Severe Storms April 9

[nrgjeff]

Could be severe weather dinner theater from Memphis north to Paducah this evening. Couple isolated cells may develop ahead of the main line. While Illinois may enjoy more turning winds with height, and a lovely retreating boundary, heating is better in the Mid South.

 

Looks like some sort of differential heating boundary or moisture surge from eastern Arkansas into far western Tennessee. While it could be a focus for cells ahead of the line, most hi-res guidance just shows a big cluster of storms developing. Very latest 15Z HRRR shows a cluster in the Delta actually cutting off flow into the main line and even the above boundary. Previous HRRR and 12Z hi-res NAM had better inflow for the main line of storms.

 

Looks like mainly wind and hail to me. I agree with the low tor probs from SPC for the Mid South. Maybe we will see nice photos of a shelf cloud over downtown Memphis this evening.

[ChattChaser]

MEM mentioned in their afternoon AFD that a secondary low may possibly form. If that actually happens does that change anything for points eastward?

[jaxjagman]

 

Probability of 2 or more tornadoes
Low (20%)
Probability of 1 or more strong (F2-F5) tornadoes
Low (<2%)
Wind
Probability of 10 or more severe wind events
Mod (50%)
Probability of 1 or more wind events > 65 knots
Low (10%)
Hail
Probability of 10 or more severe hail events
Mod (50%)
Probability of 1 or more hailstones > 2 inches
Mod (30%)
Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events
High (80%)

 

 

URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 49
   NWS STORM PREDICTION CENTER NORMAN OK
   635 PM CDT THU APR 9 2015

   THE NWS STORM PREDICTION CENTER HAS ISSUED A

   * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
     EASTERN ARKANSAS
     MISSOURI BOOTHEEL
     NORTHERN MISSISSIPPI
     WEST TENNESSEE

   * EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 635 PM
     UNTIL 100 AM CDT.

   * PRIMARY THREATS INCLUDE...
     SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2
       INCHES IN DIAMETER POSSIBLE
     SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
     A TORNADO OR TWO POSSIBLE

   THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90
   STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH OF
   DYERSBURG TENNESSEE TO 20 MILES SOUTHWEST OF GREENWOOD
   MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
   FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
   DO PRODUCE TORNADOES.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 39...WW 40...WW 41...WW
   42...WW 43...WW 44...WW 45...WW 46...WW 47...WW 48...

   DISCUSSION...SCATTERED SEVERE THUNDERSTORMS OVER AR WILL SPREAD
   EASTWARD INTO PARTS OF TN/MS DURING THE EVENING.  MODERATE
   INSTABILITY AND FAVORABLE DEEP LAYER SHEAR VALUES WILL PROMOTE
   ROTATING STORMS CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

[nrgjeff]

MEM mentioned in their afternoon AFD that a secondary low may possibly form. If that actually happens does that change anything for points eastward?

 

Sorry I did not get back on last night. While my thread seemed to have jinxed the Mid South, a secondary low is an important topic. Secondary low would be bullish for severe. It would back surface winds, perhaps strengthen winds and consolidate any boundary. Also upstairs, the same speed max or short wave creating the surface low would create more deep level shear. Secondary lows sometimes light up the South along outflow, while the main low and warm front track north.