MESOSCALE DISCUSSION NWS STORM PREDICTION CENTER

[CaptinCrunch]

MESOSCALE DISCUSSION 0503
NWS STORM PREDICTION CENTER NORMAN OK
1050 AM CDT WED APR 06 2005

AREAS AFFECTED...PORTIONS SWRN/S-CENTRAL AL...WRN FL PANHANDLE

CONCERNING...SEVERE TSTM POTENTIAL...TORNADO WATCH 130...

VALID 061550Z - 061645Z



SEVERE POTENTIAL WILL INCREASE FROM ERN EDGE OF WW 130 ACROSS SRN AL
AND WRN FL PANHANDLE THROUGH EARLY AFTERNOON. REPLACEMENT FOR WW
130 IS BEING PREPARED THAT INCLUDES MUCH OF THIS REGION.

EXPECT AIR MASS TO FURTHER DESTABILIZE...JUST INSIDE ERN GRADIENT OF
VERTICAL SHEAR ENVIRONMENT OPTIMALLY FAVORABLE FOR SUPERCELLS AND
TORNADOES. THIS KINEMATIC TRANSITION ZONE APPEARS TO BE SOMEWHERE
OVER W-CENTRAL FL PANHANDLE INVOF PAM/VPS...BASED ON COMPARISON
BETWEEN TLH VWP TRENDS...12Z TLH/SIL RAOBS...AND MOB VWP. SFC
MESOANALYSIS SHOWS WARM FRONT INTERSECTING LEADING CONVECTIVE BAND
INVOF NMM...SEWD ACROSS SERN AL TO NEAR VPS THEN SEWD ACROSS NERN
GULF. WARM FRONT SHOULD LIFT NWD 10-15 KT. ASSOCIATED WAA AND
MOIST ADVECTION WILL COMBINE WITH SFC DIABATIC HEATING TO WEAKEN
CINH TO UNDER 50 J/KG AND RAISE MLCAPES TO 1000-1500 K/KG RANGE OVER
NEXT SEVERAL HOURS. EXPECT FAVORABLE DEEP-LAYER SHEAR TO SHIFT EWD
ONLY SLOWLY -- GIVEN CHARACTER OF DEEP-LAYER CYCLONE TO THE NW AS
STACKED...SLOW-MOVING AND INCREASINGLY BAROTROPIC. HOWEVER...LOW
LEVEL HODOGRAPHS WILL REMAIN CHARACTERIZED BY 150-250 J/KG SRH IN
0-1 KM AGL LAYER...AND 0-3 KM SRH APCHG 300 J/KG ALONG AND S OF WARM
FRONT.

[CaptinCrunch]

MESOSCALE DISCUSSION 0502
NWS STORM PREDICTION CENTER NORMAN OK
1040 AM CDT WED APR 06 2005

AREAS AFFECTED...PORTIONS NERN LA...SERN AR...W-CENTRAL/NWRN MS

CONCERNING...SEVERE TSTM POTENTIAL...TORNADO WATCH 130...

VALID 061540Z - 061645Z



AIR MASS IS DESTABILIZING OVER DISCUSSION AREA...BETWEEN NWRN
PORTION WW AND SFC COLD FRONT...IN VERTICAL SHEAR ENVIRONMENT
FAVORABLE FOR SUPERCELLS. REPLACEMENT FOR WW 130 IS BEING PREPARED
THAT INCLUDES MUCH OF THIS REGION.

TORNADO POTENTIAL WILL BE MAXIMIZED E OF SFC CONFLUENCE LINE...WHICH
IS ANALYZED ROUGHLY FROM HEZ NWD UP MS RIVER TO NEAR GLH...THEN NWWD
TOWARD INTERSECTION WITH WARM FRONT NEAR SGT. EXPECT WARM FRONT TO
LIFT NWD 10-15 KT WHILE CONFLUENCE LINE MOVES EWD 10-15 KT ALSO.
HODOGRAPHS BETWEEN CONFLUENCE LINE AND WARM FRONT ARE RELATIVELY
LARGE WITH 0-1 SRH 200-300 J/KG AND 0-3 KM SRH 300-500 J/KG...BASED
ON MODIFIED RUC SOUNDINGS. SFC DIABATIC HEATING AND CONTINUED
MOISTURE TRANSPORT WILL RAISE MLCAPES INTO 1000-1500 J/KG RANGE BY
EARLY AFTERNOON. COLD FRONT IS ANALYZED FARTHER W...EXTENDING FROM
OCCLUSION POINT NEAR LIT SWD TO NEAR ELD THEN SSWWD TO NEAR
GLS...AND WILL MOVE EWD ABOUT 15 KT. AIR MASS BETWEEN CONFLUENCE
LINE AND COLD FRONT SHOULD REMAIN SIMILARLY UNSTABLE AS THAT FARTHER
E...BUT WITH SOMEWHAT SMALLER LOW LEVEL SHEARS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0504
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CDT WED APR 06 2005

AREAS AFFECTED...PORTIONS CENTRAL/NRN AR...SWRN AND EXTREME
S-CENTRAL MO...EXTREME NERN OK

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 061746Z - 061945Z



TSTMS ARE EXPECTED TO INCREASE GRADUALLY OVER NEXT 2-3 HOURS -- IN
BOTH COVERAGE AND INTENSITY. HAIL APPEARS TO BE POSSIBLE...ALONG
WITH A FEW BRIEF/SMALL TORNADOES. AREA WILL BE MONITORED FOR
POSSIBLE WW.

