MESOSCALE DISCUSSION NWS STORM PREDICTION CENTER

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   MESOSCALE DISCUSSION 0675
   NWS STORM PREDICTION CENTER NORMAN OK
   0703 AM CDT FRI APR 28 2006
   
   AREAS AFFECTED...NERN NM ACROSS THE TX/OK PNHDLS...SWRN AND CNTRL KS
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281203Z - 281400Z
   
   TSTMS ARE EXPECTED TO BECOME MORE NUMEROUS AND STRONGER IN THE NEXT
   FEW HOURS FROM NERN NM EWD AND NEWD ACROSS PORTIONS OF THE OK/TX
   PNHDLS...AND INTO KS. SOME OF THESE STORMS WILL LIKELY PRODUCE HAIL.
   WHILE IT DOES NOT APPEAR IMMINENT...A WATCH MIGHT BE  NEEDED FOR
   SOME OF THESE AREAS THIS MORNING.
   
   ELEVATED CONVECTION WAS ON THE INCREASE FROM THE SRN HIGH PLAINS TO
   THE SCNTRL PLAINS THIS MORNING AS A PAIR OF UPPER LEVEL SHORT WAVE
   TROUGHS BEGIN TO IMPOSE STRONGER LARGE SCALE ASCENT OVER THE REGION.
   AS A NRN STREAM IMPULSE DIGS SEWD ACROSS CO...A STRONG SRN STREAM
   UPPER LOW WAS DEVELOPING EAST FROM THE AZ/NM BORDER. THE MID/UPPER
   LEVEL DIFFLUENT FLOW AHEAD OF THE SRN SYSTEM HAS ENHANCED THE
   NOCTURNAL LOW LEVEL JET AND AIDED MOISTURE TRANSPORT NWD INTO A
   SW-NE ORIENTED DEFORMATION AXIS SITUATED FROM NM NEWD ACROSS KS.
   CONTINUED STRENGTHENING OF UPWARD MOTION/DPVA ASSOCIATED WITH THE
   NRN STREAM TROUGH...AND LARGE SCALE UPPER JET COUPLING BETWEEN THE
   NRN AND SRN SYSTEMS...SHOULD MAINTAIN A FAVORABLE ENVIRONMENT FOR
   INCREASINGLY WIDESPREAD CONVECTION THROUGH THE MORNING.
   
   DESPITE RECENT UPWARD TREND IN STORM COVERAGE ACROSS KS AND PRESENCE
   OF MODEST LAPSE RATES OF 7-8 C/KM...EFFECTIVE SHEAR ACROSS PARTS OF
   THE AREA APPEARS SOMEWHAT LIMITED WITHIN DEVELOPING MID LEVEL
   DEFORMATION ZONE BETWEEN NRN AND SRN STREAM SYSTEMS. HOWEVER...
   STEEPER LAPSE RATES...STRONGER SHEAR AND FORCING ARE FORECAST TO
   OVERSPREAD NM...TX/OK PNHDLS...AND SWRN KS AREAS THROUGH THE
   MORNING. MORE INTENSE CONVECTION...POSSIBLY IN THE FORM OF A FEW
   ELEVATED SUPERCELLS WITH PERSISTENT STORM UPDRAFTS AND LARGE
   HAIL...COULD DEVELOP IN THESE AREAS. A SEVERE TSTM WATCH MAY BE
   NEEDED AS ACTIVITY DEVELOPS THROUGH THE MORNING.
   
   ..CARBIN.. 04/28/2006
   
   
   ATTN...WFO...TOP...ICT...OUN...GID...DDC...GLD...AMA...PUB...ABQ...
   
   36349959 35100268 35460410 36460406 37170182 38820085
   39589834 39259703 38369687

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   MESOSCALE DISCUSSION 0676
   NWS STORM PREDICTION CENTER NORMAN OK
   1023 AM CDT FRI APR 28 2006
   
   AREAS AFFECTED...ERN TX PNHDL...WRN OK
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281523Z - 281700Z
   
   TRENDS ARE BEING MONITORED FOR INCREASING SEVERE THREAT AND
   POSSIBILITY OF A WW.
   
   NEW CONVECTIVE DEVELOPMENT IS EXPECTED ACROSS THE EASTERN TEXAS
   PANHANDLE AND PARTS OF WESTERN OKLAHOMA THROUGH THE 17-19Z TIME
   FRAME. THIS SEEMS LIKELY TO OCCUR IN ASSOCIATION WITH STRONGER
   MID-LEVEL COOLING/ASCENT IN EXIT REGION OF 70+ KT CYCLONIC 500 MB
   JET STREAK...WHICH CONTINUES TO SLOWLY NOSE INTO SOUTHWEST TEXAS.
   MID-LEVEL LAPSE RATES ARE ALREADY RATHER STEEP AND...WITH FURTHER
   DESTABILIZATION...MOST UNSTABLE CAPE FOR MOIST PARCELS ABOVE
   LINGERING NEAR SURFACE INVERSION LAYER MAY APPROACH 2000 J/KG.
   SHEAR PROFILES IN CLOUD BEARING LAYER APPEAR SUPPORTIVE OF MID-
   LEVEL UPDRAFT ROTATION...WHICH SHOULD ENHANCE POTENTIAL FOR LARGE
   HAIL IN STRONGER STORMS.
   
   ..KERR.. 04/28/2006
   
   
   ATTN...WFO...OUN...LUB...AMA...
   
