Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Honolulu HI
330 PM HST Wednesday Oct 22 2014

Synopsis...
light to moderate easterly southeasterly flow will continue tonight
with showers focusing over windward and Mauka areas. Clouds and
showers from earlier sea breeze convection will linger around
leeward and interior areas of the smaller islands through early this
evening. A high building far north of the islands will bring
moderate trade winds Thursday and Friday with showers focusing over
windward and Mauka areas. Winds will again weaken and shift to the
east southeast over the weekend as a front approaches from the
northwest.

&&

Discussion...
an east-west oriented surface ridge remains located far NE of the Aloha
state...while Tropical Storm Ana gradually approaches the French
Frigate Shoals from the S. This synoptic scenario is keeping a
rather light to moderate east/southeast wind pattern across the island chain
through tonight.

A relatively stable but moist airmass along with the southeast flow are
bringing scattered to numerous passing showers over most of the
smaller islands...with precipitable waters hovering between 1.5 and 1.7 inches.
Moisture advection from an old boundary just east of the islands will
keep feeding windward and mountain showers...while sea breeze
circulations bring cloud cover and showers over leeward and interior
areas through early this evening.

On Oahu...showers and the heaviest rain focused over the Koolau
Range...the area of Manoa Valley...the Honolulu metropolitan area and Pearl
City during the afternoon hours. On Maui County...the heaviest
showers were affecting west Molokai...windward Maui and east Lanai.
Rainfall accumulations remain generally light to moderate...but
isolated higher amounts are possible with the heaviest showers.

The Big Island will keep providing some blocking of the prevailing
southeast flow tonight with stronger flow over the NE and southeast Big Island
areas...and lighter winds around the smaller islands.

For the rest of the work week...models remain in good agreement in
depicting a gradual strengthening of the aforementioned surface ridge
far NE of the Aloha state...bringing a stronger trade wind regime
Thursday and Friday. This will shift shower activity back to mainly windward
and Mauka areas...and drier conditions over leeward areas. But this
solution will be short-lived as a frontal boundary approaches the
area from the northwest...weakening the ridge and pushing it further to the
S. This will bring back the lighter southeast flow across the islands with
another round of stronger sea breezes and afternoon showers favoring
leeward and interior areas during the upcoming weekend.

&&

Aviation...
an area of enhanced moisture moving across the state this afternoon
and tonight will continue to produce widespread cloudiness and
above normal shower activity. Periods of MVFR conditions and
mountain obscuration will be likely across many areas of the smaller
islands as well as on the windward Big Island...and airmet Sierra is
in effect. Trade winds along with a drier airmass will return to the
state on Thursday...with VFR conditions prevailing.

&&

Marine...
the north swell will continue to decrease through tonight. Then
two other small north northwest swells are expected to arrive on
Thursday and Saturday respectively. Surf from these swells should
remain below the advisory levels at north and west facing shores.
Only small surf is expected at south and east facing shores.

Winds and seas will remain below Small Craft Advisory levels through
the forecast period.



&&

Hfo watches/warnings/advisories...
none.

&&

$$

Discussion/marine...reynes
aviation...Jacobson

National Weather Service Glossary of Abbreviations