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Hawaiian Islands Synoptic Discussion and Guidance |
FXHW60 PHFO 160136
Area Forecast Discussion
National Weather Service Honolulu HI
336 PM HST Sun Jul 15 2018
High pressure far north of the area will continue to produce
trade winds across the area this week and on through next
weekend. Clouds and passing showers will tend to favor windward
and mauka areas with just a few showers expected over some leeward
High pressure is currently centered far north of the state
placing the islands in a moderate trade wind environment. Water
vapor imagery shows an upper low centered several hundred miles to
the north northwest of Kauai. This has caused a slight
destabilization of the airmass across the area. A slight chance
for thunderstorms remains in the forecast through tonight for
portions of the Puna District as heat and emissions interact with
imcoming moisture. The upper low is forecast to pull further away
tonight and Monday with an upper ridge building in across the
area. This will cause to airmass to become more stable with a
downward trend in shower activity.
With high pressure remaining north of the area, moderate trade
winds will continue to blow through the remainder of the week and
on through next weekend. An area of low pressure is seen on
satellite far to the southeast of the state. This area of low
pressure is currently being monitored for possible development
during the next few days. Latest model guidance currently shows a
weak low or trough passing by south of the state during the
Wednesday through Thursday time frame. Most of the moisture
associated with the system is forecast to remain south of the
state but some increase in showers is possible over the Big Island
as it passes by since they will be closer to the system.
Otherwise just passing showers, mainly over windward and mauka
areas, can be expected through the remainder of the week and on
into next weekend.
Moderate, to locally strong, trade winds will persist through
Monday. There will be decreasing instability across the area as
an upper low moves away to the west and northwest. However, there
remains a slight chance of thunderstorms or heavy showers for
portions of windward Big Island, especially in the Puna District.
Otherwise, low clouds and showers (brief to TEMPO MVFR
conditions) moving along with the trades will be mainly
concentrated over windward and mountain areas of the state. A few
brief showers may be carried over to leeward sections of some of
the smaller islands, but VFR conditions are expected to prevail
AIRMET Sierra is in effect for mountain obscuration on Kauai,
Oahu, Molokai, Lanai, and Maui.
High pressure north of the islands will continue to drive breezy
trade winds across the coastal waters this week. A Small Craft
Advisory (SCA) is in place over the typically windy waters around
Maui County and waters south of the Big Island through Tuesday
afternoon. Additional extensions of the SCA are likely to follow.
An area of low pressure associated with a tropical disturbance
will be pass south of the islands midweek, which may bump up the
trades another notch or two as well the need to expand the
coverage of the SCA.
Trade winds will produce surf mainly in the moderate range along
the east facing shores this week. The strengthening trades
midweek will bump up the surf to near the advisory level for the
east facing shores. The current south southwest swell will
maintain small to moderate surf along the south and west facing
shores. This swell will slowly fade through Monday night. A
moderate south swell is due in Wednesday night with a similar
sized reinforcement late Friday.
A slight chance of thunderstorms remains across the northern
offshore waters through Monday night due to the presence of an
upper level trough.
Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office
This page is maintained voluntarily by the MKWC and the UHMET faculty, staff, and students.
It was last modified on: Wed, Dec 17 2014 - 1841 UTC
Send comments to: Ryan Lyman