Photo Credit: James Grenz

Hilo

Today: Showers likely, with thunderstorms also possible after 1pm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 75. Light north northeast wind increasing to 5 to 9 mph in the afternoon. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Frequent showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 62. North northeast wind 5 to 9 mph becoming light and variable. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Monday: Frequent showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 76. West wind around 5 mph becoming calm in the morning. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

Kona

Today: Scattered showers and thunderstorms after noon. Some of the storms could produce heavy rainfall. Widespread haze. Increasing clouds, with a high near 78. Calm wind becoming west northwest around 5 mph in the afternoon. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers. Widespread haze. Cloudy, with a steady temperature around 70. Calm wind. Chance of precipitation is 40%. New precipitation amounts between a quarter and half of an inch possible.

Monday: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Widespread haze. Partly sunny, with a high near 79. Calm wind. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Waimea

Today: Scattered showers, then showers likely and possibly a thunderstorm after 1pm. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 73. Breezy, with an east wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.

Tonight: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Cloudy, with a low around 51. Breezy, with an east wind 15 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New precipitation amounts between three quarters and one inch possible.

Monday: Scattered showers, then showers likely and possibly a thunderstorm after 7am. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 73. Breezy, with an east wind 11 to 17 mph, with gusts as high as 24 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Kohala

Today: Scattered showers, then frequent showers and possibly a thunderstorm after noon. Some of the storms could produce heavy rainfall. High near 69. Windy, with an east wind 18 to 23 mph, with gusts as high as 32 mph. Chance of precipitation is 80%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Frequent showers and possibly a thunderstorm before midnight, then showers likely. Some of the storms could produce heavy rainfall. Low around 44. Breezy, with an east wind around 21 mph, with gusts as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Monday: Frequent showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 69. Breezy, with an east wind around 15 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

South Big Island

Today: Isolated showers, then scattered showers and thunderstorms after noon. Some of the storms could produce heavy rainfall. Widespread haze after noon. Increasing clouds, with a high near 78. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight: Scattered showers and thunderstorms, then showers likely and possibly a thunderstorm after midnight. Some of the storms could produce heavy rainfall. Widespread haze. Cloudy, with a low around 68. Windy, with an east northeast wind 23 to 28 mph, with gusts as high as 36 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Monday: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Widespread haze. Mostly cloudy, with a high near 79. Windy, with an east northeast wind around 26 mph, with gusts as high as 34 mph. Chance of precipitation is 70%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Puna

Today: Showers likely, with thunderstorms also possible after noon. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 75. North northeast wind 11 to 14 mph, with gusts as high as 20 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Frequent showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 60. North wind 10 to 13 mph. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.

Monday: Frequent showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 76. North northeast wind 6 to 8 mph. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.

Waikoloa

Today: A 20 percent chance of showers and thunderstorms after noon. Some of the storms could produce heavy rainfall. Increasing clouds, with a high near 78. North northeast wind 7 to 9 mph.

Tonight: Scattered showers, mainly before midnight. Cloudy, with a steady temperature around 68. East northeast wind around 9 mph. Chance of precipitation is 30%. New precipitation amounts between a tenth and quarter of an inch possible.

Monday: Scattered showers and thunderstorms. Some of the storms could produce heavy rainfall. Partly sunny, with a high near 79. East northeast wind around 5 mph becoming calm in the afternoon. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Detailed Forecast

Synopsis

Unsettled weather is likely for the upcoming week as an upper level disturbance interacts with tropical moisture. Breezy trade winds will give way to light and variable winds by mid week as a surface trough forms over the state. Strong northeast winds will then follow Friday over Kauai, and to the remaining islands over next weekend.

Discussion

Although the evening has been rather tame, there are a couple of spots that we are watching closely. The two areas are windward Kauai and windward Haleakala above Hana, where heavy showers are occurring.
There has been a significant shift in the wind forecast during the second half of the week. Instead of strong and gusty trade winds through the week, models are suggesting a surface trough forming over the islands Tuesday and remaining in the vicinity of the state through Friday. Strong and gusty northeast winds are expected to build back in to the area next weekend as high pressure passes north of the islands.
Another addition to the forecast is a slight chance of thunderstorms has been introduced for the Big Island and windward Maui starting this afternoon and remaining in forecast through at least Monday. The rest of the forecast package is pretty much the same, that is it will be showery for most of the week. This prolonged period of unsettled weather will likely warrant a Flash Flood Watch for most if not all of the islands and a Winter Weather Advisory for the Big Island Summits.
An east to west oriented upper level trough with cold temperatures of around minus 13 degrees C is located just north of the islands this morning. An upper low is forecast to form later today west of Kauai as enhanced low level moisture moves toward the Big Island from the southeast. This moisture will then spread up the island chain through Monday night. The upper low then drifts over the islands by Wednesday night and stalls through Friday. The combination of the cold temperatures aloft and the moist air mass near the surface will likely result in an extended period of heavy rains and possible thunderstorms.

Aviation

FR conditions prevail at all TAF sites with some brief periods of MVFR conditions at PHLI and PHTO in low clouds and shra. Expect these conditions to continue into the morning hours. AIRMET Sierra is currently in effect for Kauai, Maui and the Big Island due to mountain obscuration. They will be brief periods of MVFR conditions elsewhere along windward slopes through into the morning hours as low clouds interact with island terrain.
AIRMET Tango is currently in effect over and immediately south thru west of mountain ranges due to low level mechanical turbulence.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters.

Data Courtesy of NOAA.gov