Moderate Risk for Severe Weather Today & Tonight

The SPC has issued a moderate risk for severe weather today mainly for a damaging wind threat as a squall line moves across the area today and tonight. The moderate risk area will include parts of Arkansas, Mississippi, Alabama, Tennessee, Missouri, Kentucky, Illinois, Indiana, Michigan, and Ohio. There will be a 45% risk of damaging winds in these areas including an enhanced risk from Illinois to Michigan and a 10% enhanced risk for tornadoes that will cover the entire moderate risk area.

A slight risk for severe weather will surround the moderate risk and will stretch from eastern Texas to western Alabama north to the Great Lakes states.

These storms will be moving across the area in the form of a potent squall line associated with a strong upper level trough and cold front. There will also be the possibility of discrete storms forming ahead of the squall line, which will enhance the chance of tornadoes (some could be strong).

SPC Text:

 ...THERE IS A MDT RISK OF SVR TSTMS TODAY INTO THIS EVENING OVER
   PORTIONS OF SOUTHERN LOWER MI...MUCH OF IND...CENTRAL AND SOUTHERN
   IL...SOUTHEAST MO...WESTERN KY...WESTERN TN...EASTERN AR...AND
   NORTHERN MS...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM EAST TX NORTHWARD ACROSS
   MUCH OF THE MS AND OH VALLEYS...

   A LARGE UPPER TROUGH IS FORECAST TO ROTATE EASTWARD INTO THE MS
   VALLEY TODAY.  AS THIS OCCURS...AN EXPANSIVE SQUALL LINE THAT
   CURRENTLY EXTENDS FROM NORTHERN IL INTO AR/EAST TX WILL SURGE
   EASTWARD AND RESULT IN A LARGE AREA OF SEVERE THUNDERSTORM
   POTENTIAL.

   ...MI/IL/IND...
   VERY STRONG LARGE SCALE DYNAMICS WILL OVERSPREAD THE MID MS VALLEY
   AND CENTRAL GREAT LAKES REGION TODAY.  IN ADDITION TO THE STRONG
   FORCING...LOW AND MID LEVEL WIND FIELDS WILL BECOME IMPRESSIVE
   THROUGH THE DAY WITH 850MB WINDS SPEEDS OVER 60 KNOTS AHEAD OF THE
   SQUALL LINE.  12Z RAOBS AHEAD OF THE SQUALL LINE SHOW THERMODYNAMIC
   PROFILES FAVORABLE FOR STRONG DOWNDRAFTS REACHING THE SURFACE AFTER
   JUST A FEW HOURS OF HEATING.  THE END RESULT MAY BECOME A SWATH OF
   RATHER WIDESPREAD DAMAGING WINDS ACROSS PARTS OF IL/IND INTO
   SOUTHERN LOWER MI.  ANY CELLS THAT FORM AHEAD OF THE MAIN LINE WILL
   ALSO BE CAPABLE OF BECOMING SUPERCELLULAR GIVEN 0-3KM SRH VALUES OF
   300-500 M2/S2.  THIS WILL PROVIDE POTENTIAL FOR A FEW TORNADOES AS
   WELL.

   ...LA/AR/MS/TN/KY...
   THE SQUALL LINE WILL BE MOVING SLIGHTLY SLOWER OVER THIS REGION
   COMPARED TO FARTHER NORTH.  THIS WILL PROVIDE A FEW MORE HOURS OF
   DIURNAL HEATING AHEAD OF THE STORMS BEFORE THEY TRAVERSE THE MOIST
   AXIS.  SEVERAL MODEL SOLUTIONS SUGGEST THE SQUALL LINE AS WELL AS
   SEVERAL STORMS AHEAD OF THE LINE WILL INTENSIFY BY EARLY AFTERNOON. 
   AMPLE MOISTURE/INSTABILITY AND FAVORABLE LOW LEVEL/DEEP LAYER
   VERTICAL SHEAR SUGGEST SUPERCELL AND BOW STRUCTURES WILL BE POSSIBLE
   THROUGHOUT THIS REGION.  DAMAGING WINDS ARE LIKELY THE MAIN
   THREAT...BUT A FEW TORNADOES /SOME STRONG/ ARE ALSO A
   POSSIBILITY...ESPECIALLY WITH DISCRETE STORMS THAT FORM AHEAD OF THE
   SQUALL LINE.

