MESOSCALE DISCUSSION NWS STORM PREDICTION CENTER

[CaptinCrunch]

MESOSCALE DISCUSSION 0436
NWS STORM PREDICTION CENTER NORMAN OK
0200 PM CST WED MAR 30 2005

AREAS AFFECTED...NRN IL...SRN/CENTRAL WI...SERN MN AND ERN IA

CONCERNING...TORNADO WATCH 103...104...

VALID 302000Z - 302030Z



DUE TO ONGOING SVR THREAT OVER NERN IA DEVELOPING INTO SERN MN/SWRN
WI AND SVR THREAT CONTINUING ACROSS ERN/NRN PORTIONS OF WW 104
BEYOND 22Z /WW 104 EXPIRATION TIME/...A NEW TOR WW WBIS THAT WILL
REPLACE WW/S 103 AND 104.

[CaptinCrunch]

MESOSCALE DISCUSSION 0437
NWS STORM PREDICTION CENTER NORMAN OK
0306 PM CST WED MAR 30 2005

AREAS AFFECTED...NERN LA...ERN AR...NWRN MS

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 302106Z - 302300Z



ISOLATED SVR STORMS MAY BEGIN DEVELOPING OVER THE AREA BEFORE 00Z.
THUS A WW MAY BE NEEDED BEFORE 23Z.

STRONG FRONTOGENETIC FORCING AND ASCENT IN RIGHT ENTRANCE REGION OF
UPPER JET OVER THE MID MS VALLEY HAS AIDED IN A SW-NE ORIENTED BAND
OF HIGH BASED CONVECTION ACROSS CENTRAL/SWRN AR. DEEPER MOISTURE WAS
REMOVED FROM THIS STRONG ASCENT BY ABOUT 50-100 MILES AS EVIDENT BY
CU FIELD OVER THE LOW MS RIVER VALLEY. LOW LEVEL CINH
REMAINS...ABOUT 25 J/KG...BUT ETAKF SOUNDINGS WHICH SEEM TO BE
VERIFYING BEST AT 20Z WITH TEMPERATURES IN THE LOWER 80S/DEWPTS IN
THE LOWER 60S...INDICATED THAT CONTINUED HEATING MAY BE SUFFICIENT
TO ELIMINATE ANY REMAINING CINH BEFORE 23Z. RECENT SFC ANALYSIS
INDICATES THAT A GRADUAL BACKING OF THE LOW LEVEL WINDS IN TANDEM
WITH A 2 MB/2 HR PRESSURE FALL MAX SHOULD CONTINUE TO ENHANCE
CONVERGENCE ALONG DRYLINE/SFC TROUGH EXTENDING FROM NEAR JONESBORO
AR TO 30 EAST OF SHREVEPORT LA.

IF SFC BASED CONVECTION CAN DEVELOP IN THE NEXT 2-3 HOURS...MODERATE
INSTABILITY /MUCAPE OF 1500-2000 J/KG/ ALONG WITH 50-60 KTS OF DEEP
LAYER SHEAR WOULD BE MORE THAN ADEQUATE TO SUPPORT SVR STORMS
CAPABLE OF DAMAGING WINDS/LARGE HAIL. THE TORNADO THREAT WILL
INCREASE AFTER DARK WHEN LOW LEVEL RH VALUES/DEWPTS INCREASE AND LCL
HEIGHTS DECREASE.

[CaptinCrunch]

MESOSCALE DISCUSSION 0438
NWS STORM PREDICTION CENTER NORMAN OK
0318 PM CST WED MAR 30 2005

AREAS AFFECTED...ERN IL/WRN IND

CONCERNING...TORNADO WATCH 105...

VALID 302118Z - 302315Z



THE TORNADO THREAT WILL CONTINUE TO INCREASE ACROSS WW 105 OVER THE
NEXT 1-3 HOURS WITH AN ISOLATED STRONG TORNADO POSSIBLE AS
SUPERCELLS TRACK NEWD INTO CNTRL AND NRN IL.

OVER IL AND WRN IND...OBJECTIVE ANALYSIS CURRENTLY SHOWS SBCAPE
VALUES AROUND 1500 J/KG COUPLED WITH 0-6 KM SHEAR VALUES AROUND 50
KT. THIS COMBINED WITH STRONG FORCING IN THE LEFT EXIT REGION OF THE
MID-LEVEL JET AND STRONG LOW-LEVEL SHEAR IN THE NOSE OF THE
LOW-LEVEL JET WILL MAKE THE ENVIRONMENT FAVORABLE FOR TORNADIC
SUPERCELLS LATE THIS AFTERNOON INTO EARLY THIS EVENING. SEVERAL
INTENSE SUPERCELLS CAPABLE OF PRODUCING TORNADOES WILL CONTINUE TO
TRACK NEWD WITH AN ESPECIALLY INTENSE SUPERCELL APPROACHING THE I-39
CORRIDOR BETWEEN BLOOMINGTON AND ROCKFORD. THIS POTENTIALLY TORNADIC
SUPERCELL AND OTHER SUPERCELLS SHOULD AFFECT THE CHICAGO AREA BY 00Z
WITH THE POTENTIAL FOR TORNADOES (POSSIBLY STRONG)...VERY LARGE HAIL
AND WIND DAMAGE.

