Convective Outlooks

Day 1 (Today)

...SRN PLAINS/WRN OZARKS...
   MOISTENING OF THE AIRMASS ACROSS THE SRN PLAINS WILL CONTINUE TODAY
   AS THE SRN END OF A WELL-DEFINED LOW-LEVEL JET MOVES EWD ACROSS THE
   REGION. MODERATE INSTABILITY IS FORECAST BY MID TO LATE AFTERNOON
   FROM CNTRL AND NORTH TX EXTENDING NWD INTO CNTRL AND ERN OK WHERE
   FORECAST SOUNDINGS SHOW MLCAPE VALUES AROUND 2500 J/KG. IN SPITE OF
   THE INSTABILITY...A CAPPING INVERSION WILL LIKELY REMAIN IN PLACE
   FOR MUCH OF THE AFTERNOON AND EVENING SUPPRESSING CONVECTIVE
   DEVELOPMENT. SEVERAL MODEL FORECASTS INITIATE STORMS IN NE OK AND NW
   AR DURING THE LATE EVENING WITH STORMS EXPANDING SWWD ALONG A COLD
   FRONT DURING THE OVERNIGHT PERIOD. THE MODERATE INSTABILITY...STEEP
   MID-LEVEL LAPSE RATES AND STRONG DEEP LAYER SHEAR SHOULD BE
   SUFFICIENT FOR A LARGE HAIL AND WIND DAMAGE THREAT. AFTER
   MIDNIGHT...ISOLATED THUNDERSTORM DEVELOPMENT COULD OCCUR SWWD ACROSS
   CNTRL AND NORTH TX AS THE COLD FRONT MOVES INTO THE REGION FROM THE
   NORTHWEST. FORECAST SOUNDINGS IN CNTRL AND NORTH TX AT 09Z TO 12Z
   SUGGEST DEEP LAYER SHEAR MAY BE STRONG ENOUGH FOR A MARGINAL WIND
   DAMAGE AND HAIL THREAT.


Day 2 (Monday)

THE 02/12Z ECMWF IS CONSISTENT WITH ITS 02/00Z RUN...AND REMAINS THE
   SLOWEST AND FARTHEST SOUTH OF THE OPERATIONAL AND LATEST 21Z SREF
   500 MB MEAN HEIGHTS...SHOWING THE BASAL SHORTWAVE TROUGH MOVING INTO
   THE LOWER MS VALLEY DURING THE LATTER HALF OF DAY 2.  HOWEVER...EVEN
   WITH THE SLOWER ECMWF SOLUTION...60-100 METER HEIGHT FALLS ARE
   EXPECTED IN ADVANCE OF THE PROGRESSIVE FULL LATITUDE TROUGH FROM THE
   OH VALLEY TO MID SOUTH/LOWER MS VALLEY SUPPORTING STRONG DEEP LAYER
   SSWLY WIND FIELDS.  THE 03/00Z GFS COMPARED TO THIS MODEL RUN FROM
   02/00Z IS NOW INDICATING STRONGER FORCING FOR ASCENT INTO THE MID
   SOUTH BY MONDAY AFTERNOON.
  
   IN THE LOW LEVELS...THE LATEST GFS CONTINUES TO INDICATE STRONGER
   DEEPENING OF THE SURFACE LOW...WITH BOTH THE 00Z GFS/12Z ECMWF
   TRACKING THE LOW FROM THE CENTRAL GREAT LAKES TO QUEBEC.  EACH MODEL
   CONTINUES TO SHOW STRONG BAROCLINICITY AS A COLD FRONT ADVANCES EWD
   ACROSS THE OH/TN AND LOWER MS VALLEYS AND CENTRAL GULF COAST STATES.
    THE ECMWF REMAINS THE SLOWER MODEL WITH EWD PROGRESSION OF THE COLD
   FRONT...AND IN AGREEMENT WITH HPC MODEL DIAGNOSTICS HAVE KEPT SERN
   EXTENT OF THE SLIGHT RISK IN LINE WITH THE ECMWF TIMING OF THE COLD
   FRONT INTO GA BY 12Z TUESDAY.
  