SFC MESOANALYSIS SHOWS CYCLONE BETWEEN TUL-MLC...VERTICALLY STACKED
WITH INCREASINGLY BAROTROPIC MID/UPPER LEVEL VORTEX. OCCLUDED FRONT
EXTENDS EWD THEN ESEWD ACROSS SRN OZARK PLATEAU TO OCCLUSION TRIPLE
POINT NEAR WRN WHITE COUNTY AR...WITH WARM FRONT SEWD ACROSS MS AND
COLD FRONT SWD INTO NRN LA. OCCLUDED FRONT SHOULD LIFT NWD 10-15 KT
THROUGH REMAINDER AFTERNOON...ALSO FORMING EFFECTIVE DIFFERENTIAL
HEATING BOUNDARY BETWEEN CLOUDIER/SHOWERY CONDITIONS TO ITS N AND
DRY SLOT FARTHER S. MOST ACTIVITY SHOULD REMAIN ALONG AND N OF THIS
FRONT OVER MO/AR..WHERE VIS IMAGERY SHOWS INCREASING VERTICAL
DEVELOPMENT TO CUMULIFORM CLOUDS ATTM. DEEP-LAYER SHEAR INCREASES
WITH EWD EXTENT FROM CYCLONE CENTER...INCREASING POTENTIAL FOR STORM
ROTATION OVER CENTRAL/ERN OZARKS. HOWEVER...THIS AREA WILL BE
SLOWER TO DESTABILIZE THAN PORTIONS NWRN AR AND PERHAPS NERN
OK...WHERE SFC DIABATIC HEATING WILL COMBINE WITH MIDLEVEL COLD CORE
TO STEEPEN LAPSE RATES. EXPECT 300-800 J/KG MLCAPE INVOF OK/AR
BORDER...ESEWD ALONG OCCLUDED FRONT.

ALTHOUGH LOW LEVEL WIND FIELDS AND VERTICAL SHEAR ARE WEAK NEAR
CYCLONE CORE...HAIL IS POSSIBLE. ALSO...NONSUPERCELL TORNADOES
CANNOT BE RULED OUT ALONG LINES OF VORTICITY AND HORIZONTAL SHEAR
INTERACTING WITH MOST VIGOROUS CONVECTIVE TOWERS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0505
NWS STORM PREDICTION CENTER NORMAN OK
0121 PM CDT WED APR 06 2005

AREAS AFFECTED...PORTIONS S-SCENTRAL SERN LA...CENTRAL/SRN
MS...EXTREME SERN AR...SRN AL...WRN FL PANHANDLE

CONCERNING...TORNADO WATCH 131...132...

VALID 061821Z - 061945Z



PRIMARY BAND OF TSTMS -- EXTENDING AT 18Z FROM TERREBONNE PARISH
ENEWD ACROSS PLAQUEMINES PARISH...CHANDELEUR ISLANDS...APCHG MOB
AREA...NWD TO MS/AL BORDER E OF MEI. SEVERAL STORMS WITHIN THIS
LINE HAVE PRODUCED TORNADOES AND WIND DAMAGE IN PAST COUPLE HOURS.
THIS ACTIVITY WILL CONTINUE MOVING ENEWD TO NEWD FROM WW 131 INTO
MORE OF WW 132...AND MOVING INTO FAVORABLY BUOYANT/SHEARED INFLOW
ENVIRONMENT. EMBEDDED BOWS AND SUPERCELLS ARE LIKELY TO CONTINUE
WITH THIS LINE...EACH MODE CARRYING TORNADO AND WIND DAMAGE THREAT.
DAMAGING HAIL WILL BE MORE PROBABLE WITH SUPERCELLS.

VERTICAL SHEAR IS EXPECTED TO INCREASE WITH TIME OVER ERN PORTIONS
OF WW 132...MATCHING CURRENT VALUES JUST AHEAD OF LINE SUCH
AS...55-60 KT 0-6 KM SHEAR...AND ROUGHLY 500 J/KG SRH IN 0-3...0-1
AND EFFECTIVE LAYERS. MODIFIED JAN RAOB AND FCST SOUNDINGS INDICATE
PRE-STORM AIR MASS OVER WW 132 IS CHARACTERIZED BY MODEST LAPSE
RATES OF AROUND 6.5 DEG C/KM BUT DEEP BUOYANT LAYER...RESULTING IN
MLCAPES AROUND 1000 J/KG. SIMILAR CONDITIONS EXTEND W OF PRIMARY
CONVECTIVE BAND TO CONFLUENCE LINE -- ANALYZED ALONG LINE FROM
HUM...HEZ...GLH...TO WARM FRONTAL INTERSECTION 50 SW MEM. WARM
FRONT CONTINUES LIFTING NWD OVER NWRN AND E-CENTRAL MS...AND IS
REDEVELOPING IN DRIER AIR ACROSS SERN AL NEAR MGM/AUO. ADDITIONAL
DEVELOPMENT IS UNDERWAY OVER MUCH OF WW 131 E OF CONFLUENCE
LINE...SOME OF WHICH ALSO MAY BECOME TORNADIC.

ACTIVITY ACROSS W-CENTRAL AND SWRN AL...AWAY FROM COAST...MAY BECOME
MORE OUTFLOW DOMINANT AS IT MOVES INTO RELATIVELY DRY AIR MASS AND
DEEPER MIXED LAYERS...CHARACTERIZED BY SFC DEW POINTS LOW 60S/UPPER
50S F.

[CaptinCrunch]

MESOSCALE DISCUSSION 0506
NWS STORM PREDICTION CENTER NORMAN OK
0231 PM CDT WED APR 06 2005

AREAS AFFECTED...FAR SERN MN...CENTRAL/SRN WI...NERN IA...AND
CENTRAL LOWER MI

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 061931Z - 062200Z



THUNDERSTORM DEVELOPMENT EXPECTED TO INCREASE ALONG AN EAST-WEST
AXIS FROM FAR SERN MN ACROSS SRN WI. ISOLATED THUNDERSTORM
DEVELOPMENT ALSO POSSIBLE ACROSS CENTRAL LOWER MI THROUGH EARLY
EVENING. THREAT EXISTS FOR ISOLATED LARGE HAIL WITH STRONGER CELLS.
MARGINAL/ISOLATED NATURE OF THREAT SUGGESTS WW WILL LIKELY NOT BE
NECESSARY IN THE SRN GREAT LAKES REGION.

