Tornado Outbreak April 29-May 2, HIGH RISK AR, TN, MS

[RL3AO]

Looking like I will be getting my first thunderstorm of the year in the next hour or two.

[KWT]

Here is todays outlook, still held at a slight risk as well....


DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 AM CDT FRI APR 30 2010

VALID 301200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MOST OF THE MS VLY AND
ERN PLAINS...

...SYNOPSIS...
110 KT H5 JET STREAK ROUNDING THE EXTENSIVE WRN STATES UPR TROUGH
WILL EJECT FROM THE SRN HIGH PLAINS TO THE UPR MS VLY REGION BY
FRIDAY EVENING AS THE NEXT IMPULSE DIGS TOWARD NRN MEXICO. PRIMARY
SFC LOW WILL DEVELOP IN CNTRL MN WITH A TRAILING CDFNT EXPECTED TO
SWEEP EWD INTO THE MIDWEST...LWR OH VLY AND CNTRL TX BY EARLY
SATURDAY MORNING.

...MID/UPR MS RVR VLY...
VERY STRONG LLVL FLOW IN ADVANCE OF THE WRN STATES UPR TROUGH WILL
TRANSPORT RICH GULF/CARIBBEAN MOISTURE NWD BENEATH STEEP MID-LVL
LAPSE RATES INTO THE MIDWEST. BY FRIDAY AFTN...SFC DEW POINTS NEAR
60F WILL EXIST IN THE UPR MS VLY/UPR MIDWEST..CONTRIBUTING TO
MLCAPES OF 1000-1500 J/KG OVER A BROAD REGION.

TSTMS WILL LIKELY BE ONGOING EARLY FRIDAY MORNING ACROSS PORTIONS OF
THE UPR MS VLY SWWD INTO ERN KS. THIS ACTIVITY MAY TEMPORARILY
WEAKEN THROUGH LATE MORNING. BUT...AS THE NEXT IMPULSE TRANSLATES
INTO THE CNTRL PLAINS DURING PEAK HEATING...RESIDUAL OUTFLOW/
DIFFERENTIAL HEATING BOUNDARIES WILL SERVE AS AFTN FOCI FOR TSTM
INITIATION FROM THE UPR MS VLY INTO WRN MO. SUFFICIENT
CROSS-BOUNDARY FLOW WILL EXIST FOR A MIX OF ORGANIZED
DISCRETE/LINEAR MODES. ANY SUSTAINED SUPERCELLS WILL PRODUCE VERY
LARGE HAIL AND A FEW TORNADOES. ACTIVITY WILL QUICKLY MOVE ENE AND
CROSS THE MS RVR VLY MID-EVENING BEFORE WEAKENING OVER CNTRL/ERN WI
AND WRN/NRN IL OVERNIGHT.

...MID-SOUTH/OZARKS/ARKLATEX/LWR MS RVR VLY...
SIGNIFICANT SURGE OF CARIBBEAN/GULF MOISTURE WILL OCCUR OVER THE
REGION FRIDAY AFTN/NIGHT WITH SFC DEW POINTS UPR 60S/LWR 70S. NAM IS
OUTLIER ON ORGANIZED CONVECTIVE COMPLEX FRIDAY MORNING/AFTN ACROSS
THE LWR MS VLY ALONG NRN EDGE OF RETURNING MOISTURE. EXPECT A FEW
SHOWERS/TSTMS MAY OCCUR THROUGH THE AFTN...BUT PRIMARY SVR FOCUS
WILL BE LATER IN THE AFTN/NIGHT.

