MWN Special Weather Statement – Tuesday, December 3, 2013

MWN Special Weather Statement
Cirrus Weather Solutions, LLC
MemphisWeather.net
3:20pm CST, Tuesday, December 3, 2013

— WINTER STORM LIKELY TO BRING FREEZING RAIN TO THE METRO FRIDAY
— SECONDARY STORM TO BRING ANOTHER ROUND SATURDAY NIGHT/SUNDAY

Despite unseasonably warm conditions today and tomorrow, with temperatures into the 70s possible Wednesday afternoon, a potent weather system is heading east that promises a drastic change for Mid-South weather by the end of the week.

A strong cold front, followed by an Arctic airmass, will move into the region early Thursday morning. The front will be accompanied by rain and perhaps a few rumbles of thunder. The front will stall across north Alabama and Mississippi, but cold air will flood into the region, causing temperatures to fall from the lower 60s early Thursday morning to the 40s by late Thursday afternoon. As temperatures continue to fall into Friday morning, rain will change over to freezing rain during the day Friday before tapering off Friday evening. Based on this morning’s model data, northern counties in the metro (Crittenden, Tipton) will see the changeover to freezing rain occur by mid-morning (9-11am), while Memphis and Shelby County and Fayette County will see a changeover between 10am-noon.  North Mississippi counties will likely change to freezing rain after noon. As far as frozen precipitation amounts, the timing of the changeover will directly affect amounts of ice expected. Those changing over earlier will have a higher potential for significant icing than those that transition later. Given the timing and precip amounts however, a significant icing event that reaches Ice Storm Warning criteria (1/4″ or more) is possible, perhaps likely, for most of the metro, especially areas along and north of I-40.  In fact, amounts above 1/2″ are possible in Memphis and Shelby County and points north.

After precip tapers off Friday evening, the majority of Saturday is expected to be dry, but very cold, with temperatures in the morning in the mid 20s and afternoon high temperatures in the lower to mid 30s with a fair amount of cloud cover. These conditions will hinder melting, thus potentially prolonging hazardous conditions from Friday.

By Saturday evening, a second round of precipitation is expected to arrive. This precipitation event will also likely begin as freezing rain, lasting through the night Saturday night and into Sunday morning before transitioning to regular rain as temperatures warm above freezing Sunday morning (though high temperatures will still be in the 30s). This round of precipitation is expected to end by Sunday evening.  Ice accumulations are hard to pinpoint at this time, but an additional 1/4″ is possible before changing to rain Sunday.

Finally, a third round of precipitation now looks to be on the horizon on Monday. We are hopeful that temperatures will remain above freezing throughout that event, but will have to watch trends very closely. Temperatures tend to not warm as much as forecast when ice is present on the ground.

Now is the time to begin preparation for a possibly significant ice storm on Friday and another round of ice on Saturday night. Disruptions to ground and air travel, commerce, and perhaps utility service are expected starting late Friday morning and possibly lasting throughout the weekend. It only takes one-quarter of an inch of ice to create hazardous travel conditions, even less on overpasses and bridges.  The saving grace for non-elevated roads may be the very warm air ahead of this system, though precipitation will quickly cool road surfaces as well.  It is too early to tell how bad roads could get, but secondary roads will definitely be more of a concern than primary roads/interstates (except on bridges).

We will provide additional updates and details as the event draws closer. In addition, we are planning a live Google+ Hangout Wednesday at 9pm to discuss the latest model data and forecast information, as well as how best to prepare. You will be able to watch live via YouTube or watch a recorded version afterwards, as well as ask questions via live chat.  Links will be posted via our social media feeds.

Finally, Winter Storm Watches from the National Weather Service would be issued beginning about 48 hours prior to the onset of the event, or perhaps early Wednesday morning.  Follow us on social media at the links below and download the MWN mobile app for StormView Radar with winter precipitation type, current conditions, our latest forecast, and optionally, StormWatch+ pinpoint weather alerts via push notification.

Erik Proseus
Meteorologist, MemphisWeather.net

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