Active weather will continue across mainly the middle third of the country through the next few days as an upper level weather system gradually moves into the region and the lower levels of the atmosphere become increasingly unstable.
There will be a threat of severe weather in a relatively small geographic area this afternoon and evening. The threat of severe weather will expand dramatically (in both coverage and intensity) by Sunday and Monday.
For today, there is a risk of severe storms this afternoon and evening within the yellow shaded area on the image below:
Severe Weather Outlook for Today, Saturday, 3-17-12
This risk of severe weather includes the cities of St. Louis, Springfield, Cape Girardeau, and Evansville.
Strong to severe thunderstorms are expected to develop across extreme northern Arkansas into southern Missouri by mid to late afternoon and then move and/or develop Eastward. Large hail will be the primary threat, with damaging wind gusts also possible. An isolated tornado cannot be ruled out, but that is not expected to be a significant threat today.
There is also a "conditional" risk of severe storms across west-central and southwest Texas late this afternoon and early this evening. If any thunderstorm is able to form along the surface dryline in this region, it would likely become severe. The chance of thunderstorm development is expected to be limited by a strong capping inversion across this area.
A much more significant threat of severe weather will develop across the High Plains region on Sunday. The latest severe weather outlook for Sunday is indicated on the image below, with severe storms forecast in the yellow shaded area:
Severe Weather Outlook for Sunday, 3-18-12
A stronger band of winds in the middle and upper atmosphere will interact with a disturbance as well as an increasingly moist and unstable low level atmosphere to produce a significant threat of severe weather by mid to late afternoon into Sunday evening.
Tornadoes, hail greater than 2 inches in diameter and damaging wind gusts are possible, particularly within the red and black hatched areas on the image below:
Significant Severe Weather Outlook for Sunday, 3-18-12
This risk of significant severe weather for Sunday afternoon and evening includes the cities of Garden City, Dodge City, Woodward, Altus, Lubbock, Childress and San Angelo.
It continues to appear that the greatest threat of widespread severe weather over the next three days will come together on Monday. Unfortunately, this will also correspond with a shift in the threat area to a more heavily populated region in the central and southern Plains. The severe weather threat for Monday is outlined within the yellow shaded areas on the image below:
Severe Weather Outlook for Monday, 3-19-12
Once again, there will be a threat of significant severe weather, including tornadoes, hail greater than 2 inches in diameter and damaging thunderstorm wind gusts on Monday afternoon and evening. The threat of significant severe weather will primarily exist within the red and black hatched areas on the image below:
Significant Severe Weather Outlook for Monday, 3-19-12
The threat of significant severe weather for Monday afternoon and evening includes the cities of Tulsa, Ardmore, McAlester, the Dallas/Ft. Worth Metroplex and the Austin/San Antonio corridor along I-35.
The threat of severe weather will likely extend into the overnight hours Monday and into the pre-dawn hours of Tuesday, toward the Eastern part of the above outlook area.
Folks living across all of the above mentioned areas, and particularly the significant threat areas for Sunday and Monday, should take the time now to prepare for severe weather. Make sure that you have a sheltering plan in place at home, school or the office, and listen for later updates as this situation unfolds over the next few days.
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