WEAK LARGE SCALE HEIGHT FALLS WILL GRAZE THE BROADENING WARM SECTOR
IN THE EVENING WITH ROUGHLY 45-50 KTS OF SWLY H5 FLOW ATOP 35-40 KTS
OF SSWLY LLVL WINDS. HEATING...WEAK SFC-H85 CONFLUENCE AND LLVL
MOISTENING WILL AID IN WEAKENING CINH AND ISOLD/WDLY SCTD TSTMS
SHOULD INITIATE BY MID-AFTN NE TX INTO PARTS OF WRN/SRN AR.
MAGNITUDE OF DEEP LAYER SHEAR AND LAPSE RATES WILL BE FAVORABLE FOR
SUPERCELLS WITH VERY LARGE HAIL AND A FEW TORNADOES. ACTIVITY MAY
PERSIST WELL INTO THE NIGHT INTO THE MID-SOUTH/LWR MS VLY WITH A
CONTINUED RISK FOR HAIL/ISOLD TORNADOES AMIDST A VERY MOIST AIR
MASS.

[wx247]

I am planning to chase today for the first time in years. This will bring back memories. I am as bad as a kid on Christmas eve!!

I am going to do some more analysis this morning before deciding which direction to go. Lots of options...

[Bunkertor]

Here is todays outlook, still held at a slight risk as well....

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 AM CDT FRI APR 30 2010

That will not stand, i suppose.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT FRI APR 30 2010

VALID 301300Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARKLATEX AND LWR MS
VLY NWD INTO THE MID/UPR MS VLYS...

...SYNOPSIS...
UPR LOW OVER THE WRN DAKOTAS EXPECTED TO DEEPEN SLIGHTLY AS IT MOVES
SLOWLY NE INTO SRN MB THIS PERIOD. ATTENDANT POSITIVE TILT TROUGH
OVER THE CNTRL/SRN RCKYS LIKELY WILL SHOW MINIMAL EWD MOVEMENT AS
SHORTWAVE IMPULSE NOW OVER SRN CA/NV CONTINUES SE INTO NW MEXICO.

STRENGTHENING OF THE DAKOTAS LOW APPEARS TO BE TIED...IN PART...TO
100+ KT 500 MB JET STREAK NOW OVER THE SRN HI PLNS. THIS FEATURE
SHOULD REDEVELOP NNE TO THE LWR MO VLY BY THIS EVE...AND INTO THE
UPR GRT LKS EARLY SAT. AT THE SFC...THE ABOVE CHANGES WILL BE
ACCOMPANIED BY AN EWD ACCELERATION AND INTENSIFICATION OF COLD FRONT
NOW OVER THE UPR MS VLY. THE BOUNDARY SHOULD EXTEND FROM NRN MI
THROUGH SRN IL TO CNTRL TX BY 12Z SAT.

...MID/UPR MS VLY...
VERY STRONG LOW LVL FLOW WILL PREVAIL AHEAD OF STRENGTHENING COLD
FRONT OVER THE MID/UPR MS VLY TODAY...WITH 850 MB SSW FLOW AOA 50
KTS. THIS WILL ALLOW INCREASINGLY RICH MOISTURE TO OVERSPREAD
REGION...WITH PW RANGING FROM AROUND 1.25 INCHES IN WI TO ABOVE 1.50
INCHES IN MO. SFC DEW POINTS NEAR 60F SHOULD YIELD SBCAPE OF
1000-1500 J/KG...WITH THE HIGHEST VALUES EXPECTED IN MO.

A FEW ELEVATED TSTMS MAY PERSIST THROUGH THE MORNING FROM ERN KS
INTO THE UPR MS VLY. THIS ACTIVITY SHOULD BE JOINED AND/OR REPLACED
BY NEW SFC-BASED DEVELOPMENT AS SFC HEATING DESTABILIZES REGION BY
EARLY AFTN. THE STORMS LIKELY WILL CONTINUE TO STRENGTHEN THROUGH
THE REST OF THE DAY AS UPR JET STREAK REDEVELOPS NNE ACROSS REGION.
CLOUDS AND DIFFUSE NATURE OF EXISTING FRONTAL ZONE/OUTFLOW
BOUNDARIES COMPLICATE THE PICTURE. BUT ATTM IT APPEARS THAT THE
AXIS OF STRONGEST STORM DEVELOPMENT WILL EXTEND FROM WRN/CNTRL MO
NNE INTO CNTRL/ERN IA AND WRN WI AS UPLIFT FOCUSES ALONG RESIDUAL
OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES NEAR FRONT.

