Dixie Alley Storm Chasers

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.

Significant Severe Weather Event Possible On Thursday

The SPC has just upgraded tomorrow’s slight risk to a moderate risk for severe weather. The moderate risk will include parts of Mississippi, Louisiana, Arkansas, Tennessee, Missouri, Kentucky, Illinois, Indiana, and Michigan. These areas will have a 45% enhanced risk for severe weather including tornadoes (some strong possible) and damaging winds. A slight risk area will surround the moderate risk and will stretch from Texas to Alabama and north to the Great Lakes. A large portion of the slight risk area will have a 30% enhanced risk for severe weather.

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 storms forming ahead of the squall line, which will enhance the chances of severe weather.

SPC Text:

...GREAT LAKES TO THE WRN/CNTRL GULF COAST...
   FAIRLY EXTENSIVE BANDS OF CONVECTION SHOULD BE ONGOING AT 12Z/THU
   ALONG BOTH FRONTAL ZONES. DIURNAL HEATING WITHIN A RICHLY MOIST AIR
   MASS FROM THE WRN GULF INTO THE MIDWEST CHARACTERIZED BY 60S TO
   LOWER 70S SURFACE DEW POINTS AMIDST A REMNANT EML PLUME EMANATING
   N/NEWD ACROSS THE S-CNTRL CONUS...SHOULD RESULT IN A MODERATELY
   UNSTABLE WARM SECTOR WITH MLCAPE REACHING 1000-2000 J/KG.
   LOWER-LEVEL SHEAR/HODOGRAPHS WILL BE IMPRESSIVELY LARGE WITH NRN
   EXTENT ACROSS THE BULK OF THE WARM SECTOR. THESE FACTORS COMBINED
   WITH STRONGLY FORCED ASCENT WILL LIKELY YIELD AN EXTENSIVE QLCS THAT
   WILL INTENSIFY AND INCREASE IN FORWARD SPEED DURING THE LATE MORNING
   THROUGH THE AFTERNOON. BOWING SEGMENTS AND EMBEDDED SUPERCELLS WILL
   BE FAVORED...ESPECIALLY WITH NRN EXTENT GIVEN THE DEGREE OF SHEAR.
   POTENTIAL WILL ALSO EXIST FOR DISCRETE SUPERCELLS DEVELOPING AHEAD
   OF THE QLCS AS MLCIN BECOMES MINIMAL. THIS WOULD SEEM TO BE MORE
   PREVALENT WITH SRN EXTENT WHERE LARGE-SCALE ASCENT WILL BE
   PROGRESSIVELY WEAKER. SWATHS OF WIDESPREAD DAMAGING WINDS APPEAR
   PROBABLE ALONG WITH A ROBUST TORNADO RISK /SOME OF WHICH COULD BE
   SIGNIFICANT/. THE OVERALL SEVERE THREAT WILL LIKELY DIMINISH BY LATE
   EVENING/OVERNIGHT AS THE SURFACE MOISTURE PLUME IS PINCHED OFF WITH
   NRN EXTENT GIVEN DOWNSLOPE DRYING OFF THE SRN APPALACHIANS INTO THE
   CNTRL/UPPER OH VALLEY.

NWS Text:

..SEVERE WEATHER EVENT LOOKING LIKELY LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT...

.DISCUSSION...WATER VAPOR IMAGERY THIS MORNING REVEALS AN UPPER
LEVEL SHORTWAVE PUSHING INTO THE LOWER MS VALLEY FROM THE WEST AND
SOUTHWEST. THIS WAVE WILL TRACK ACROSS THE FORECAST AREA THROUGH
THIS EVENING. WELL TO OUR NORTH ALONG A STALLED FRONT IN THE OHIO
VALLEY OVERNIGHT CONVECTION VIEWED IN IR SATELLITE IMAGERY SEEMS TO
HAVE KICKED A GRAVITY WAVE IN OUR DIRECTION...ALTHOUGH THIS FEATURE
IS HARD TO SPOT AT PRESENT. EXAMINING MORNING JAN/BMX/OHX SOUNDINGS
REVEALS A SHARED STABLE LAYER IN THERMAL CAP AT 700 MB THAT WOULD BE
GOOD SURFACE FOR LONG DISTANCE WAVE PROPAGATION. APPARENTLY THAT IS
WHAT IS GOING ON IN MANY OF THE MODELS THAT WANT TO SHOW BACKDOORING
TYPE CONVECTION COMING INTO AT LEAST MY NORTHEAST ZONES THIS
AFTERNOON/EARLY EVENING FROM OUT OF THE TENNESSEE VALLEY. GRAVITY
WAVE SEEMS ONLY REASONABLE INSTIGATOR FOR THIS ACTIVITY SINCE
MOVEMENT OTHERWISE COMPLETELY BUCKS FLOW AND MESO BETA PROPAGATION
POTENTIAL DOES NOT ACCOUNT FOR OVERALL SOUTHWEST MOVEMENT.

