Wednesday, March 23, 2016

Severe Thunderstorms Target South, Midwest Wednesday and Thursday (FORECAST)

March 23,2016
The threat of severe thunderstorms returns to parts of the South and Midwest into Wednesday evening on the warm side of Winter Storm Selene. Additional severe storms are likely on Thursday.
NOAA's National Weather Service has issued the following severe weather watches for parts of the region:
  • A tornado watch has been posted until 10 p.m. CDT for portions of southern Iowa and northern Missouri.
  • A severe thunderstorm watch is in effect until midnight CDT for much of southeast Oklahoma and a small portion of northwest Arkansas.
  • A severe thunderstorm watch is also in effect until midnight CDT for portions of North Texas, including the Dallas-Fort Worth metroplex.
(MORE: Don't Ignore Severe T-Storm Warnings)
The severe weather setup features a deep, sharp southward dip in the jet stream, or upper trough, pushing out into the Plains states. At the surface, a strong low-pressure system will tap warm, moist air from the Gulf of Mexico.
Converging air ahead of the cold front, along a dryline ahead of the front, and near the warm front will give lift for thunderstorms. Changing winds with height known as wind shear may allow thunderstorms to initially become supercells.
Damaging winds and large hail will be the main threats from any severe storms that develop, though isolated tornadoes are also possible.
Radar, Watches, Warnings

Current Radar with Watches and Warnings
Guide to Watches and Warnings
(MORE: View National Interactive Radar Map | Difference Between a Watch and a Warning)
Below is our latest forecast thinking on the timing and magnitude of the severe threats this week.

Severe Weather Outlook

Into Wednesday Evening
  • Scattered severe t-storms will flare up into Wednesday night from Iowa and Missouri, southward across eastern Oklahoma, western Arkansas and East Texas.
  • Damaging thunderstorm winds and large hail will be the main threats, though isolated tornadoes are possible.
  • CITIES: St. Louis | Little Rock | Shreveport, Louisiana | Houston

Wednesday Night's Forecast
Thursday
  • Thunderstorms should be numerous from the Deep South northward into the Ohio Valley.
  • The greatest threat of severe storms is focused on the Gulf Coast states and Tennessee Valley, where instability will be the greatest.
  • Again, damaging winds and large hail will be the main threats, though isolated tornadoes are also possible.
  • Currently, the highest risk for tornadoes appears to be in Alabama. This is where the TOR:CON has been raised to 6 out of 10 by severe weather expert Dr. Greg Forbes of The Weather Channel. This means there is a 60 percent chance of a tornado within 50 miles of any location.
  • TOR:CON Explained
  • CITIES: Atlanta | Birmingham | Mobile, Alabama | Nashville

Thursday's Forecast
(MAPS: 7-Day Rain/Snow Maps | 10-Day Highs/Lows/Weather)

South Pounded By Flooding and Severe Weather in Recent Weeks

Sometimes it seems an area can't get much of a break from the weather pattern. It's as if they're a meteorological punching bag.

Estimated Rainfall This Month
So goes parts of the Lower Mississippi Valley and Southern Plains in recent weeks.
Roughly two weeks ago, an early March deluge of locally over 20 inches of rain triggered massive flash flooding and river flooding from parts of east Texas to Arkansas, Louisiana, Mississippi and west Tennessee, setting record flood crests along the Sabine River.
(RECAP: Record Flooding in Parts of the South)
In fact, that river flood event continues. As of this writing, numerous locations in the Lower Mississippi Valley are still above flood stage, a few still in "major" flood.
Then last week, not one but two hailstorms pelted the Ft. Worth, Texas metro area, smashing car windshields, even punching holes in some roofs.
(RECAP: Impacts From Damaging Hailstorms)
If that wasn't enough, a severe thunderstorm dumped piles of hail on West Monroe, Louisiana, Friday, one week after receiving over 20 inches of rain.
Then there's the tornadoes.
The Weather Channel severe weather expert, Dr. Greg Forbes, estimates a preliminary count of 142 tornadoes have occurred in the U.S. from February 1 through March 17, about 84 percent above the 20-year average count for that late-winter time period.
This is a far cry from last March. Not a single severe thunderstorm or tornado watch was issued anywhere in the nation the first 24 days of March 2015, something that had never happened dating to 1970, according to then NOAA Storm Prediction Center warning coordination meteorologist Greg Carbin.
But that was last year, and March is a prime tornado month in parts of the southern Plains and a corridor known as "Dixie Alley" in the Deep South.
(MORE: Your Monthly Tornado Risk | Your Odds of Being Hit by a Tornado)
MORE: Southern Flooding, Severe Weather March 8-10, 2016 (PHOTOS)

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