NWS Text:

...SEVERE WEATHER EVENT EXPECTED THIS AFTERNOON INTO TONIGHT...

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...BIGGEST CHANGE FROM LAST
NIGHT`S THINKING CONCERNING THE POTENTIAL FOR SEVERE WEATHER TODAY
IS THE POTENTIAL FOR A WEAKER AND EARLIER DISSIPATING CAP. THIS MAY
ALLOW FOR DEVELOPMENT OF DISCRETE CELLS EARLIER THIS AFTERNOON AND
AHEAD OF THE MAIN SQUALL LINE WHICH IS STILL SLATED OVER OUR
NORTHWEST ZONES BY EARLY EVENING.

WATER VAPOR IMAGERY/RUC ANALYSIS HAS A RATHER AMPLIFIED TROUGH OVER
THE CENTRAL PLAINS THAT IS EXPECTED TO FURTHER DEEPEN TODAY AS IT
SHIFTS EAST AND DEEPEN A SURFACE LOW NEAR THE GREAT LAKES REGION
THAT WILL SEND A STRONG COLD FRONT ACROSS OUR CWA TONIGHT. REGIONAL
RADARS ARE ALREADY LIT UP THIS MORNING WITH A LONG LINE OF STORMS
ALONG THE COLD FRONT EXTENDING FROM CENTRAL TEXAS NORTHEAST TO
THE GREAT LAKES. THIS LINE OF STORMS IS EXPECTED TO INTENSIFY TODAY
DURING PRIME HEATING AND MOVE INTO OUR NORTHWEST ZONES LATE THIS
AFTERNOON OR EARLY EVENING. THE EXPECTED ENVIRONMENT OVER OUR AREA
AHEAD OF THE APPROACHING SQUALL LINE HAS CHANGED LITTLE INCLUDING
SURFACE DEWPOINTS IN THE UPPER 60S TO NEAR 70 DEGREES...MLCAPES
AROUND 1000J/KG...0-6KM BULK SHEAR 40-50KTS AND 0-3KM SRH 200-400
M2/S2. THE LATEST OUTLOOK FROM THE STORM PREDICTION CENTER PLACES
THE AREA NORTH OF I-20 IN A MODERATE RISK OF SEVERE WEATHER WITH
HATCHED SHADING WARNING OF POTENTIAL FOR STRONG TORNADOES AND/OR
WIND GUSTS UP TO 80 MPH. THE AREA ALONG AND SOUTH OF INTERSTATE 20
STILL HAS A CONSIDERABLE RISK FOR SEVERE WEATHER ALTHOUGH THE
POTENTIAL FOR SIGNIFICANT WINDS OR STRONG TORNADOES IS LOWER THAN
IN THE MODERATE RISK.

THE MAIN RISK FOR SEVERE WEATHER TODAY WILL COME WITH THE SQUALL
LINE PRIMARILY IN THE FORM OF WIDESPREAD WIND DAMAGE AND TORNADOES.
HAIL AND LOCALLY HEAVY RAIN WILL BE SECONDARY THREATS. HOWEVER...ANY
DISCRETE CELLS THAT DEVELOP AHEAD OF THE SQUALL LINE COULD PRODUCE
TORNADOES...SOME OF WHICH COULD BE STRONG ESPECIALLY IN THE NORTH.
THIS TIMING OF THE LINE HAS CHANGED LITTLE...MOVING INTO THE
NORTHWEST DELTA 4-6 PM...NEAR NATCHEZ TRACE CORRIDOR BY MIDNIGHT AND
MOVING SOUTHEAST OF OUR CWA BEFORE 6 AM. STRONG SOUTHERLY WINDS
TODAY AHEAD OF THE APPROACHING SYSTEM WILL MAKE FOR WINDY CONDITIONS
ACROSS THE NORTHWEST AND BREEZY CONDITIONS ELSEWHERE. A WIND
ADVISORY REMAINS IN EFFECT TODAY NORTHWEST OF A LINE FROM WINNSBORO
LOUISIANA TO YAZOO CITY AND GRENADA MISSISSIPPI.