Mother Nature ignores the calendar as the never-ending winter continues

Meteorological spring begins tomorrow and astronomical spring is only 3 weeks away, but it appears our furry friend Phil may have been on to something a month ago!

Another in a seemingly never-ending chain of Arctic outbreaks will push through the Mid-South late this weekend with yet another round of winter weather possible. So far the majority of the metro has been spared the worst of the snow and ice this winter, though our friends in Tipton County would gladly invite us up to help in debris cleanup from significant ice a couple of weeks ago!  I've also said that the first weekend in March sometimes brings us winter surprises.  It appears this year the month will start off like a lion!

While most of the weekend should be decent with low rain chances and well above freezing temperatures, the period of concern is late Sunday into early Monday. During the day Sunday, an Arctic front will drop through the area, causing temps to plummet from around 60 or a little higher early Sunday afternoon to the lower 30s by Sunday evening. Most precipitation with this system will be along and behind the front, as temperatures are falling.  As always in these scenarios, how quickly the precipitation exits versus when sufficient cold air arrives to change precip type over to a wintry mix will be the key.

As of 2:20pm, the National Weather Service has issued a Winter Storm Watch for northeast AR, the Missouri Bootheel, and west TN generally north of I-40, including Tipton and Crittenden Counties in the metro (blue counties in the map below).

So how do we expect it will play out? Showers will be likely during the day Sunday, the front will move through by mid-day, and temps will fall during the afternoon.  Given fairly consistent model data (though all could and will still adjust some between now and Sunday night), it appears that we'll be in the mid 30s by 6pm Sunday along the I-40 corridor, then continue to fall below freezing a couple of hours after that.

Forecast temperatures at noon Sunday, according to the NAM model. Notice the sharp divide between 60s in the metro and 30s in northeast AR along the front.

Forecast temperatures at 6pm Sunday, according to the NAM model.  The front is south of the metro by this time.

The amount of precipitation falling in cold air is the biggest question mark, but model data currently points to anywhere from about 1/3" to nearly an inch in the metro.  The Winter Storm Watch calls for up to 1/4" of freezing rain and 1/2" of sleet, plus minor snow accumulations, but that is for the entire watch area with higher amounts expected in northern areas and lesser amounts across the metro, including Memphis and Shelby County.  These estimates are highly subject to change.  Most of that will fall before midnight, tapering off after midnight with little additional precip.

As mentioned, precipitation type at this time appears to be mostly ice, perhaps ending as light snow.  As regular readers of the blog know, freezing rain is much more hazardous than sleet as it glazes exposed surfaces, creating an ice skating rink.  Sleet is the type that bounces and, though slippery, does have a little traction to it and does not adhere to power lines like freezing rain.  If we are going to get ice, we want sleet.

Forecast precipitation amounts (liquid) from the NAM model between 6pm-midnight Sunday night show more than 0.25" across the metro.  The NAM is faily conservative on the amount during this time period as compared to other models.

We'll continue to closely monitor the event as it gets closer and provide updates as we have new information or confidence increases one way or another. For now, prepare for the possibility of icy conditions by early Sunday evening that could last into Monday if enough falls.  Temperatures on Monday will be frigid - starting in the 20s and only rising to the mid 30s with a gusty wind that will keep wind chills in the teens to low 20s.

Fortunately, the extended outlook shows a fairly quick warm-up after a couple of cold days to start the week.  Follow our social feeds (listed below) and blog for the latest info and don't get sucked into "hype-casts" based on a single model or an untrusted (or unknown) source.

Erik Proseus, MWN Meteorologist

----
Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!

Cold weather returns along with some precip tonight - will winter ever end??

8:00 UPDATE
We are receiving lots of reports of sleet and even a little thunder in the area this evening as freezing levels are low and air fairly dry, promoting sleet development. Temps remain in the 40s at this time and will fall into the 30s, but no travel issues are expected this evening due to sleet.

---

Following a beautiful weekend that felt an awful lot like spring, I got questions like "is spring finally here?" and "is winter gone for good?"  My response: "It's still February." Alas, Mother Nature is throwing a stark reminder of that our way in the coming week.  The only good thing about cold weather this time of year is that typically it doesn't last as long and isn't QUITE as cold.  Of course that is all relative...  It has been a long and cold winter in the Mid-South!

An Arctic cold front moves through the region tonight, shifting wind to the north and becoming gusty, while also causing temps to plummet.  Meanwhile, some precipitation is expected to move through the area as well.  Computer models differ slightly on the placement and timing of precipitation, but all seem to agree that most of it will fall across north MS, while the southern half of west TN and east AR could see light precip prior to snow-cold air arriving.

Thus, there is a low chance that light rain could briefly change to light snow or sleet for a couple hours after midnight before ending before dawn in the metro. Areas just south of the metro in north MS have a slightly better chance of seeing light snow, but even that is not much.

The latest NAM model output indicates precip falling along and south of the TN-MS line at midnight with the 32 degree line (blue line) dropping south across the metro. A brief changeover to snow is possible if this scenario pans out. Other models keep the precip a little further south.

Temps will fall to the upper 20s by dawn, so any light precip that falls overnight COULD freeze or create black ice on elevated roadways or objects, though a gusty north wind will help in the drying process and most roadways will be plenty warm enough to keep from freezing.  The probability of travel issues in the metro Wednesday morning is low.

Forecast temperatures from the NAM model at 7am Wednesday morning. Wind chills will be in the teens.

Cold air sticks around the rest of the week with highs on Wednesday in the 30s and wind chills in the 20s despite abundant sunshine. Lows Thursday morning drop well into the 20s, perhaps some upper teens in the coldest outlying areas as wind goes nearly calm. Mid to upper 40s are expected Thursday and Friday afternoon and we'll have to monitor Friday morning for possible precip into sub-freezing air, though it appears at this time as though rain would hold off until temps were well above freezing Friday.

Warmer temps (50s and 60s) are expected this weekend with low rain chances before yet another major cold front arrives Sunday or Monday, depending on which model solution plays out.  This front will bring a potential for thunderstorms and then another blast of cold air as we start March off like a lion.  One more time, we'll monitor how fast the cold air moves in on the heels of precipitation departing.  Click here for the complete MWN Forecast, which is highly subject to change for this weekend's system.

NOAA predicts equal chances of above/below normal March temperatures so hopefully we can shed winter and get some spring cleaning done in March!

March 2014 temperature outlook from NOAA indicating below normal temps should stay to our north with equal chance of above and below normal temps across the Mid-South.

----
Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!