We'll start with the "easier" part. A potent cold front stretching from southern Canadian into the Gulf of Mexico will move through the Mid-South overnight tonight, tapping an abundance of moisture that will produce widespread rainfall, mainly from evening through the overnight hours. In addition, a weak surface low will form in the Lower Mississippi Valley, which could provide enough lift for some scattered rumbles of thunder and periods of heavy rainfall. Rainfall amounts of up to 2"+ are not out of the question tonight.
|Surface map valid at 6am Sunday showing a cold front near the Tennessee River and low pressure over northeast MS|
|24-hour projected rainfall totals from HPC/NWS through 6am Sunday|
|The European model shows upper level low pressure centered over the Mid-South on Monday morning|
|The European model shows the upper level low moving east into the TN Valley on Tuesday morning|
Computer models don't necessarily know that though and can spit out some pretty incredible forecasts, such as the overnight run of the NAM from last night (shown below), which brings Memphis a couple of inches of snow on Sunday night! The very next run of the same model (this morning) indicates less than 1" for the Memphis area and 8-10"+ for middle TN! (I wouldn't bet on either one, by the way... fickle models!) This is what we meteorologists get to deal with and why southern snow forecasts can be the hardest of them all!
|Total snowfall forecast from the NAM midnight model run showing 4"+ over Memphis... not likely|
|For comparison, the Saturday morning NAM model run, which now shows <1" for Memphis and 8"+ for middle TN|
Further updates to the blog can be expected through the weekend.
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