Looks like today is the big day before the shortwave deamplifies
Posted by JAC on 6/7/2009, 10:12 am


SPC AC 071230
 
  DAY 1 CONVECTIVE OUTLOOK 
  NWS STORM PREDICTION CENTER NORMAN OK
  0730 AM CDT SUN JUN 07 2009
 
  VALID 071300Z - 081200Z
 
  ...THERE IS A MDT RISK OF SVR TSTMS OVER PORTIONS OF NERN KS/SERN
  NEB/SWRN IA/NWRN MO...
 
  ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH PLAINS
  INTO THE MID MS RIVER VALLEY...
 
  ...CENTRAL PLAINS ACROSS THE MID MS RIVER VALLEY...
  WV IMAGERY INDICATES MID/UPPER LEVEL VORT CENTER EJECTING NEWD
  ACROSS THE 4-CORNERS REGION THIS MORNING.  50-60 KT SWLY MID LEVEL
  JET ATTENDANT TO THIS SYSTEM WILL OVERSPREAD THE CENTRAL PLAINS
  THROUGH THE AFTERNOON AS IMPULSE EJECTS ACROSS THE CENTRAL ROCKIES.
  INCREASING DEEP ASCENT...STRENGTHENING SHEAR AND PERSISTENT BOUNDARY
  LAYER MOISTENING ACROSS THE SRN PLAINS UNDER IMPRESSIVE EML /AS
  EVIDENCED ON 12Z SOUNDINGS/ SHOULD LEAD TO A REGIONAL OUTBREAK OF
  SEVERE THUNDERSTORMS LATE TODAY THROUGH TONIGHT.
 
  SURFACE FRONT NOW EXTENDING FROM SRN WI/NERN IA SWWD INTO SWRN KS
  WILL LIKELY STALL TODAY...WITH TRIPLE POINT LOW DEEPENING OVER SWRN
  KS AHEAD OF APPROACHING SYSTEM.  IN ADDITION....OUTFLOW BOUNDARY
  FROM SATURDAY NIGHT/S MCS SHOULD PERSIST OVER NERN KS/SERN NEB AND
  THE IA/MO BORDER REGION THROUGH THE AFTERNOON.  COLD FRONT WILL
  LIKELY SURGE SWD ACROSS THE CENTRAL HIGH PLAINS LATER THIS
  EVENING/OVERNIGHT BEHIND MAIN LOW CENTER WHICH WILL EJECT NEWD INTO
  CENTRAL IA ATTENDANT TO UPPER SYSTEM BY THE END OF THE PERIOD.
 
  CAPPING WILL LIKELY KEEP WARM SECTOR RELATIVELY VOID OF DEEP MOIST
  CONVECTION FOR MUCH OF THE DAY.  HOWEVER...STRONG HEATING AND
  INCREASING ASCENT SHOULD SUPPORT RAPID DEVELOPMENT OF SEVERE
  THUNDERSTORMS LATE IN THE DAY/THIS EVENING NEAR THE FRONT ONCE CAP
  BREAKS.  VERY STEEP LAPSE RATES AND PRESENCE OF STRONG INSTABILITY
  SHOULD FOSTER DEVELOPMENT OF VERY LARGE HAIL AS STORMS MATURE INTO
  SUPERCELLS QUICKLY GIVEN 40-50 KT EFFECTIVE SHEAR.  INCREASED SELY
  LOW LEVEL FLOW THROUGH THE EVENING /INVOF 35-45 KT LLJ/ WILL ALSO
  FAVOR LARGE LOW LEVEL HODOGRAPHS AND THE POTENTIAL FOR TORNADOES.
  SEVERE THREAT WILL SPREAD ACROSS ERN KS/ERN NEB INTO IA/NRN MO
  DURING THE LATE EVENING...IMMEDIATELY AHEAD OF SFC LOW.  ONE OR MORE
  COMPLEXES /INCLUDING POSSIBILITY OF DAMAGING BOW ECHOES/ SHOULD
  EVOLVE INTO THE MID MS VALLEY DURING THE OVERNIGHT HOURS INVOF
  WSW-ENE ORIENTED SURFACE FRONT.  LARGE HAIL AND DAMAGING WINDS WILL
  BECOME THE PRIMARY SEVERE THREATS AS MCS/S MATURE.
 
  ...CENTRAL HIGH PLAINS...
  APPEARS SURFACE FRONT WILL STALL ALONG THE FRONT RANGE AND SUSTAIN
  UPSLOPE FLOW INTO NERN CO AS SURFACE LOW NEAR N-CENTRAL CO ALLOWS
  FLOW TO BECOME MORE SELY.  INFLUX OF MID 50S F SURFACE DEW
  POINTS...STEEP LAPSE RATES AND STRENGTHENING VERTICAL MOTION AHEAD
  OF APPROACHING SHORTWAVE TROUGH SHOULD SUPPORT SECOND AREA OF
  SUPERCELLS INTO THIS REGION LATER TODAY.  HODOGRAPHS ARE FORECAST TO
  BE A BIT MORE STRAIGHT OVER THIS AREA AND SHOULD SUPPORT SPLITTING
  STORMS...WITH POTENTIAL FOR VERY LARGE HAIL AND ISOLATED TORNADOES.
  THIS ACTIVITY WILL LIKELY EVOLVE AS A STRONG TO SEVERE MCS AND TRACK
  NEWD JUST BEHIND SURFACE COLD FRONT INTO ERN NEB OVERNIGHT.
 
  ...SRN HIGH PLAINS...
  ISOLATED-SCATTERED THUNDERSTORMS WILL ONCE AGAIN DEVELOP ALONG
  DRYLINE ACROSS WEST TX AS TEMPERATURES RISE INTO THE UPPER 90S TO
  NEAR 100F.  HIGH BASED CONVECTION MAY PRODUCE A FEW SEVERE WIND
  GUSTS OR LARGE HAIL BEFORE DIMINISHING DURING THE MID TO LATE
  EVENING.
 
  ...FL...
  A FEW STRONG STORMS MAY ALSO DEVELOP ALONG THE EAST COAST OF SOUTH
  FL.  FORECAST SOUNDINGS SUGGEST SUFFICIENT CAPE FOR ROBUST UPDRAFTS
  WITHIN MARGINAL SHEARED ENVIRONMENT.  ISOLATED LARGE HAIL OR
  MICROBURSTS ARE THE THREATS WITH THIS DIURNAL ACTIVITY.
 
  ..EVANS/HURLBUT.. 06/07/2009
14
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Possible Severe Weather for IL Monday - JAC, 6/5/2009, 1:48 pm
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