SPC AC 111957

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0257 PM CDT MON MAY 11 2015

   VALID 112000Z - 121200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS OVER PARTS OF LOWER MI/OH...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR GRT
   LKS/OH VLY...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF S TX AND THE LWR
   MS VLY...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE GRT LKS REGION SW INTO
   THE RIO GRANDE VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER A SMALL PART OF ORE/NRN CA
   AND NW NV...

   ...SUMMARY...
   SCATTERED THUNDERSTORMS WILL CONTINUE ALONG AND AHEAD OF A COLD
   FRONT CROSSING THE GREAT LAKES REGION...THE OHIO...TENNESSEE...AND
   LOWER MISSISSIPPI VALLEYS...AND THE SOUTHERN HALF OF TEXAS. 
   DAMAGING WINDS AND HAIL MAY OCCUR WITH SOME STORMS...ALONG WITH A
   FEW TORNADOES OVER THE SOUTHERN GREAT LAKES AND MID-OHIO VALLEY.

   ...20Z UPDATE...
   OVERALL FORECAST REASONING REMAINS LARGELY UNCHANGED FROM PRIOR
   OUTLOOK...BUT SOME SPATIAL ADJUSTMENTS HAVE BEEN MADE. MARGINAL
   WIND-RELATED PROBABILITIES WERE EXPANDED FOR ONGOING STRONG STORMS
   ACROSS THE SOUTHERN APPALACHIANS/CAROLINAS...REFERENCE MESOSCALE
   DISCUSSION 613 FOR MORE DETAILS. OTHERWISE...THE PEAK CORRIDOR OF
   SEVERE WEATHER POTENTIAL IS STILL ANTICIPATED ACROSS PARTS OF THE
   MIDWEST AND MIDDLE/UPPER OH RIVER VALLEY INTO THIS EVENING...WITH
   DAMAGING WINDS AND SOME TORNADO RISK REMAINING THE PRIMARY CONCERNS.
   POTENTIAL ALSO EXISTS ACROSS THIS REGION FOR SOME STRONGER
   THUNDERSTORM REDEVELOPMENT FARTHER WEST/SOUTHWEST NEAR THE COLD
   FRONT THROUGH LATE AFTERNOON/EARLY EVENING.

   ..GUYER.. 05/11/2015

   .PREV DISCUSSION... /ISSUED 1129 AM CDT MON MAY 11 2015/

   ...SYNOPSIS...
   ERN SD CLOSED LOW EXPECTED TO DEVOLVE INTO AN OPEN WAVE AS IT
   CONTINUES ENE INTO NRN MN LATER TODAY AND ACROSS LK SUPERIOR EARLY
   TUE. AS THIS OCCURS...ASSOCIATED SHORTWAVE IMPULSE NOW OVER MO
   SHOULD SHEAR NE ACROSS THE LWR OH VLY AND MI THIS AFTN AND
   EVE...WHILE STRONGER UPSTREAM DISTURBANCE TRACKS FROM THE CNTRL HIGH
   PLNS TO THE MID-MS VLY.

   AT LWR LVLS...MN UPR LOW WILL TRACK E INTO NRN WI BY AS TRAILING
   COLD FRONT AND PRE-FRONTAL OUTFLOW BOUNDARY CONTINUE STEADILY E
   ACROSS THE WRN GRT LKS AND LWR OH VLY. PROGRESS OF THESE SAME
   FEATURES WILL BE SOMEWHAT SLOWER ACROSS THE LWR MS VLY AND S TX.