ANYWAY...NOT POSITIVE WE WILL GET MENTIONED CONVECTION IN MORE THAN
VERY ISOLATED FASHION THIS AFTERNOON GIVEN CAP STRENGTH AND
POTENTIALLY LIMITED LIFT FOR MOST OF THE REGION. I DID EXPAND 20
POPS IN NORTHERN AND NORTHEASTERN AREAS (OF MAINLY MS) IN
CONSIDERATION OF CONSOLIDATED WEAK LIFT FROM TRADITIONAL SHORT WAVE
AND GRAVITY WAVES BEING JUXTAPOSED. GIVEN ABOVE NORMAL WARMTH
ANTICIPATED AND HIGH MOISTURE ANY VIGOROUS STORMS COULD BE CAPABLE
OF BRIEF GUSTY WINDS AND AT LEAST SMALL HAIL. IF CONVECTION STARTS
AT LEAST WEAKLY ORGANIZING TO OUR NORTHEAST THROUGH EARLY AFTERNOON
WE MAY MENTION SUCH WORDING IN THE HWO FOR NORTHEAST ZONES WHILE
BUMPING UP POPS.

OTHERWISE...ANTICIPATE CURRENTLY MOSTLY CLOUDY TO PARTLY SKIES
BECOMING MAINLY PARTLY CLOUDY THROUGH THE DAY WITH WARM HIGH
TEMPERATURES IN THE MID TO UPPER 80S. MAIN UPDATE FOCUSING ON SEVERE
WEATHER LATE TOMORROW INTO TOMORROW NIGHT WILL BE COMING WITH THE
AFTERNOON PACKAGE. /BB/

Severe Weather Expected Today and Tomorrow

Wednesday:

The SPC has issued a slight risk for severe weather to include parts of Texas, Louisiana, Mississippi, Arkansas, Tennessee, and Missouri in the south. The slight risk area also includes parts of the Ohio Valley to the Altlantic coast. A 5% tornado risk will exist today from northern Louisiana through Arkansas into southern Missouri. There will also be a 30% wind and a 30% hatched risk for hail across these areas. A modes of severe weather will be possible in these areas.

Images:

Thursday:

A slight risk for severe weather has also been issued for Thursday, which will include areas from eastern Mississippi to the Carolinas and up to the Ohio Valley. A 30% risk for severe weather will exist for parts of Mississippi, Alabama, Florida, Georgia, Tennesse, and Kentucky with a 15% risk for severe surrounding that for all other areas included in this outlook. Damaging winds and tornadoes will be the primary threats in these areas on Thursday.

Images:

Severe Weather Outbreak Possible Next Week

We’re posting on this event a bit earlier than we normally do, but things appear to be increasingly coming together for a significant severe weather event Wednesday into Thursday next week. Things can certainly change between now and then, so we’ll post what we’re looking at so far. The SPC’s day 6 outlook puts areas from eastern Texas and south central Louisiana up through Mississippi, Arkansas, and Tennessee to south central Illinois.

As of right now it looks like this event will get kicked off in northwest Kansas on Monday (day4) and spread further across the central and southern plains into Missouri and Arkansas on day 5. The Tuesday (day 5) time frame will provide the best chances for discrete supercell development ahead of a dryline across the area. As a strong cold front merges with the dryline, an extensive squall line should develop and push east into the lower/mid Mississippi valleys on Wednesday afternoon into Thursday. This will  bring the threat of damaging winds and tornadoes to our area. There is still some uncertainty regarding timing with this system, so things can certainly change as we get closer to this system’s arrival.