[CaptinCrunch]

MESOSCALE DISCUSSION 0439
NWS STORM PREDICTION CENTER NORMAN OK
0354 PM CST WED MAR 30 2005

AREAS AFFECTED...SERN MN...CENTRAL/SRN WI...NERN IA/NWRN IL

CONCERNING...TORNADO WATCH 106...

VALID 302154Z - 302300Z



ISOLATED TORNADO THREAT WILL CONTINUE OVER WW 106...MAINLY WITH LEAD
SUPERCELLS AND ADDITIONAL CONVECTION DEVELOPING OVER SERN/ECENTRAL
WI DURING THE NEXT 2 HOURS. FARTHER WEST...LINEAR ORGANIZATION OF
PRIMARY CONVECTIVE LINE SUGGESTS THAT TORNADO THREAT HAS
LESSENED...BUT A SVR THREAT WILL CONTINUE OVER FAR SERN
MN..SWRN/CENTRAL WI AND NWRN IL AHEAD OF THIS LINEAR AS STEEP LAPSE
RATES EXIST IN THE BOUNDARY LAYER. A RAIN COOLED AIRMASS BEHIND THIS
LINE SUGGESTS THAT SVR THREAT IS WANING OVER NERN IA...FAR SWRN
WI/FAR NWRN IL.

ISOLATED SUPERCELLS OVER DODGE AND WRN FOND DU LAC CO/S WILL
CONTINUE TO MOVE ENEWD TOWARDS THE COOLER TEMPERATURE OF NERN
WI/LAKESHORE COUNTIES OF ECENTRAL WI DURING THE NEXT HOUR. PRIOR TO
MOVING INTO A MORE UNFAVORABLE ENVIRONMENT...SUPERCELL INTERACTION
WITH NWD RETREATING WARM FRONT WILL CONTINUE TO ENHANCE LOW LEVEL
SHEAR AND SUPPORT THREAT FOR TORNADOES FOR THE NEXT HOUR.

[CaptinCrunch]

MESOSCALE DISCUSSION 0454
NWS STORM PREDICTION CENTER NORMAN OK
0653 AM CST THU MAR 31 2005

AREAS AFFECTED...EXTREME SERN MS...CNTRL/SRN AL...CNTRL/SRN GA...WRN
SC...WRN FL PNHDL

CONCERNING...SEVERE THUNDERSTORM WATCH 112...

VALID 311253Z - 311400Z



WS 112 EXPIRES AT 14Z. THERE WILL LIKELY CONTINUE TO BE DAMAGING
WIND AND HAIL THREATS THROUGH LATE MORNING CNTRL/SRN AL INTO GA AND
ANOTHER WW IS BEING CONSIDERED.

09Z RUC SUGGESTS THAT MAIN CORE OF THE H85 JET SHIFTS NEWD INTO ERN
AL AND WRN GA THROUGH 15Z. THE LOW-LEVEL FLOW SHOULD BECOME
INCREASINGLY DIVERGENT ACROSS THE LOWER MS VLY AS HEIGHT FALLS
INCREASE UPSTREAM ACROSS THE SRN PLAINS AHEAD OF THE NEXT H5 TROUGH.
THIS MAY LESSEN THE SEVERE/TSTM RISK WITH TIME THIS MORNING ACROSS
SRN MS. BUT...FAVORABLE INSTABILITY AND SHEAR PROFILES WILL EXIST
DOWNSTREAM INTO CNTRL/SRN AL AND PARTS OF GA TO CONTINUE THE
HAIL/WIND RISKS THROUGH LATE MORNING.

[CaptinCrunch]

MESOSCALE DISCUSSION 0455
NWS STORM PREDICTION CENTER NORMAN OK
1032 AM CST THU MAR 31 2005

AREAS AFFECTED...SRN AL THROUGH S CNTRL GA

CONCERNING...SEVERE THUNDERSTORM WATCH 113...

VALID 311632Z - 311800Z



LIMITED THREAT OF ISOLATED DAMAGING WIND WILL PERSIST NEXT COUPLE
HOURS ALONG SQUALL LINE FROM SRN AL THROUGH S CNTRL GA. HEAVY RAIN
WITH RATES FROM 1 TO 1.5 INCHES PER HOUR WILL ALSO PERSIST...
ESPECIALLY OVER SRN AL ALONG SWRN PORTIONS OF THE LINE. STORMS ARE
BEGINNING TO EXIT SERN PARTS OF WW 113. WW WILL LIKELY BE CANCELLED
WITHIN THE NEXT HOUR OR TWO SINCE THREAT DOES NOT APPEAR HIGH ENOUGH
TO WARRANT ANOTHER WW FARTHER SE.

