Thursday, April 24, 2014

Details on severe weather risk this evening

A potent upper-level disturbance and trailing cold front will move into the Mid-South this evening as conditions becoming increasing unstable this afternoon on gusty south wind. The Storm Prediction Center has placed the Memphis metro in the center of a Slight Risk area with the main threat being damaging thunderstorm wind gusts and a secondary threat of large hail or a possible tornado.

According to SPC, there is a 30% probability of wind 60 mph or greater, a 15% chance of 1" hail, and a 5% risk of a tornado in the metro (see graphic below). The expected timing for the storms is between 6-10pm for the metro, or just before and during the Grizzlies-Thunder playoff game. Unfortunately it appears the Thunder are bringing their Oklahoma City storms with them! Most storms should be moving east of the metro by 10pm so there is little risk of severe weather after that time.

Severe weather threats for this evening
Below is a look at what one high-resolution model with a good track record (the HRRR) thinks radar will look like at 7pm and 10pm, or near the beginning and end of the event in Shelby County. NOTE: This is a MODEL, not a FORECAST and is intended to provide an idea of what will unfold. The first line of storms is fueled by the upper level disturbance, while the second line in central AR at 7pm is along the cold front. This model believes the second line falls apart as it nears the metro due to it moving into a "worked over" atmosphere that previously was stormy, as well as heating being on the decline.

Finally, here is our MWN Significant Weather Outlook for today, highlighting the damaging wind threat this evening. In addition, the storms could be heavy rain producers, even though they will move through fairly quickly. Some minor flooding in urban areas could be possible behind heavy downpours.

Now is the time to make your preparations for possible severe weather this evening. Know where you will be and what your safety plan is at that location - mainly where you will shelter if necessary. It's also necessary to know how you will get severe weather information. If you'll be away from home, get the MWN mobile app w/ StormView Radar and activate and setup StormWatch+ so that you will receive severe weather alerts no matter where you are. Download links are below. We'll provide the latest information and nowcast the storms as they move through via social media (FacebookTwitter).

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Southern Yankee said...

My prediction: If timing of scenario at 7 pm is accurate, that line has got to be much further east at 10 pm.

Meteorologist Erik Proseus said...

The window covers the beginning of storms in the western metro to the end of the storms in the eastern metro (3 counties wide) with a buffer of 30-60 minutes on either side for error. There's also a second line in far western AR... :)