60-70 KT DEEP SSWLY SHEAR ORIENTED ROUGHLY PARALLEL TO THE LOW LVL
FOCUSING FEATURES SHOULD BE FAVORABLE FOR A MIX OF SEMI-DISCRETE
SUPERCELLS AND/OR BROKEN LINES WITH EMBEDDED SUPERCELLS/LEWPS.
GIVEN THE STRENGTH OF THE MEAN FLOW AND INCREASING MOISTURE...ANY
SUSTAINED STORMS WILL POSE A RISK FOR HIGH WIND...HAIL...AND A FEW
TORNADOES. FAST NNE STORM MOVEMENT SHOULD EXTEND THE SVR THREAT
INTO ERN WI AND WRN/NRN IL BY EVE. A DIMINISHING THREAT MAY PERSIST
INTO EARLY SAT OVER ERN/SRN IL.

...ARKLATEX/SRN OZARKS/LWR MS RVR VLY...
SATELLITE AND GPS DATA SHOW AN AREA OF MORE SIGNIFICANT MOISTURE
/WITH PW NEAR 1.50 INCHES/ NOW ALONG THE NWRN GULF THAT SHOULD
CONTINUE TO MOVE N INTO E TX...THE LWR MS VLY AND SRN OZARKS THROUGH
THE PERIOD. SCTD TSTMS...MOST OF WHICH MAY BE ELEVATED...MAY FORM
OVER NE TX/ERN OK AND AR LATER THIS MORNING THROUGH EARLY THIS AFTN
AS LOW CLOUDS LIMIT SFC HEATING. BUT THE MAIN FOCUS FOR SVR WX OVER
THE REGION SHOULD BE LATER THIS AFTN INTO TONIGHT AS INCREASINGLY
MOIST/CONFLUENT FLOW PERSISTS BENEATH DIFLUENT HIGH LVL
JET...SUPPORTING BANDS OF SUSTAINED STORMS.

WHILE HEIGHT CHANGES WILL BE NEGLIGIBLE...COMBINATION OF 45-50 KT
SWLY 500 MB FLOW ATOP 35-40 KT SSWLY LLJ SHOULD SUPPORT EMBEDDED
SUPERCELLS WITH VERY LARGE HAIL AND A FEW TORNADOES. THE STORMS MAY
PERSIST WELL INTO THE NIGHT INTO ERN AR AND THE LWR TN VLY AS COLD
FRONT SAGS SE INTO REGION AND PROVIDES AN ADDITIONAL SOURCE OF LOW
LVL ASCENT AMIDST INCREASING MOISTURE.

..CORFIDI/GARNER.. 04/30/2010

[CrazyC83]

SEL1

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 111
NWS STORM PREDICTION CENTER NORMAN OK
1020 AM CDT FRI APR 30 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

EASTERN IOWA
NORTHERN AND CENTRAL MISSOURI

EFFECTIVE THIS FRIDAY MORNING AND AFTERNOON FROM 1020 AM UNTIL
300 PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES EAST
NORTHEAST OF WATERLOO IOWA TO 45 MILES SOUTH OF KNOB NOSTER
MISSOURI. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...COMBINATION OF STRONG FORCING ALOFT AND GRADUALLY
MOISTENING AND DESTABILIZING ATMOSPHERE SHOULD BECOME MORE FAVORABLE
FOR SEVERE STORMS INTO THE AFTERNOON HOURS. THE STORMS ARE CURRENTLY
ELEVATED AND LOCATED A SHORT DISTANCE TO THE WEST OF THE FRONT...SO
THE PRIMARY SEVERE THREAT THIS MORNING WILL BE HAIL. HOWEVER...AS
THE STORMS EVENTUALLY BECOME CO-LOCATED WITH THE FRONT...AND
POSSIBLY EVOLVE INTO A LINEAR SYSTEM...THE THREAT FOR WIND DAMAGE
WILL INCREASE INTO THE AFTERNOON HOURS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 23040.


