Strong Tornado Risk for Nebraska Sunday
Posted by JAC on 6/18/2011, 3:42 pm






DAY 2 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  1231 PM CDT SAT JUN 18 2011
 
  VALID 191200Z - 201200Z
 
  ...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF NEBRASKA...
 
  ...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN/HIGH PLAINS SEWD
  ACROSS TO THE CAROLINAS...
 
  ...SYNOPSIS...
  A FAIRLY DEEP MID JUNE UPPER TROUGH IS FORECAST TO TRANSLATE EWD
  FROM THE GREAT BASIN ACROSS THE INTERMOUNTAIN REGION AND INTO THE
  PLAINS STATES BY EARLY MONDAY. AHEAD OF THIS TROUGH...SHORTWAVE
  RIDGING WILL OCCUR OVER THE MS VALLEY REGION. HOWEVER...40-50 KT MID
  LEVEL WINDS WILL ALSO EXIST EAST OF THIS TROUGH AND EXTEND FROM THE
  CENTRAL/SRN PLAINS NEWD INTO THE MID MS VALLEY...AND THEN SEWD INTO
  THE CAROLINAS. WITH THE MOIST BOUNDARY LAYER COINCIDENT WITH AN
  ELEVATED MIXED LAYER...EXPECT SUNDAY TO BE AN ACTIVE SEVERE WEATHER
  DAY ACROSS A LARGE PORTION OF THE CONUS EAST OF THE ROCKIES.
 
  ...NRN/CENTRAL PLAINS...
  MODELS ARE CONSISTENT IN EJECTING A PRONOUNCED SHORTWAVE TROUGH AND
  ACCOMPANYING MID/HIGH LEVEL SPEED MAX INTO THE HIGH PLAINS DURING
  THE AFTERNOON...WITH 12 HOUR HEIGHT FALLS OF 30-60M.
  WITHIN EXIT REGION OF UPPER JET...SURFACE LOW IS FORECAST TO FORM
  AND DEEPEN NEAR THE KS/CO BORDER DURING THE DAY. AS THIS HAPPENS
  ...FRONT CURRENTLY LOCATED OVER PORTIONS OK/TX...WILL MOVE NWD AND
  SHARPEN E-W ACROSS NRN KS AND INTO NRN MO AS A WARM FRONT. THE
  COMBINATION OF SUSTAINED UPSLOPE FLOW...NORTH OF I-70 FROM NERN CO
  INTO MT...AND APPROACHING UPPER IMPULSE SHOULD RESULT IN STORMS
  FORMING ACROSS THE CENTRAL/NRN PLAINS MID/LATE AFTERNOON. STRONG
  INSTABILITY PLUS STRONGLY VEERING WIND PROFILES WILL BE FAVORABLE
  FOR SUPERCELLS. VERY LARGE HAIL WILL BE THE PRIMARY THREAT...THOUGH
  THE MOIST BOUNDARY LAYER NORTH OF THE FRONT AND STRONG LOW LEVEL
  VEERING WIND PROFILES WILL BE FAVORABLE FOR TORNADOES...ESPECIALLY
  IN NEB AND EARLY ON WHEN STORMS ARE MORE DISCRETE. DURING THE
  EVENING...LOW LEVEL JET INCREASES TO 70 KT AND STORM OUTFLOWS ARE
  EXPECTED TO EVOLVE INTO AN INTENSE EWD MOVING LINEAR
  MCS...ESPECIALLY ACROSS CENTRAL/ERN NEB. THE MODELS INDICATE THESE
  STORMS WILL MOVE NEWD WITHIN THE MEAN FLOW... THOUGH THE VEERING LOW
  LEVEL JET SUGGESTS THE MCS/WIND THREAT SHOULD SPREAD MORE EWD INTO
  PORTIONS OF NRN MO/IA OVERNIGHT. A SECONDARY LOW LEVEL JET MAY ALSO
  RESULT IN STORMS TO DEVELOP OVERNIGHT ACROSS PORTIONS OF MO/IL...
  WITH SEVERE HAIL AND WIND DAMAGE POSSIBLE WITH THESE STORMS ALSO.
 
  ...TN/LOWER OH VALLEY SEWD INTO CAROLINAS...
  MODELS HAVE A STRONG SIGNAL THAT AN OVERNIGHT MCS LIKELY WILL BE
  ONGOING SOMEWHERE IN THE SERN MO/WRN KY/WRN TN AREA AT DAYBREAK
  SUNDAY. GIVEN THE RIDGING TO THE WEST...THE FLOW ALOFT WILL BE WNWLY
  AND REMNANT STORMS ARE LIKELY TO TRACK ESEWD/SEWD THROUGH THE DAY.
  WITH HEATING...VERY UNSTABLE AIR MASS AND DEEP WNWLY FLOW THROUGHOUT
  MUCH OF THE TROPOSPHERE WOULD FAVOR THIS MCS INTENSIFYING...WITH A
  THREAT OF PRIMARILY WIND DAMAGE UNTIL IT MOVES OFFSHORE.
  ELSEWHERE...WITH HEATING...OTHER STORMS MAY DEVELOP ON MORNING
  OUTFLOW BOUNDARIES...WITH SHEAR AND INSTABILITY SUPPORTIVE OF
  ORGANIZED THUNDERSTORM CLUSTERS AND PERHAPS A FEW SUPERCELLS
  STRUCTURES. THESES STORMS WOULD PRODUCE MAINLY HAIL AND WIND DAMAGE.
 
 
  ...KS SWD INTO NWRN TX...
  FARTHER SOUTH ALONG THE DRYLINE...VERY HOT SFC TEMPERATURES WILL
  ONCE AGAIN BE NOTED FROM SOUTH CENTRAL KS...SWD INTO NWRN TX WHERE
  TEMPERATURES WILL SOAR UP TO 110F IN SOME AREAS. THE SRN PORTION OF
  AN UPPER TROUGH MOVING INTO THE CENTRAL PLAINS MAY BRUSH THE DRYLINE
  LATE AFTERNOON AND AID IN STORMS DEVELOPING. ALTHOUGH 700 MB
  TEMPERATURES WILL BE IN THE 14-16C RANGE...THE WEAK FORCING AND
  EXTREME HEATING MAY BE SUFFICIENT FOR THE BOUNDARY LAYER MIXED TO
  500-600 MB TO BE LIFTED INTO HIGH BASED STORMS. ALTHOUGH STORMS
  WOULD BE VERY SPARSE IN COVERAGE...PW VALUES ABOVE 1 INCH AND 50 DEG
  SFC TEMP/DEW POINT SPREADS INDICATE THAT ANY STORMS WOULD BE CAPABLE
  OF LOCAL SEVERE DOWNBURSTS.
 
  ..IMY.. 06/18/2011
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Strong Tornado Risk for Nebraska Sunday - JAC, 6/18/2011, 3:42 pm
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