A rough afternoon for N LA Tuesday
Posted by JAC on 3/7/2011, 6:10 am
Looks like they will be getting the worst of the front coming thru.

A shortwave with a slight negative tilt and 70 knot jet.

Possible F1 / F2 tornadoes due to afternoon heating and moderate theta-e feed from the GOM.

Not a big outbreak with this system.

Actually, I am suprised we are not seeing a stronger theta-e feed as the system digs thru the Mid-west.






SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
321 AM EST MON MAR 07 2011

VALID 12Z MON MAR 07 2011 - 12Z WED MAR 09 2011

ON TUESDAY ... AS THE STORM EMERGES ONTO THE PLAINS ... MOISTURE
FROM THE GULF OF MEXICO WILL STREAM NORTHWARD OVER THE PLAINS
PRODUCING SHOWERS AND THUNDERSTORM OVER PARTS OF THE SOUTHERN
PLAINS MOVING INTO THE LOWER/MIDDLE MISSISSIPPI VALLEY BY TUESDAY
EVENING.  THE STORM PREDICTION CENTER HAS ISSUED A SLIGHT RISK OF
SEVERE WEATHER ASSOCIATED WITH THESE THUNDERSTORM.  RAIN WILL
DEVELOP OVER PARTS OF THE CENTRAL PLAINS BY TUESDAY MORNING ...
MOVING INTO THE LOWER/MIDDLE MISSOURI VALLEY BY TUESDAY EVENING.
LIGHT SNOW WILL DEVELOP OVER OTHER PORTIONS OF THE
CENTRAL/NORTHERN PLAINS.    

ZIEGENFELDER





 DAY 2 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  1222 AM CST MON MAR 07 2011
 
  VALID 081200Z - 091200Z
 
  ...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN PARTS OF THE SRN
  PLAINS/OZARKS TO THE MID-SOUTH/LOWER MS VALLEY...
 
  ...SYNOPSIS...
  MID-LEVEL WAVE CURRENTLY MOVING INTO THE WRN GREAT BASIN WILL
  AMPLIFY MONDAY NIGHT IN THE SRN ROCKIES AS ADDITIONAL JET ENERGY
  DROPS SEWD FROM THE GULF OF AK.  THE RESULT WILL BE A STRONG UPPER
  WAVE THAT WILL TURN ENE INTO THE SRN PLAINS TUESDAY AFTERNOON AND
  THE MIDWEST/MID-SOUTH BY EARLY WEDNESDAY.  PRIMARY SFC LOW WILL
  TRACK FROM CNTRL OK AT 12Z TUESDAY TO NERN MO/WCNTRL IL BY 12Z
  WEDNESDAY.
 
  ...ERN PARTS OF SRN PLAINS TO THE LOWER/MID MS VALLEY...
  STRONG RETURN FLOW AHEAD OF THE APPROACHING UPPER WAVE WILL LIKELY
  DRIVE A CONSIDERABLE AMOUNT OF ELEVATED CONVECTION/CLOUDS THROUGH A
  GOOD PART OF DAYLIGHT TUESDAY ACROSS THE OZARKS SWD INTO THE WRN
  GULF COAST REGION.  WHILE HAIL CANNOT BE RULED OUT WITH THIS
  ACTIVITY...PRIMARY SEVERE EVENT SHOULD EVOLVE LATE AFTERNOON/NIGHT.
 
  INCREASING SSWLY LOW-LEVEL FLOW WILL TRANSPORT LOWER-MID 50S DEW
  POINTS AS FAR N AS CNTRL/ERN OK AND SRN MO BY LATE TUESDAY AFTERNOON
  AND LOWER-MID 60S ACROSS CNTRL/SRN AR SWD TO THE GULF COAST.
  RETURNING MOISTURE WILL BE CAPPED BY A STOUT ELEVATED MIXED LAYER
  THROUGH AT LEAST MID-AFTERNOON.
 
