Current Conditions
Temp0.2 C
RH15 %
WindW 8 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 181338

Area Forecast Discussion
National Weather Service Honolulu HI
338 AM HST Tue Jan 18 2022

Generally dry and pleasant weather with light winds can be
expected through most of the week. A few showers will be possible
over windward slopes and coasts, mainly over the eastern islands
during nights and mornings, with a few showers developing over the
island interiors each afternoon. A weakening front may bring an
increase in showers late Friday through Saturday night as it moves
down the island chain, particularly for windward areas. Drier
weather appears to build in behind the front for Sunday and next
Monday, with minimal shower activity.


Currently at the surface, a 1024 mb high is centered around 1650
miles northeast of Honolulu, with a ridge axis extending
southwestward to a location near Kauai. Land breezes are present
over the smaller islands, with light to moderate trades over
unsheltered sections of the Big Island. Infrared satellite imagery
shows clear to partly cloudy conditions in most areas, with a bit
more cloud cover over windward sections of Maui and the Big
Island. Radar imagery shows scattered showers moving into windward
sections of Maui and the Big Island, with mainly dry conditions
elsewhere. Main short term concern revolves around rain chances
during the next few days.

The ridge of high pressure will remain nearly stationary near or
just north of Kauai through Thursday, before settling southward
over the islands Thursday night and Friday as a front approaches
from the northwest. This will keep light and variable winds in
place featuring overnight land breezes and daytime sea breezes for
the western islands, with light to locally moderate trade winds
prevailing over the eastern end of the state. The front is
forecast to move southward into Kauai Friday night then push
southward through the remainder of the island chain Saturday and
Saturday night, while high pressure builds in north of the state.
Light trade winds could make a return as early as Friday night,
with moderate trades then filling in over the entire state over
the weekend and holding in place through early next week.

As for the remaining weather details, fairly dry conditions will
continue through the remainder of the work week. A few showers
will be possible over the windward slopes and coasts during nights
and mornings, mainly over the eastern end of the state, while a
couple showers will be possible each afternoon over the island
interiors. Shower coverage and intensity may be a bit higher on
Friday over Kauai as some deeper moisture appears to move in here
in advance of the front. As the front moves down the island chain
Friday night through Saturday night, we should see an increase in
shower coverage, particularly over windward slopes and coasts.
Drier weather appears to build in behind the front for Sunday and
next Monday, with minimal shower activity.


The latest sfc obs, satellite and radar trends show some
scattered low/middle lvl clds and spotty showers in the vicinity
of the state early this morning, largely resulting from
redirected flow around the Big Island. Otherwise, high pressure
ridge in place and weakly organized surface wind pattern, will
continue to reinforce diurnal sea and land breeze circulations
through the TAF period, allowing for sea breeze cloud and shower
development for interior sections and along slopes again this
afternoon. The transition to land breeze development during the
evening will help diminish showers and clouds. Overall, expect
mainly VFR conditions to continue through tonight, however some
MVFR cigs remain possible again this afternoon in heavier showers.

AIRMET Tango for a period of mod upper lvl turb will be issued
during the scheduled morning AIRMET issuance, for the inter-
island air routes and flight areas within 40nm of the Hawaiian
Islands. Mod turb conditions are possible through this afternoon.


A weak surface ridge axis remains centered over the island chain.
A couple of cold fronts moving down from the northwest this week
will do little to the ridge in terms of movement. The result will
be light and variable breezes over the western end of the state
and light to moderate southeasterlies over eastern waters through
Friday. The passage of a couple of large, west- northwest swells
may push combined seas above Small Craft Advisory criteria
Wednesday and then again Friday evening through next weekend over
exposed waters.

Buoy 51001, northwest of the state, has just now begun to rise
with the new northwest (310 degrees) swell over the last couple of
hours. The swell appears to be running later than guidance, so
swell heights will likely rise locally later this afternoon
through tonight, with a peak Wednesday. Surf generated by this
swell is expected to reach High Surf Advisory (HSA) criteria along
most north and west facing shores of the smaller islands on
Wednesday. With its slightly more westerly direction, this swell
could push surf near or above the 8 foot HSA criteria along west
facing shores of the Big Island later Wednesday. This swell will
gradually lower Thursday before the initial forerunners from a
larger northwest swell arrive early Friday. This swell is expected
to rise rapidly, with resulting surf likely exceeding High Surf
Warning (HSW) thresholds along most north and west facing shores
of the smaller islands from as early as Friday afternoon, but most
likely that evening. An HSA will likely be required for the west
facing shores of Big Island Friday night as well, with a possible
HSW by early Saturday morning.






Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office