   35740108 36420043 36519957 35549887 33849909 33300064
   34400082 35090117

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   MESOSCALE DISCUSSION 0677
   NWS STORM PREDICTION CENTER NORMAN OK
   1043 AM CDT FRI APR 28 2006
   
   AREAS AFFECTED...TEXAS SOUTH PLAINS
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281543Z - 281715Z
   
   A TORNADO WATCH WILL LIKELY BE NEEDED...POSSIBLY BEFORE NOON.
   
   TIMING OF INITIATION OF SURFACE-BASED CONVECTIVE DEVELOPMENT IS A
   BIT UNCERTAIN. HOWEVER..LATEST OBJECTIVE ANALYSIS SUGGESTS
   INHIBITION HAS BECOME RATHER WEAK NEAR/JUST AHEAD OF DRY LINE...FROM
   THE LUBBOCK AREA SOUTHWARD TO NEAR SAN ANGELO...WHERE MIXED LAYER
   CAPE IS ON THE ORDER OF 1500 J/KG.  FURTHER DESTABILIZATION WILL
   OCCUR WITH CONTINUING INSOLATION...AND A GRADUAL MID-LEVEL COOLING
   AS MID/UPPER JET NOSES ACROSS WEST TEXAS.  A 30+ KT SOUTHERLY
   LOW-LEVEL JET IS CONTRIBUTING TO SHEAR PROFILES EASILY SUFFICIENT
   FOR SUPERCELLS...WHICH COULD FORM AS EARLY AS 17-18Z.  LATEST TRENDS
   IN SATELLITE IMAGERY SUGGEST THIS IS MOST LIKELY JUST TO THE
   SOUTHEAST OF LUBBOCK.
   
   ..KERR.. 04/28/2006
   
   
   ATTN...WFO...SJT...LUB...MAF...
   
   33750182 33530079 32980042 32240067 31360115 31290199
   32080193 32800219

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   MESOSCALE DISCUSSION 0678
   NWS STORM PREDICTION CENTER NORMAN OK
   1235 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...ERN DAKOTAS
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281735Z - 281930Z
   
   ISOLATED SVR HAIL IS EXPECTED TO DEVELOP BY MID AFTERNOON. IN
   ADDITION...A WEAK/BRIEF TORNADO CANNOT BE RULED OUT.
   
   LATEST SURFACE ANALYSIS SHOWS TEMPERATURES WARMING INTO THE MID 60S
   ACROSS NERN SD. MODIFIED 12Z ABR SOUNDING SHOWS VERY STEEP LAPSE
   RATES IN PLACE SFC AND ALOFT. WITH NO CAPPING IN PLACE...AND
   CONTINUED HEATING...SCATTERED THUNDERSTORMS ARE LIKELY OVER THE NEXT
   FEW HOURS...A FEW OF WHICH COULD CONTAIN SVR HAIL. VIS IMAGERY WAS
   ALREADY SHOWING BUILDING CU FIELDS OVER SERN ND AND NERN SD...WHERE
   LOW LEVEL MOISTURE IS MAXIMIZED WITH UPPER 40S DEWPOINTS.
   
   FURTHER...LATEST GIVEN VERY STEEP LAPSE RATE AND VORTICITY RICH
   ENVIRONMENT ASSOCIATED WITH THE LOW...BRIEF/WEAK TORNADOES CANNOT BE
   RULED OUT WITH THE STRONGER CELLS...BUT GIVEN THE LACK OF VERTICAL
   WIND SHEAR...MOST OF THE STORMS SHOULD REMAIN SHORT LIVED. THE
   LONGEST LIVED CELLS WILL LIKELY BE NEAR LOW CENTER WHERE CONVERGENCE
   IS STRONGEST.
   
   ..JEWELL.. 04/28/2006
   
   
   ATTN...WFO...FGF...FSD...ABR...BIS...
   
   44530081 47500063 48730005 48899837 48229737 46689699
   45669681 44679701 44119783 43629832 43719957

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   MESOSCALE DISCUSSION 0679
   NWS STORM PREDICTION CENTER NORMAN OK
   0104 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...N CNTRL TX THRU S CNTRL/SE OK
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281804Z - 281930Z
   
   TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN ADDITIONAL WW
   EAST OF WW 256.
   
   WHILE SURFACE-BASED CONVECTIVE INITIATION APPEARS UNDERWAY ALONG DRY
   LINE...SOUTHEAST OF LUBBOCK THROUGH AREAS EAST/SOUTHEAST OF
   MIDLAND...AN INCREASE IN CONVECTIVE DEVELOPMENT IS ALSO ONGOING
   NORTH OF THE TEXAS HILL COUNTRY INTO AREAS NEAR/WEST OF DALLAS/FORT
   WORTH. THIS APPEARS BASED ABOVE AT LEAST SHALLOW NEAR SURFACE
   INVERSION LAYER...IN ASSOCIATION WITH BROADER AREA OF ISENTROPIC
   ASCENT... DOWNSTREAM OF SOUTHERN PLATEAU CLOSED LOW.  THIS FORCING
   WILL SPREAD NORTHEASTWARD ACROSS THE RED RIVER VALLEY THROUGH THE
   20-21Z TIME FRAME...AS UPPER SYSTEM SHIFTS INTO THE SOUTHERN
   ROCKIES.
   