A SQUALL LINE EXTENDS FROM SRN AL NEWD THROUGH S CNTRL GA MOVING
SEWD AT 20 TO 25 KT. WIDESPREAD CLOUDS ARE LIMITING THE DEGREE OF
INSTABILITY DOWNSTREAM FROM THE LINE. THE OUTFLOW BOUNDARY IS MOVING
SEWD WITH THE MEAN STEERING FLOW ORIENTED PARALLEL TO THE LINE. THIS
IS RESULTING IN A TENDENCY FOR MANY OF THE CELLS TO BE UNDERCUT BY
THE OUTFLOW OVER SW PORTIONS OF THE LINE. THREAT FOR ISOLATED WIND
DAMAGE MAY BE A LITTLE HIGHER WITH PORTION OF LINE BETWEEN WILCOX
AND LAURENS COUNTIES IN SERN GA WHERE DOWNSTREAM TEMPERATURE-
DEWPOINT SPREADS ARE LARGER. HOWEVER...INSTABILITY IS ALSO MORE
LIMITED IN THIS REGION. THREAT FOR HEAVY RAIN APPEARS HIGHER OVER
SRN AL ALONG SLOWER MOVING SWRN PARTS OF LINE WHERE STORMS WILL HAVE
THE OPPORTUNITY TO TRAIN LONGER.

[CaptinCrunch]

MESOSCALE DISCUSSION 0456
NWS STORM PREDICTION CENTER NORMAN OK
1134 AM CST THU MAR 31 2005

AREAS AFFECTED...SERN CO...NERN NM...FAR WRN OK PANHANDLE/NWRN TX
PANHANDLE

CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION

VALID 311734Z - 312130Z



MOD TO HVY SNOW ACCOMPANIED BY BLIZZARD CONDITIONS AT TIMES WILL
GRADUALLY SHIFT SWD OUT OF SERN CO/FAR NERN NM INTO FAR WRN OK/NWRN
TX PANHANDLE THROUGH THE AFTERNOON. HRLY SNOWFALL RATES UP 2 INCHES
WILL REMAIN POSSIBLE OVER THE UPSLOPE REGION OF THE RATON MESA
THROUGH 21Z...BEFORE DIMINISHING TRENDS EXPECTED THEREAFTER.
ELSEWHERE...1/2 TO 1 INCH/HR SNOWFALL RATES ANTICIPATED TO DEVELOP
BETWEEN 18Z AND 21Z.

STRONG PRESSURE GRADIENT /10 MB OVER 150 MILES/ WILL CONTINUE TO
DEVELOP SWD INTO THE NWRN TX/OK PANHANDLE THROUGH 21Z AS SURFACE LOW
MOVES INTO THE SRN TX PANHANDLE. THIS WILL SUPPORT SUSTAINED NNWLY
WINDS AROUND 30 MPH WITH GUSTS UP TO 50 MPH DEVELOPING SWD ACROSS
THE WRN PANHANDLES DURING THIS TIME. PRONOUNCED DEFORMATION ZONE ON
THE NW SIDE OF MID LEVEL CYCLONE WILL CONTINUE TO FAVOR ENHANCED
SNOWFALL RATES OVER SERN CO...WHILE GRADUALLY DIMINISHING FROM N-S
THROUGH THE AFTERNOON. A NEW AREA OF ENHANCED CLOUD TOP
COOLING/CONVECTIVE PRECIP OVER SWRN KS WILL ROTATE INTO THE WRN
OK/NWRN TX PANHANDLE DURING THE AFTERNOON. SNOW LEVELS CURRENTLY AT
5500 FT ARE EXPECTED TO FALL TO AROUND 4000-4500 FT BY 21Z AS
DYNAMIC COOLING ENSUES WITH HVY PRECIP. THUS A CHANGEOVER TO MOD-HVY
SNOW IS EXPECTED OVER THE LOWER ELEVATIONS OF FAR NERN NM...AND
HIGHER ELEVATIONS OF THE NWRN TX PANHANDLE/WRN OK PANHANDLE DURING
THE AFTERNOON HOURS. HEAVIEST SNOWFALL RATES AROUND 2 IN/HR WILL
REMAIN OVER THE NRN UPSLOPE REGION OF THE RATON MESA /LAS ANIMAS
COUNTY CO...NCENTRAL/NERN COLFAX COUNTY NM/ THROUGH 21Z.

[CaptinCrunch]

MESOSCALE DISCUSSION 0457
NWS STORM PREDICTION CENTER NORMAN OK
1140 AM CST THU MAR 31 2005

AREAS AFFECTED...SERN LA AND EXTREME SRN MS

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 311740Z - 311945Z



SERN LA IS BEING MONITORED FOR THUNDERSTORM INITIATION. SUPERCELLS
WITH LARGE HAIL APPEAR TO BE THE PRIMARY THREAT. WW WILL LIKELY BE
ISSUED SOON.

