Assessing Icing Conditions in the High Elevations of the Northeast

(L to R) IT Manager Pete Gagne, volunteer Mitch Hansen and Outreach Coordinator Jeff DeRosa take a break from setting up the Mesonet site at the Cog Railway.s 4500-foot mark. This site is a key field location for this project.

Goals: The two goals of this project are to understand the meteorological conditions that produce icing conditions in the Northeast and to develop numerical computer models that can predict the timing, location, and severity of icing conditions.

Objectives: The goals of this project will be addressed 1) through the observation and analysis of atmospheric conditions that produce icing and 2) by using icing observations to improve forecasts from a high-resolution numerical computer model.

Icing detectors will measure icing accretion rates for the 2011-12 and 2012-13 winters at the Mt. Washington summit (6288'), Cog Railway Halfway house (4500'), Cannon Mountain (4032'), and Mount Mansfield (3950'), Vermont. A graduate student at Plymouth State University is cataloging significant icing events (≥24 hours) and analyzing the regional-scale weather conditions that produce these icing events. A NASA satellite icing product will be verified for accuracy with the icing observations and radiometers at the base of Mt. Washington will provide measurements of cloud content of supercooled water droplets (which freeze on surfaces to form icing). During the 2012-13 winter, there will be multiple intensive observation periods during which weather balloons will be launched to gather vertical profiles of meteorological conditions through the lower troposphere during icing events.

The Weather and Research Forecasting (WRF) model will be run at high resolution (~1 km) for the 2011-12 and 2012-13 winters to determine its accuracy in predicting icing around the high elevations of northern Vermont and New Hampshire. Icing observations at the four sites will be used to verify the model and identify icing and non-icing conditions that the WRF model does not accurately predict to help develop ways to improve WRF model forecasts. The WRF model will be coupled with a high resolution digital terrain model and the FASST Land-Surface Model to incorporate atmospheric-surface interactions (exchanges of heat and moisture) that should help improve icing forecasts.

Atmospheric conditions at Mt. Washington will also be analyzed to differentiate between those conditions that produce rime icing (the white, feathery icing that is brittle), glaze icing (clear icing that is dense and most dangerous for airplanes), and mixed icing (rime and glaze icing).