   STEEP MID-LEVEL LAPSE RATES ARE CONTRIBUTING TO MOST UNSTABLE CAPE
   ON THE ORDER OF 1000 J/KG OVER A FAIRLY BROAD AREA OF THE SOUTHERN
   PLAINS.  THIS WILL SUPPORT RISK OF LARGE HAIL IN STRONGEST
   CELLS...THOUGH INCREASINGLY WIDESPREAD NATURE OF CONVECTION MAY TEND
   TO MITIGATE THREAT MOST AREAS NORTH/EAST OF DALLAS/FORT WORTH. BEST
   HAIL POTENTIAL SEEMS LIKELY TO REMAIN CONFINED TO AREAS WEST OF THE
   METROPLEX INTO THE EDWARDS PLATEAU...IN CLOSER PROXIMITY STEEPENING
   LOW-LEVEL LAPSE RATES.
   
   ..KERR.. 04/28/2006
   
   
   ATTN...WFO...SHV...TSA...FWD...OUN...EWX...SJT...
   
   32009985 33419856 34069811 34639740 34709621 34359515
   33719492 32009692 31089794 30869953

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   MESOSCALE DISCUSSION 0680
   NWS STORM PREDICTION CENTER NORMAN OK
   0113 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...SWRN TX
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 281813Z - 281915Z
   
   A TORNADO WATCH WILL BE ISSUED SHORTLY.
   
   ATMOSPHERE C0NTINUES TO DESTABILIZE E OF DRYLINE WITH CLOUD COVER
   ERODING FROM THE WEST. LOW LEVEL MOISTURE REMAINS RICH WITH MID TO
   UPPER 60S DEWPOINTS.  STRONG COOLING ALOFT WITH UPPER TROUGH WILL
   ALLOW FOR RAPID THUNDERSTORM DEVELOPMENT ALONG DRYLINE AND OVER THE
   MTNS OF NRN MEXICO. WIND PROFILES ARE QUITE FAVORABLE FOR SUPERCELLS
   WITH STRENGTHENING SLY LOW LEVEL JET IN PLACE OVER MUCH OF
   CENTRAL/ERN TX...AS WELL AS INCREASING FLOW ALOFT. TORNADO THREAT
   WILL INCREASE WITH TIME AS LOW LEVEL SHEAR CONTINUES TO STRENGTHEN.
   
   ..JEWELL.. 04/28/2006
   
   
   ATTN...WFO...FWD...EWX...SJT...MAF...
   
   31319879 31149821 29739893 29630073 29780250 31040235

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   MESOSCALE DISCUSSION 0681
   NWS STORM PREDICTION CENTER NORMAN OK
   0120 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...PARTS OF SERN TX PNHDL...NW TX
   
   CONCERNING...TORNADO WATCH 256...
   
   VALID 281820Z - 281945Z
   
   CONTINUE WW.  TORNADO POTENTIAL IS EXPECTED TO INCREASE WITHIN NEXT
   1 TO 3 HOURS.
   
   VIGOROUS CONVECTIVE DEVELOPMENT IS UNDERWAY...BASED IN DEEPENING
   MOIST BOUNDARY LAYER WITH CAPE NOW IN EXCESS OF 1500 J/KG.
   ADDITIONAL HEATING MAY YIELD MIXED LAYER CAPE IN EXCESS OF 2000 J/KG
   BY PEAK HEATING...SUPPORTING GROWING RISK FOR VERY LARGE HAIL.
   TORNADO POTENTIAL IS EXPECTED TO INCREASE BY THE 20-21Z TIME FRAME
   ...AS SOUTHWESTERLY MID-LEVEL FLOW ASSOCIATED WITH APPROACHING UPPER
   JET STREAK STRENGTHENS IN EXCESS OF 70 KT.  BACKED/SOUTHEAST
   BOUNDARY LAYER FLOW AHEAD OF DRY LINE...NORTH OF REMNANT WARM FRONT
   INTO VICINITY OF PRIMARY TRIPLE POINT LOW...IS CONTRIBUTING TO LARGE
   CLOCKWISE CURVED HODOGRAPHS BENEATH 30 KT SOUTHERLY LOW-LEVEL JET
   AXIS.  AN ISOLATED STRONG TORNADO OR TWO APPEARS POSSIBLE NORTHWEST
   OF ABILENE INTO AREAS EAST OF LUBBOCK/SOUTHEAST OF AMARILLO...AS FAR
   NORTH AS CHILDRESS/WICHITA FALLS.
   
   ..KERR.. 04/28/2006
   
   
   ATTN...WFO...OUN...SJT...LUB...AMA...MAF...
   
   34630150 34920102 34570045 34399967 33369972 32960016
   32440118 33770130

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   MESOSCALE DISCUSSION 0682
   NWS STORM PREDICTION CENTER NORMAN OK
   0338 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...SERN TX PNHDL...NW TX
   
   CONCERNING...TORNADO WATCH 256...
   
   VALID 282038Z - 282245Z
   
   CONTINUE TORNADO WATCH 256.
   
   MIXED BOUNDARY LAYER CAPE IN WARM SECTOR EAST OF DRY LINE UNAFFECTED
   BY RAINFALL IS NOW IN THE 1500 TO 2000 J/KG RANGE...AND CONTINUES TO
   SUPPORT SCATTERED VIGOROUS CONVECTIVE DEVELOPMENT.  NEAR REMNANT
   WARM FRONT...VAD WIND PROFILER DATA AND OBJECTIVE ANALYSIS INDICATE
   MOST FAVORABLE LOW-LEVEL HODOGRAPHS AND DEEP LAYER SHEAR FOR
   TORNADIC SUPERCELLS ARE NOW FOCUSED ACROSS THE ABILENE AREA.  NEW
   STORMS ARE NOW RAPIDLY DEVELOPING TO THE WEST OF ABILENE...AND
   ADDITIONAL ACTIVITY WILL DEVELOP ALONG AND AHEAD OF DRY LINE THROUGH
   THE REMAINDER OF THE AFTERNOON...WITH PRIMARY UPPER IMPULSE STILL
   SLOWLY PROGRESSING ACROSS THE SOUTHERN ROCKIES.
   