LATE THIS MORNING...A CONVECTIVE OUTFLOW BOUNDARY EXTENDS FROM THE
BOOTHEEL OF MS WWD INTO SERN LA. THE SERN PART OF THIS BOUNDARY IS
MOVING SWD WHILE THE WRN PART OVER SRN LA HAS STALLED. RICH LOW
LEVEL MOISTURE BELOW STEEP MID LEVEL LAPSE RATES WILL CONTRIBUTE TO
STRONG INSTABILITY...ESPECIALLY AS LOW CLOUDS BEGIN TO MIX OUT.
MLCAPE FROM 2500 TO 3000 J/KG APPEARS LIKELY. WITH ONLY A WEAK CAP
IN PLACE...PERSISTENT CONVERGENCE AND DESTABILIZATION IN THE
VICINITY OF THE BOUNDARY MAY CONTRIBUTE TO THUNDERSTORM INITIATION
WITHIN THE NEXT COUPLE HOURS. LOW LEVEL FLOW/SHEAR IS RATHER WEAK.
HOWEVER...THE SHEAR THROUGH A DEEPER LAYER AND MAGNITUDE OF CAPE IS
MORE THAN SUFFICIENT FOR SUPERCELLS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0458
NWS STORM PREDICTION CENTER NORMAN OK
1208 PM CST THU MAR 31 2005

AREAS AFFECTED...PARTS OF SOUTH TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 311808Z - 312015Z



ISOLATED SVR STORMS MAY DEVELOP ALONG SFC TROUGH/DRYLINE IN THE
VICINITY OF SAT WITHIN THE NEXT 1-2 HOURS. A WW MAY BE NEEDED IF
CURRENT TRENDS CONTINUE.

18Z SFC ANALYSIS SHOWS A 1010 MB LOW LOCATED JUST NW OF SAT. A SFC
TROUGH/DRYLINE EXTENDS NE-SW FROM THE LOW FROM SE OF DRT TO NEAR
AUS. ALTHOUGH DEPTH OF MOISTURE AHEAD OF THIS TROUGH WAS LIMITED TO
BELOW 850 MB...WARM TEMPERATURES IN THE 80S AND DEWPTS IN THE LOWER
60S WILL CONTRIBUTE TO 1500-2000 J/KG OF MUCAPE AND MINIMAL CINH
AHEAD OF THE TROUGH/LOW BY 20Z. THE DECREASING CINH FIELDS ARE NOTED
BY MORE VIGOROUS CUMULUS GROWTH ALONG THE TROUGH AXIS DURING THE
LAST HOUR. HOWEVER...VERY DRY MID LEVELS EVIDENT BY WV IMAGERY WILL
LEAD TO SIGNIFICANT DRY AIR ENTRAINMENT INTO UPDRAFTS...AND MAY
LIMIT MORE VIGOROUS CONVECTIVE DEVELOPMENT...AS THE SHORT TERM MODEL
SUITES SUGGEST WITH LACK OF CONVECTIVE PRECIP IN THE NEXT 3 HOURS.
HOWEVER...IF CURRENT TRENDS CONTINUE AND STORMS DO INDEED
INITIATE...THE DEGREE OF MID LEVEL FLOW/DEEP LAYER SHEAR COMBINED
WITH STEEP BOUNDARY LAYER LAPSE RATES WILL SUPPORT THE THREAT FOR
SVR WIND/HAIL.

[CaptinCrunch]

MESOSCALE DISCUSSION 0460
NWS STORM PREDICTION CENTER NORMAN OK
0215 PM CST THU MAR 31 2005

AREAS AFFECTED...CENTRAL/ERN TX...NWRN LA AND FAR SCENTRAL/SERN OK

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 312015Z - 312215Z



THUNDERSTORMS ARE EXPECTED TO DEVELOP BY 00Z OVER THE AREA...WITH
THE GREATEST SVR POTENTIAL EXPECTED OVER PORTIONS OF CENTRAL/NERN TX
EVENTUALLY SPREADING INTO NWRN LA AFTER DARK. A WW MAY BE NEEDED FOR
THIS AREA BEFORE 00Z.

INCREASING ISENTROPIC LIFT IN THE 850-600 MB LAYER OVER
NCENTRAL/NERN TX/SCENTRAL OK WAS EVIDENT BY EXPANDING MID LEVEL
CLOUD DECK. SFC ANALYSIS SHOWS BOUNDARY LAYER MOISTURE SLOWLY
EXPANDING NWWD ACROSS ERN TX...TO THE WEST OF A DRYLINE/LEE TROUGH
EXTENDING ALONG THE I-35 CORRIDOR AT 20Z. RECENT RUC SOUNDINGS
INDICATE THAT MLCINH HAS DECREASED TO LESS THAN 25 J/KG OVER
ECENTRAL TX IN THE VICINITY OF TYR AND OVER CENTRAL TX IN THE
VICINITY OF TEMPLE/CLL. THE COMBINATION OF A DEVELOPING SFC LOW IN
THIS AREA ENHANCING LOW LEVEL CONVERGENCE AND ANOTHER 1-2 HOURS OF
HEATING AND MOISTENING IN THE LOWER LEVELS MAY BE SUFFICIENT FOR
THUNDERSTORMS INITIATION IN THIS AREA BY 00Z. INSTABILITY WILL BE
MEAGER /LESS THAN 500 J/KG OF MUCAPE/ ACROSS FAR SCENTRAL/SERN OK/
AND FAR NERN TX. HOWEVER...STRENGTH OF CLOUD LAYER SHEAR AND COLDER
MID LEVEL PROFILES MAY BE SUFFICIENT FOR ISOLATED LARGE HAIL WITH
ANY STORMS THAT DEVELOP IN THIS AREA. FARTHER SOUTH OVER THE
REMAINDER OF NERN TX/ECENTRAL TX...GREATER INSTABILITY /1000-1500
MUCAPE/ WILL EXIST AND THIS IS WHERE A WW WOULD MOST LIKELY BE
NEEDED BY LATE THIS AFTERNOON.

