Is it possible or practical to predict vog? The Vog Measurement and Prediction Project (VMAP) is a feasibility study in which scientists will evaluate [are evaluating] whether vog forecasts are achievable and useful. Project collaborators are making the feasibility study available to the public through this Web site, but as an ongoing investigation, VMAP currently provides limited service and reliability. Thus, VMAP users should have no expectation of accuracy or timeliness, and project data should not be used for decision making purposes at this time. Comments and inquiries can be directed to the appropriate contact.

Vog is primarily a mixture of sulfur dioxide (SO2) gas and sulfate (SO4) aerosol. SO2 (invisible) reacts with oxygen and moisture in the air to produce SO4 aerosol (visible). SO2 is expected to be the main problem in areas near the vent (Hawai`i Volcanoes National Park, Pahala, Na`alehu, Hawaiian Ocean View Estates) and SO4 aerosol is expected to be the main problem at locations far from the vent (Kona and farther north and west).

 

Forecast Discussion

VOG Forecast Discussion for 9:30 AM HST Friday December 30th 2011

Current Measured Conditions:

Light to moderate trades should continue to decrease throughout the day. Decreasing winds and sea breeze development should begin to shift higher sulfur dioxide concentrations near the summit over the next 24 hours. For the latest sulfur dioxide emissions rates, please refer to the USGS eruption update. For the latest sulfur dioxide and aerosol concentrations, please refer to the current conditions table.

Island of Hawaii Forecast:

The pressure gradient has continued to weaken with the approaching front and weakening high pressure north of the state. Weather models indicate light trades will give way to light and variable winds with land and sea breezes by tomorrow. The vog model predicts increasing sulfur dioxide concentrations near the summit today and moderate aerosol concentrations near Hilo tomorrow. With variable winds and sea breezes expected, all locations on the Island of Hawaii can expect increasing concentrations of both pollutants lasting through Monday. Light trades should return by Tuesday which should begin to lower sulfur dioxide concentrations near the summit and sulfate aerosol concentrations for the east portion of the island. Until then, expect increasing concentrations of both pollutants and voggy conditions over the New Years weekend.

Western Hawaiian Islands Forecast:

Light variable winds and sea breezes should allow the Kilauea plume to shift north later today as indicated by the custom vog model. Sulfate aerosol concentrations should increase from east to west near Maui and then Oahu by tomorrow. This trend should continue through Monday before light trades are forecast to return on Tuesday and shift the plume south of the smaller islands.

Model Performance and Biases:

Over the last 24 hours the vog model has predicted increase concentrations of both pollutants near Pahala. Kailua-Kona has additional sources of sulfate aerosols which contribute to higher observed aerosol values than what is predicted. All other locations have ambient sources of aerosols which can cause observed values to be slightly higher as well but to a lesser degree. Known biases in the model include higher predicted concentrations of sulfate aerosols in Pahala and lower predicted concentrations of sulfate aerosols than those observed in Kailua-Kona. Please refer to the Model Performance page for graphical analysis of model performance.

Forecast issued by: Roy Huff

 

Click the image below to view meteograms for each location.

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

 

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