   ..KERR.. 04/28/2006
   
   
   ATTN...WFO...OUN...SJT...LUB...MAF...
   
   34150092 34570014 34059913 32579949 32149965 31610014
   31470095 31470150 32180161 32640104 33910098

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   MESOSCALE DISCUSSION 0683
   NWS STORM PREDICTION CENTER NORMAN OK
   0342 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...SWRN TX
   
   CONCERNING...TORNADO WATCH 257...
   
   VALID 282042Z - 282245Z
   
   SEVERE THREAT WILL CONTINUE TO INCREASE ACROSS WW 257 WITH VERY
   LARGE HAIL LIKELY AND ISOLATED TORNADOES BY LATE AFTERNOON.
   
   SURFACE ANALYSIS SHOWS COOL POCKET WITH TEMPERATURES IN THE LOW TO
   MID 70S SLOWLY ERODING ACROSS THE HILL COUNTRY...AS GUSTY SELY WINDS
   ADVECT WARMER AIR NWWD WITH TEMPERATURES IN THE MID TO UPPER 80S.
   MODIFIED 18Z DRT SOUNDING YIELDS STRONG INSTABILITY WITH AMPLE SPEED
   AND DIRECTIONAL SHEAR FOR SUPERCELLS. WATER VAPOR IMAGERY SHOWS
   MOISTENING ACROSS SWRN TX SUGGESTING INCREASING LIFT ALOFT...THUS
   STORMS SHOULD CONTINUE TO INCREASE IN INTENSITY...WITH HIGHEST
   TORNADO THREAT WITH SRN STORMS AS THEY TREK ENEWD ALONG SURFACE
   THERMAL GRADIENT.
   
   ..JEWELL.. 04/28/2006
   
   
   ATTN...WFO...FWD...EWX...SJT...MAF...
   
   29540235 31060235 31269853 29789858

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   MESOSCALE DISCUSSION 0684
   NWS STORM PREDICTION CENTER NORMAN OK
   0607 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...NWRN TX INTO SWRN/CENTRAL OK
   
   CONCERNING...TORNADO WATCH 256...
   
   VALID 282307Z - 290000Z
   
   WW 256 EXPIRING AT 7 PM CDT WILL NEED TO BE REPLACED WITHIN THE
   HOUR...LIKELY EXTENDING EWD TOWARD I-35.
   
   COMPLEX SCENARIO EXPECTED TO UNFOLD ACROSS MUCH OF THE SRN PLAINS
   THIS EVENING/OVERNIGHT AHEAD OF STRONG UPPER LOW NOW JUST SPREADING
   INTO THE SRN HIGH PLAINS.  AHEAD OF THIS SYSTEM STRONG SLY LLJ WILL
   INTENSIFY THROUGH THE EVENING...WHILE RAIN-INDUCED E-W ORIENTED
   SURFACE BOUNDARY/COLD FRONT SAGS SWD ACROSS CENTRAL AND INTO SWRN
   OK. MESO-LOW APPEARS TO BE ENHANCING SUPERCELLS INTO FAR SWRN OK
   ALONG INTERSECTION OF THIS FRONT WITH PRIMARY SURFACE COLD FRONT
   MOVING SWD INTO W-CENTRAL TX.  IN ADDITION...DRY LINE APPEARS TO
   BECOMING BETTER DEFINED N-S ACROSS WEST TX...WITH TRIPLE POINT LOW
   EXPECTED TO DEVELOP EWD ACROSS NWRN TX THROUGH THE EVENING. 
   
   EXTENSIVE CONVECTION HAS COOLED/STABILIZED AIR MASS INTO CENTRAL
   OK/N-CENTRAL TX LATE TODAY.  HOWEVER...60+ KT SLY LLJ MAY ALLOW
   MODEST INSTABILITY TO DEVELOP NWD THIS EVENING WITH EFFECTIVE WARM
   FRONT SHIFTING NWD TOWARDS THE RED RIVER THIS EVENING. SHEAR WILL
   REMAIN QUITE STRONG...WITH ENHANCED LOW LEVEL SHEAR NEAR TRACK OF
   SURFACE LOW.  OTHER DEVELOPMENT SHOULD CONTINUE TO INCREASE ALONG
   COLD FRONT ACROSS WRN OK.  LARGE HAIL WILL BE PRIMARY SEVERE THREAT
   THROUGH THE EVENING...THOUGH ISOLATED TORNADOES ARE STILL
   ANTICIPATED ACROSS PORTIONS OF SWRN/S-CENTRAL OK AND NWRN/N-CENTRAL
   TX.
   
   ..EVANS.. 04/28/2006
   
   
   ATTN...WFO...FWD...OUN...SJT...LUB...AMA...
   
   33459677 33039689 33010076 34700063 35469856 35399747
   34429684

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   MESOSCALE DISCUSSION 0685
   NWS STORM PREDICTION CENTER NORMAN OK
   0618 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...CENTRAL TX
   
   CONCERNING...TORNADO WATCH 256...
   
