(WGHP) – After a warm and dry past month and a half, the Triad should prepare for the weather pattern to change starting on Thursday.  Since Oct. 1, the Triad has only observed 0.34 inches of rain compared to the normal 4.54 inches during the same 43-day period.  Has the Piedmont Triad ever gotten snow on Thanksgiving? Looking back at weather over the years The last time the Triad observed significant rainfall was at the end of September when Helene caused catastrophic flooding in Western North Carolina. The last time the Triad observed more than half an inch of rain in one day was on Sept. 30.  Thursday has the potential to bring over an inch of rain in some spots.  Thursday’s rain will be widespread and moderate to heavy at times. Keep the umbrella with you from when you first step out the door until you get home from work.  Since the rain starts in the morning, the morning commute will likely be wet for many so be sure to take it slower on the roads and allow for extra travel time. Data shows the rain pushing eastward and out of our area through the evening hours. Not only are we talking our first significant rainfall in over a month on Thursday, but we’re also talking seriously cold temperatures.  Our temperatures will likely remain in the 40s all day Thursday thanks to the increased cloud cover and steady rainfall.  This would be our coldest afternoon in 258 days if the forecasted high temperature verifies. The last time we observed high temperatures in the 40s was on March 1 with a high of 47 degrees.  Why is it going to be cold and rainy on Thursday?  There’s a couple different reasons for the cold and rainy weather in the forecast on Thursday. The first is a cold-air damming event that is expected to take place. What does that mean? Cold-air damming occurs when cold air is trapped by topography, like the mountains. It can occur when a high pressure system is located over a north-south mountain range which for North Carolina is the Appalachian mountains because the winds rotate clockwise around the high pressure center, drawing cold air from the north.  This is part of what is happening on Wednesday with the cooler afternoon temperatures. A high-pressure system is drawing the colder air in from the north.  As we transition to Thursday, the high-pressure system will shift off to the northeast and weaken and two separate low-pressure systems will approach from the west. The high-pressure system will leave us with cooler temperatures and the position of the low-pressure systems will force the cold air to stick around as the low rotates counterclockwise, pushing the cold air against the mountains.  Since the mountains act as a “wall,” the cold air will be trapped and will spread back east over the foothills and Triad.  Not only do we have cold-air damming but the widespread rainfall on Thursday will also limit temperatures in the afternoon.