SFC ANALYSIS AT 19Z INDICATES A QUASI-STATIONARY FRONT EXTENDING
FROM 45SE RST TO 30 S OSH TO 40 SE MBL TO SOUTH OF SAGINAW BAY. AIR
MASS WAS WARMED INTO THE LOW TO MID 70S SOUTH OF THE FRONT...WITH
DEWPOINTS IN THE MID 40S TO LOW 50S CONTRIBUTING TO SBCAPE VALUES OF
AROUND 1000 J/KG. IT APPEARS THAT NRN STREAM SHORTWAVE TROUGH NEAR
WRN END OF LAKE SUPERIOR WILL HAVE SOME INFLUENCE ON VERTICAL MOTION
FIELD ACROSS CENTRAL/WRN WI AS IT PROGRESSES EWD THROUGH THIS
EVENING. WITH MUCH OF IA/WI IN DEFORMATION ZONE BETWEEN SRN PLAINS
UPPER LOW AND NRN STREAM SHORTWAVE...0-6KM SHEAR IS MARGINAL
/20-25KT/ FOR ORGANIZED CONVECTION. HOWEVER...STEEP LOW-MID LEVEL
LAPSE RATES SUGGEST PULSE OR MULTICELLULAR CONVECTION THAT MAY
CONTAIN SEVERE HAIL. CONVERGENCE ALONG FRONTAL ZONE/LAKE BREEZE
BOUNDARIES AND ENHANCED BY UPPER WAVE SHOULD PROVIDE A FOCUS FOR
ISOLATED THUNDERSTORMS THROUGH THE REMAINDER OF THE DAYTIME HOURS.
EXPECTED HAIL THREAT SHOULD REMAIN MARGINAL ENOUGH TO PRECLUDE WW
ISSUANCE.

[CaptinCrunch]

MESOSCALE DISCUSSION 0516
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT THU APR 07 2005

AREAS AFFECTED...ERN FL PANHANDLE / NRN FL

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL

VALID 071252Z - 071445Z



THUNDERSTORMS CONTINUE MOVING SLOWLY EWD ACROSS THE E CENTRAL AND
NERN GULF OF MEXICO NNEWD ACROSS THE ERN FL PANHANDLE INTO E CENTRAL
AND SERN GA. ALONG WITH ONGOING THREAT FOR HEAVY RAIN...LIMITED
SEVERE THREAT WILL CONTINUE ACROSS THE FL COASTAL BEND AND
EVENTUALLY INTO N FL.

MODERATELY-STRONG / VEERING DEEP-LAYER WIND FIELD IS REVEALED BY
AREA VWPS AND AREA 12Z RAOBS. THOUGH INSTABILITY REMAINS
LIMITED...PERSISTENT TRAINING OF STORMS CONTINUES ACROSS PARTS OF
THE FL PANHANDLE AND INTO GA.

CONVECTION HAS SHOWN A SLIGHT EWD ACCELERATION OVER THE PAST 1-2
HOURS...INCLUDING PERSISTENT / LARGE SUPERCELL JUST SW OF AAF
/APALACHICOLA FL/. INLAND AIRMASS REMAINS ONLY MARGINALLY
UNSTABLE...AND UPPER CLOUDS ASSOCIATED WITH ERN GULF CONVECTION
SHOULD SPREAD EWD LIMITING DAYTIME HEATING ACROSS N FL.
NONETHELESS...WITH STORMS LIKELY MOVING ONSHORE OVER COASTAL NWRN FL
OVER THE NEXT 1 TO 2 HOURS...AT LEAST SOME THREAT FOR LOCALLY
DAMAGING WINDS OR AN ISOLATED TORNADO SHOULD EXIST.

IN ADDITION...LOCALLY HEAVY RAINFALL WILL CONTINUE...THOUGH ONGOING
THREAT MAY BE MITIGATED TO SOME EXTENT BY SOMEWHAT MORE RAPID EWD
MOTION OF CONVECTIVE LINE EXHIBITED RECENTLY.

[CaptinCrunch]

MESOSCALE DISCUSSION 0517
NWS STORM PREDICTION CENTER NORMAN OK
1103 AM CDT THU APR 07 2005

AREAS AFFECTED...PORTIONS W-CENTRAL/NWRN GA...E-CENTRAL THROUGH
N-CENTRAL/NERN AL...MIDDLE/SERN TN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 071603Z - 071800Z



TSTMS FCST TO DEVELOP AND INCREASE IN COVERAGE ACROSS THIS REGION
OVER NEXT SEVERAL HOURS...WITH POTENTIAL FOR OCCASIONAL HAIL AND
STRONG-SEVERE GUSTS. SMALL/BRIEF TORNADOES ALSO CANNOT BE RULED
OUT. AREA WILL BE MONITORED FOR POSSIBLE WW.

AMIDST CLOUD BREAKS...DIABATIC HEATING IS CONTRIBUTING TO BOUNDARY
LAYER DESTABILIZATION AND RAPIDLY DIMINISHING CINH ACROSS THIS
REGION. MODIFIED FFC RAOB AND RUC FCST SOUNDINGS INDICATE PARCELS
SHOULD BE SFC BASED ATTM. MLCAPES SHOULD RISE INTO 500-1000 J/KG
RANGE...AS SFC TEMPS RISE THROUGH MID 60S/LOWER 70S F WITH DEW
POINTS GENERALLY UPPER 50S/LOW 60S. DEEP LAYER AND LOW LEVEL SHEAR
PROFILES INCREASE WITH DISTANCE FROM DEEP-TROPOSPHERIC CYCLONE --
NOW EVIDENT IN SFC ANALYSIS...REFLECTIVITY LOOPS AND WATER VAPOR
IMAGERY OVER WRN TN. THIS SHEAR PATTERN IS EVIDENT IN CURRENT VWP
DATA. FCST HODOGRAPHS FROM RUC ALSO EXPAND WITH SEWD EXTENT OVER
REGION...WITH 0-1 KM SRH LESS THAN 50 J/KG IN MID TN BUT EXCEEDING
200 J/KG AROUND ATL...IN 17-19Z TIME FRAME. THEREFORE...
PROBABILITY OF DISCRETE SUPERCELLS WILL BE GREATER OVER GA AND
ADJACENT AL BORDER PORTION OF AREA THAN N-CENTRAL AL OR MIDDLE TN.
NEGATIVE SFC THETAE ADVECTION ASSOCIATED WITH SFC FRONT -- NOW
MOVING EWD ACROSS EXTREME WRN AL -- SHOULD REDUCE SEVERE POTENTIAL
FROM W-E ACROSS NRN AL THIS AFTERNOON.

