SPC AC 111954

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0254 PM CDT TUE JUN 11 2013

   VALID 112000Z - 121200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF SRN SD...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN AND CNTRL PLAINS
   INTO THE MID-UPPER MS VALLEY REGION...

   ...NRN AND CNTRL HIGH PLAINS INTO THE MID-UPPER MS VALLEY AREA...

   HAVE MADE ONLY MINOR ADJUSTMENTS TO CURRENT FORECAST AS SCENARIO
   STILL APPEARS TO BE ON TRACK. STORMS ARE DEVELOPING OVER THE NRN
   ROCKIES. INCREASING ISENTROPIC ASCENT ON NOSE OF STRENGTHENING LLJ
   AND HEIGHT FALLS AHEAD OF EJECTING SHORTWAVE TROUGH WILL PROMOTE
   ADDITIONAL STORMS OVER SD/WRN NEB THIS EVENING...ESPECIALLY NORTH OF
   E-W BOUNDARY AND CONTINUING EWD INTO THE OVERNIGHT. ACTIVITY WILL
   LIKELY GROW UPSCALE INTO CLUSTERS AND LINE SEGMENTS WITH DAMAGING
   WIND AND LARGE HAIL LIKELY.

   ...CNTRL IL INTO THE OH VALLEY...

   A FEW STORMS CONTINUE DEVELOPING ACROSS CNTRL THROUGH NERN IL THIS
   AFTERNOON...BUT ACTIVITY IS ELEVATED ABOVE A CAPPING INVERSION. THE
   OVERALL SEVERE THREAT IN THIS REGION REMAINS CONDITIONAL...AND IT
   APPEARS UNLIKELY THAT STORMS WILL BE ABLE TO ROOT IN THE BOUNDARY
   LAYER GIVEN RELATIVELY HIGH LFCS...WEAK MESOSCALE FORCING AND WEAK
   COLD POOLS WITH ONGOING STORMS. WILL MAINTAIN 5% SEVERE
   PROBABILITIES GIVEN THE CONDITIONAL NATURE OF THE THREAT.

   ...SRN NEW ENGLAND...

   REF SWOMCD 1030

   ..DIAL.. 06/11/2013

   .PREV DISCUSSION... /ISSUED 1134 AM CDT TUE JUN 11 2013/

   ...SYNOPSIS...
   ELONGATED SUBTROPICAL RIDGE NOW EXTENDING FROM THE SRN RCKYS INTO
   THE CNTRL/SRN PLNS WILL EXPAND EWD THIS PERIOD IN WAKE OF UPR
   IMPULSE THAT CROSSED THE TN VLY YESTERDAY. AT THE SAME TIME...POTENT
   SHORTWAVE TROUGH NOW OVER UT WILL CONTINUE ENE INTO THE NRN/CNTRL
   HIGH PLNS THIS EVE...BEFORE TURNING E AS IT CRESTS THE RIDGE TO
   REACH SD/NEB EARLY WED.

   GIVEN THE ABOVE PATTERN...EXPECT STOUT EML...WELL-DEPICTED IN THE
   MORNING RAOB DATA...TO REMAIN IN PLACE INTO TNGT FROM THE N CNTRL HI
   PLNS EWD INTO MID-MS/LWR OH VLYS.

   AT THE SFC...CNTRL HIGH PLNS LEE LOW SHOULD REMAIN NEARLY STNRY
   TODAY BEFORE ADVANCING E ACROSS SRN NEB TNGT AHEAD OF UPR TROUGH. A
   CORRIDOR OF FAIRLY RICH BOUNDARY LAYER MOISTURE AND LOW-LVL ELY FLOW
   WILL PERSIST N OF A W-E FRONT EXTENDING E FROM THE LOW INTO MID-MS
   VLY.