We’ll be updating this post for sure over the next few days as we get closer to this event taking place. Everyone in these areas should pay very close attention to this system.

Images:

SPC Text:

...SEVERE WEATHER APPEARS LIKELY EARLY NEXT WEEK FROM THE CNTRL/SRN
   PLAINS TO THE MID/LOWER MS VALLEY...

   WHILE RICH GULF MOISTURE HAS BECOME CONFINED TO THE SWRN PORTION OF
   THE BASIN IN THE WAKE OF A COLD FRONT THAT HAS REACHED THE YUCATAN
   PENINSULA...AIR MASS MODIFICATION WILL OCCUR THIS WEEKEND AND
   ESPECIALLY EARLY NEXT WEEK AHEAD OF AN AMPLIFIED UPPER-LEVEL TROUGH
   OVER THE WEST. THE WRN TROUGH WILL EJECT INTO THE CNTRL CONUS BY
   MID-WEEK AS A POTENT MID-LEVEL JET STREAK ROUNDS THE BASE OF THE
   TROUGH. BY THIS TIME...SEASONABLY RICH GULF MOISTURE WILL BE PRESENT
   ALONG THE DRYLINE AND EVENTUAL COLD FRONT THAT WILL PUSH EWD TOWARDS
   THE MS VALLEY. WITH SEVERAL DAYS OF MOISTURE RETURN OCCURRING
   BENEATH A STOUT EML...A MODERATE TO STRONGLY UNSTABLE AIR MASS WILL
   LIKELY DEVELOP.

   DESPITE AVERAGE DIFFERENCES BETWEEN MODELS WITH REGARD TO
   TIMING/PLACEMENT OF THE KEY SYNOPTIC FEATURES BY D5-6...INCREASING
   FORCING FOR ASCENT ALONG WITH STEEP MID-LEVEL LAPSE RATES AND
   STRENGTHENING DEEP-LAYER SHEAR SHOULD RENDER A SETUP FAVORABLE FOR
   POTENTIALLY SIGNIFICANT AND WIDESPREAD SEVERE WEATHER DURING THIS
   TIME FRAME. GREATEST DISCRETE SUPERCELL POTENTIAL WITH PRIMARILY
   VERY LARGE HAIL AND TORNADOES SHOULD EXIST ON D5 AHEAD OF THE
   DRYLINE. AS A PACIFIC COLD FRONT MERGES WITH THE DRYLINE...AN
   EXTENSIVE SQUALL LINE SHOULD FORM AND DEVELOP EWD TOWARDS THE MS
   VALLEY WITH PRIMARY RISKS BECOMING DAMAGING WINDS AND TORNADOES ON
   D6. PRIOR TO D5...A LOCALIZED BUT ENHANCED RISK FOR VERY LARGE
   HAIL/FEW TORNADOES SHOULD EXIST NEAR THE DRYLINE/WARM FRONT
   INTERSECTION EXPECTED TO BE INVOF NWRN KS ON MON EVENING.

NWS Jackson:

THINGS GET MORE INTERESTING FOR THE WED-THU PERIOD AS OUR AREA SEES
ENERGY EJECT EASTWARD FROM THE LARGE WESTERN TROUGH. THIS ENERGY AND
LIFT WILL CLASH WITH INCREASING DEEP MOISTURE AND INSTABILITY. THIS
TIME OF YEAR IS THE CLIMATOLOGICAL PEAK OF SEVERE WEATHER FOR OUR
REGION AND THIS SYSTEM LOOKS TO HAVE THE POTENTIAL TO BRING THAT
SORT OF WEATHER. MULTIPLE ELEMENTS LOOK TO BE IN PLACE FOR SEVERE
STORMS/HEAVY RAINFALL AND WILL CONTINUE TO MENTION THIS RISK IN THE
HWO AND GRAPHICS. AS FOR TIMING...IT TOO EARLY FOR SPECIFICS...BUT
GUIDANCE SUPPORTS A GENERAL TIMEFRAME FROM WED AFTERNOON INTO THU.
IF ANYTHING...A BIT SLOWER TIMING WOULD BE PREFERRED AS I DON`T
EXPECT A FASTER SOLUTION DUE TO CAPPING AND A STOUT RIDGE AXIS JUST
TO OUR EAST.