[CaptinCrunch]

MESOSCALE DISCUSSION 0461
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CST THU MAR 31 2005

AREAS AFFECTED...WRN/CENTRAL OK

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 312059Z - 312300Z



ISOLATED SVR STORMS CAPABLE OF PRODUCING LARGE HAIL WILL LIKELY
DEVELOP FROM WCENTRAL INTO CENTRAL/SCENTRAL OK BETWEEN 22-00Z.
OVERALL THREAT AND CONVECTIVE COVERAGE COULD BE SUFFICIENT THAT A
SVR WW MAY BE NEEDED BY 22Z.

RECENT RUC FORECAST SOUNDINGS INDICATE THAT AROUND 500 J/KG OF
MUCAPE EXTENDED ALONG AN AXIS FROM ADM TO OUN TO CSM...WHERE
TEMPERATURES WERE AROUND 70 AND DEWPTS WERE IN THE 38-44 DEGREE
RANGE. STEEP MID LEVEL LAPSE RATES NEAR UPPER LOW CENTER WILL
SUPPORT LARGE HAIL UP TO AROUND 1 INCH. DEGREE OF STRONG ISENTROPIC
LIFT COUPLED WITH SWD MOVING COLD FRONT WILL AID IN CONVECTIVE
DEVELOPMENT FROM WCENTRAL OK INTO CENTRAL/SCENTRAL OK BETWEEN
22-00Z.

[CaptinCrunch]

MESOSCALE DISCUSSION 0462
NWS STORM PREDICTION CENTER NORMAN OK
0327 PM CST THU MAR 31 2005

AREAS AFFECTED...SRN LA THROUGH EXTREME SRN MS

CONCERNING...SEVERE THUNDERSTORM WATCH 114...

VALID 312127Z - 312300Z



POTENTIAL FOR THUNDERSTORM INITIATION IS EXPECTED TO INCREASE NEXT 1
TO 2 HOURS. ONCE STORMS DEVELOP...LARGE HAIL IS EXPECTED TO BE THE
MAIN THREAT.

A STATIONARY CONVECTIVE OUTFLOW BOUNDARY EXTENDS FROM JUST S OF
MOBILE AL WWD THROUGH SRN LA JUST S OF NEW ORLEANS...THEN FARTHER
WWD TO JUST S OF LAKE CHARLES. THE ATMOSPHERE NEAR AND S OF THIS
BOUNDARY REMAINS QUITE UNSTABLE WITH RICH LOW LEVEL MOISTURE AND
STEEP MID LEVEL LAPSE RATES SUPPORTING MLCAPE FROM 2000 TO 2500
J/KG. HOWEVER...THE BOUNDARY LAYER HAS REMAINED CLOUDY MUCH OF THE
DAY. THIS ALONG WITH SHORTWAVE RIDGING ALOFT...WEAK LOW LEVEL
FORCING AND POSSIBLE ENTRAINMENT ASSOCIATED WITH DEEP DRY AIR
PRESENT IN THE MID LEVELS HAVE LIKELY DELAYED THE DEVELOPMENT OF
DEEP CONVECTION. HOWEVER...CURRENT VISIBLE IMAGERY IS SHOWING AN
INCREASE IN CONVECTIVE TOWERS ALONG THE BOUNDARY ACROSS SRN LA.
MOREOVER...THE LOW LEVEL FLOW SHOULD BEGIN TO STRENGTHEN LATER THIS
AFTERNOON INTO THE EVENING...WHICH SHOULD ENHANCE LIFT AND POTENTIAL
FOR ADDITIONAL DEVELOPMENT IN THE VICINITY OF THE BOUNDARY.

[CaptinCrunch]

MESOSCALE DISCUSSION 0464
NWS STORM PREDICTION CENTER NORMAN OK
0517 PM CST THU MAR 31 2005

AREAS AFFECTED...SCENTRAL/SERN TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 312317Z - 010115Z



ISOLATED SVR STORMS CAPABLE OF LARGE HAIL/DAMAGING WINDS MAY DEVELOP
FROM THE I-35 CORRIDOR BETWEEN AUS/SAT IN THE NEXT 1-2 HOURS. IF
COVERAGE CONTINUES TO INCREASE...A SMALL WW MAY BE NEEDED SOUTH OF
WW 115.

LATEST VIS IMAGERY SHOWS TOWERING CU NOW FROM AUS TO SAT ALONG SFC
TROUGH. INCREASING WNWLY FLOW TO THE WEST OF DRYLINE/TROUGH WILL AID
IN SUFFICIENT CONVERGENCE...THAT GIVEN WEAK CINH...ISOLATED SVR
STORMS MAY DEVELOP WITHIN THIS ACTIVITY IN THE NEXT HOUR. AREA
REMAINS RELATIVELY DISPLACED FROM STRONGER UPPER LEVEL
FORCING/COLDER TEMPERATURES ALOFT...AND GIVEN WEAK STORM RELATIVELY
INFLOW INTO THIS AREA...CONVECTION MAY END UP WEAKENING WITHIN AN
HOUR OR TWO OF SUNSET BEFORE APPROACHING THE HOU METRO AREA. TRENDS
WILL CONTINUE TO BE MONITORED FOR A POSSIBLE WW.