   ...E TX TO CENTRAL GULF COAST STATES NWD TO TN/OH VALLEYS...
   GREATEST SEVERE WEATHER THREAT AREA /COVERAGE AND INTENSITY/...
   INCLUDING POTENTIAL FOR TORNADOES...DAMAGING WINDS AND HAIL IS
   EXPECTED TO BE ACROSS THE LOWER MS/TN VALLEYS.
  
   DESPITE THE MODEL DIFFERENCES DISCUSSED IN THE SYNOPSIS...EVEN 60-90
   METER HEIGHT FALLS PER ECMWF FROM THE OH VALLEY TO THE MID
   SOUTH/LOWER MS VALLEY AND MID-UPPER LEVEL TROUGH BECOMING NEUTRALLY
   ORIENTED WILL SUPPORT FORCING FOR ASCENT SPREADING EWD ATOP THE COLD
   FRONT AND ADJACENT WARM SECTOR.  STEEP MIDLEVEL LAPSE RATES /8-9 C
   PER KM/ ACROSS THE SLIGHT RISK AREA AT 12Z MONDAY WILL INITIALLY CAP
   THE AIR MASS.  HOWEVER...THE HEIGHT FALLS ARE EXPECTED TO ELIMINATE
   THE CAP EARLY IN THE PERIOD /MONDAY MORNING/.  FORCING ATTENDANT TO
   THE TROUGH SHOULD MAINTAIN ONGOING TSTMS ALONG THE FRONT WHICH WILL
   EXTEND FROM LOWER MI SWWD TO NERN AND CENTRAL TX...WHILE NEW STORMS
   WILL ALSO DEVELOP AS THE CAP WEAKENS FROM W-E MONDAY MORNING INTO
   THE AFTERNOON.
  
   SLY LOW LEVEL WINDS WILL SPREAD MOISTURE NWD IN ADVANCE OF THE COLD
   FRONT...WITH SURFACE DEWPOINTS IN THE LOWER 60S SPREADING ACROSS THE
   OH VALLEY...AND MID-UPPER 60S SWD FROM TN.  VALUES AROUND 70 SHOULD
   BE ALONG THE GULF COAST.  THIS MOISTURE COMBINED WITH RELATIVELY
   STEEP MIDLEVEL LAPSE RATES SHOULD RESULT IN MODERATE INSTABILITY
   FROM E TX TO CENTRAL GULF COAST STATES AND INTO PARTS OF THE TN
   VALLEY.  INCREASING DEEP LAYER SHEAR VECTORS BECOMING LESS PARALLEL
   TO THE COLD FRONT ACROSS THIS REGION SUGGESTS SUPERCELLS WILL BE
   MORE LIKELY.  GIVEN THE STRENGTH OF THE LOW LEVEL SHEAR...TORNADOES
   WILL BE POSSIBLE IN ADDITION TO DAMAGING WINDS AND HAIL /SOME VERY
   LARGE/.  SEVERE WEATHER THREAT SHOULD PERSIST ACROSS THE CENTRAL
   GULF COAST STATES MONDAY NIGHT AS THE COLD FRONT SPREADS EWD INTO A
   MODERATELY UNSTABLE AND STRONGLY SHEARED ENVIRONMENT.
  
   FARTHER N INTO THE OH VALLEY INSTABILITY WILL BE WEAKER.  HOWEVER...
   FORCING FOR ASCENT WITH THE UPPER TROUGH AND POSSIBLY ASSOCIATED
   WITH A LEAD IMPULSE WILL SUPPORT TSTM DEVELOPMENT AS THE COLD FRONT
   ADVANCES EWD.  BULK SHEAR VECTORS ORIENTED MORE PARALLEL TO THE
   FRONT SUGGEST A LINEAR MODE WITH THE STRENGTH OF LOW LEVEL WINDS
   /50-60 KT/ SUGGEST DAMAGING WINDS WILL BE THE PRIMARY THREAT.