Categorical Graphic
Probabilistic Graphic
Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.

   SPC AC 081730
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT SUN MAY 08 2011
   
   VALID 091200Z - 101200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
   MIDWEST...
   
   ...SYNOPSIS...
   AN INCREASINGLY AMPLIFIED/BLOCKY LONGWAVE UPPER FLOW REGIME WILL
   PREVAIL INTO MONDAY OVER THE CONUS...WITH A NEARLY STATIONARY CLOSED
   LOW OVER THE WESTERN ATLANTIC AND A BROAD TROUGH OVER THE WESTERN
   STATES. IN REGARDS TO THE WESTERN CONUS UPPER TROUGH...A LEAD
   SHORTWAVE PORTION OF THIS TROUGH IS EXPECTED TO ADVANCE
   NORTHEASTWARD FROM THE CENTRAL ROCKIES TO THE NORTHERN HIGH PLAINS
   ON MONDAY...WHILE THE BASAL PORTION OF THE WEST TROUGH DIGS
   SOUTHWARD OVER SOUTHERN CA AND THE LOWER CO RIVER VALLEY.
   
   ...NORTHERN PLAINS...
   AN INFLUX OF LOW LEVEL MOISTURE WILL CONTINUE TO SURGE CYCLONICALLY
   ON THE EASTERN/NORTHERN PERIPHERY OF A DEEPENING/GRADUAL
   EAST-NORTHEASTWARD SHIFTING NORTH-CENTRAL HIGH PLAINS SURFACE
   LOW...AS A WARM FRONT BECOMES INCREASINGLY ESTABLISHED NORTHWARD
   INTO EXTREME NORTHERN NEB AND SOUTHERN/CENTRAL SD. WITH INCREASING
   DYNAMIC FORCING FOR ASCENT AS AIDED BY A LEAD SHORTWAVE TROUGH
   ADVANCING FROM THE CENTRAL ROCKIES TO THE NORTHERN HIGH
   PLAINS...SURFACE BASED TSTMS ARE LIKELY TO DEVELOP/INCREASE BY
   MID/LATE AFTERNOON...INITIALLY IN THE LEE OF THE ROCKIES FRONT RANGE
   AND/OR VICINITY OF THE BLACK HILLS. A SUBSEQUENT UPSWING IN DEEP
   CONVECTIVE COVERAGE/VIGOR IS ANTICIPATED INTO EARLY/MID EVENING AS
   STORMS DEVELOP EAST-NORTHEASTWARD ACROSS SD IN VICINITY OF THE WARM
   FRONT/LOW-LEVEL MOIST AXIS. INCREASINGLY STRONG/DIFFLUENT FLOW ALOFT
   WILL SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL...IN ADDITION TO THE
   POSSIBILITY OF TORNADOES. A NOCTURNALLY STRENGTHENING LOW LEVEL
   JET/ISENTROPIC LIFT REGIME NORTH OF THE WARM FRONT WILL SUPPORT AT
   LEAST AN ISOLATED SEVERE HAIL THREAT CONTINUING THROUGH THE NIGHT
   FROM THE EASTERN DAKOTAS INTO MN.
   
   ...MIDWEST/MS VALLEY/LOWER OH VALLEY...
   SPREAD AMONGST NUMERICAL GUIDANCE AND THE POTENTIAL DEGREE OF
   AFTERNOON CAPPING CONTINUES TO LIMIT FORECAST CONFIDENCE FOR MONDAY.
   THAT SAID...THE MOST LIKELY SCENARIO IS FOR CLUSTERS OF ELEVATED
   TSTMS TO BE ONGOING ACROSS PORTIONS OF IA AND/OR IL/EASTERN MO
   MONDAY MORNING...WITH SOME OF THESE STORMS CAPABLE OF SEVERE HAIL. A
   VEERING LOW LEVEL JET WILL PROBABLY MAINTAIN AT LEAST ELEVATED
   STORMS EAST-NORTHEAST TOWARD THE GREAT LAKES REGION DURING THE DAY.
   
   THEREAFTER...THE ELEVATED MIXED LAYER NEAR THE WARM FRONT WILL ONLY
   STRENGTHEN DURING THE DAY...WITH CONSIDERABLE UNCERTAINTY REGARDING
   THE LIKELIHOOD OF SURFACE BASED TSTM DEVELOPMENT DURING THE
   AFTERNOON/EARLY EVENING. THAT SAID...THERE IS CONDITIONAL-TYPE
   CONCERN THAT ISOLATED SURFACE BASED TSTMS COULD DEVELOP SOMEWHERE IN
   A NEAR WARM FRONTAL CORRIDOR FROM IA INTO CENTRAL IL. AT LEAST IN A
   CONDITIONAL SENSE...VERY STEEP MID LEVEL LAPSE RATES AND FAVORABLE
   EFFECTIVE SHEAR WOULD BE FAVORABLE FOR SUPERCELLS CAPABLE OF LARGE
   HAIL/DAMAGING WINDS AND PERHAPS A FEW TORNADOES.
   
   ...SOUTHEAST STATES...
   BACKDOOR FRONTAL BOUNDARY WILL CONTINUE TO SETTLE SOUTHWESTWARD FROM
   SC TO GA/FAR NORTH FL ON MONDAY. GIVEN A WEAK CAP...SCATTERED TSTMS
   ARE LIKELY TO DEVELOP ALONG/JUST SOUTHWEST OF THE SURFACE FRONT
   DURING THE AFTERNOON WITHIN A MOIST/MODERATELY UNSTABLE BOUNDARY
   LAYER. AIDED BY 20-30 KT NORTHWESTERLY MID LEVEL FLOW...THESE
   MULTICELLULAR TSTMS MAY ORGANIZE INTO SOUTHWARD-MOVING LINEAR
   CLUSTERS CAPABLE OF DAMAGING WINDS/SOME SEVERE HAIL.
   
   ...WEST-CENTRAL TX...
   12Z BASED NUMERICAL GUIDANCE IMPLIES THAT GRADUAL HEIGHT FALLS WILL
   OCCUR ON MONDAY IN ASSOCIATION WITH A LEAD IMPULSE ACROSS WEST TX.
   VARIOUS NUMERICAL GUIDANCE SUCH AS THE 12Z WRF-NAM AND VARIOUS 09Z
   SREF MEMBERSHIP IMPLY ISOLATED TSTM DEVELOPMENT IS POSSIBLE IN
   VICINITY OF THE DRYLINE MONDAY LATE AFTERNOON/EARLY
   EVENING...ALTHOUGH SOME OF THIS MAY PARTIALLY BE ATTRIBUTABLE TO THE
   CAP BEING AGGRESSIVELY ERODED BY THE BMJ SCHEME VIA MID LEVEL
   MOISTENING. REGARDLESS...AT LEAST A LOW PROBABILITY OF TSTMS SEEMS
   WARRANTED...AND THIS REGION WILL BE SUBSEQUENTLY REEVALUATED FOR
   WHAT COULD BE AN ISOLATED SEVERE RISK IN THE FORM OF HAIL IN
   VICINITY OF THE DRYLINE.
   
   ..GUYER.. 05/08/2011
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z