Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
1000 am HST Thursday Jul 2 2015
light winds will continue across the smaller islands through much of
Friday...with some hints of light trade winds returning Saturday.
Widespread moderate trades should return state wide during the
middle of next week. Light winds today and tomorrow will continue to
bring land and sea breezes...along with afternoon clouds and
showers. The light trade winds Saturday and Sunday will allow for
localized land and sea breezes. Expect more typical trade winds as
the middle of next week approaches.
satellite and radar data both show more clouds and showers over The
Big Island and the portions of Maui this morning than over the
remaining islands. Precipitable water shows a slightly drier airmass
over the Western Islands this morning...but values remain around
normal for this time of year. Clouds are beginning to form over the
Koolau Range on Oahu...and over the interior of Kauai at 9 am. With
this combination...do feel that afternoon clouds and showers remain
a possibility...particularly over leeward and interior sections of
the smaller islands. Have updated the forecast to trend the probability of precipitation
higher...following guidance from all the models...global and high
Although we do expect trades to return...it will be a very slow
return. Light winds today and tomorrow will continue to bring
widespread land and sea breezes to the islands. This combination
will continue to bring warm and humid conditions to the islands. As
the winds start to pick up this weekend...even though they will
start to be from a more trade wind direction...wind speeds will
remain light...particularly over the smaller islands. As
such...localized land and sea breezes will persist. However the
background flow will be from the northeast...which should focus
limited shower activity to the eastern sides of the islands.
The light winds are due to a front to the northwest of the islands
pushing the surface ridge over the islands. The low associated with
the front...far north of the islands...is expected to lift north
through the weekend. As it lifts north...the front will lift to the
north...allowing the ridge to retreat to the north. The high
pressure system will remain far northeast of the islands. The
resultant pressure gradient over the islands will prevent trades
from exceeding moderate levels in most areas during the second half
of next week.
a cold front approx 100nm northwest of Kauai has pushed the ridge over the
islands. Light and variable winds will prevail over the smaller
islands and leeward Big Island and allow for a sea/land breeze
regime to remain into Friday. A light east-southeast flow will remain around
windward Big Island.
Mimic total precipitable water imagery shows a swath of enhance
moisture over Maui County and the The Big Island. Morning soundings
estimate 1.58 and 1.17 inches of precipitable water over phto and
phli respectively. While Oahu and Kauai are in a dry slot this
morning...forecast models shows the area of enhanced moisture
spreading west into Friday. Expect sea breezes to allow for
interior clouds and showers to form over interior areas on all
islands this afternoon. Some showers may bring MVFR conditions and
tops up to 150...especially over Maui and The Big Island.
Small Craft Advisory /sca/ conditions are not anticipated through
the Holiday weekend. There is the potential for Small Craft Advisory in the windier
marine zones around Maui and The Big Island early next week due to
the strengthening trades.
The south shores will see quite a bit of swell action over the
weekend due to a fairly active weather pattern in the southern
hemisphere the past several days. Swells generated by several
fast-moving lows are on their way here that will result in a small
to moderate size surf over the Holiday weekend. Peaks in surf
heights are expected tonight and on Sunday...approaching but staying
below advisory levels.
A northwest swell has reached the islands and as expected. This
swell is expected to peak below advisory levels later today...and
then slowly subside through Friday.