[CaptinCrunch]

MESOSCALE DISCUSSION 0463
NWS STORM PREDICTION CENTER NORMAN OK
0443 PM CST THU MAR 31 2005

AREAS AFFECTED...ERN TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 312243Z - 312345Z



ISOLATED SVR THUNDERSTORMS ARE STILL EXPECTED TO DEVELOP BY 00Z. A
WW WILL BE ISSUED BY 23Z FOR MUCH OF E/NE TX.

INCREASING ASCENT AHEAD OF WRN TX UPPER TROUGH EVIDENT BY HIGH BASED
THUNDERSTORM ACTIVITY INCREASING TO THE WEST OF A DRYLINE/TROUGH
EXTENDING ALONG THE I-35 CORRIDOR WILL CONTINUE TO OVERSPREAD MOIST
SECTOR EAST OF I-35 IN THE NEXT FEW HOURS. FORECAST SOUNDINGS
INDICATE SUFFICIENT INSTABILITY COUPLED WITH MODERATE SHEAR OF 40-50
KTS TO SUPPORT ROTATING STORMS CAPABLE OF LARGE HAIL/DAMAGING WINDS.
TWO SCENARIOS FOR SVR CONVECTIVE DEVELOPMENT ARE POSSIBLE IN THE
NEXT 1-2 HOURS. 1) HIGH BASED CONVECTION CURRENTLY IN DRY AIR WILL
MOVE EAST INTO MOIST AXIS OVER ERN TX AND BECOME ROOTED IN MORE
UNSTABLE BOUNDARY LAYER. OR 2) THE FORCING FOR THE HIGH BASED
CONVECTION ACTS ENHANCE CONVERGENCE ALONG LEE TROUGH/SFC LOW OVER
NERN TX AND AID IN SFC BASED CONVECTIVE DEVELOPMENT ALONG LEE TROUGH
AND NW-SE WARM FRONT OVER ECENTRAL/NERN TX.

RELATIVELY WEAK LOW LEVEL SHEAR ANTICIPATED TO LAST THROUGH AROUND
03Z WILL LIMIT THE POTENTIAL FOR TORNADOES. THUS GIVEN A 4 HOUR
WINDOW OF MAINLY WIND/HAIL THREAT...WW WILL LIKELY BE SVR.

[CaptinCrunch]

MESOSCALE DISCUSSION 0475
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CST FRI APR 01 2005

AREAS AFFECTED...CENTRAL AND ERN FL PANHANDLE AND NRN FL INTO SRN GA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 011344Z - 011545Z



SEVERE THREAT IS EXPECTED TO INCREASE ACROSS PARTS OF NRN FL / THE
FL PANHANDLE INTO SRN GA. WE WILL CONTINUE TO MONITOR AIRMASS
DESTABILIZATION ACROSS THIS REGION...AND ASSOCIATED POTENTIAL FOR
NEW WW IN THE NEXT 1 TO 2 HOURS.

LATEST RADAR REFLECTIVITY LOOP SHOWS MESOLOW DEVELOPING OVER S
CENTRAL AL ATTM. STORMS WHICH WERE EARLIER OVER SRN LA / SRN MS /
SRN AL HAVE EVOLVED INTO A BOW-SHAPED ECHO S OF THIS MESOLOW /
ACROSS WRN PORTIONS OF THE FL PANHANDLE.

THOUGH BOUNDARY-LAYER AIRMASS REMAINS STABLE ATTM AS OUTFLOW
BOUNDARY REMAINS OFF THE FL PANHANDLE COAST IN THE NERN GULF...THIS
BOUNDARY SHOULD RETURN NWD AS A WARM FRONT AS SURFACE WIND INCREASES
FROM THE S AHEAD OF MESOLOW. AS BOUNDARY LAYER RETREATS AND LIMITED
HEATING COMMENCES THROUGH BREAKS IN OVERCAST...DESTABILIZING
BOUNDARY LAYER SHOULD ALLOW BOWING LINE OF STORMS TO BECOME
INCREASINGLY SURFACE-BASED. THUS...GIVEN FAVORABLY-STRONG
DEEP-LAYER WIND FIELD OBSERVED ACROSS THIS REGION...EXPECT THREAT
FOR DAMAGING WINDS TO INCREASE OVER THE NEXT COUPLE OF HOURS --
POSSIBLY REQUIRING WW ISSUANCE.

[CaptinCrunch]

MESOSCALE DISCUSSION 0476
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CST FRI APR 01 2005

AREAS AFFECTED...NE MS/FAR NRN AL INTO MIDDLE TN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 011716Z - 011945Z



LARGE HAIL THREAT EXPECTED TO DEVELOP THROUGH EARLY AFTERNOON ACROSS
NE MS/FAR NRN AL INTO MIDDLE TN. ALTHOUGH WW NOT CURRENTLY
ANTICIPATED...CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED.