   COMBINATION OF LOW-LVL MOISTURE INFLOW...SFC HEATING...AND
   APPROACHING UPR TROUGH LIKELY WILL LEAD TO STRONG TSTM DEVELOPMENT
   BY MID TO LATE AFTN OVER PARTS OF ERN WY AND WRN SD. THIS ACTIVITY
   LIKELY WILL GROW UPSCALE INTO A SVR MCS THAT MOVES GENERALLY E ALONG
   THE NRN FRINGE OF THE EML CAP AND ALONG LOW-LVL MOIST AXIS THROUGH
   EARLY WED. IN THE MEANTIME...SCTD AREAS OF STRONG TO LOCALLY SVR
   DIURNAL STORMS MAY OCCUR TODAY OVER PARTS OF THE EAST AND
   INTERMOUNTAIN WEST. IN ADDITION...WDLY SCTD ELEVATED STORMS WITH
   HAIL MAY OCCUR EARLY WED IN STRENGTHENING WAA ZONE ON NE FRINGE OF
   THE EML OVER THE OH VLY.

   ...N CNTRL HIGH PLNS TO MID MS VLY TODAY THROUGH EARLY WED...
   LOW-LVL MOISTURE WILL FURTHER INCREASE ACROSS SD...NRN NEB...ERN
   WY...AND SE MT TODAY IN ELY UPSLOPE FLOW N OF STALLED FRONT/LEE LOW.
   COUPLED WITH STRONG SFC HEATING AND INCREASING UPR LVL
   DIVERGENCE/DCVA WITH APPROACH OF UT UPR VORT...SETUP WILL BECOME
   FAVORABLE FOR STRONG TSTM DEVELOPMENT NEAR THE HIGHER TERRAIN AND
   ALONG LEE TROUGH AND BY MID TO LATE AFTN. COMBINATION OF STRONG
   INSTABILITY /MUCAPE TO 2500 J PER KG/ AND 40 KT WSWLY DEEP SHEAR
   LIKELY WILL YIELD SCTD SUPERCELLS CAPABLE OF VERY LARGE
   HAIL...LOCALLY DMGG WIND...AND TORNADOES...ESPECIALLY IN SW SD...NE
   WY...AND NW NEB.

   GIVEN VERY DEEP/STRONG EML...PRESENCE OF 40-50 KT UNIDIRECTIONAL WLY
   MID/UPR-LVL FLOW...AND MOIST/ELY LOW-LVL FLOW...SETUP APPEARS
   FAVORABLE FOR UPSCALE DEVELOPMENT INTO A SVR FORWARD-PROPAGATING/
   POSSIBLE DERECHO-PRODUCING CONVECTIVE SYSTEM. SUCH A SYSTEM COULD
   EXTEND A RISK FOR SVR WIND...HAIL..AND ISOLD TORNADOES E INTO NE
   NEB/NW A/SE SD AREA BY 12Z WED. FARTHER E...SMALLER...SOMEWHAT
   ELEVATED CONVECTIVE SYSTEMS/STORMS MAY FORM DURING THE OVERNIGHT
   OVER PARTS OF IL/IND/OH IN ZONE OF STRENGTHENING WAA/MOISTURE
   TRANSPORT ON NERN FRINGE OF EML.

   ...SRN NEW ENGLAND/LWR HUDSON VLY/NJ THIS AFTN...
   SFC HEATING IN NARROW CORRIDOR OF CLEARING ON SW SIDE OF CLOUD
   SHIELD ASSOCIATED WITH CAPE COD AREA SFC LOW MAY SUPPORT DEVELOPMENT
   OF SCTD STRONG AFTN/EVE STORMS WITH GUSTY WINDS IN ASSOCIATED ZONE
   OF WEAK LOW-LVL CONFLUENCE.

   ...PARTS OF GA/SC THIS AFTN...
   WDLY SCTD STRONG STORMS ALSO MAY FORM IN ZONE OF WEAK ASCENT ON
   TRAILING SW END OF UPR IMPULSE THAT CROSSED THE TN VLY YESTERDAY.
   WIND AND THERMODYNAMIC ENVIRONMENT MAY SUPPORT AN INSTANCE OR TWO OF
   LOCALLY DMGG WIND/MARGINALLY SVR HAIL.

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