Oct 13, 2014 1630 UTC Day 1 Convective Outlook
Updated: Mon Oct 13 16:34:40 UTC 2014 (20141013 1630Z Day 1 shapefile | 20141013 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...Severe thunderstorms expected over parts of the mid-south and lower mississippi valley today into tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20141013 1630 UTC Day 1 Outlook Graphic
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 70,001 4,682,341 Memphis, TN...Jackson, MS...Jackson, TN...Jonesboro, AR...Monroe, LA...
SLIGHT 233,897 29,472,095 Houston, TX...Indianapolis, IN...Nashville, TN...New Orleans, LA...St. Louis, MO...
Probabilistic Tornado Graphic
20141013 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 68,062 4,553,525 Memphis, TN...Jackson, MS...Jackson, TN...Jonesboro, AR...Monroe, LA...
10 % 24,938 1,198,669 Tuscaloosa, AL...Meridian, MS...Florence, AL...Carbondale, IL...Northport, AL...
5 % 70,634 6,047,089 St. Louis, MO...Baton Rouge, LA...Evansville, IN...Lafayette, LA...Clarksville, TN...
2 % 102,366 16,293,206 Houston, TX...Nashville, TN...New Orleans, LA...Birmingham, AL...Montgomery, AL...
Probabilistic Damaging Wind Graphic
20141013 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
45 % 70,175 4,638,028 Memphis, TN...Jackson, MS...Jackson, TN...Jonesboro, AR...Monroe, LA...
30 % 74,550 5,959,294 St. Louis, MO...Evansville, IN...Clarksville, TN...Tuscaloosa, AL...Hattiesburg, MS...
15 % 161,227 23,767,640 Houston, TX...Indianapolis, IN...Nashville, TN...New Orleans, LA...Louisville, KY...
5 % 148,192 29,389,580 Chicago, IL...Atlanta, GA...Toledo, OH...Cincinnati, OH...Lexington-Fayette, KY...
Probabilistic Large Hail Graphic
20141013 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 42,307 3,296,889 Memphis, TN...Jackson, TN...Bartlett, TN...Southaven, MS...Collierville, TN...
5 % 168,951 18,558,899 Houston, TX...New Orleans, LA...St. Louis, MO...Baton Rouge, LA...Mobile, AL...
   SPC AC 131634

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1134 AM CDT MON OCT 13 2014

   VALID 131630Z - 141200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF
   LA/AR/MS/AL/TN/MO/KY/IL...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GULF COAST STATES
   NORTHWARD TO IL/INDIANA...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED INTO TONIGHT ACROSS THE LOWER AND
   MIDDLE MISSISSIPPI VALLEY AND PARTS OF THE TENNESSEE VALLEY...OHIO
   VALLEY AND GULF COAST STATES. WIDESPREAD DAMAGING WINDS AND SOME
   TORNADOES ARE EXPECTED.

   ...LOWER/MIDDLE MS RIVER VALLEY TO OH/TN VALLEYS AND GULF COAST...
   A COMPOSITE SQUALL LINE CONTINUES TO MAKE A SLOW/STEADY EASTWARD
   PROGRESSION TOWARD THE MISSISSIPPI RIVER AT MIDDAY...EXTENDING FROM
   NEAR THE ST LOUIS AREA SOUTH-SOUTHWESTWARD TO FAR EASTERN AR AND
   WESTERN/NORTHERN LA AS OF 16Z. WHILE CLOUD COVER REMAINS FAIRLY
   EXTENSIVE AT MIDDAY WITHIN THE COLD FRONT/SQUALL LINE-PRECEDING WARM
   SECTOR...AT LEAST SOME THINNING IS NOTED IN VISIBLE SATELLITE
   PARTICULARLY ACROSS MS/WESTERN AL AND TN...COINCIDENT WITH
   INCREASINGLY PREVALENT UPPER 60S/NEAR 70F SURFACE DEWPOINTS WITHIN
   THIS CORRIDOR.