   ...LWR MI/MID-OH VLY THIS AFTN/EVE...'
   SCTD TO BROKEN LINES OF TSTMS SHOULD FORM ALONG PRE-FRONTAL OUTFLOW
   BOUNDARY OVER IND AND LWR MI THIS AFTN...WITH DEVELOPMENT AUGMENTED
   BOTH BY DAYTIME HEATING AND THE APPROACH OF MO UPR IMPULSE.
   ASSOCIATED STRENGTHENING OF 700-500 MB FLOW...ALREADY IN PROGRESS
   PER VWP TRENDS IN IND /WHERE SPEEDS ARE AOA 50 KTS/...MAY PROMOTE
   FORMATION OF SUSTAINED STORMS/SUPERCELLS. EMBEDDED SMALL-SCALE BOWS
   AND LEWPS MAY YIELD NARROW SWATHS OF DMGG WIND...AND POSSIBLY A FEW
   TORNADOES. THE LATTER SUCH THREAT SHOULD BE GREATEST IN LWR
   MI...WHERE SFC FLOW IS LIKELY TO BE SLIGHTLY BACKED INVOF WARM FRONT
   EXTENDING E FROM MN-WI LOW. COMPARATIVELY LARGER
   TEMPERATURE-DEWPOINT SPREADS MAY COMPENSATE FOR WATER LOADING
   PROCESSES TO LOCALLY ENHANCE WIND GUSTS IN THE OH STORMS. THE
   CONVECTION SHOULD GRADUALLY WEAKEN AFTER SUNSET.

   ...S TX/LWR RIO GRANDE VLY THROUGH EARLY TUE...
   PERIODIC...DIURNALLY-ENHANCED ROUNDS OF STRONG TO SVR STORMS ARE
   EXPECTED INVOF STALLING SFC FRONT OVER S TX. DEVELOPMENT WILL BE
   FOSTERED BY PRESENCE OF PERSISTENT...MOIST...LOW-LVL ELY FLOW
   BENEATH MODERATE WSWLY MID-LVL SRN STREAM JET. A CLUSTER OR TWO OF
   STRONG TO INTENSE STORMS...POSSIBLY CONTAINING ONE OR TWO
   SLOWLY-MOVING...HP-SUPERCELLS WITH LARGE HAIL...LOCALLY DMGG
   WIND...AND POSSIBLY A TORNADO COULD FORM OVER THE HIGHER TERRAIN OF
   NRN MEXICO AND SPREAD E INTO S TX LATER TODAY...WITH
   OTHER...SLIGHTLY ELEVATED ACTIVITY REDEVELOPING NEAR OR N OF THE
   FRONT. LATER TNGT AND EARLY TUE...ANOTHER ROUND OF
   SLOWLY-PROGRESSIVE STRONG TO SVR STORMS COULD FORM IN ASSOCIATION
   WITH DEAMPLIFYING SRN STREAM IMPULSE NOW OVER NRN CHIHUAHUA.

   ...LWR MS VLY THIS AFTN...
   SCTD DIURNALLY-ENHANCED PULSE STORMS WITH A RISK FOR LOCALLY DMGG
   WIND AND HAIL EXPECTED TO FORM WITH SFC HEATING ALONG AND AHEAD OF
   DECELERATING PRE-FRONTAL OUTFLOW BOUNDARY CROSSING PARTS OF THE LWR
   MS VLY.  A MORE CONDITIONAL RISK WILL EXIST FOR A BRIEFLY SVR STORM
   OR TWO ALONG THE ACTUAL COLD FRONT.

   ...UPSTATE NY AREA THIS AFTN...
   A FEW STRONG TO LOCALLY SVR STORMS MAY FORM THIS AFTN ALONG SEGMENT
   OF QSTNRY FRONT OVER UPSTATE NY...WHERE 25 KT WLY 700 MB FLOW
   PARALLEL TO THE BOUNDARY WILL PREVAIL.

   ...SERN ORE VICINITY THIS AFTN/EVE...
   A FEW STORMS WITH MARGINALLY SVR HAIL/WIND MAY FORM WITH AFTN
   HEATING OF THE HIGHER TERRAIN DOWNSTREAM FROM NEG-TILT SHORTWAVE
   TROUGH. MODEST HEATING AND LIMITED MOISTURE SHOULD LIMIT OVERALL
   THREAT.

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