...IMY

[johnmarkthom]

Upgrade to moderate for parts of MO, IL and IA

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 AM CDT FRI APR 30 2010

VALID 301630Z - 011200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF IL AND MO...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MS
VALLEY...WRN GREAT LAKES...OZARKS AND SRN PLAINS...

...MID TO UPPER MS VALLEY/OZARKS...
AN MCS CURRENTLY OVER NCNTRL MO WILL CONTINUE ENEWD INTO NCNTRL IL
THIS AFTERNOON. A BROAD LOW-LEVEL JET SOUTH OF THE MCS ACROSS SCNTRL
MO AND AR WILL RESULT IN STRONG MOISTURE ADVECTION. EXPECT MODERATE
DESTABILIZATION ACROSS MUCH OF MO AND AR BY LATE THIS AFTERNOON AS
SFC DEWPOINTS INCREASE INTO THE MID 60S F. MODEL FORECASTS ARE IN
GOOD AGREEMENT...INITIATING NUMEROUS SFC-BASED THUNDERSTORMS ALONG
THE WRN EDGE OF A WELL-DEVELOPED LOW-LEVEL JET FROM ECNTRL MO SSWWD
INTO THE ARKLATEX. THE SHEAR ENVIRONMENT ALONG THIS CORRIDOR WITH
0-6 KM SHEAR VALUES AROUND 50 KT SHOULD BE FAVORABLE FOR NUMEROUS
SEVERE STORMS INCLUDING SUPERCELLS AND ORGANIZED BOWING
LINE-SEGMENTS. A SIGNIFICANT SEVERE WEATHER EVENT WILL BE POSSIBLE
ACROSS THE MODERATE RISK AREA THIS AFTERNOON THROUGH TONIGHT.

THE CURRENT THINKING IS THAT THE LINE OF STORMS IN NW MO WILL BECOME
INCREASINGLY ORGANIZED MOVING ENEWD ACROSS NRN MO AND SE IA THIS
AFTERNOON INTO WRN IL EARLY THIS EVENING. A LINEAR MCS IS EXPECTED
WITH THE STORMS MOVING INTO INCREASING LOW-LEVEL FLOW WHERE FORECAST
SOUNDINGS SHOW ABOUT 50 KT AT 850 MB LATE THIS AFTERNOON. THIS ALONG
WITH INCREASING LARGE-SCALE ASCENT DUE TO A UPPER-LEVEL SYSTEM TO
THE NORTHWEST AND STRENGTHENING MID-LEVEL FLOW ASSOCIATED WITH THE
RIGHT ENTRANCE REGION OF A 90 TO 100 KT MID-LEVEL JET WILL LIKELY
PROMOTE STRONG LINEAR DEVELOPMENT FROM WRN IL SWD ACROSS ECNTRL MO
EARLY THIS EVENING WHERE THE WIND DAMAGE THREAT SHOULD BECOME
ENHANCED. TORNADOES AND LARGE HAIL WILL ALSO BE POSSIBLE ESPECIALLY
WITH SUPERCELLS EMBEDDED IN THE LINE. A 45 PERCENT WIND DAMAGE
PROBABILITY HAS BEEN ADDED FROM NRN IL SWWD ACROSS MOST OF ECNTRL
MO.

FURTHER SOUTH ACROSS SERN MO AND AR...MODEL FORECASTS ARE IN GOOD
AGREEMENT...DEVELOPING NUMEROUS THUNDERSTORMS ALONG THE INSTABILITY
AXIS. THE ENVIRONMENT SHOULD BE CHARACTERIZED BY MODERATE
INSTABILITY AND STRONG DEEP LAYER SHEAR ESPECIALLY NORTH OF LITTLE
ROCK WHERE INTENSE SUPERCELL DEVELOPMENT IS POSSIBLE BY EARLY THIS
EVENING. IN NRN AR...LARGE-SCALE ASCENT IS FORECAST TO BE WEAKER
THAN AREAS TO THE NORTH WHICH SHOULD HELP THE SUPERCELLS REMAIN
DISCRETE BUT THE STORMS MAY BE MORE ISOLATED AS WELL. IN
ADDITION...FORECAST SOUNDINGS ACROSS CNTRL AND NRN AR SHOW SFC WINDS
BACKED TO THE SOUTH SOUTHEAST WHICH COMBINED WITH LOW LCL HEIGHTS
COULD BE FAVORABLE FOR AN ISOLATED STRONG TORNADO. THE MORE DOMINANT
SUPERCELL STRUCTURES SHOULD BE CAPABLE OF PRODUCING TORNADOES AND
POSSIBLY VERY LARGE HAIL. THE THREAT FOR VERY LARGE HAIL SHOULD
EXIST ACROSS AR SWWD INTO NE TX WHERE MODERATE TO STRONG INSTABILITY
IS FORECAST.

