Vog Forecast Discussion for 10:45 AM HST Tuesday, Apr 17th 2018

Summary:

The return of trade winds means vog will be limited to the southwestern and western sides of the Island of Hawai'i into the middle of next week (4/17-4/23).

The primary pollutants in vog are sulfur dioxide gas and fine particulate matter. See the Vog Dashboard for information and protective measures for vog: http://www.ivhhn.org

Current Measured Conditions:

As of 10:45 AM HST on Tuesday, Apr 17th 2018, Pahala reports 0.03 ppm SO2. Ocean View reports 0.01 ppm SO2. No other sites report any detectable SO2. All sites have acceptable air quality.
For current conditions, please see: http://weather.hawaii.edu/vmap/current/index.cgi.

Island of Hawai'i Forecast:

Vog will affect the western to southwestern side of the Island of Hawai'i from Kona to Ocean View to Pahala and southwestern parts of the Hawaii Volcanoes National Park (HVNP) through the middle of next week (4/17-4/23).

The primary pollutants in vog are sulfur dioxide gas and fine particulate matter. See the Vog Dashboard for information and protective measures for vog: http://www.ivhhn.org

State-wide Forecast:

Vog will be limited to the Island of Hawai'i through the middle of next week (4/17-4/23).

The primary pollutants in vog are sulfur dioxide gas and fine particulate matter. See the Vog Dashboard for information and protective measures for vog: http://www.ivhhn.org

Forecast issued by: L. D. Holland

Revisit this page periodically for updates as forecast conditions change.

 

Visit Steven Businger's Hawaiian Weather Blog for discussions of recent vog episodes.

 

News and Items of Interest

Vog Climatology

The transport of volcanic aerosols, or volcanic smog (Vog), is primarily controlled by two factors - (1) the wind direction and (2) the height of the tradewind temperature inversion. The winds determine which direction the vog will be transported. Typically the winds in Hawaii are out of the northeast or east, as demonstrated by the graph below. This results in the vog being transported around the southern tip of the Big Island of Hawaii. The winds wrap around the westside of Hawaii and are often found over Kailua-Kona during these periods. When the winds are southerly, or are light, the vog is transported north over the northern end of Hawaii and across the northern islands of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Again, from the graph below it can be seen that this will most likely occur during the winter months but can also happen in the spring and autumn. It is least likely to occur in summer (June, July, August) whenthe northeast trade winds are most persistent. The tradewind temperature inversion determines how high the vog can mix in the atmosphere. The trade wind inversion is typically between 2000 meters (6500 feet) and 2500 meters (8200 feet). Since the volcanic emissions are quite hot when they exit the vents the gas and aerosols rise quite rapidly, however, they mix with the surrounding air and cool just as fast. This results in large amounts of vog at higher elevations where it is trapped by the tradewind inversion, which it cannot mix across. Regions downwind of the volcano, be it to the south or north, are thus greatly effected near the base of the tradewind inversion and may experience high concentrations of vog periodically.

 

Photograph by M. Poland, November 13, 2008, USGS HVO.