  FIRST AREA OF ATTENTION WILL FOCUS ON GRADUAL DEVELOPMENT OF
  SURFACE-BASED STORMS ALONG THE DRYLINE CIRCULATION LATE TUESDAY
  AFTERNOON.  HERE...MODEST DIABATIC HEATING AND COOLING/MOISTENING OF
  THE MID-LEVELS OWING TO THE APPROACH OF THE UPPER SYSTEM WILL
  CONTRIBUTE TO WEAKENING CINH AND MLCAPES APPROACHING 1000 J/KG.
  INITIAL CELLS WILL BE EMBEDDED IN 55-65 KTS OF EFFECTIVE VERTICAL
  SHEAR AND VERY STEEP LAPSE RATES...SUFFICIENT FOR EVENTUAL
  SUPERCELLS WITH VERY LARGE HAIL AND POSSIBLY A TORNADO OR TWO.
 
  GIVEN ORIENTATION OF THE DEEP LAYER SHEAR VECTORS LARGELY
  PERPENDICULAR TO THE DRYLINE AND INCREASING LINEAR FORCING SHOULD
  YIELD QUICK TRANSITION INTO A QLCS.  THIS FEATURE WILL ACCELERATE
  ENE INTO THE MO/AR OZARKS WITH POSSIBLE DAMAGING WINDS/HAIL.
  INSTABILITY WILL DROP OFF QUICKLY THROUGH THE MO OZARKS AND MID-MS
  VALLEY SUGGESTING A PRECIPITOUS DECREASE IN THE SVR THREATS THAT FAR
  N.
 
  MEANWHILE...SRN EDGE OF THE QLCS WILL LIKELY THRIVE THROUGH THE
  EVENING AS IT DEVELOPS FROM SE OK/NE TX INTO CNTRL/SRN AR AND NRN
  LA.  CONCERN HERE IS THAT THE SLY LOW-LEVEL FLOW ACCELERATES TO OVER
  45 KTS...EFFECTIVELY RESULTING IN LARGE-CYCLONIC LOOPED HODOGRAPHS.
  THE BOUNDARY LAYER SHOULD CONTINUE TO MOISTEN/DESTABILIZE AFTER DARK
  WITH THE WARM FRONT JUMPING INTO PARTS OF CNTRL/SRN AR.  BOTH BOW
  AND EMBEDDED SUPERCELL MODES WILL BE POSSIBLE WITH THREAT FOR
  TORNADOES /ISOLATED STRONG/ ALONG WITH CORRIDORS OF DAMAGING WINDS
  AND HAIL. THE ACTIVITY WILL REACH THE MID-SOUTH BY 12Z
  WEDNESDAY...ALTHOUGH PROBABLY NOT AS FAR E AS THE 00Z GFS SUGGESTS.
 
  FINALLY...ANOTHER AREA OF FOCUS WILL BE ACROSS THE LOWER MS VALLEY
  ALONG THE RETREATING WARM FRONT TUESDAY NIGHT AS MODEST 500 MB
  HEIGHT FALLS GRAZE THE REGION.  ALTHOUGH STRONGEST LOW-LEVEL JET
  WILL AIM/DEVELOP N OF THE REGION...AT LEAST 35-40 KTS OF SLY CURRENT
  AMIDST MID-60S DEW POINTS WILL BE FAVORABLE FOR DEEPENING MOIST
  CONVECTION.  THIS ACTIVITY MAY ALSO JOIN SRN FRINGES OF THE
  AFOREMENTIONED AR STORMS OVERNIGHT.  LOW-LEVEL TURNING ALONG THE
  WARM FRONT WILL BE ESPECIALLY FAVORABLE FOR SUSTAINED STORMS WITH
  ATTENDANT TORNADO THREATS.
 
  ..RACY.. 03/07/2011








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A rough afternoon for N LA Tuesday - JAC, 3/7/2011, 6:10 am
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