIATION...Houston
MARINE...Almanza