Slight Risk for Severe Weather on Saturday

There will be a slight risk for severe weather on Saturday and Saturday night. This area will include parts of Louisiana, Mississippi, Alabama, Georgia, and Florida. As of now there is a 30% risk for severe weather for most of the slight risk area with a 15% risk covering the rest.

A warm front advecting moisture northward and intersecting with an advancing cold front with increasing southwesterly flow, and mixed layer CAPE values from 500-1500 j/kg will create an environment supportive of linear storm development (squall line) along the cold front and more cellular (rotating) storm development along the warm front. The main threats with these storms will be large hail, damaging winds, and isolated tornadoes.

Images:

Significant Severe Weather Outbreak Possible Tuesday and Wednesday (Updated 1/28/13)

Update:

The SPC has upgraded parts of Louisiana, Arkansas, and Mississippi, and Tennessee to a moderate risk for severe weather as of this morning. The slight risk area has also been expanded to include larger portions of the same states listed yesterday.

Forecast models are still very consistent on the potential for a significant severe weather outbreak Tuesday and Wednesday. The GFS is still slightly faster on progression than the rest of the models, but overall they tend to agree on the evolution of this system. Dewpoints in mid/upper 60s, mixed layer CAPE values from 500-1000 j/kg, and very high SRH (wind shear) values as well as an intensifying low level jet will be supportive of a squall line (QLCS) with embedded supercells and bowing segments. This will enhance the tornado risk along these areas of the line.

Damaging winds up to 80 mph and tornadoes (some possibly strong) will be the primary threats with the line that will move across the south Tuesday and Wednesday. There will also be the possibility that discrete storms will develop ahead of main line. The tornado threat may also increase overnight especially in the moderate risk area as the low level jet intensifies to in excess of 70 kt.

We will post another update in the morning if needed as we get closer to this system’s arrival.

_____________________________________________________________________

Tuesday/Wednesday:

As of now a slight risk for severe weather has been issued by the SPC on Tuesday for parts of Texas, Oklahoma, Louisiana, Arkansas, Missouri, Mississippi, Tennessee, Kentucky, Illinois, and Indiana. Most of the slight risk area includes a 15% risk of severe weather. However, a 30% risk currently exists for parts of Texas, Oklahoma, Louisiana, Arkansas, Mississippi, and Tennessee. On Tuesday a very large and strong upper level trough will move across these areas bringing the potential for a significant widespread severe weather outbreak. During this time all modes of severe weather will be possible including the potential for strong tornadoes in some areas. This outlook will also have a chance of being upgraded to a moderate risk before Tuesday.

It is looking likely that this system will move through the area Tuesday evening and overnight into Wednesday in the form of a squall line (QLCS), but there could also be a possibility of discrete supercells forming ahead of the main line as it moves through. We’ll update with more information as we get closer to this event.

Graphics:

Moderate Risk For Severe Weather & Strong Tornadoes On Christmas Day

A moderate risk for severe weather has been issued by the SPC on Christmas Day for central Louisiana, central & southern Mississippi, and west central Alabama. This area includes a 45% hatched (enhanced) risk for severe weather that includes the possibility of strong long track tornadoes. A slight risk area also covers parts of Texas, Louisiana, Arkansas, Mississippi, Tennessee, Alabama, Florida, and Georgia. Parts of the slight risk area will also include a 30% hatched risk for severe weather.

As of now a strong mid-level closed low pressure area will move in over the southern plains with an associated deepening surface low that will move northeast across northern Louisiana, Mississippi, Alabama, and Tennesse. This system will force strong mid/upper level winds over the gulf coast states with winds of 70-90 kts at 500 mb and 110+ kt winds at 250 mb. This will create deep layer sheer supportive of rotating updrafts. With focused low level convergence/warm advection along a warm front that will be positioned over central Louisiana, Mississippi, and Alabama, surface dewpoints south of the warm front will be in the lower 60s. This combined with CAPE values of 1000-1250 j/kg along the coast to 500 j/kg along the warm front and effective 0-6 km bulk shear approaching 60 kts will support supercells and tornadoes along and south of the warm front. 0-3 km storm relative helicity values of 350-400 m2/s2 will be supportive of strong tornadoes. Damaging winds in excess of 70 kts and quarter size hail will also be possible with these storms.

