Monday, June 13, 2011

A conditional possibility of severe weather today

11:20am UPDATE:  A Severe Thunderstorm Watch has been issued for the area until 4pm.  Storms are following the track forecast earlier this morning, now beginning to move out of southeast MO into northeast AR.  Scattered storms are expected to move through the metro area this afternoon. Some of the storms will be strong and possibly severe, with the primary threat being damaging wind and a lesser threat of large hail. Tornadoes are not expected.

Outline of thunderstorm watch box.  Radar imagery valid at 11:20am. 
Visit the MWN Storm Center to follow this developing weather situation.


Monday morning setup - click for larger image
The Mid-South is positioned in what meteorologists term "northwest flow" - meaning that the steering winds at mid and upper levels of the atmosphere are from northwest to southeast over the area.  A ridge of high pressure is to our west, a trough is to our east and between those the wind is blowing from the northwest. Typically when we refer to northwest flow in this region of the country, we are looking at the possibility of storms that develop upstream (to our northwest) moving into the area.

The graphic above shows what is happening early this morning to our northwest.  Storms are beginning to develop over Missouri and will move southeast on the "northwest flow."  The Storm Prediction Center indicates that there is a Slight Risk of severe storms today downstream from these developing storms right into  northeast AR and parts of west TN.  While the chance of rain is not high today, we'll be monitoring this area of weather as it moves southeast to see if anything moves into the metro. This is called a "conditional risk" - meaning that if storms are able to form or move into the area, they could be strong to severe. The main threats with any storms will be strong gusty wind and large hail.

MWN is forecasting most of the storms today to be to our north and east, as high pressure is ridging just enough into the metro area to keep the storms away.  However, it bears watching. In the meantime, expect another hot day with partly cloudy skies, highs in the mid 90s, a very high UV index, and some humidity.

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