[CaptinCrunch]

MESOSCALE DISCUSSION 0518
NWS STORM PREDICTION CENTER NORMAN OK
1146 AM CDT THU APR 07 2005

AREAS AFFECTED...PORTIONS ERN SC...CENTRAL/ERN NC

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 071646Z - 071845Z



SEVERE TSTM POTENTIAL FCST TO INCREASE NEXT SEVERAL HOURS ACROSS
PIEDMONT AND COASTAL PLAIN OF CAROLINAS...ALONG AND E OF OUTFLOW
BOUNDARY FROM PRE-EXISTING/NONSEVERE CONVECTION. MAIN THREAT WILL
BE DAMAGING GUSTS...ISOLATED HAIL ALSO POSSIBLE. WW MAY BE
REQUIRED.

AIR MASS IS DESTABILIZING AND SBCINH DIMINISHING RAPIDLY E OF
OUTFLOW BOUNDARY THAT WAS ANALYZED ALONG A LINE FROM GSO...30 W
SOP...30 SW FLO...NBC...AS OF 1630Z. POTENTIAL EXIST FOR
REINTENSIFICATION AND BOW ECHO DEVELOPMENT WITHIN LINE...AS WELL AS
FORMATION OF SUPERCELLS AND BOWS TO ITS E WHERE DEEPENING TCU AND
SHOWERS ARE EVIDENT ATTM IN VIS/REFLECTIVITY ANIMATIONS. VERTICAL
WIND PROFILES SHOULD REMAIN NEARLY UNIDIRECTIONAL WITH 35-40 KT 0-6
KM AGL SHEAR. ANY DISCRETE CELLS THAT DEVIATE RIGHTWARD -- MOVING
NE TO ENE -- MAY ROTATE AMIDST 0-1 KM SRH 100-150 J/KG...BASED ON
PRE-STORM VWP AND RUC FCST HODOGRAPHS. AS HEATING CONTINUES...DEW
POINT DEPRESSIONS WILL INCREASE TO 15-25 DEG F RANGE. ASSOCIATED
DEEPER MIXING OF SUBCLOUD LAYER WILL AUGMENT POTENTIAL FOR
STRONG-SEVERE DOWNDRAFTS TO REACH SFC.

[CaptinCrunch]

MESOSCALE DISCUSSION 0520
NWS STORM PREDICTION CENTER NORMAN OK
0318 PM CDT THU APR 07 2005

AREAS AFFECTED...FL PENINSULA

CONCERNING...SEVERE THUNDERSTORM WATCH 137...

VALID 072018Z - 072145Z



MAINTAIN WW ALONG/AHEAD OF MAIN CONVECTIVE BAND -- MOVING EWD ACROSS
ST JOHNS/PUTNAM/MARION/CITRUS COUNTIES ATTM WITH A FEW EMBEDDED BOW
ECHOES. ADDITIONAL OR REPLACEMENT WW MAY BE REQUIRED WITHIN NEXT
HOUR OR TWO THAT WOULD COVER PORTIONS CENTRAL/SRN FL S OF WW 137.

NRN FL CONVECTIVE BAND GENERALLY IS STRENGTHENING ACROSS NRN FL IN
RESPONSE TO COMBINATION OF MOIST ADVECTION IN INFLOW LAYER...AND
STRONG HEATING NOW NEAR DIURNAL PEAK. ACCORDINGLY MODIFIED RUC
SOUNDINGS YIELD 2000-2500 J/KG MLCAPE...WHICH WILL HOLD STEADY IN
PRE-STORM ENVIRONMENT FOR ANOTHER HOUR OR TWO BEFORE GRADUALLY
DIMINISHING. SOME SFC VEERING HAS DIMINISHED DEEP-LAYER
SHEAR...WITH 0-6 KM VALUES NOW IN 30-35 KT RANGE...HOWEVER
HODOGRAPHS REMAIN LARGE ENOUGH TO SUPPORT BOWS AND PERHAPS EMBEDDED
SUPERCELLS...GIVEN ROUGHLY 30 DEG OR MORE RIGHTWARD DEVIANCE IN
MOTION. 0-1 KM SRH UP TO 150-200 J/KG RANGE REMAIN POSSIBLE.

SEVERE POTENTIAL OVER FL W COAST -- FROM TBW AREA SWD -- AND OVER
INLAND SRN/CENTRAL FL MAY BE INCREASING. VERTICAL SHEAR AND
BUOYANCY PROFILES ARE SIMILARLY FAVORABLE OVER THOSE AREAS.
DISCRETE DEEP CONVECTIVE TOWERS ARE EVIDENT IN VIS IMAGERY OVER
KISSIMMEE VALLEY N OF LAKE OKEECHOBEE...AND INVOF SEA BREEZE
INTERSECTION WITH HORIZONTAL ROLLS SW OF THAT LAKE. COMPLEX OF
TSTMS AROUND 100 WSW SRQ -- AS OF 20Z -- ALSO MAY AFFECT W COAST
LATE THIS AFTERNOON.

[CaptinCrunch]

MESOSCALE DISCUSSION 0564
NWS STORM PREDICTION CENTER NORMAN OK
1023 AM CDT TUE APR 12 2005

AREAS AFFECTED...WRN MO...CNTRL AND SRN IL...WRN KY...SWRN IND

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 121523Z - 121700Z



TSTMS ARE EXPECTED TO INCREASE ACROSS PORTIONS OF THE MIDWEST...
PRIMARILY EAST OF THE MS RIVER AND NORTH OF THE OH RIVER...OVER THE
NEXT FEW HOURS. ACTIVITY SHOULD GRADUALLY INTENSIFY AND POSSIBLY
RESULT IN SEVERE WEATHER. A WATCH MAY BE NEEDED BY NOON EDT.