It is looking right now like these storms will quickly develop into broken line segments with embedded fast moving bow echoes and supercells as it moves across Louisiana and the southern half of Mississippi. Discrete supercells will also be possible out ahead of the QLCS, which will enhance the tornado risk south of the warm front. Elevated supercells will also be possible north of the warm front. Once again the possibility for strong long track tornadoes will exist with any long lived fast moving supercells.

People in these areas need to closely monitor the weather between 10 am and 8 pm and be prepared to act quickly as warnings are issued.

Severe Weather w/ Poss. Tornadoes Overnight Wednesday Into Thursday

A slight risk for severe weather has been issued by the SPC for parts of Louisiana, Mississippi, Arkansas, Tennessee, Missouri, Illinois, and Kentucky. A 5% tornado risk area is currently placed over Arkansas, but that should spread eastward as a broken line of storms develops and moves across the area overnight. Damaging winds and a few tornadoes will be the primary threats with these storms.

SPC Text:

...MO TO ARKLATEX AND MS DELTA REGIONS...
   BAND OF LOW-TOPPED CONVECTION WITH AT LEAST ISOLATED TO WIDELY
   SCATTERED EMBEDDED TSTMS IS FCST TO DEVELOP INVOF SFC COLD FRONT
   AFTER DARK BETWEEN SRN MO AND E TX.  ACTIVITY WILL SHIFT EWD ACROSS
   LA/AR...PORTIONS WRN TN AND NRN/WRN MS BY END OF PERIOD.  MAIN
   THREAT IS DAMAGING WIND.  DESPITE APPARENT DOMINANCE OF LINEAR
   FORCING...STG LOW-LEVEL SHEAR AND LARGE HODOGRAPHS ARE EXPECTED OVER
   NARROW CORRIDOR OF SFC-BASED WARM-SECTOR INFLOW IMMEDIATELY
   PRECEDING FROPA.  AS SUCH...SPORADIC TORNADO THREAT EXISTS...WHETHER
   WITH SUPERCELLULAR STRUCTURES OR QLCS CIRCULATIONS.  

   FCST SOUNDINGS SUGGEST WEAKER LAPSE RATES ALOFT WITH SWD
   EXTENT...OFFSET JUST ENOUGH BY INCREASING MOISTURE TO MAINTAIN
   NARROW BELT OF 300-700 J/KG MLCAPE...AMIDST 250-400 J/KG EFFECTIVE
   SRH AND 40-50 KT EFFECTIVE SHEAR MAGNITUDE.  PRIMARY LIMITING FACTOR
   WITH THIS SYSTEM REMAINS WEAKNESS OF LOW-LEVEL MOISTURE RETURN AND
   RELATED MARGINALITY OF THETAE WHERE FRONTAL AND SYNOPTIC-SCALE LIFT
   WILL BE GREATEST...ACROSS PORTIONS MO/AR.  HOWEVER...GIVEN STRENGTH
   OF DEEP-LAYER WIND FIELDS OVER BROAD AREA...MAINTENANCE OF MOST OF
   PREVIOUS OUTLOOK AREA APPEARS WARRANTED ATTM. 

   GIVEN ITS SLGT POSITIVE TILT...STRONGEST MIDLEVEL DCVA PRECEDING
   TROUGH ALOFT WILL REMAIN BEHIND SFC COLD FRONT...EXCEPT INVOF SFC
   LOW AND PERHAPS ACROSS PORTIONS SWRN/S-CENTRAL MO.  VERY NARROW
   JUXTAPOSITION OF MOST FAVORABLE LARGE-SCALE ASCENT/COOLING ALOFT
   WITH NWRN FRINGE OF WARM SECTOR MAY BE BARELY ADEQUATE FOR 100-300
   J/KG MLCAPE...WITH SFC-BASED/NEUTRALLY STABLE EFFECTIVE INFLOW
   PARCELS FRONTALLY FORCED INTO CONVECTIVE PLUME.  UNCERTAINTY
   REGARDING UNCONDITIONAL WIND THREAT INCREASES WITH NWD EXTENT FROM
   OZARKS AS THETAE DECREASES.

 











 

Severe Weather for the Deep South on Sunday

A slight risk for severe weather has been issued by the Storm Prediction Center for Sunday and Sunday night for areas including southeast Texas and most of Louisiana, Mississippi, and Alabama. A 15% risk of severe weather will exist in these areas. Damaging winds and hail will be the primary threats with storms, but isolated tornadoes will also be possible.

