146 
FXHW60 PHFO 110610
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
810 PM HST Thu Mar 10 2022

.SYNOPSIS...
Trade winds will increase on Friday, and remain moderate to 
locally breezy through the weekend, delivering just a few windward
showers. Little change is expected into next week.

&&

.DISCUSSION...
With the forecast on track, not expecting any changes to the grids
in the short term, and not expecting any significant changes
needed for the morning package. 

The latest high resolution models continue to support moderate to
locally breezy trade winds building back in Friday. An east to 
west oriented surface ridge north of the islands will linger 
through the weekend, maintaining the trade wind flow. Winds will
be slightly weaker over Kauai and Oahu due to their proximity to
the ridge, with winds a touch stronger over Maui County and the
Big Island.

A more stable airmass is setting up over the islands. The
afternoon soundings from Lihue and Hilo showed 500 mb temperatures
back to normal around -8 celsius. Both soundings also showed a
trade wind inversion topping out around 7000 feet. The inversion
was stronger at Lihue, but expecting a more pronounced trade wind
inversion at Hilo by Friday afternoon. 

The models are in good agreement with an upper level ridge pushing
in over the islands from the west as an upper level trough
continues to move away to the east. The upper level ridging looks
to remain in place through the weekend, and then weaken some as we
head into the middle of next week.

A stable airmass with trade winds means that clouds and showers
will be focused over the windward sides of the islands.
Precipitable water (PW) values look to remain at or below normal
for this time of year, which will likely limit rainfall totals
for the forecast period. 

With no significant rain events on the horizon, drought 
conditions are worsening, with details contained in the recently 
updated Drought Information Statement (DGTHFO), which can be found
on the web at weather.gov/hfo/DGT. 

&&

.AVIATION...
The transition toward strengthening easterly trade winds 
continues across the state through Friday, as a ridge of high 
pressure builds north of the islands. Drier and more stable
conditions associated with this developing pattern, will limit 
clouds and showers across the TAF sites, with trade winds focusing
a majority of showers over windward areas through Friday. However,
a lighter wind pattern lingering over leeward Big Island, will 
still allow for some sea breeze clouds and isolated showers to
develop inland of the Big Island Friday afternoon. Mainly VFR 
conditions are expected through the TAF period with brief MVFR 
cigs in developing showers.

No AIRMETs are currently in effect or expected through Friday.

&&

.MARINE...
A surface ridge is located about 260 nm north of Lihue early this
evening. This feature is maintaining light to moderate trade 
winds across the area. The forecast guidance continues to indicate
this surface ridge will build as it moves slowly north on Friday.
This will likely cause the trade winds to become locally strong, 
which will result in Small Craft Advisory (SCA) conditions 
developing over the typically windier waters adjacent to the 
islands of Maui County and the Big Island. Therefore, a SCA is 
being issued for these waters from Friday morning through Saturday
afternoon. This SCA may need to be extended into Sunday based on 
the latest model guidance. The surface ridge is expected to weaken
later this weekend, so the SCA may not be required after Sunday 
afternoon.

The long-period west-northwest swell continues to fill in across
the state early this evening. This swell appears to be about a
foot or so below the wave model guidance when compared with 
recent observations at the National Data Buoy Center buoys 
located northwest of Kauai. We will monitor the observations at 
the buoys overnight, and adjust the surf forecast for Friday as 
needed. Based on the wave model guidance, we expect surf to 
eventually increase to near the seasonal average along most north
and west facing shores during the peak of the swell on Friday. 
This west-northwest swell will gradually lower from Friday night 
through early Sunday. The next northwest swell will likely arrive
late Sunday, and peak near, or just above ,the seasonal average 
along most north and west facing shores of the smaller islands 
Monday. This swell will slowly lower from Tuesday through the 
middle of next week.

The current small, long-period south swell will continue to
produce a slight bump in surf heights along south facing shores 
into Friday. Expect surf to return to more typical small, 
background heights along south facing shores this weekend.
Elsewhere, modest, choppy surf will persist along east facing 
shores through early next week.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory from 6 AM Friday to 6 PM HST Saturday for 
Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island 
Leeward Waters-Big Island Southeast Waters.

&&

$$


DISCUSSION...M Ballard
AVIATION...SWR
MARINE...Houston