Another PDS Saturday - Strong Theta-E advecting from GOM
Posted by JAC on 5/1/2010, 10:33 am





ZCZC SPCPWOSPC ALL
  WOUS40 KWNS 010915
  ARZ000-ILZ000-INZ000-MOZ000-MSZ000-TNZ000-011800-
 
  PUBLIC SEVERE WEATHER OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  0415 AM CDT SAT MAY 01 2010
 
  ...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER
  MISSISSIPPI...LOWER TENNESSEE...AND LOWER OHIO VALLEYS THIS
  AFTERNOON AND TONIGHT...
 
  THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
  DEVELOPMENT OF A FEW STRONG TORNADOES...DAMAGING WIND...AND HAIL
  OVER PARTS OF THE LOWER MISSISSIPPI...THE LOWER TENNESSEE...AND THE
  LOWER OHIO VALLEYS THIS AFTERNOON AND TONIGHT.
 
  THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE
 
         CENTRAL AND EASTERN ARKANSAS
         SOUTHERN ILLINOIS
         SOUTHERN INDIANA
         SOUTHEAST MISSOURI
         NORTHERN MISSISSIPPI
         WESTERN AND MIDDLE TENNESSEE
 
  ELSEWHERE...SEVERE STORMS ARE ALSO POSSIBLE SURROUNDING THE MODERATE
  RISK AREA FROM EAST TEXAS AND PARTS OF THE OZARKS INTO THE UPPER
  OHIO VALLEY
 
  A STRONG LOW-LEVEL FLOW OF VERY MOIST AIR WILL CONVERGE OVER PARTS
  OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS TODAY...BENEATH A
  BELT OF VERY FAST...HIGH-ALTITUDE JET STREAM WINDS.
 
  THE APPROACH OF A DISTURBANCE IN THE JET STREAM...AND DAYTIME
  HEATING...WILL SUPPORT THE DEVELOPMENT OF LONG-LIVED...SUPERCELL
  THUNDERSTORMS ALONG A STALLED FRONT OVER PARTS OF
  ARKANSAS...MISSISSIPPI...AND TENNESSEE TODAY.  THESE STORMS WILL
  PERSIST OVER THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS INTO
  TONIGHT...AND ALSO SPREAD NORTHEAST INTO PARTS OF THE OHIO
  VALLEY...AS THE JET STREAM DISTURBANCE CONTINUES NORTHEASTWARD.
 
  STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS DEVELOPING
  SITUATION.  THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE
  WEATHER SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA
  WEATHER RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS
  THROUGH TONIGHT.






DAY 1 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  0756 AM CDT SAT MAY 01 2010
 
  VALID 011300Z - 021200Z
 
  ...THERE IS A HIGH RISK OF SVR TSTMS OVER PARTS OF AR...MS...TN AND
  THE MO BOOTHEEL...
 
  ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK AREA
  OVER PARTS OF THE LWR MS...LWR TN AND LWR OH VLYS...
 
  ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ABOVE AREAS
  FROM E TX NEWD INTO THE UPR OH VLY...
 
  ...SYNOPSIS...
  HIGH AMPLITUDE CNTRL STATES TROUGH WILL MOVE ONLY SLOWLY E THIS
  PERIOD AS ASSOCIATED NRN PLAINS UPR LOW REMAINS QSTNRY AND ATTENDANT
  SHORTWAVE TROUGH NOW ENTERING CHIHUAHUA SHEARS ENE ACROSS W
  TX...OK...AND...BY SUN MORNING...KS/MO.  MID/UPR LVL
  SPEED MAX WITH THE CHIHUAHUA SYSTEM WILL REDEVELOP NE INTO N TX/OK
  BY THIS EVE...AND FURTHER EXPAND NE ACROSS MID MS VLY/UPR GRT LKS
  EARLY SUN.
 
  AT THE SFC...MAIN FRONTAL ZONE WILL REMAIN NEARLY STNRY FROM LWR MI
  TO E TX TODAY...WITH COMPOSITE OUTFLOW BOUNDARY LEFT BY OVERNIGHT
  STORMS LIKELY TO LIFT SLOWLY N ACROSS AR AND THE LWR TN VLY.  A WAVE
  SHOULD FORM OVER NE TX OR THE ARKLATEX LATER TODAY...NEAR
  INTERSECTION OF OUTFLOW BOUNDARY WITH FRONT.  THE WAVE SHOULD TRACK
  NNE INTO THE LWR OH VLY TONIGHT/EARLY SUN.
 