SPC Text:

...THERE IS A SLGT RISK OF SVR TSTMS SOUTHEAST TX/CENTRAL GULF COAST
   STATES...

   ...SOUTHEAST TX/CENTRAL GULF COAST REGION TO TN VALLEY...
   BROAD CYCLONIC UPPER FLOW WILL PREVAIL OVER THE MAJORITY OF THE
   CONUS ON SUNDAY. SEVERAL LOW AMPLITUDE DISTURBANCES ALOFT WILL CROSS
   THE REGION /AND ADJACENT MIDWEST/ DURING THE PERIOD...BUT MORE
   SUBSTANTIAL TROUGH AMPLIFICATION IS EXPECTED TO OCCUR OVER THE
   PLAINS/OZARKS SUNDAY NIGHT/EARLY MONDAY. 

   ISOLATED TO SCATTERED SHOWERS/SOME TSTMS WILL LIKELY BE ONGOING
   ACROSS THE REGION EARLY SUNDAY IN ASSOCIATION WITH PERSISTENT WARM
   ADVECTION AND A STEADY MOISTURE INFLUX AHEAD OF A FRONT. RELATIVELY
   WEAK LAPSE RATES ALOFT AND A LIMITED NORTHWARD MOISTURE
   RETURN...ALONG WITH CLOUD COVER/POSSIBLE PRECIPITATION...SHOULD
   LIMIT THE DEGREE OF DESTABILIZATION ACROSS THE REGION. EVEN
   SO...SOME OF THESE STORMS COULD BECOME SURFACE BASED AS THE BOUNDARY
   LAYER WARMS...WITH AT LEAST SOME ISOLATED SEVERE WIND/PERHAPS
   TORNADO POTENTIAL.

   THE MOST PROBABLE SCENARIO FOR STORM INTENSIFICATION MAY OCCUR
   ACROSS PARTS OF SOUTHEAST TX INTO LA/PARTS OF MS SUNDAY AFTERNOON
   AND SUNDAY NIGHT/EARLY MONDAY NEAR AN ADVANCING/ACCELERATING COLD
   FRONT. SOMEWHAT STRONGER DESTABILIZATION IS LIKELY IN THESE AREAS IN
   THE PRESENCE OF A HIGHER THETA-E AIRMASS...WITH THE REGION
   INCREASINGLY COMING UNDER THE INFLUENCE OF THE AMPLIFYING UPPER
   TROUGH OVER THE PLAINS/OZARKS BY SUNDAY NIGHT. WHERE STORMS DO
   INCREASE/MATURE...VERY STRONG DEEP LAYER SOUTHWESTERLY FLOW AND
   ASSOCIATED VERTICAL SHEAR OF 50-80 KT /0-6 KM/ WILL SUPPORT
   FAST-MOVING LINE SEGMENTS/SOME SUPERCELLS WITH ASSOCIATED POTENTIAL
   FOR DAMAGING WIND/ISOLATED TORNADOES.

 

Severe Weather With Tornadoes Possible Wednesday Into Thursday

UPDATE:

Just wanted to post a quick update on today’s severe weather event with some updated graphics.

As of this morning the SPC has expanded today’s slight risk area to include most of Arkansas, Louisiana, and Mississippi. The risk area also includes parts of Tennessee, Alabama, Missouri, Kentucky, Illinois, and the southern tip of Indiana. The outlook area has also been updated with a 10% risk for tornadoes, and this includes west central and northwest Mississippi, northeast Louisiana, and eastern Arkansas. There is also a hatched area over the Mississippi, Louisiana, and Arkansas delta regions that will be at an increased risk for strong tornadoes. A 30% wind risk and 15% hail risk will also exist for much of the slight risk area.

Not much has changed with the general timing and position of the cold front as it makes its way southeastward across the area. There will still be plenty of moisture, wind shear, instability, etc. over most of these areas to support a severe weather event beginning later this afternoon and tonight. Also, it still appears that the initial storm mode will be supercells that will quickly increase in coverage forming line segments / LEWPS and multicell clusters before eventually forming into a QLCS / squall line as it moves through the mid and lower Mississippi Valleys throughout the night.

Images:

NWS Jackson: