Sunday, December 9, 2012

Sunday afternoon update on potential severe weather

UPDATED 7:15pm:
7:15pm Regional satellite & radar composite. The cold front is easily identified along the squall line
Severe weather threat continues for the entire metro though in a slightly diminished state.  Strong wind gusts and hail are possible within and east of the watch box, including the entire metro.  The NWS indicates that a watch box is not likely to be issued for areas east of the current area (see below for counties under Tornado Watch 677), though storm warnings are still possible in cells that exhibit strong to severe characteristics.

We expect to see the line approach the western portion of the metro (Crittenden, northwest Tipton Co) around 8:30pm and progress slowly east, exiting the eastern side of the metro (Marshall Co) around 11pm.

Finally, based on the latest forecast model data, a slight chance of sleet will be introduced into the morning forecast as precipitation tapers off and very cold air filters into the lowest few thousand feet of the atmosphere. Any wintry precip would be A) brief, B) light, and C) NOT stick due to ground temps that will still be very warm.

MWN will continue to monitor and advise you of any changes on our social channels - Facebook and Twitter - where we have been in live nowcasting mode much of the day.

UPDATED 3:40pm:

A Tornado Watch was issued a bit ago for most of central and northeast AR, far northwest TN, and areas to the north until 9pm.  In the metro, only Crittenden Co is included.  There is a chance that the watch could be extended further east into west TN and northwest MS later on, or another watch for those areas could be issued.  The probability of a tornado still remains low, but is higher in the current tornado watch than it is for areas east of the Mississippi River.  We'll continue to monitor and advise you of any changes on our social channels - Facebook and Twitter.

Tornado Watch #677 for parts of the Mid-South until 9pm

Not a lot has changed since yesterday's post regarding our chances of severe weather tonight.  I encourage you to read that, as even the timing has remain virtually unchanged.

The latest outlook from the Storm Prediction Center [SPC] (below) has the Mid-South placed in a Slight Risk area for the possibility of storms containing damaging straight-line wind, hail, and a low threat of tornadoes.

A Slight Risk zone encompasses the Mid-South due to the possibility of damaging wind, hail, or an isolated tornado during the evening hours today.

What to expect:

Scattered thunderstorms will break out across AR this afternoon, which has prompted SPC to begin considering a Tornado Watch. These storms will pose the best threat for a tornado, and even that is not particularly high.  A few of these storms could push into the metro early this evening prior to the organization of a squall line of storms in AR. That line will move east just ahead of the cold front and likely affect the metro between 8-11pm. The squall line will bring our best chance of severe weather - in the form of straight line wind and hail.

After the line passes, rain will be likely overnight until mid-morning Monday and temperatures will plummet as Arctic air overruns the region.  Look for temperatures in the lower 40s (perhaps upper 30s just to our north) all day Monday. In fact, if temperatures aloft cool enough while it is still raining, we cannot completely rule out a few sleet pellets mixed with the rain Monday morning.  Ground temperatures will still be warm and nothing would stick.  Rain ends by lunchtime and temps remain some 25-30 degrees colder than today.

Prepare ahead of time

Now is a good time to make sure you have multiple ways of getting severe weather warnings, especially if you happen to be asleep. Weather radios are a great tool, as are TV and commercial radio broadcasts. However, you should also strongly consider a smartphone app for receipt of severe weather information. We put a great deal of effort into our mobile app with StormWatch+ severe weather notification. StormWatch+ is designed to warn you ONLY IF YOU are in the path of the storm, and it will wake you up for the most dangerous storms.  Peace of mind is only a download away!

In addition, we will be bringing you the latest information as storms develop and move through with our social media nowcast service via Facebook and Twitter. Check us out!

Last, the NWS relies on eyes and ears on the ground to know whether storms are producing severe weather. If you are on Twitter, you can relay severe weather reports to the NWS by using #mSpotter. Reporting can even be done through our MWN mobile apps!  Learn more about #mSpotter (what types of weather they need and how to report ) by clicking here.

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