   VALID 282318Z - 290045Z
   
   TORNADO THREAT CONTINUES OVER WW 256...AND THREAT WILL INCREASE
   FARTHER E WHERE A NEW WW WILL LIKELY BE REQUIRED.
   
   A MULTITUDE OF STORM MODES CURRENTLY EXIST ACROSS CENTRAL AND W TX
   AS OF 23Z. LINE SEGMENTS OVER SJT CWA HAVE BECOME MORE CELLULAR WITH
   TIME...THUS TORNADO THREAT SHOULD INCREASE WITH THESE CELLS GIVEN
   STRONG AND INCREASING LOW LEVEL SHEAR/ENLARGED HODOGRAPHS. FARTHER
   E...EXTENT OF STORM COVERAGE AND/OR NEW DEVELOPMENT IS LESS CERTAIN
   FROM THE METROPLEX SWD...HOWEVER SURFACE ANALYSIS SHOWS TEMPERATURES
   INTO THE 80S WHICH MAY BE ENOUGH TO BREAK CAP JUDGING FROM MODIFIED
   FORECAST SOUNDINGS.
   
   GIVEN CONTINUED COOLING ALOFT...MULTIPLE SURFACE BOUNDARIES AND
   INCREASING LOW LEVEL JET...EXPECT ALL MODES OF CONVECTION WITH
   GREATEST TORNADO THREAT ALONG AND SOUTH OF WARM FRONT WHERE
   TEMPERATURES WILLS REMAIN IN UPPER 70S INTO THE LOWER 80S THROUGH
   THE EVENING.
   
   ..JEWELL.. 04/28/2006
   
   
   ATTN...WFO...HGX...FWD...EWX...SJT...
   
   30359847 30229976 30180077 31980076 32589993 33059875
   33339659 31579638 30619624

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   MESOSCALE DISCUSSION 0686
   NWS STORM PREDICTION CENTER NORMAN OK
   0844 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...SOUTHERN OK...NORTH CENTRAL TX
   
   CONCERNING...TORNADO WATCH 258...
   
   VALID 290144Z - 290315Z
   
   ...SEVERE THREAT IS INCREASING ACROSS THE METROPLEX...
   
   COMPLEX PATTERN HAS EVOLVED ACROSS NORTH CENTRAL TX INTO THE RED
   RIVER REGION OF SRN OK THIS EVENING.  STRENGTHENING WARM ADVECTION
   BENEATH LLJ APPEARS TO BE PARTLY RESPONSIBLE FOR EXPANDING SEVERE
   CLUSTERS ALONG THE RED RIVER...TRAILING SWWD INTO STEPHENS COUNTY
   TX.  ONE LONG LIVED DESTRUCTIVE SUPERCELL OVER GRAYSON COUNTY TX
   SEEMS TO HAVE BEEN ENHANCED BY STRONG LOW LEVEL SHEAR ALONG
   RETREATING BOUNDARY THAT IS LOSING IDENTITY OVER NERN TX.  RECENT
   TRENDS SUGGEST AN UPWARD EXPANSION OF ACTIVITY FROM WEST-NORTH OF
   THE METROPLEX. THIS CONVECTION WILL SPREAD ACROSS THE REMAINDER OF
   NORTH CENTRAL TX LATER THIS EVENING INTO THE EARLY MORNING HOURS.
   
   ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG ADVANCING COLD
   FRONT AS IT SWEEPS SEWD LATER TONIGHT.
   
   ..DARROW.. 04/29/2006
   
   
   ATTN...WFO...TSA...FWD...OUN...
   
   34199808 34449553 33629538 33399626 32979682 32339750
   32339892

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   MESOSCALE DISCUSSION 0687
   NWS STORM PREDICTION CENTER NORMAN OK
   1003 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...EAST TX
   
   CONCERNING...TORNADO WATCH 258...259...
   
   VALID 290303Z - 290430Z
   
   ...SEVERE THREAT WILL INCREASE EAST OF WATCHES 258/259 ACROSS EAST
   TX BY THE EARLY MORNING HOURS. TORNADO WATCH WILL BE ISSUED BY
   MIDNIGHT...
   
   COLD FRONT CONTINUES TO SURGE SWD ACROSS THE TX HIGH PLAINS WHILE
   WARM ADVECTION APPEARS TO BE THE PRIMARY AGENT IN SEVERE
   THUNDERSTORM CLUSTERS FROM NEAR THE RED RIVER...SWD INTO THE HILL
   COUNTRY.  AS LARGE SCALE FORCING SPREADS ACROSS CNTRL TX CONVECTION
   SHOULD BEGIN TO DEVELOP NEAR THE ERN EDGE OF TORNADO
   WATCHES...BENEATH STRONG LLJ.  LATEST THINKING IS SEVERE
   THUNDERSTORM CLUSTERS OVER THE HILL COUNTRY...AND OVER THE DFW
   METROPLEX WILL BE APPROACHING THE ERN EDGE OF TORNADO WATCHES BY
   MIDNIGHT.  GIVEN THE STRONG LOW LEVEL SHEAR...40KT
   SFC-1KM/HELICITY...500-700M2/S2...NEW TORNADO WATCH WILL BE ISSUED
   DOWNSTREAM TO ACCOUNT FOR THIS EVOLUTION.
   
   ..DARROW.. 04/29/2006
   
   
   ATTN...WFO...SHV...HGX...FWD...EWX...
   