WATER VAPOR/VISIBLE SATELLITE IMAGERY DEPICTS SHORTWAVE IMPULSE
PROGRESSING EWD ACROSS THE OZARKS...WITH BUILDING CB/S DURING THE
PAST HALF HOUR ATOP LOWER CLOUD DECK ACROSS FAR NRN MS. GIVEN EWD
PROGRESSION OF DYNAMIC ASCENT...SIMILAR DEVELOPMENT TREND EXPECTED
TO CONTINUE E/NE ACROSS FAR NRN AL INTO MIDDLE TN ALONG/NORTH OF SFC
BAROCLINIC ZONE. CONDITIONAL HAZARD OF LARGE HAIL WILL EXIST AS MID
LEVEL LAPSE RATES CONTINUE TO STEEPEN THROUGH EARLY AFTERNOON...WITH
15Z RUC SOUNDINGS DEPICTING AS MUCH AS 500-750 J/KG OF ELEVATED
MUCAPE AMIDST SUFFICIENT CLOUD BEARING SHEAR.

[CaptinCrunch]

MESOSCALE DISCUSSION 0477
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CST FRI APR 01 2005

AREAS AFFECTED...ERN MS THROUGH WRN AND CNTRL AL

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 011720Z - 011915Z



SURFACE BASED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON OVER PORTIONS OF ERN MS/WRN AL AND CONTINUE EWD INTO THE
EVENING. A WW WILL LIKELY BE NEEDED FOR THIS AREA BY EARLY
AFTERNOON.

A NEAR STATIONARY SURFACE FRONT EXTENDS ACROSS NRN AL THEN SWWD AS A
COLD FRONT THROUGH CNTRL/WRN MS. SURFACE HEATING IN THE WAKE OF
EARLIER MCS WILL CONTRIBUTE TO STEEPENING LOW LEVEL LAPSE RATES AND
DESTABILIZATION FROM ERN MS THROUGH AL. THE RICHER LOW LEVEL
MOISTURE HAS BEEN SHIFTED OFFSHORE S OF CONVECTIVE OUTFLOW...BUT
RESIDUAL BOUNDARY LAYER MOISTURE WITH DEWPOINTS IN THE LOW 60S
SHOULD BE SUFFICIENT FOR MODERATE INSTABILITY THIS AFTERNOON GIVEN
RELATIVELY COOL MID LEVEL TEMPERATURE PROFILES. FORCING FOR ASCENT
ALONG FRONT AND AHEAD OF UPPER SPEED MAX/VORTICITY CENTER WILL
SPREAD EWD INTO THE DESTABILIZING ATMOSPHERE AND SHOULD CONTRIBUTE
TO SURFACE BASED THUNDERSTORM DEVELOPMENT BY EARLY AFTERNOON. THE
LOW LEVEL JET WILL STRENGTHEN THROUGH AL AHEAD OF THE SHORTWAVE
TROUGH...AND VERTICAL SHEAR PROFILES WILL SUPPORT SUPERCELLS.
INITIAL STORMS WILL LIKELY BE DISCRETE SUPERCELLS. HOWEVER... STORMS
DEVELOPING ALONG THE FRONT WILL LIKELY EVOLVE INTO LINES WITH
EMBEDDED SUPERCELLS AND BOWING STRUCTURES. OTHER MORE PERSISTENT
DISCRETE STORMS MAY ALSO DEVELOP IN WARM SECTOR AHEAD OF THE FRONT.

[CaptinCrunch]

MESOSCALE DISCUSSION 0478
NWS STORM PREDICTION CENTER NORMAN OK
0116 PM CST FRI APR 01 2005

AREAS AFFECTED...SRN GA THROUGH NRN FL

CONCERNING...TORNADO WATCH 121...

VALID 011916Z - 012115Z



THREAT FOR ISOLATED DAMAGING WIND AND ISOLATED TORNADOES IS EXPECTED
TO PERSIST INTO THE AFTERNOON FROM THE CNTRL AND ERN FL PANHANDLE
EWD INTO NRN FL AND EXTREME SRN GA.

A SQUALL LINE EXTENDS FROM SRN GA SWWD THROUGH THE CNTRL AND ERN FL
PANHANDLE. STRONGEST STORMS WITHIN THE LINE EXTEND FROM JUST SE OF
TALLAHASSEE SWWD TO NEAR APALACHICOLA...MOVING EAST AT 35 KT. THE
ATMOSPHERE NEAR AND S OF THIS BOUNDARY CONTINUES TO DESTABILIZE AS
TEMPERATURES WARM INTO THE 80S AND DEWPOINTS RISE INTO THE MID 60S
WITH MLCAPE FROM 800 TO 1200 J/KG. SURFACE ANALYSIS AND SATELLITE
DATA SHOW AN OUTFLOW BOUNDARY HAS SETTLED SWD INTO NRN FL...AND LOW
LEVEL WINDS JUST N OF THIS BOUNDARY HAVE SHIFTED TO THE NE ACROSS
SRN GA/EXTREME NRN FL. THIS BOUNDARY SHOULD HELP TO FOCUS
CONVERGENCE AND ENHANCE LOW LEVEL SHEAR AS THE STORMS CONTINUE TO
DEVELOP EASTWARD THROUGH NRN FL.