SMALL CONVECTIVE CELLS HAVE BEEN INCREASING NEAR AND NORTH OF THE
MS/OH RIVER CONFLUENCE. THIS ACTIVITY IS NEAR THE TRIPLE POINT LOW
ASSOCIATED WITH DEEP COLD CORE OCCLUDED CYCLONE CENTERED OVER IA/MO.
RELATIVELY MOIST BOUNDARY LAYER AIR MASS /SFC DEWPOINTS IN THE UPPER
50S F/ AND POCKETS OF GREATER SFC HEATING HAVE CONTRIBUTED TO A
GRADUAL INCREASE IN INSTABILITY AND DIMINISHING INHIBITION ACROSS
SRN IL AND ERN MO THIS MORNING. LARGE SCALE FORCING AHEAD OF THE
DEEP CYCLONE COUPLED WITH CONTINUED DESTABILIZATION SHOULD RESULT IN
AN INCREASE IN TSTMS ACROSS THE REGION OVER THE NEXT FEW HOURS. DEEP
LAYER SHEAR PROFILES ACROSS THE AREA CURRENTLY SUPPORT SUPERCELL
STORM STRUCTURE AND PRIMARY SEVERE POTENTIAL...AT LEAST
INITIALLY...APPEARS TO BE HAIL. SHEAR IS FCST TO DECREASE WITH TIME
AS SLACK FLOW NEAR THE MID/UPPER LEVEL CIRCULATION MOVES OVERHEAD.
HOWEVER...THIS WILL OCCUR COINCIDENT WITH AN INCREASE IN INSTABILITY
AND THE MAINTENANCE OF LARGE SCALE UPWARD MOTION. THEREFORE...THE
WEAKENING SHEAR MAY NOT OCCUR SOON ENOUGH TO OFFSET THE SEVERE
WEATHER THREAT AND A WATCH MAY BE NEEDED SHORTLY.

[CaptinCrunch]

MESOSCALE DISCUSSION 0565
NWS STORM PREDICTION CENTER NORMAN OK
0206 PM CDT TUE APR 12 2005

AREAS AFFECTED...ERN MO...SRN AND CNTRL IL...WRN KY...AND SWRN IND

CONCERNING...SEVERE THUNDERSTORM WATCH 156...

VALID 121906Z - 122030Z



NUMEROUS TSTMS AND A SEVERAL SMALL SUPERCELLS HAVE CONTINUED TO
INCREASE ACROSS SEVERE TSTM WATCH 156 THIS AFTERNOON. FUNNEL CLOUDS
AND HAIL HAVE OCCURRED WITH A FEW OF THE STRONGER UPDRAFTS. SEVERE
HAIL AND ISOLATED/BRIEF TORNADO POTENTIAL SHOULD PERSIST ACROSS THE
WATCH AREA FOR A FEW MORE HOURS.

BULK OF TSTM ACTIVITY IS FOCUSED NEAR THE TRIPLE-POINT LOW NOW
ANALYZED OVER SCNTRL IL. A SLOW-MOVING COLD/OCCLUDED FRONT BISECTS
THE LOW CENTER AND STRONG CONVERGENCE/LIFT ASSOCIATED WITH THE FRONT
WAS ORIENTED NW-SE...FROM SERN IA TO WRN KY. INSTABILITY HAS
CONTINUED TO INCREASE GRADUALLY WITHIN THIS CORRIDOR AND WILL REMAIN
SUFFICIENT FOR STOUT UPDRAFTS. FAVORABLE FORCING FOR ASCENT WITHIN
THE ERN QUADRANT OF MID/UPPER LOW...COUPLED WITH RELATIVELY HIGH
BOUNDARY LAYER MOISTURE AND STEEPENING MID LEVEL LAPSE RATES WILL
CONTINUE TO SUPPORT A FEW SEVERE HAILSTORMS. POTENTIAL FOR A BRIEF
TORNADO MAY INCREASE FROM NEAR THE SFC LOW ESEWD ACROSS WRN/SWRN IND
OVER THE NEXT COUPLE OF HOURS. STRONG BAROCLINICITY AND HIGHER 0-1KM
DIRECTIONAL SHEAR ACROSS THE WARM FRONT SITUATED ACROSS THIS AREA
COULD PROMOTE/ENHANCE LOW LEVEL STORM ROTATION.

[CaptinCrunch]

MESOSCALE DISCUSSION 0566
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT TUE APR 12 2005

AREAS AFFECTED...NRN AL/GA INTO NWRN SC AND MIDDLE/ERN TN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 121953Z - 122130Z



WARM SECTOR AIRMASS CONTINUES TO GRADUALLY DESTABILIZE ACROSS THE
SOUTH AND SOUTHEAST THIS AFTERNOON. STRONG FORCING FOR ASCENT WITHIN
LEFT EXIT REGION OF APPROACHING MID LEVEL JET STREAK WILL ACT TO
ENHANCE AND FOCUS LIFT AHEAD OF COLD FRONT MOVING INTO THE REGION
FROM THE WEST. A SEVERE TSTM WATCH MAY BE NEEDED SHORTLY.