  ...E TX/LWR MS VLY INTO THE LWR TN/LWR OH VLYS THROUGH TONIGHT...
  WSW-ENE ORIENTED QLCS OVER THE LWR MS AND TN VLYS MAY FURTHER WEAKEN
  LATER THIS MORNING AS WEAK HEIGHT RISES OVERSPREAD REGION AND SFC
  TEMPERATURES REACH DIURNAL MINIMUMS.  SFC HEATING AND CONTINUED
  INFLOW OF VERY MOIST AIR SHOULD...HOWEVER...SUPPORT REDEVELOPMENT OF
  SOME STORMS IN WHAT IS LEFT OF THE MCS BY EARLY AFTN...WITH
  ADDITIONAL DEVELOPMENT POSSIBLE TO ITS S OVER SRN/CNTRL AR AND NRN
  MS.  OTHER STORMS MAY FORM LATER THIS MORNING AND THIS AFTN OVER NE
  TX AND SE OK...AS ISENTROPIC ASCENT DOWNSTREAM FROM CHIHUAHUA UPR
  IMPULSE INCREASES ATOP SHALLOW FRONT.
 
  COMBINATION OF DAYTIME HEATING AND RICH MOISTURE /PW 1.50-1.75
  INCHES WITH SFC DEWPOINTS IN THE LOW 70S/ SHOULD ALLOW FOR
  SUBSTANTIAL LOW LVL DESTABILIZATION ALONG AND S OF MCS OUTFLOW
  BOUNDARY AND E OF FRONT...WITH SBCAPE EXPECTED TO BE AOA 2000 J/KG
  WITH MINIMAL CINH.  COUPLED WITH STRONGLY-SHEARED LOW TO MID LVL
  WIND FIELD...SETUP COULD SUPPORT SCTD SUSTAINED SUPERCELLS WITH
  TORNADOES/SVR HAIL.
 
  AS THE CHIHUAHUA SYSTEM AND ASSOCIATED MID/UPR LVL SPEED MAX /WITH
  250 MB FLOW AROUND 150 KTS/ CONTINUE NEWD LATER THIS AFTN AND
  TONIGHT...DOWNSTREAM SLY LLJ SHOULD MARKEDLY INCREASE OVER THE LWR
  MS AN TN VLYS.  THIS SHOULD SUPPORT ENHANCEMENT OF EXISTING
  STORMS...AS WELL AS ADDITIONAL DEVELOPMENT...FROM THE ARKLATEX
  E/NEWD INTO THE LWR TN AND LWR OH VLYS THROUGH THE
  EVENING/OVERNIGHT.
 
  60 KT DEEP SWLY SHEAR AND DEEPLY-MOIST ENVIRONMENT WITH NEARLY
  UNIDIRECTIONAL MID/UPR LVL FLOW WILL BE FAVORABLE FOR SUPERCELL ECHO
  TRAINING/LEWPS AS SFC WAVE TRACKS NE TOWARD THE OH VLY.  THE SETUP
  ULTIMATELY MAY SUPPORT MULTIPLE CORRIDORS HAVING A POTENTIAL FOR
  STRONG TORNADOES FROM MUCH OF AR AND NRN MS NEWD INTO WRN/CNTRL
  TN...WRN/CNTRL KY AND PERHAPS SRN IL/SRN INDIANA TONIGHT/EARLY SUN.
 
  ...MIDDLE/UPR OH VLY...
  ERN END OF AFOREMENTIONED QLCS SHOULD CONTINUE E ACROSS ERN KY AND
  CNTRL/ERN OH THROUGH LATER THIS MORNING.  DIURNAL DESTABILIZATION
  AND MODEST LOW LVL MOISTURE INFLOW MAY SUPPORT A MODEST SVR THREAT
  /DMGG WINDS OR AN ISOLD TORNADO/ THROUGH EARLY EVE.  ADDITIONAL
  STRONG TO SVR ACTIVITY MAY AFFECT THE REGION LATE IN THE PERIOD
  /AFTER 06Z SUN/ AS SFC WAVE MOVES NE TOWARD THE LWR OH VLY AND
  ASSOCIATED LLJ STRENGTHENS OVER ERN KY/OH.
 


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Another PDS Saturday - Strong Theta-E advecting from GOM - JAC, 5/1/2010, 10:33 am
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