[CaptinCrunch]

MESOSCALE DISCUSSION 0479
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CST FRI APR 01 2005

AREAS AFFECTED...EXTREME E CNTRL MS THROUGH CNTRL AND NRN AL INTO S
CNTRL TN

CONCERNING...SEVERE THUNDERSTORM WATCH 122...

VALID 012100Z - 012230Z



THREAT FOR ISOLATED DAMAGING WIND AND HAIL WILL PERSIST AS SQUALL
LINE MOVES THROUGH AL AND SRN MIDDLE TN NEXT FEW HOURS.

THIS AFTERNOON A SQUALL LINE EXTENDS FROM MIDDLE TN SWWD THROUGH NRN
AL NEAR HUNTSVILLE AND FARTHER SW INTO EXTREME ERN MS NEAR MERIDIAN.
THE LINE IS MOVING EAST AT AROUND 30 KT. DEVELOPING SURFACE LOW OVER
NRN AL ASSOCIATED WITH INCREASING ASCENT WITHIN THE EXIT REGION OF
CYCLONICALLY CURVED UPPER JET HAS PROMOTED INCREASING SSELY LOW
LEVEL FLOW ACROSS CNTRL/NRN AL. HOWEVER...THIS FLOW IS RESULTING IN
LOW LEVEL TRAJECTORIES FROM AIR THAT HAS BEEN PARTIALLY STABILIZED
BY EARLIER MCS. SO DESPITE PARTIAL CLEARING IN WAKE OF THE
MCS...MLCAPE OF ONLY 500 TO 1000 J/KG EXISTS AHEAD OF THE LINE WITH
SURFACE DEWPOINTS AROUND 60. DESPITE THIS LIMITING FACTOR...THE
STRENGTHENING LOW LEVEL JET AND FAVORABLE VERTICAL SHEAR PROFILES
WILL CONTINUE TO SUPPORT ORGANIZED STRUCTURES...INCLUDING
SUPERCELLS...WITHIN THE LINE DURING THE NEXT SEVERAL HOURS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0501
NWS STORM PREDICTION CENTER NORMAN OK
0929 AM CDT WED APR 06 2005

AREAS AFFECTED...PORTIONS S-CENTRAL/SERN LA...S-CENTRAL/SERN
MS...SWRN AL

CONCERNING...TORNADO WATCH 130...

VALID 061429Z - 061630Z



CONTINUE WW. BROKEN LINE OF SUPERCELLS -- SEVERAL WITH HISTORY OF
DAMAGING TORNADOES AND OTHERS POTENTIALLY TORNADIC WITH INTENSE LOW
LEVEL MESOCYCLONES -- EXTENDS FROM LEAKE/NESHOBA COUNTIES MS SWWD
ACROSS TANGIPAHOA PARISH. THIS ACTIVITY SHOULD CONTINUE TO PRODUCE
ALL SEVERE MODES -- INCLUDING THREAT FOR ADDITIONAL STRONG/VIOLENT
TORNADOES -- AS IT SHIFTS EWD TOWARD MSY-PIB-MEI AXIS THROUGH
APPROXIMATELY 16Z. BASED ON MODIFIED 12Z RAOBS AND RUC
SOUNDINGS...WARM SECTOR AIR MASS SHOULD REMAIN CHARACTERIZED IN NEAR
TERM BY 500-1000 J/KG MLCAPE AND LARGE LOW LEVEL HODOGRAPHS -- WITH
ALMOST 400 J/KG SRH IN 0-1 KM AGL LAYER.

14Z SFC MESOANALYSIS SHOWS SHARPLY DEFINED WARM FRONT -- EXTENDING
FROM NEAR PNS NWWD THROUGH NMM TO WINSTON/CHOCTAW COUNTIES...WHERE
IT INTERSECTS PRIMARY CONVECTIVE BAND. WARM FRONT IS EXPECTED TO
MOVE NEWD ABOUT 10 KT. TORNADO POTENTIAL SHOULD DECREASE FOR
INDIVIDUAL TSTMS AFTER THEY CROSS WARM FRONT AND BECOME
PROGRESSIVELY MORE ELEVATED OVER RELATIVELY DRY/STABLE LAYER TO ITS
NE...HOWEVER LARGE HAIL WILL REMAIN POSSIBLE WITH SUCH ACTIVITY.
ADDITIONAL DEVELOPMENT IS UNDERWAY AND SHOULD CONTINUE OVER SWRN
PORTIONS WW -- ACROSS S-CENTRAL LA. AIRMASS OVER WRN PORTION WW
REMAINS FAVORABLE FOR SUPERCELLS DESPITE SOMEWHAT VEERED SFC FLOW
AND SMALLER HODOGRAPHS RELATIVE TO FARTHER E. COLD FRONT REMAINS W
OF WW ACROSS SABINE RIVER AREA...WITH FAVORABLE BUOYANCY REMAINING
ACROSS ENTIRE WW.