   30039740 33589625 33109433 30049552

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   MESOSCALE DISCUSSION 0688
   NWS STORM PREDICTION CENTER NORMAN OK
   1114 PM CDT FRI APR 28 2006
   
   AREAS AFFECTED...SOUTH CENTRAL TX
   
   CONCERNING...TORNADO WATCH 259...
   
   VALID 290414Z - 290545Z
   
   ...SEVERE THREAT IS INCREASING ACROSS SOUTH CENTRAL TX...WW WILL
   LIKELY BE ISSUED JUST SOUTH OF WW259...
   
   LATEST DIAGNOSTIC DATA SUGGESTS LOW LEVEL CONVERGENCE WILL PROVE
   SUFFICIENT IN FORCING BOUNDARY LAYER PARCELS TO THEIR LFC ALONG
   ADVANCING WIND SHIFT.  RADAR TRENDS SUPPORT THIS WITH SWWD
   DEVELOPMENT ALONG PRE-FRONTAL BOUNDARY INTO NERN MEXICO WEST OF DRT.
    FORECAST SOUNDINGS SUGGEST STRONG CAP JUST SOUTH OF CURRENT WW259
   WILL BE REMOVED THROUGH VERTICAL ASCENT/COOLING.  DEVELOPING SQUALL
   LINE WILL LIKELY ADVANCE INTO PORTIONS OF SOUTH CENTRAL TX NOT
   CURRENTLY COVERED BY TORNADO WATCH.  FOR THIS REASON WILL LIKELY
   ISSUE ANOTHER SMALL WATCH TO ACCOUNT FOR THIS EVOLUTION.
   
   ..DARROW.. 04/29/2006
   
   
   ATTN...WFO...EWX...
   
   30230053 30109845 29209826 28679926 29120077

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   MESOSCALE DISCUSSION 0689
   NWS STORM PREDICTION CENTER NORMAN OK
   0151 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...TX
   
   CONCERNING...TORNADO WATCH 258...259...
   
   VALID 290651Z - 290715Z
   
   A NEW TORNADO WATCH IS BEING PLANNED FOR PARTS OF SCNTRL TX EARLY
   TODAY. THIS WATCH WILL REPLACE PORTIONS OF WW 259. MEANWHILE WW 258
   IS SET TO EXPIRE AT THE TOP OF THE HOUR.
   
   VERY STRONGLY SHEARED ENVIRONMENT PERSISTS ACROSS SCNTRL TX THIS
   MORNING WITH AREA VWP AND PROFILER DATA INDICATING OVER 50KT OF SLY
   FLOW JUST ABOVE THE SURFACE. MEANWHILE...PREFRONTAL SQUALL LINE FROM
   UVALDE...BANDERA...AND KENDALL COUNTIES NEWD TO WILLIAMSON AND BELL
   COUNTIES CONTINUES EAST AT UP TO 35KT. SRN PARTS OF THIS LINE APPEAR
   TO BE WEAKENING AS OUTFLOW OUTRUNS THE DEEPER UPDRAFTS.
   HOWEVER...COMMA-HEAD CELL IN THE NRN PORTION OF THE LINE WAS
   TRACKING ALONG PREVIOUS OUTFLOW BOUNDARY ACROSS BELL COUNTY AND THIS
   CELL HAS WIND DAMAGE AND HAIL POTENTIAL. IT APPEARS THAT MOST OF THE
   CURRENT CONVECTION HAS OUTRUN THE STRONGER LARGE SCALE FORCING
   ASSOCIATED WITH THE UPPER TROUGH OVER WEST TX...AND STORMS WERE ALSO
   ENCOUNTERING GREATER INHIBITION ACROSS THE REGION. HOWEVER...GIVEN
   SHEAR IN PLACE AND PRESENCE OF STRONG UPSTREAM SYSTEM...ADDITIONAL
   SEVERE STORM DEVELOPMENT THROUGH EARLY MORNING REMAINS A
   POSSIBILITY. THUS A NEW WATCH WILL BE OUT SHORTLY.
   
   ..CARBIN.. 04/29/2006
   
   
   ATTN...WFO...HGX...FWD...CRP...EWX...
   
   31109759 30329811 28749950 28829668 29749583 31059526

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   MESOSCALE DISCUSSION 0690
   NWS STORM PREDICTION CENTER NORMAN OK
   0403 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...ERN/SERN TX...EXTREME SERN OK/SWRN AR
   
   CONCERNING...TORNADO WATCH 260...261...
   
   VALID 290903Z - 291000Z
   
   PREFRONTAL SQUALL LINE WITH EMBEDDED LEWPS/BOWS CONTINUES MOVING
   EAST INTO MODERATELY UNSTABLE AND WEAKLY CAPPED AIR MASS ACROSS
   ERN/SERN TX THIS MORNING. WARM SECTOR CONDITIONS WILL CONTINUE TO
   SUPPORT FAST-MOVING STORMS WITH A CHANCE FOR GREATER STORM
   ORGANIZATION/PERSISTENCE AND ROTATION NEAR OUTFLOW BOUNDARY
   INFLECTIONS ALONG THE LARGER SCALE LINE.
   