WIDESPREAD CLOUD COVER HAS INHIBITED STRONGER HEATING ACROSS THE
SOUTH AND TN VLY THROUGH THIS AFTERNOON. HOWEVER...LATEST OBJECTIVE
DATA WAS INDICATING MLCAPE HAS NOW CLIMBED ABOVE 500 J/KG ACROSS
PARTS OF NRN AL AND GA. THIS INCREASING INSTABILITY AND WEAKENING
CAP WERE RESULTING IN TSTM DEVELOPMENT ACROSS THE WARM SECTOR IN GA
AND NRN AL ATTM. GIVEN APPROACHING FRONT AND MID LEVEL WIND
MAX...EXPECT CONVECTION TO CONTINUE TO INCREASE ACROSS THE REGION
INTO THE EVENING. WITH MID LEVEL FLOW STRENGTHENING...AND PRESENCE
OF LOW LEVEL FOCUSING ALONG THE COLD AND WARM FRONT...SHEAR PROFILES
SHOULD BECOME INCREASINGLY FAVORABLE FOR ORGANIZED STORMS. HAIL AND
WIND POTENTIAL IS EXPECTED TO INCREASE WITH THIS ACTIVITY INTO THE
EVENING AND A WATCH MAY BE ISSUED SHORTLY.

[CaptinCrunch]

MESOSCALE DISCUSSION 0583
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT MON APR 18 2005

AREAS AFFECTED...ECENTRAL/SERN NM...TX/OK PANHANDLES...TX SOUTH
PLAINS/SWRN TX AND SWRN KS

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 181909Z - 182115Z



ISOLATED SVR THUNDERSTORMS CAPABLE OF PRODUCING SVR HAIL/DAMAGING
WINDS MAY DEVELOP BY 21Z ALONG TWO SEPARATE DRYLINES...ONE OVER ERN
NM...AND THE OTHER EXTENDING FROM SWRN KS SWD INTO THE WRN TX SOUTH
PLAINS/SWRN TX. ERN PORTIONS OF THE AREA WILL CONTINUED TO BE
MONITORED FOR A POSSIBLE WW.

18Z SFC ANALYSIS AND RADAR IMAGERY FROM CANNON AFB 88-D SHOWS A
DOUBLE DRYLINE STRUCTURE OVER ERN NM/FAR WRN TX. THE WRN MOST
/PRIMARY/ DRYLINE EXTENDED FROM EXTREME SERN CO...TO JUST EAST OF
CLAYTON SWWD TO GUADALUPE COUNTY...THEN SWD TO THE ERN FOOTHILLS OF
THE SACRAMENTO MTNS TO JUST WEST OF THE GUADALUPE MTNS. A SECONDARY
DRYLINE EXTENDED FROM A SFC LOW OVER FAR SERN CO SWWD TO CVS TO HOB
TO THE DAVIS MTNS. DRIER LOW LEVELS HAS LEAD TO MARGINAL INSTABILITY
OF AROUND 500 J/KG OF MLCAPE AHEAD OF THE WRN DRYLINE. THE AIRMASS
DOWNSTREAM OF THE SECONDARY /ERN MOST/ DRYLINE WAS MORE
UNSTABLE...WITH MLCAPES FROM 1000-1500 J/KG OBSERVED. RECENT TRENDS
IN THE TCU AND WSM PROFILERS SUGGESTS A MID LEVEL /4-5 KM/ 30-35 KT
SPEED MAX WAS MOVING ACROSS THE REGION. COMBINED WITH LOW LEVEL
SSWLY FLOW TO THE EAST OF BOTH DRYLINES...AROUND 30 KTS OF DEEP
LAYER SHEAR WILL BE PRESENT OVER THE REGION THROUGH THE AFTERNOON.

WEAK ASCENT ASSOCIATED WITH APPROACHING MID LEVEL WAVE OVER WRN NM
COMBINED WITH SFC CONVERGENCE IN THE VICINITY OF THE TWO
DRYLINES...AND WEAKENING CINH SUGGESTS AT LEAST ISOLATED SVR
THUNDERSTORMS MAY DEVELOP AHEAD OF ONE OR BOTH DRYLINES BETWEEN
20-21Z. RECENT SAT IMAGERY CONFIRMS THIS POTENTIAL WITH CU
DEVELOPING ALONG BOTH DRYLINES OVER ERN NM AND TOWERING CU OVER
DAVIS MTNS. AHEAD OF WRN MOST DRYLINE ACROSS ECENTRAL/SERN NM...HIGH
BASED NATURE OF CONVECTION AND MORE LIMITED MLCAPE/HIGHER DCAPE
SUGGESTS THAT MARGINALLY SVR WINDS WILL BE THE PRIMARY THREAT WITH
THE SVR HAIL THREAT VERY MINIMAL. FARTHER EAST...AHEAD OF THE ERN
MOST DRYLINE FROM SWRN KS SWD ITO THE WRN TX SOUTH PLAINS/SWRN
TX....GREATER INSTABILITY SUGGESTS THAT ISOLATED LARGE HAIL WILL BE
MORE LIKELY...ALONG WITH THE THREAT FOR DAMAGING WINDS. THIS AREA
WILL BE MONITORED FOR A POSSIBLE WW BY 21Z.

[CaptinCrunch]

MESOSCALE DISCUSSION 0650
NWS STORM PREDICTION CENTER NORMAN OK
1056 AM CDT FRI APR 22 2005

AREAS AFFECTED...ERN IL...SWRN IND...WRN KY

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 221556Z - 221730Z



...THUNDERSTORMS SHOULD DEVELOP ACROSS PORTIONS OF ERN IL INTO WRN
IND BY EARLY AFTERNOON...WW IS ANTICIPATED SHORTLY...

STRONG BOUNDARY LAYER HEATING HAS DEVELOPED AHEAD OF UPPER LOW
ACROSS MUCH OF SRN/CNTRL PORTIONS OF IL...INTO WRN PORTIONS OF KY.
PARTIAL CLEARING IS NOW OBSERVED INTO SWRN IND WHERE DESTABILIZATION
SHOULD INCREASE SHORTLY. LATEST THINKING IS CONVECTION WILL DEVELOP
AND DEEPEN AHEAD OF WEAK SFC LOW AND ATTENDANT SFC TROUGH NEAR OR
SHORTLY AFTER 18Z WITH SWD DEVELOPMENT INTO PORTIONS OF KY.
ADDITIONAL SUPPORT FOR INTENSIFICATION IS THE STRONG EXIT REGION OF
UPPER JET AND COOLING MID LEVEL TEMPERATURES. WW WILL BE REQUIRED
FOR THIS REGION AS SCENARIO UNFOLDS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0651
NWS STORM PREDICTION CENTER NORMAN OK
1106 AM CDT FRI APR 22 2005

AREAS AFFECTED...ERN TX...WRN/CENTRAL LA...AND WRN/CENTRAL MS

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 221606Z - 221800Z



SEVERE THUNDERSTORM THREAT IS EXPECTED TO INCREASE THROUGH THIS
AFTERNOON ACROSS ERN TX...WRN/CENTRAL LA...AND WRN/CENTRAL MS. WW
WILL LIKELY BE NEEDED SOON.

