Air Temperatures – The following high temperatures (F) were recorded across the state of Hawaii Monday…along with the low temperatures Monday:

84 73  Lihue, Kauai
87 74  Honolulu, Oahu
83 73  Molokai
8671  Kahului AP, Maui
86 72  Kona Int’l AP
8063  Hilo AP, Hawaii

Here are the latest 24-hour precipitation totals (inches) for each of the islands as of Monday evening:

0.20  Mount Waialeale, Kauai
0.17  Poamoho RG !, Oahu
0.00  Molokai
0.00  Lanai
0.01  Kahoolawe

0.23  Puu Kukui, Maui
1.32  Saddle Quarry, Big Island

The following numbers represent the strongest wind gusts (mph) as of Monday evening:

29  Waimea Heights, Kauai
32  Honolulu AP, Oahu
27  Molokai
35  Lanai

42  Kahoolawe
35   Maalaea Bay, Maui 
36  Puu Mali, Big Island

Hawaii’s MountainsHere’s a link to the live webcam on the summit of our tallest mountain Mauna Kea (nearly 13,800 feet high) on the Big Island of Hawaii. This webcam is available during the daylight hours here in the islands, and at night whenever there’s a big moon shining down. Also, at night you will be able to see the stars — and the sunrise and sunset too — depending upon weather conditions.

Aloha Paragraphs
A late season cold front is just to Kauai’s north
Hawaii is between a cold front north…and high cirrus clouds south
Clear to partly cloudy…cloudy areas locally
Showers here and there –
Looping radar image

