Thursday, January 24, 2013

Threat of freezing rain tonight, mainly north and east of the metro

As discussed yesterday, we had two chances of light icing in the area - one was this morning (which didn't materialize and had a very low probability anyway), and another is tonight.  The prospects for ice in the metro tonight are also looking less likely, which is a good thing because the precipitation chances and amounts are higher than they were last night!

The situation, in a nutshell, is this: a cold front that moved through overnight last night has stalled to our south and will begin moving north again tonight, as low pressure moves into the region from the west.  In the wake of the cold front, temperatures in the 30s are common, as you know if you have stepped outside today. It's cold!
A Freezing Rain Advisory is in effect for northeast AR, the MO bootheel, and west TN north of I-40, excluding Shelby County.  Light freezing rain and hazardous travel conditions are possible, especially in northern portions of the advisory area, overnight.
Thanks to cloud cover and wind that will be slowly shifting from east to southeast, temperatures are not expected to drop much overnight though.  In fact, low temperatures will likely be reached before midnight, then will slowly rise during the overnight hours.  Precipitation is expected mainly after midnight.  With temps rising overnight, the vast majority of the metro will remain above freezing all night and any precipitation will occur as plain rain.

Midnight temps (about when precipitation develops) should be above freezing for the metro according to this hi-res short-term model (RAP) graphic.  Greens are 35+, light blues are 30-35.
There is a chance however that the far northern portions of the metro (Tipton County in particular) could drop to freezing for a few hours as the precipitation starts, before rising above freezing by dawn.  This could mean a very light coating of ice, mainly on grassy, exposed, or elevated surfaces.  The main hazard would be for a few slick spots on bridges during the pre-dawn hours.  We predict the chance of light freezing rain in the northern metro to be about 20-30%.  The chance of icing that would cause any significant issues within the metro, including Tipton County, is less than 10%.  (Remember: freezing rain falls as a liquid and freezes on contact with a surface and temperatures at the ground must be 32F or lower.)

NOAA predicts that any significant icing (more than 0.10") will be found across the northern tier of TN, well north of the metro.
The high-res NAM model predicts temps (red line) to remain above freezing (dashed blue line) in Memphis tonight with precip (green boxes) falling between midnight and noon.  Diagram is read from right to left (starting at 7am Thursday on the right and continuing past 7pm Friday on the left).
The threat of freezing rain diminishes to near zero after dawn tomorrow morning, while rain showers stick around through mid-day as temperatures rise into the mid 40s.

If you are traveling early Friday morning east on I-40 towards Nashville north into northwest Tennessee, we recommend watching weather conditions in those areas closely.  Icing is more likely north and east of Jackson into middle TN and northern AL, especially before noon.

We'll continue to monitor new weather data as it arrives and let you know if we see any changes via our social feeds below.  You can always get the latest on current and forecast weather conditions via our mobile apps as well.  Download them via the links below.

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