   RECENT STORM INTENSIFICATION/ROTATION ACROSS VAN ZANDT COUNTY
   APPEARS LINKED TO THIS CELL CROSSING MESOSCALE THERMAL GRADIENT
   LEFT IN THE WAKE OF EARLIER CONVECTION. PRESSURE RISE/FALL COUPLET
   ALSO EXISTS ACROSS THE ADVANCING SQUALL LINE AND WAS LIKELY AIDING
   MESOSCALE FORCING NEAR LEWP/BOW SEGMENTS. ONE AREA OF ENHANCED WIND
   DAMAGE POTENTIAL MAY OCCUR WITH THE BOWING CONVECTION THAT WILL MOVE
   ACROSS LEON AND NRN HOUSTON COUNTIES OVER THE NEXT HOUR. ANOTHER
   FAVORED LOCATION FOR STORM ORGANIZATION AND POSSIBLE WIND DAMAGE MAY
   BE DEVELOPING EAST FROM SRN ROBERTSON COUNTY...EWD ACROSS PARTS OF
   BURLESON AND BRAZOS COUNTIES IN THE NEXT HOUR.
   
   ..CARBIN.. 04/29/2006
   
   
   ATTN...WFO...LZK...LCH...SHV...TSA...HGX...FWD...OUN...CRP...EWX...
   
   28709816 28599893 29689879 30639805 31089776 31429690
   32879636 33449585 34599562 34259388 33269373 32539406
   31899409 30979427 29979517 29009700 28719751

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   MESOSCALE DISCUSSION 0691
   NWS STORM PREDICTION CENTER NORMAN OK
   0737 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...ERN TX...WRN LA...SWRN AR
   
   CONCERNING...TORNADO WATCH 262...
   
   VALID 291237Z - 291400Z
   
   STRONG MOISTURE FLUX ON 50KT LOW LEVEL SLY FLOW OFF THE NWRN GULF
   WILL CONTINUE TO FUEL ROBUST STORMS ALONG ADVANCING PRE-FRONTAL
   SQUALL LINE FROM THE TX GULF COAST INLAND TO THE ARKLATEX THIS
   MORNING. FURTHERMORE...LOW LEVEL JET WAS TOPPED BY DIFFLUENT WSWLY
   FLOW OF UP TO 80KT AT MID LEVELS RESULTING IN STRONG DEEP LAYER
   SHEAR THAT WILL CONTINUE TO SUPPORT STORM ORGANIZATION.
   QUASI-DISCRETE CELLS WITHIN TRAILING PORTIONS OF THE SQUALL
   LINE...ON THE TX COASTAL PLAIN AND THE SABINE RIVER AREA...HAVE
   SHOWN SOME TENDENCY TO ROTATE. ACTIVITY ACROSS THESE AREAS WILL
   CONTINUE TO HAVE SOME TORNADIC POTENTIAL GIVEN VERY STRONG LOW LEVEL
   SHEAR AND HIGH BOUNDARY LAYER RH/LOW LFC.
   
   FARTHER NORTH...STRONGER CELLS WEST OF SHV ARE WELL EMBEDDED WITHIN
   HEAVY RAIN. WHILE SRM LOOPS HAVE INDICATED OCCASIONAL SHEAR COUPLETS
   WITHIN A FEW OF THE STRONGER UPDRAFTS...LATEST RAOB FROM SHV
   SUGGESTS THAT CONVECTION IS LIKELY ROOTED JUST ABOVE SURFACE-BASED
   INVERSION. TORNADO/WIND POTENTIAL WITH THIS ACTIVITY MAY BE LOWER
   THAN IN STORMS FARTHER SOUTH.
   
   ..CARBIN.. 04/29/2006
   
   
   ATTN...WFO...JAN...LZK...LCH...SHV...HGX...
   
   29519396 28669584 33799458 33259228 31969181 30949223
   29609266

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   MESOSCALE DISCUSSION 0692
   NWS STORM PREDICTION CENTER NORMAN OK
   0957 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...UPPER TX COAST INTO SW LA
   
   CONCERNING...TORNADO WATCH 262...
   
   VALID 291457Z - 291700Z
   
   CONTINUE REMAINING VALID PORTION OF WW.
   
   PRE-FRONTAL LOW-LEVEL CONFLUENT ZONE ASSOCIATED WITH 45-50 KT
   SOUTHERLY LOW-LEVEL JET REMAINS A FOCUS FOR VIGOROUS CONVECTIVE
   DEVELOPMENT.  THOUGH LAPSE RATES ARE NOT STEEP...TONGUE OF 70F DEW
   POINTS IS CONTRIBUTING TO AT LEAST WEAK MIXED LAYER CAPE ON THE
   ORDER OF 500 J/KG FROM UPPER TEXAS COASTAL AREAS INTO THE LOWER
   SABINE VALLEY. INTENSIFYING LOW-LEVEL JET CORE IS PROGGED TO
   DEVELOP NORTH NORTHEASTWARD INTO CENTRAL ARKANSAS THROUGH EARLY
   AFTERNOON...BUT FLOW CLOSER TO COASTAL AREAS IS NOT EXPECTED TO
   WEAKEN...AND EXTREME LOW-LEVEL SHEAR WILL MAINTAIN A RISK FOR
   ISOLATED TORNADOES/WIND DAMAGE.  NORTH/EAST OF THE FORT POLK AREA...
   SATURATED PROFILES/SHALLOW SURFACE-BASED STABLE LAYER ARE MINIMIZING
   SEVERE THREAT AT THE PRESENT TIME...BUT THIS COULD CHANGE WITH AT
   LEAST WEAK SURFACE WARMING BY AFTERNOON.
   
   ..KERR.. 04/29/2006
   
   
   ATTN...WFO...LCH...SHV...HGX...
   