..BROYLES/STOPPKOTTE.. 04/30/2010

[srainhoutx]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 113
NWS STORM PREDICTION CENTER NORMAN OK
105 PM CDT FRI APR 30 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

EASTERN IOWA
NORTHWESTERN ILLINOIS
SOUTHERN AND EASTERN WISCONSIN
LAKE MICHIGAN

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 105 PM UNTIL 800
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHWEST OF GREEN
BAY WISCONSIN TO 40 MILES EAST OF BURLINGTON IOWA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 111...WW 112...

DISCUSSION...STRONG UPPER FORCING WILL OVERSPREAD THE AREA THIS
AFTERNOON... WITH THUNDERSTORMS EXPECTED TO INCREASE IN NUMBER AND
INTENSITY FROM SOUTHWEST TO NORTHEAST ACROSS THE WW. A WARMING AND
MOISTENING BOUNDARY LAYER HAS RESULTED IN MODERATE INSTABILITY...
AND IN CONJUNCTION WITH 50 KT OF DEEP LAYER SHEAR...SUPERCELLS ARE
EXPECTED. STRONG LOW LEVEL SHEAR WILL SUPPORT A THREAT FOR
TORNADOES...AND THE STRONG FLOW ALOFT WILL FAVOR FAST MOVING BOW
ECHOES WITH WIND DAMAGE.

[KWT]

Yep upto a moderate risk. Already looking very linear at the moment with bands of severe thunderstorms, so wouldn't surprise me if high winds is the biggest issue with today, though of course tornadoes+large hail is always going to be possible with supercells.

Doesn't seem frm the webcam I'm watching from chasers heading through the western band of precip that it'll be the best day for photographic imags of these beasts, but we will see.

[srainhoutx]

May need to watch a bit further S as well...



MESOSCALE DISCUSSION 0422
NWS STORM PREDICTION CENTER NORMAN OK
0111 PM CDT FRI APR 30 2010

AREAS AFFECTED...FAR NE TX...ERN OK...WRN AR INTO SW MO

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 301811Z - 302015Z

CONVECTION CURRENTLY MOVING INTO ERN OK AND SW MO HAS BEEN
INCREASING IN INTENSITY THE LAST HOUR AND THIS TREND SHOULD CONTINUE
WHILE DEVELOPING FURTHER SWD INTO FAR NE TX. STRONG MOISTURE
ADVECTION AHEAD OF A DRYLINE/COLD FRONT FROM WRN MO THROUGH ERN OK
INTO CNTRL TX HAS ALLOWED DEW POINTS TO CLIMB INTO THE UPPER
60S/LOWER 70S WITH TEMPERATURES IN THE 70S TO LOW 80S. MIXED LAYER
CAPE VALUES HAVE INCREASED TO AROUND 1000-2000 J/KG AND WITH A
QUICKLY ERODING CAPPING INVERSION...DISCRETE STORM DEVELOPMENT IS
EXPECTED TO INCREASE OVER THE NEXT COUPLE OF HOURS. BULK SHEAR
VALUES AROUND 40-60 KT WITH MID LEVEL LAPSE RATES AROUND 8 C/KM WILL
SUPPORT SUPERCELLS WITH LARGE HAIL AND POSSIBLE TORNADOES.

