SPC AC 291941

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0241 PM CDT WED MAY 29 2013

   VALID 292000Z - 301200Z

   ...THERE IS A MDT RISK OF SVR TSTMS FROM NWRN TX INTO SWRN NEB...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
   SWRN TX INTO THE UPPER MS VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NERN
   U.S....

   FEW CHANGES REQUIRED TO 1630Z OUTLOOK.

   ...MDT RISK REGION OF THE HIGH PLAINS...

   WELL DEFINED SHORT-WAVE TROUGH IS PROGRESSING STEADILY EWD ACROSS
   THE HIGH PLAINS WITH TROUGH AXIS NOW EXTENDING FROM THE CO/KS
   BORDER...SWD INTO WEST TX.  STRONGEST MID LEVEL FLOW APPEARS TO
   EXTEND ACROSS THE CNTRL HIGH PLAINS AND 18Z SOUNDING FROM DDC
   SUPPORTS THIS WITH 50KT AT 500MB.  VIS IMAGERY DEPICTS CONSIDERABLE
   AMOUNT OF DEEPENING CU ALONG THE DRYLINE ACROSS WRN KS AND THIS
   ACTIVITY SHOULD EXPERIENCE UPWARD GROWTH WITHIN AN ENVIRONMENT
   FAVORABLE FOR SUPERCELLS.

   CONSIDERABLE AMOUNT OF CLOUDINESS ACROSS THE WARM SECTOR FROM NCNTRL
   TX INTO OK HAS PREVENTED MEANINGFUL TSTM DEVELOPMENT. 
   HOWEVER...STEEP LOW LEVEL LAPSE RATES ARE SPREADING/DEVELOPING
   ACROSS NWRN TX INTO SWRN OK AND WITH TEMPERATURES NOW INTO THE MID
   80S MINIMAL INHIBITION IS NOTED ACROSS THIS REGION.  THUNDERSTORMS
   SHOULD EVOLVE/MATURE ACROSS THIS PORTION OF THE MDT RISK OVER THE
   NEXT SEVERAL HOURS.

   ...ELSEWHERE...

   NUMEROUS TSTMS HAVE EVOLVED ACROSS IA INTO SERN MN IN ASSOCIATION
   WITH WEAK SHORT-WAVE TROUGH.  THIS ACTIVITY IS COINCIDENT WITH LLJ
   THAT IS EXPECTED TO REMAIN FOCUSED ACROSS THE ERN PLAINS INTO NWRN
   IA.  RENEWED CONVECTION MAY BE NOTED WITHIN THIS
   CORRIDOR...ESPECIALLY LATER TONIGHT AS LLJ STRENGTHENS.

   OTHER STRONG STORMS ARE SLOWLY EVOLVING ALONG SRN FRINGE OF
   SHORT-WAVE TROUGH ACROSS UPSTATE NY.  DEEP WLY FLOW SHOULD ALLOW
   THIS ACTIVITY TO PROPAGATE TOWARD THE HUDSON VALLEY OVER THE NEXT
   FEW HOURS.

   ..DARROW.. 05/29/2013

   .PREV DISCUSSION... /ISSUED 1123 AM CDT WED MAY 29 2013/

   ...SYNOPSIS...

   STRONG MID AND UPPER-LEVEL JET STREAKS FROM THE NERN PACIFIC INTO
   SRN ROCKIES WILL DEVELOP EWD/SEWD THROUGH THE BASE OF AND EVENTUALLY
   DOWNSTREAM FROM A NEGATIVELY TILTED LONG-WAVE TROUGH EXTENDING FROM
   THE PACIFIC NW INTO CNTRL/SRN PLAINS.  MORNING WATER VAPOR IMAGERY
   SHOWS SEVERAL VORTICITY MAXIMA EMBEDDED WITHIN THIS LARGE-SCALE
   PATTERN...ONE OVER THE SRN HIGH PLAINS WHICH WILL SHIFT INTO LOWER
   ELEVATIONS OF THE CNTRL/SRN PLAINS TODAY...AND ANOTHER MORE COMPACT
   SYSTEM OVER THE CNTRL ROCKIES WHICH WILL EVOLVE INTO A CLOSED
   CIRCULATION WHILE ADVANCING NEWD INTO THE DAKOTAS AND NEB. AN MCV
   OVER CNTRL KS WILL MOVE NNEWD INTO THE MID-MO VALLEY AHEAD OF THESE
   TWO FORMER FEATURES.  ELSEWHERE...A MIGRATORY SHORT-WAVE TROUGH OVER
   THE GREAT LAKES WILL TRANSLATE EWD THROUGH QUEBEC AND NEW ENGLAND
   TODAY INTO TONIGHT.

   IN THE LOW LEVELS...A LEE CYCLONE INITIALLY OVER THE CNTRL HIGH
   PLAINS WILL CALVE A LOW CENTER THAT WILL DEVELOP NWD THROUGH WRN NEB
   TODAY BEFORE OCCLUDING OVER NWRN SD TONIGHT.  MEANWHILE...THE
   RESIDUAL LEE LOW WILL SLOWLY DEVELOP SEWD INTO NWRN OK BY 30/12Z. 
   AN ASSOCIATED DRYLINE WILL MIX EWD ACROSS THE HIGH PLAINS TODAY
   BEFORE BEING OVERTAKEN BY A PACIFIC FRONT TONIGHT.  OVER THE LOWER
   GREAT LAKES INTO NEW ENGLAND...A WARM FRONT WILL ADVANCE EWD ACROSS
   THE REGION.  

   ...CNTRL/SRN PLAINS TODAY AND TONIGHT...

