Tuesday, December 22, 2009, 4:00 p.m.
The National Weather Service (NWS) has issued a Winter Storm Watch for Lake County and surrounding areas, and current forecasts suggest that we face an ugly mixture of winter weather over the next few days.
We participated in a conference call with the Chicago office of the NWS earlier this afternoon, and want to make sure everyone is aware of this potentially hazardous weather situation. Because small changes in the storm track and temperature profiles can cause significant impacts to what form of precipitation falls, we encourage you to pay attention to local media and weather information sources, such as the NWS webpage at
http://www.crh.noaa.gov/lot/.
A strong winter storm system now is forecast to track up the upper Mississippi River Valley over the next few days, bringing substantial moisture to our area. For Lake County, the lingering snow is expected to move out later today before the arrival of the more significant storm system on Wednesday. Precipitation is expected to begin Wednesday as very light snow, sleet, or freezing drizzle. Temperatures in the mid to upper 20's are forecast to rise slowly through Thursday morning, when they should be just above freezing. The rate of precipitation is expected to increase through the day on Wednesday, and the combination of this heavier precipitation and the temperature profile of the atmosphere suggests that the predominant type of precipitation will be freezing rain. This freezing rain is not expected to cause widespread traffic problems, because temperatures should be close to the freezing point. However, it is possible that from a quarter to a half inch of ice may accumulate on untreated walking surfaces, trees, antenna towers and utility wires. As temperatures continue to slowly rise, the freezing precipitation should change over to all rain by Thursday morning, before the moist air moves out of our area. Cooler temperatures will return on the back side of the storm, with a chance for some snow Friday night and Saturday and low temperatures in the teens.
Potential hazards with this storm include ice-glazed walking surfaces, localized flooding from heavy rain, and damage to trees and utility infrastructure from icing and wind. Forecast models suggest that there may be 1.5 inches or more of precipitable water in this storm, which could lead to some flooding of roadways and yards. Winds are expected to increase through the day on Wednesday, to sustained speeds of 15-20 mph with gusts of 25-30 mph. These winds combined with any icing that occurs will lead to an increased risk of tree branches falling and damaging electric and communication infrastructure.
The NWS forecasters continually update the forecast information, and will likely decide early Wednesday morning about upgrading the Winter Storm Watch to a warning or replacing it with an advisory of some type. Please check the NWS website or your local weather information sources for updated information during the day Wednesday.
Lake County Emergency Management Agency does not anticipate providing any further update messages about this weather system.
As a reminder, contact your local Emergency Manager or Lake County EMA to report storm-related damage or to request resources. During business hours, Lake County EMA personnel can be reached at 847-377-7100. After hours or on holidays, call the Lake County Sheriff's 9-1-1 center at 847-529-5200 and ask for the on-call EMA person to be contacted.