   A DOMINANT QUASI-LINEAR/SQUALL LINE MODE IS LIKELY TO
   PERSIST...PARTICULARLY GIVEN A TENDENCY FOR BACKING MID-LEVEL WINDS
   /TO SOUTH-SOUTHWESTERLY/ THIS AFTERNOON INTO TONIGHT. THAT SAID...AT
   LEAST SOME INCREASE IN LINE-PRECEDING STORMS IS EXPECTED WITHIN THE
   WARM SECTOR GIVEN INCREASING BOUNDARY LAYER MOISTURE/REDUCED
   CONVECTIVE INHIBITION. EVEN WITH NEARLY UNIDIRECTIONAL VERY STRONG
   SOUTH-SOUTHWESTERLY WINDS ABOVE 3KM...ELONGATED LOW-LEVEL HODOGRAPHS
   WILL BE HIGHLY FAVORABLE FOR EMBEDDED BOWING STRUCTURES/LOW-LEVEL
   CIRCULATIONS CAPABLE OF CORRIDORS OF DAMAGING WINDS AND SOME
   TORNADOES. THIS INCLUDES A CONDITIONAL RISK FOR ISOLATED SIGNIFICANT
   EVENTS GIVEN THE MAGNITUDE OF THE LOWER TROPOSPHERIC WINDS/SRH.

   REGARDING THE NORTHERN EXTENT OF THE SEVERE RISK INTO THE
   MIDWEST...ONGOING STRATIFORM-LEADING CONVECTIVE BANDS OVER THE
   MID-SOUTH WILL CONTINUE TO BUILD NNEWD WHILE THE LARGER-SCALE
   COLLECTION OF BANDS TRANSLATES EWD THROUGH TONIGHT. THIS WILL OCCUR
   AS A STRONG LLJ PRECEDING THE STRENGTHENING DEEP CYCLONE ENCOURAGES
   AN INFLUX OF RICHER BOUNDARY-LAYER MOISTURE TO THE SE OF A
   FRONTOGENETIC BOUNDARY BRANCHING NEWD FROM THE SFC LOW. AS A
   RESULT...MIDDLE 60S SFC DEWPOINTS WILL ALLOW MARGINAL INSTABILITY TO
   EXTEND NWD TO NEAR/JUST N OF THE I-70 CORRIDOR. INTENSE LOW-LEVEL
   SHEAR BENEATH 50-60-KT H85 SLYS WILL BOLSTER UPDRAFTS VIA
   STORM-SCALE DYNAMIC PERTURBATIONS...DESPITE LIMITED BUOYANCY...TO
   THE NRN EXTENT OF THE SLIGHT-RISK AREA. CONVECTIVE MOMENTUM
   TRANSPORT WILL AID IN THE POTENTIAL FOR ISOLATED DMGG WIND GUSTS IN
   BOWING SEGMENTS...WITH 30-35 KT OF 0-1-KM SHEAR YIELDING SOME
   POTENTIAL FOR A FEW TORNADOES. THE SVR RISK WILL PRECIPITOUSLY
   DECREASE WITH NWD DISPLACEMENT FROM I-70.

   REGARDING LATE TONIGHT FOR THE CENTRAL GULF COAST/TN VALLEY...THE
   LARGE-SCALE DEEPENING OF THE UPPER SYSTEM WILL BE RELATED TO A
   MODEST SPATIAL EXPANSION OF STRONGER LOW-LEVEL MASS FLUXES
   PERIPHERAL TO THE DEEPER SYSTEM. AS A RESULT...A STRONG
   FRONT/SQUALL-LINE-LEADING LLJ WILL CONTINUE TO FOSTER AMPLE
   GULF-MOISTURE TRANSPORT /UPPER 60S-LOWER 70S SFC DEWPOINTS/ THROUGH
   TONIGHT. DIURNALLY ENHANCED CONVECTION WILL CONTINUE TO TRACK EWD
   INTO THE OVERNIGHT HOURS...WHILE ADDITIONAL THUNDERSTORMS DEVELOP
   NWD/NEWD ALONG CONFLUENT BANDS PRECEDING THE FRONT. THE LOW-LEVEL
   BUOYANCY/SHEAR COMBINATION IS FORECAST TO REMAIN SUFFICIENT FOR AT
   LEAST ISOLATED SVR STORMS...WITH DMGG WINDS AND TORNADOES POSSIBLE
   FROM MIXED CONVECTIVE MODES INCLUDING DISCRETE/SEMI-DISCRETE
   SUPERCELLS.

   ..GUYER/COHEN.. 10/13/2014

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