Small Craft Advisory
…many of the windiest coasts and channels statewide


~~~ Hawaii Weather Narrative ~~~


Broad Brush Overview: The trades will increase and become stronger through Tuesday, as a strengthening high pressure system passes by far north of the islands. Showers embedded in the trades may be enhanced somewhat, as a weak upper level trough of low pressure moves across the state through Tuesday. Trades will gradually weaken during the latter half of the week, becoming light and variable by the upcoming holiday weekend…as a surface trough of low pressure is expected to edge towards the island chain then.

Details: Moderate trade winds prevail across the islands, as a high pressure system far northwest of the area…moves east-northeast. There’s a weakening frontal cloud band just northwest of the islands, which will remain in place through Tuesday. Satellite imagery revealed rather limited low clouds in the vicinity at the time of this writing, except around Big Island, which are bringing a few showers. There’s also some thin high cirrus clouds passing over the eastern islands, keeping the skies a bit cloudy.

As the high pressure cell moves by far to the north through Tuesday, trades will increase…becoming locally quite strong through Tuesday. These breezy trades are expected for the next couple of days, with passing low clouds and showers mainly along the windward sides. Winds will be strong enough to carry low clouds and a few  showers to the leeward sides at times. Meanwhile, a weak upper level trough is expected to pass over the state later today through Tuesday. The cooler temperatures aloft associated with this feature, will allow the atmosphere to be somewhat more unstable, with passing showers becoming a little heavier at times locally.

Looking Further Ahead: The trades will gradually decrease in strength toward the later part of the week, as an upper level trough moves closer from the northwest. This in turn could lead to the possible development of a weak surface trough near the islands…by the start of the holiday weekend. Thus, winds will become lighter, prompting widespread daytime sea breezes to develop. Moisture from the old frontal cloud band to our north may finally spread down over the islands, especially especially over Kauai and Oahu. This unsettled weather pattern may linger through the Memorial Day weekend.

Here’s a wind profile of the Pacific Ocean – Closer view of the islands / Here’s the vog forecast animation / Here’s the latest weather map

Marine environment details: With trade winds on the increase, a small craft advisory (SCA) is in effect for the typically windier zones around Maui and the Big Island. More areas are likely to be added, later today or tonight, as high pressure strengthens across the area. Winds will begin to weaken by mid-week.

The current south swell will gradually lower through Wednesday. Wave model guidance continues to show a larger south-southwest swell arriving later in the week, persisting through most of the Memorial Day weekend. This swell has the potential of boosting surf along south-facing shores to the high surf advisory level. In addition, the combination of swell energy and greater than normal tides, may result in minor coastal flooding due to wave run up along south facing shores this coming weekend…especially during each high tide.

The next moderate northwest swell is arriving, and will peak today, before slowly subsiding and swinging around to a north-northwest through mid-week. This swell is expected to increase surf along north and west facing shores, although remaining below advisory level. A small north swell is expected to follow Thursday and Friday, before shifting around to a north-northeast swell by the weekend. Also, choppy wind waves will return along east facing shores…as the trade winds gradually strengthen.

Strengthening trades

San Francisco Bay Weather Brief:
Look for cooler conditions through most of the week, as an onshore flow combines with the deepening marine layer. Minor warming is then expected during the upcoming weekend…especially for inland locations.
Low clouds and fog slipping inland locally

World-wide tropical cyclone activity

>>> Here’s Monday’s Pacific Disaster Center’s (PDC) Weather Wall Presentation

>>> Atlantic Ocean: The 2017 hurricane season begins June 1st

>>> Caribbean: The 2017 hurricane season begins June 1st

>>> Gulf of Mexico: The 2017 hurricane season begins June 1st

Here’s a satellite image of the Caribbean Sea…and the Gulf of Mexico

Here’s the link to the National Hurricane Center (NHC)

>>> Eastern Pacific: No active tropical cyclones

Here’s the NOAA 2016 Hurricane Season Summary for the Eastern Pacific Basin

Here’s a wide satellite image that covers the entire area between Mexico, out through the central Pacific…to the International Dateline.

Here’s the link to the National Hurricane Center (NHC)

Central Pacific
: The 2017 hurricane season begins June 1st

Here’s the NOAA 2016 Hurricane Season Summary for the Central Pacific Basin

Here’s a link to the Central Pacific Hurricane Center (CPHC)

>>> Northwest Pacific Ocean: No active tropical cyclones

>>> South Pacific Ocean:

North and South Indian Oceans / Arabian Sea:
No active tropical cyclones

Here’s a link to the Joint Typhoon Warning Center (JTWC)

Significant groundwater loss in California’s Central Valley during recent droughts
– A new study from researchers at UCLA and the University of Houston reveals estimates of significant groundwater loss in California’s Central Valley during the recent drought and sparks questions of sustainability for the important agricultural area.

Researchers tracked net groundwater consumption in the Central Valley from 2002 to 2016, when a drought from 2007 to 2009 and a more severe drought from 2012 to 2016 hit the area. Published in Geophysical Research Letters, their findings estimate that a total of 4 cubic miles and 9.6 cubic miles of water were lost during between the 2007-2009 and 2012-2016 droughts, respectively.

The more recent drought accounted for more than 2.4 cubic miles of water lost per year. Researchers attributed this to reduced precipitation and snow melt, a change in the type of crops being cultivated, and hotter temperatures.

“For perspective, the amount of material associated with the 1980 eruption of Mount St. Helens was about one cubic kilometer,” said Dennis Lettenmaier, the UCLA professor of geography who led the study. “So, we’re talking about 40 times that amount in the recent drought.”

Decreases in groundwater worsened even with a reduction in the amount of irrigated land, which decreased 7 percent from 2007–2009 compared to the 2012–2016 drought. Higher temperatures during the more recent drought period and a transition into high-value and thirsty tree crops accounted for most of groundwater loss between the two droughts, and more than offset the effects of a reduction in irrigated land, Lettenmaier said.

The study accounted for evapotranspiration, which is water released into the air through plant transpiration and soil evaporation, as well as precipitation, and surface water flowing into and out of the Central Valley.

“It’s fair to assume that there’s going to be another drought, and fair to assume that there will be usage of groundwater in that drought too; the wells are already there,” Lettenmaier said. “Now that this most recent drought is in the rear-view mirror, there are still questions about how much natural recovery we can expect in groundwater and how water will be managed in the Central Valley.”

California’s Central Valley is more than 18,000 square miles from the coast to the Sierra Nevada Mountains and is one of the largest agricultural hubs in the United States, providing over half of America’s fruit, vegetable, and nut crops. Researchers said they hope future studies will address how much actual recovery happened between droughts and whether recovery from the most recent drought is on track to replenish the system.