..STOPPKOTTE.. 04/30/2010


ATTN...WFO...LZK...SGF...SHV...TSA...FWD...OUN...

[srainhoutx]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 114
NWS STORM PREDICTION CENTER NORMAN OK
145 PM CDT FRI APR 30 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

WESTERN ARKANSAS
SOUTHERN MISSOURI
EASTERN OKLAHOMA
NORTHEASTERN TEXAS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 145 PM UNTIL 800
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES NORTHEAST OF
SPRINGFIELD MISSOURI TO 15 MILES SOUTHEAST OF PARIS TEXAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU4).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 111...WW 112...WW 113...

DISCUSSION...STORMS HAVE RECENTLY BEEN DEVELOPING AND INTENSIFYING
IN ERN OK... ALONG AND JUST AHEAD OF A SLOW MOVING COLD FRONT.
MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR IS VERY FAVORABLE
FOR SUPERCELLS...AS THE STORMS DEVELOP/MOVE EWD THROUGH THE
AFTERNOON HOURS. THE VERY MOIST BOUNDARY LAYER AND 30-40 KT LOW
LEVEL SHEAR WILL BE SUPPORTIVE OF TORNADOES AND LARGE HAIL.

[CrazyC83]

Tornado probs on that are 70/40 - close to PDS levels, and much of the area is not even in a Slight Risk! Expect changes at 2000Z.

[srainhoutx]

About to get interesting. I am concerned about the slow movement of this storm system and the amount of rainfall suggested by guidance over the weekend. Stay Safe Folks!



MESOSCALE DISCUSSION 0424
NWS STORM PREDICTION CENTER NORMAN OK
0208 PM CDT FRI APR 30 2010

AREAS AFFECTED...ERN MO...WRN IL

CONCERNING...SEVERE THUNDERSTORM WATCH 111...

VALID 301908Z - 302015Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 111
CONTINUES.

CONVECTIVE INHIBITION IS GRADUALLY ERODING ALONG/AHEAD OF WIND SHIFT
OVER MO AND WCNTRL IL. 18Z SOUNDING FROM SGF VERIFIES THIS TREND
WITH SBCAPE ON THE ORDER OF 2500 J/KG AND EARLIER CAP NOW COMPLETELY
DEPLETED. IT APPEARS THIS CAP EROSION WILL SPREAD NEWD ACROSS MUCH
OF ERN MO INTO WRN IL ALLOWING FOR FRONTAL CONVECTION TO INTENSIFY.
ALTHOUGH SIGNIFICANT ELEVATED THUNDERSTORM ACTIVITY MAY LINGER
WITHIN THE POST FRONTAL ENVIRONMENT...ATTENTION IS BEGINNING TO
SHIFT TO WARM SECTOR WHERE A TORNADO WATCH WILL BE NEEDED SOON.

..DARROW.. 04/30/2010


ATTN...WFO...ILX...LSX...DVN...SGF...

[CrazyC83]

SEL5

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 115
NWS STORM PREDICTION CENTER NORMAN OK
240 PM CDT FRI APR 30 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

WESTERN AND CENTRAL ILLINOIS
EASTERN MISSOURI

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
1000 PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 15 MILES EAST NORTHEAST OF
PEORIA ILLINOIS TO 30 MILES SOUTHEAST OF VICHY MISSOURI. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU5).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES SEVERE
THUNDERSTORM WATCH NUMBER 111. WATCH NUMBER 111 WILL NOT BE IN
EFFECT AFTER 240 PM CDT. CONTINUE...WW 112...WW 113...WW 114...

DISCUSSION...COLD FRONT WAS MOVING THROUGH CENTRAL MO AND WILL AID
IN THUNDERSTORMS DEVELOPING ALONG AND AHEAD OF IT DURING THE NEXT
FEW HOURS. THE AIR MASS HAS BECOME MODERATELY UNSTABLE AHEAD OF THE
FRONT AND THE DEEP LAYER SHEAR WILL BE VERY SUPPORTIVE OF
SUPERCELLS. A MOISTENING BOUNDARY LAYER...WITH DEWPOINTS IN THE MID
60S AND INCREASING LOW LEVEL WINDS/SHEAR WILL FAVOR TORNADOES AND
VERY LARGE HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 23045.