AT 1550Z...ISOLATED THUNDERSTORMS CONTINUE ALONG SURFACE COLD FRONT
RED RIVER PARISH LA WSWWD TO ANDERSON COUNTY TX. FRONT SHOULD
CONTINUE TO MOVE SEWD ACROSS THE DISCUSSION AREA THIS AFTERNOON.
SURFACE HEATING COMBINED WITH MID 60S BOUNDARY LAYER DEWPOINTS WILL
LEAD TO MLCAPE VALUES 1500-2500 J/KG. AXIS OF STEEP LOW-MID LEVEL
LAPSE RATES ALONG FRONT SHOULD LEAD TO INCREASING CONVECTIVE
COVERAGE AS CIN CONTINUES TO DECREASE. DEEP LAYER FLOW IS PRIMARILY
PARALLEL TO FRONT...SUGGESTING A BROKEN LINE OF STORMS WITH EMBEDDED
SEVERE/LONG-LIVED CORES CONTAINING LARGE HAIL AND ISOLATED DAMAGING
WINDS. CONVECTIVE COVERAGE SHOULD ALSO BE AIDED BY STRONG 500-300MB
DIVERGENCE BETWEEN SWRN U.S. RIDGE AND CYCLONIC FLOW AROUND THE
UPPER LOW CENTERED ACROSS MO. AS COVERAGE OF STORMS INCREASES...WW
WILL LIKELY BE REQUIRED BY 17Z.

[CaptinCrunch]

MESOSCALE DISCUSSION 0652
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CDT FRI APR 22 2005

AREAS AFFECTED...NWRN GA...ERN TN...WRN NC

CONCERNING...CONVECTIVE TRENDS

VALID 221618Z - 221815Z



...THUNDERSTORMS WILL GRADUALLY INCREASE AND OVERSPREAD PORTIONS OF
NRN GA INTO WRN NC...

LEADING EDGE OF OVERNIGHT MCS APPEARS TO BE REGENERATING AS BOUNDARY
LAYER WARMS DOWNSTREAM ACROSS NRN GA INTO THE SRN PORTIONS OF THE
APPALACHIANS. STRONGER FLOW ALOFT HAS YET TO OVERSPREAD THIS
ACTIVITY AND FORWARD PROPAGATION IS NOT PARTICULARLY FAST AT THIS
TIME. FOR THIS REASON IT APPEARS ONLY ISOLATED STORMS EMBEDDED
ALONG THIS LEADING EDGE WILL BE CAPABLE OF PRODUCING SOME HAIL OR
PERHAPS GUSTY WINDS. WW IS NOT ANTICIPATED.

[CaptinCrunch]

MESOSCALE DISCUSSION 0682
NWS STORM PREDICTION CENTER NORMAN OK
0111 PM CDT MON APR 25 2005

AREAS AFFECTED...PORTIONS OF CENTRAL AND SRN OK

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 251811Z - 251915Z



WW MAY BE REQUIRED FOR PORTIONS OF CENTRAL/SRN OK.

VIS IMAGERY SHOWED CU FIELD DEVELOPING ALONG/EAST OF DRY LINE WHICH
EXTENDED FROM WRN OK SWD TO NEAR SPS AND THEN SWWD TO JUST EAST OF
SJT. SLY LOW LEVEL WINDS IN THE WARM SECTOR WILL CONTINUE TO ADVECT
MOISTURE NWD...WHILE ADDITIONAL SURFACE HEATING IS EXPECTED TO
FURTHER WEAKEN THE CAP ACROSS THIS REGION...RESULTING IN
THUNDERSTORM INITIATION. COLD MID LEVEL TEMPERATURES /-20 C AT 500
MB/ ATOP THIS DESTABILIZING BOUNDARY LAYER WILL FURTHER ENHANCE
INSTABILITY WITH MUCAPE VALUES UP TO 1500 J/KG. STEEP LAPSE RATES
OF 7.5-8 C/KM AND STRONG DEEP LAYER SHEAR WILL FAVOR SEVERE
HAIL...WITH DAMAGING WINDS ALSO A THREAT.

[CaptinCrunch]

MESOSCALE DISCUSSION 0683
NWS STORM PREDICTION CENTER NORMAN OK
0134 PM CDT MON APR 25 2005

AREAS AFFECTED...CENTRAL AND N-CENTRAL TX INCLUDING DFW METRO AREA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 251834Z - 252000Z



CENTRAL AND N-CENTRAL TX IS BEING MONITORED FOR CONVECTIVE
INITIATION AND A POSSIBLE TORNADO WATCH THIS AFTERNOON. CURRENT
TRENDS SUGGEST THREAT OF A FEW SUPERCELL STORMS WITH VERY LARGE HAIL
/IN EXCESS OF 2" DIAMETER/ AND ISOLATED TORNADOES.