   30459433 30999378 31859366 32649334 32699267 32279228
   30849255 30149300 29709368 29319434 29239516 29919482

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   MESOSCALE DISCUSSION 0693
   NWS STORM PREDICTION CENTER NORMAN OK
   1005 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...ERN OK / NERN TX
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL
   
   VALID 291505Z - 291700Z
   
   THREAT FOR SEVERE HAIL AND DAMAGING WINDS WILL INCREASE INTO THE
   EARLY AFTERNOON HOURS OVER MUCH OF ERN OK INTO NERN TX. MONITORING
   FOR POSSIBLE WW.
   
   LARGE AREA OF CONVECTION HAS FORMED OVER CENTRAL AND WRN OK INTO FAR
   NRN TX IN ASSOCIATION WITH STRONG UPPER VORT CENTER AND SFC COLD
   FRONT.
   
   THIS AREA OF FORCING WILL SHIFT EWD AND ENCOUNTER AN INCREASINGLY
   DESTABILIZING AIR MASS. MORNING VISIBLE IMAGERY SHOWED AREAS OF
   CLEARING OVER ERN OK/NERN TX WHICH WILL ALLOW TEMPERATURES TO RISE
   INTO THE UPPER 60S/LOWER 70S. GIVEN COOLING TEMPERATURES ALOFT...AND
   SURFACE DEWPOINTS IN THE LOWER 60S...THIS WILL PROVIDE SUFFICIENT
   INSTABILITY FOR SEVERE STORMS. HAIL WILL BE LIKELY AND WIND THREAT
   WILL INCREASE AS SURFACE INVERSION/CAPPING ERODES. ISOLATED
   TORNADOES WILL BE POSSIBLE MAINLY DURING THE LATE AFTERNOON OVER FAR
   ERN OK/NERN TX WHERE SURFACE WINDS WILL REMAIN BACKED.
   
   ..JEWELL.. 04/29/2006
   
   
   ATTN...WFO...TSA...FWD...OUN...
   
   33749780 34469783 34989754 35869644 35999563 35689509
   34779502 33699537 33079575 33029673 33389749

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   MESOSCALE DISCUSSION 0694
   NWS STORM PREDICTION CENTER NORMAN OK
   1155 AM CDT SAT APR 29 2006
   
   AREAS AFFECTED...ERN TX...PARTS OF SE OK...SRN AR...WRN/CNTRL
   LA...PARTS OF SW MS
   
   CONCERNING...TORNADO WATCH 262...
   
   VALID 291655Z - 291800Z
   
   ADDITIONAL WW OR WWS WILL BE NEEDED BY 18Z.
   
   PRE-FRONTAL CONFLUENCE/CONVECTIVE LINE NEAR LOW-LEVEL JET AXIS
   CONTINUES TO VERY SLOWLY SHIFT EASTWARD TOWARD THE LOWER MISSISSIPPI
   VALLEY.  LAPSE RATES THROUGH MUCH OF THIS REGION WILL NOT LIKELY
   STEEPEN SUBSTANTIALLY...BUT POSITIVE BUOYANCY ASSOCIATED WITH
   SURFACE DEW POINTS NEAR 70F MAY COMPENSATE...MAINTAINING ISOLATED
   TORNADO/DAMAGING WIND POTENTIAL IN PRESENCE OF EXTREME SHEAR BENEATH
   45 TO 50 KT LOW-LEVEL JET.  NORTHWARD EXTENT OF TORNADO THREAT IN
   THE VICINITY OF THE MISSISSIPPI RIVER IS STILL UNCERTAIN...BUT
   BOUNDARY LAYER DESTABILIZATION SEEMS POSSIBLE WITH MOISTURE RETURN
   ALONG AN AXIS EASTWARD THROUGH LAFAYETTE LA...AND POSSIBLY AS FAR
   NORTH AS THE NATCHEZ MS BY 22-23Z TIME FRAME.
   
   OTHERWISE...LOW-LEVEL MOISTURE IN WAKE OF ONGOING CONVECTION ACROSS
   THE SABINE RIVER VALLEY INTO THE ARKLATEX REMAINS SUPPORTIVE OF
   SIGNIFICANT DESTABILIZATION.  INCREASING AFTERNOON INSOLATION AND
   MID-LEVEL COOLING ASSOCIATED WITH APPROACHING UPPER TROUGH WILL
   CONTRIBUTE TO STEEPENING LAPSE RATES...AND MIXED LAYER CAPE UP TO
   AROUND 1000 J/KG.  AREA OF STRONGER MID/UPPER FORCING FOR UPWARD
   VERTICAL MOTION WILL BEGIN TO OVERSPREAD THIS AREA DURING THE 18-21Z
   TIME FRAME...LIKELY SUPPORTING ADDITIONAL CONVECTIVE DEVELOPMENT.
   THOUGH STRONGER LOW-LEVEL FLOW WILL SHIFT ON TO THE EAST AHEAD OF
   LEADING CONVECTION...50 TO 70+ KT CYCLONIC MID- LEVEL FLOW WILL
   CONTRIBUTE TO SUFFICIENT DEEP LAYER SHEAR FOR SUPERCELLS.
   
   ..KERR.. 04/29/2006
   
   
   ATTN...WFO...JAN...LIX...LZK...LCH...SHV...HGX...FWD...
   
   33359548 34139467 34069348 33659275 32989186 31879122
   31549108 30339135 29809241 29919335 29799444 30409437
   31289445 32629502