Winter Storm Warnings and Winter Weather Advisories for Indiana

The National Weather Service of North Webster, Indiana has issued a Winter Storm Warning (pink) for LaPorte, St. Joseph and Elkhart Counties in Indiana until 7 pm EST Friday December 19. Winter Weather Advisories (dark blue) are also being issued across Indiana at this time. The main window for snowfall will be late Thursday evening into Friday morning.

Primary Hazards:

• Strong winds from the west to nothwest at 25-30 mph with gusts up to 50 mph or higher
• Snow accumulation of 2-5 inches through midday Friday in Winter Storm Warning areas and 1-2 inches in Winter Weather Advisory areas.
• Hazardous travel conditions: Strong winds will impact high profile vehicles and high potential for ice on roadways and bridges.
• Blowing snow and reduced visibility with near white out conditions possible especially near Lake Michigan or in rural areas..
• Minor wind damage and power outages.

Please use your NOAA Weather Radio or go to weather.gov for more information.

Forecast Discussion 12/19/2012

Quite the active weather pattern is setting up across much of the Great Plains into the Great Lakes region running the meteological gambit from blizzard conditions to winter storm and even severe weather. We begin by focusing on the wintry side of this strong low pressure system coming off of the Rockies, especially with the first day of the Winter Solstice set for December 21st at 11:12 UTC.

Watches and Warnings from the NWS valid at 12:12 am EDT

Currently a series of Blizzard Warnings (red) have been issued for western Kansas, eastern Colorado and parts of southern Nebraska while Winter Storm Warnings (pink) and Winter Weather Advisories (Blue) stretch northeast through Iowa, Missouri, Illinois, Wisconsin and ending in Michigan.

A quick look at water vapor imagery reveals a trough digging in with the trough axis over southern California while current surface observations and 4z RAP analysis indicates a surface low sitting near the Four Corners region. Once these two features connect, explosive development of this low will occur resulting in rapid cyclogenesis and heavy snow fall.

Water Vapor Imagery at 4:45 UTC

4Z Run of the RAP 0fhr 10m wind and MSLP

Once the upper level support connects with the surface low, models have been very consistent in recent runs with the path of this system.  A few variances exist, especially with ensemble runs starting to want to shift further south towards Indianapolis than their operational counterparts  but overall most models are in agreement taking the surface low through the panhandles across to St. Louis and finally just southwest of Chicago before they begin diverging on a solution. The only main discrepancies have been timing of the low pressure system. In the mean time, I wouldn't expect any major changes in the next few model runs as the upper level trough will be fully ashore and sampled by the radiosonde network for model input. As this low pressure system moves north east, a strong blast of Arctic air will sweep down behind it providing the cold air necessary for plentiful snow. More than sufficient upper level support and dynamic forcing exist and will be discussed in the next blog entry for this system, as well as details on what impacts this system will have across Indiana. 

Multiple model tracks of MSLP from the 0Z 18 December runs