...IMY

[Dave]

Looks like it may be an interesting weekend up here, flash flood watches have been posted for the Indy & Lousiville districts already, waiting on Wilmington oh next. And that doesn't include anything else that comes in from the west. Thought if I stayed quiet it would go away...wrong.

[CrazyC83]

2000Z: MDT significant expanded...

[Dave]

From KIND Indianapolis:

A cold front will move into central Indiana and the Ohio Valley tonight, becoming stationary near the Ohio River for much of the weekend. Several areas of low pressure will track along the front bringing the potential for heavy rainfall and strong to severe thunderstorms beginning late tonight and continuing through Sunday. Rainfall amounts of 2 to 3 inches of rain are possible, with locally higher amounts possible across south central Indiana.

============
From KLVX Louisville:

Several weather disturbances moving northeast along a surface front combined with a moist, unstable atmosphere will result in periods of showers and thunderstorms from early Saturday morning through Sunday night. Periods of heavy rainfall are likely, with total rainfall amounts during the period of 2 to 6 inches over many areas, with more than 6 inches possible in some areas. This will likely lead to flooding issues. In addition, strong storms will be possible. A stronger low pressure system riding northeast along the front Sunday could cause some severe storms (a squall line) with damaging winds and isolated tornadoes possible.

[CrazyC83]

SPC AC 301950

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0250 PM CDT FRI APR 30 2010

VALID 302000Z - 011200Z

...THERE IS A MDT RISK OF SVR TSTMS LATE THIS AFTN AND EVE ACROSS
PARTS OF WRN/NRN AND CNTRL ARKANSAS...SRN AND ERN MISSOURI...W CNTRL
AND NW ILLINOIS...

...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND TONIGHT
ACROSS MUCH OF THE MISSISSIPPI VALLEY...

...20Z UPDATE...
MODERATE RISK THREAT AREA HAS BEEN EXTENDED SOUTH SOUTHWESTWARD
THROUGH A LARGE PORTION OF WESTERN/NORTHERN AND CENTRAL ARKANSAS. A
NARROW CORRIDOR OF STRONGER SURFACE HEATING IS ONGOING AHEAD OF A
SLOWLY EASTWARD ADVANCING CONGLOMERATE OUTFLOW BOUNDARY...ALONG AN
AXIS NORTH OF THE ARKLATEX THROUGH THE MISSOURI OZARKS. DEW POINTS
ARE INCREASING THROUGH THE MID 60S TO NEAR 70F ALONG THIS
AXIS...CONTRIBUTING TO MIXED LAYER CAPE OF 1000-2000 J/KG...IN THE
PRESENCE OF STEEP MID-LEVEL LAPSE RATES AND STEEPENING LOW-LEVEL
LAPSE RATES. THIS FEATURE IS EXPECTED TO BE THE FOCUS FOR DISCRETE
SUPERCELL DEVELOPMENT LATE THIS AFTERNOON AND EVENING...IN A
STRONGLY SHEARED REGIME FAVORABLE FOR TORNADOES...INCLUDING THE RISK
FOR STRONG TORNADOES. RAPID NORTHEASTWARD MOVEMENT OF ACTIVITY IS
EXPECTED THROUGH MID EVENING...AIDED BY 40-50+ KT SOUTHWESTERLY DEEP
LAYER MEAN FLOW.

ELSEWHERE...IN THE WAKE OF THE PRE-FRONTAL CONVECTIVE BOUNDARY NOW
ADVANCING INTO WISCONSIN/ILLINOIS...EASTERN IOWA AND NORTH CENTRAL
THROUGH SOUTHWEST MISSOURI...CONVECTIVE POTENTIAL IS DIMINISHING
...AND THE OUTLOOK HAS BEEN ADJUSTED ACCORDINGLY.

[CrazyC83]

15H tornado introduced as well in Arkansas. Seeing that makes you realize a significant tornado event is possible.