   A CLUSTER OF ELEVATED TSTMS HAVE DEVELOPED THIS MORNING ACROSS PARTS
   OF NEB/IA/KS AHEAD OF AN MCV LIFTING NEWD THROUGH CNTRL KS.  THE 12Z
   TOP/OAX SOUNDINGS SHOWED THE PRESENCE OF AN ALREADY MODERATELY
   UNSTABLE ENVIRONMENT FOR PARCELS BASED AROUND 850 MB AND LARGE HAIL
   WILL BE POSSIBLE WITH THIS ACTIVITY AS IT PROGRESSES THROUGH THE
   MID-MO VALLEY TODAY.  OTHERWISE...12Z REGIONAL SOUNDINGS INDICATE
   THE POTENTIAL FOR STRONG AIR MASS DESTABILIZATION TODAY OWING TO
   8.0-9.0+ C/KM 700-500-MB LAPSE RATES ATOP A MOIST BOUNDARY LAYER
   WITH LOWEST-100-MB MEAN MIXING RATIOS OF GENERALLY 13.5-14.5 G/KG.

   THE ONGOING STORMS OVER THE CNTRL PLAINS/MID-MO VALLEY AND APPARENT
   EARLY EMERGENCE OF THE LOWER LATITUDE IMPULSE INTO THE SRN PLAINS
   CAST UNCERTAINTY ON SPECIFIC DETAILS REGARDING SURFACE-BASED STORM
   EVOLUTION TODAY.  IT DOES APPEAR THAT THE PRIMARY FOCUS FOR TSTM
   DEVELOPMENT WILL BE THE DRYLINE BY EARLY TO MID AFTERNOON FROM SWRN
   NEB SWD THROUGH FAR SWRN KS INTO THE CNTRL OR ERN TX PNDHL.  THE
   COMBINATION OF MODERATE TO STRONG INSTABILITY AND MODERATELY STRONG
   DEEP-LAYER SHEAR WILL SUPPORT SUPERCELLS AS THE INITIAL STORM MODE. 
   LARGE HAIL AND TORNADOES WILL BE THE PRIMARY HAZARDS WITHIN THE
   FIRST FEW HOURS OF INITIATION.  WHILE A FEW STRONG TORNADOES APPEAR
   POSSIBLE...THE TENDENCY FOR VEER-BACK SIGNATURES IN FORECAST
   HODOGRAPHS MAY RESULT IN AN EVENTUAL TRANSITION TO MIXED STORM MODES
   /I.E. SUPERCELLS EMBEDDED IN LINE SEGMENTS/ WHICH IS SUGGESTED BY
   SOME RECENT CONVECTION-ALLOWING MODEL GUIDANCE.

   THERE IS ALSO SOME SUGGESTION BY LATEST MODEL GUIDANCE THAT A SECOND
   BAND OF TSTMS DEVELOPS THIS AFTERNOON E OF THE DRYLINE FROM CNTRL KS
   SWD INTO N-CNTRL TX.  UNCERTAINTY IN THIS SCENARIO REMAINS
   HIGH...BUT SHOULD IT UNFOLD...ENVIRONMENTAL CONDITIONS WILL BE
   SUPPORTIVE OF EMBEDDED SUPERCELL STRUCTURES WITH A RISK FOR A FEW
   TORNADOES...LARGE HAIL...AND DAMAGING WINDS.  

   UPSCALE GROWTH OF STORMS INTO ONE OR MULTIPLE MCS/S IS ANTICIPATED
   TONIGHT WITH A HAIL/DAMAGING WIND THREAT SPREADING EWD ACROSS LOWER
   ELEVATIONS OF THE GREAT PLAINS.

   ...NRN PLAINS INTO THE UPPER MIDWEST TODAY INTO TONIGHT...

   EPISODES OF ELEVATED TSTMS /CAPABLE OF SEVERE HAIL/ WILL BE POSSIBLE
   TODAY ACROSS PARTS OF ERN SD AND MN IN CONJUNCTION WITH A COUPLE OF
   MCV/S LIFTING NNEWD.  FARTHER W...SURFACE-BASED TSTM DEVELOPMENT IS
   ANTICIPATED THIS AFTERNOON ALONG A LEE/INVERTED TROUGH OVER THE NRN
   HIGH PLAINS...ALONG AND AHEAD OF THE SURFACE LOW DEVELOPING NWD. 
   SOME STORM ORGANIZATION IS POSSIBLE GIVEN AT LEAST MODEST AMOUNTS OF
   INSTABILITY AND VERTICAL SHEAR WITH HAIL AND DAMAGING WINDS
   POSSIBLE.  

   ...LOWER GREAT LAKES INTO NEW ENGLAND THIS AFTERNOON AND EVENING...

   DECREASING CLOUDS COUPLED WITH INCREASING BOUNDARY LAYER MOISTURE IN
   THE WAKE WARM FRONTAL PASSAGE WILL CONTRIBUTE TO RAPID AIR MASS
   DESTABILIZATION TODAY ACROSS THE REGION.  FORCING FOR ASCENT
   ATTENDANT TO THE SHORT-WAVE TROUGH MENTIONED IN THE SYNOPSIS WILL
   FOSTER WIDELY SCATTERED TSTMS BY AFTERNOON FROM SWRN ONTARIO TO THE
   LEE OF THE LOWER GREAT LAKES.  THIS ACTIVITY WILL RAPIDLY SPREAD EWD
   THROUGH THE HUDSON VALLEY LATER THIS AFTERNOON WITHIN A STRONG...WLY
   WIND FIELD.  A MIXTURE OF SUPERCELLS AND BOWING STRUCTURES APPEAR
   POSSIBLE WITH A RISK FOR DAMAGING WINDS...LARGE HAIL...AND PERHAPS A
   COUPLE OF TORNADOES.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z