SFC PATTERN AT 1830Z FEATURES A DEEPENING SFC LOW OVER FAR SWRN OK
WITH A CONFLUENCE AXIS/DEVELOPING DRYLINE EXTENDING SWD FROM SPS TO
BWD. MEANWHILE...A MESOSCALE COLD POOL EXISTS EAST OF I-35 AND
NORTH OF I-20 IN ASSOCIATION WITH THE CONTINUATION OF WEAK ELEVATED
THUNDERSTORM ACTIVITY THAT CONTINUES TO TRACK EWD. AXIS OF
ONGOING...STRONG SFC HEATING BETWEEN THE FORMING DRYLINE AND WRN
PERIPHERY OF OUTFLOW BOUNDARY SHOULD PROVIDE DESTABILIZATION
NECESSARY FOR THUNDERSTORM DEVELOPMENT BY LATE AFTERNOON. CONTINUED
SLY LOW-LEVEL MOISTURE RETURN SHOULD ALLOW DEWPOINTS TO RISE INTO
THE UPPER 50S TO NEAR 60. THESE FACTORS WILL LEAD TO MUCAPE VALUES
UP TO 2000 J/KG IN ADVANCE OF THE DRYLINE IN CENTRAL/N-CENTRAL TX
DURING THE MID-LATE AFTERNOON.

EXPERIMENTAL NMM WRF AT 4KM RESOLUTION INDICATES CONVECTIVE
DEVELOPMENT ACROSS THE DISCUSSION AREA BEGINNING NEAR 21Z. STRONG
ZONAL UPPER FLOW ACROSS THE REGION...WITH SFC-6KM SHEAR VALUES IN
EXCESS OF 20 M/S...SUGGESTS SUPERCELL STRUCTURES WILL BE SUPPORTED.
ADDITIONALLY...COLD TEMPERATURES ALOFT AND STEEP MID-LEVEL LAPSE
RATES SUGGEST VERY LARGE HAIL IS POSSIBLE. MOISTURE APPEARS TOO
MARGINAL FOR NUMEROUS TORNADOES... HOWEVER...VERY FAVORABLE
LOW-LEVEL SHEAR PROFILES SHOULD ALLOW FOR AT LEAST A FEW TORNADOES
DESPITE THE LESS THAN OPTIMAL BOUNDARY LAYER MOISTURE. TORNADO
THREAT MAY BE ENHANCED WHERE STORMS INTERACT WITH REMNANT OUTFLOW
BOUNDARY TO THE EAST.

[CaptinCrunch]

MESOSCALE DISCUSSION 0692
NWS STORM PREDICTION CENTER NORMAN OK
0949 AM CDT TUE APR 26 2005

AREAS AFFECTED...CNTRL/SRN AL INTO WRN GA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 261449Z - 261645Z



AREA IS BEING MONITORED FOR ADDITIONAL WW.

SHORT WAVE...PROGRESSING THROUGH BASE OF LARGER-SCALE AMPLIFYING
UPPER TROUGH OVER THE MISSISSIPPI VALLEY...APPEARS TO BE PROVIDING
FORCING FOR ONGOING CONVECTIVE LINE ACROSS WEST CENTRAL ALABAMA/
CENTRAL MISSISSIPPI. AS LINE CONTINUES EAST OF THE INTERSTATE 59
CORRIDOR NEXT FEW HOURS...THERE APPEARS TO BE INCREASING POTENTIAL
FOR INTENSIFICATION...WITH RISK FOR DAMAGING WINDS IN ADDITION TO
LARGE HAIL.

COOL MID-LEVEL AIR MASS IS ALREADY PRESENT ACROSS THE CENTRAL/
EASTERN GULF COAST REGION...WITH FURTHER COOLING LIKELY AS BOUNDARY
LAYER POSSESSING MID 50S+ DEW POINTS BEGINS TO WARM. BREAKS IN
CLOUD COVER ARE ALREADY PRESENT IN BROAD CORRIDOR FROM MOBILE TO
MONTGOMERY...WHICH SHOULD ALLOW SUFFICIENT INSOLATION FOR MIXED
LAYER CAPE IN EXCESS OF 1000 J/KG BY 18-20Z.

AS BOUNDARY LAYER DESTABILIZES...ONGOING CONVECTIVE LINE SHOULD
INTENSIFY...WITH WEAK CAP ALSO ALLOWING MORE ISOLATED CONVECTIVE
DEVELOPMENT ACROSS SOUTHERN/EASTERN ALABAMA...WHERE SHEAR PROFILES
WILL REMAIN FAVORABLE FOR SUPERCELLS.

[CaptinCrunch]

MESOSCALE DISCUSSION 0694
NWS STORM PREDICTION CENTER NORMAN OK
1219 PM CDT TUE APR 26 2005

AREAS AFFECTED...NRN FL...SRN GA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL

VALID 261719Z - 261915Z



AREA IS BEING MONITORED FOR POSSIBLE WW.

SURFACE RIDGING ACROSS EASTERN GULF/SOUTH ATLANTIC COASTAL AREAS IS
BEGINNING TO SLOWLY WEAKEN...AS LOW-LEVEL WARM ADVECTION REGIME
OVERSPREADS REGION...DOWNSTREAM OF APPROACHING LARGE-SCALE TROUGH
AXIS. SIGNIFICANT INCREASES IN SURFACE TEMPERATURES/DEW POINTS HAVE
BECOME EVIDENT ALONG NORTHERN FLORIDA GULF COASTAL AREAS...AND
INLAND THERMAL/MOISTURE ADVECTION WILL CONTINUE THIS AFTERNOON.

ONGOING CONVECTIVE ACTIVITY ACROSS THE FLORIDA PANHANDLE APPEARS TO
BE SUPPORTED BY ENHANCED DIVERGENT UPPER FLOW FIELD BETWEEN
INTERACTING BELTS OF STRONGER FLOW ACROSS THE SOUTHEAST. THIS IS
EXPECTED TO SPREAD ACROSS THE REMAINDER OF NORTHERN FLORIDA/
SOUTHERN GEORGIA THROUGH THE REMAINDER OF THE AFTERNOON.

VERTICAL SHEAR PROFILES ARE CURRENTLY VERY FAVORABLE FOR SUPERCELLS.
THOUGH LOW-LEVEL HODOGRAPHS MAY WEAKEN SOME AS LOW-LEVEL JET VEERS
THIS AFTERNOON...ONGOING DESTABILIZATION OF BOUNDARY LAYER MAY
COMPENSATE FOR THIS...SUPPORTING RISK FOR AN ISOLATED TORNADO OR