Next Round of Severe Weather Begins 4/19, Midwest

[OverlandHurricane]

I know that this may not be too noteworthy in a sever weather thread, but some models have this system depositing 14 inches of snow on the Twin Cities. While the ground is too warm for all of that to stay snow, the prospect of 3-7" of slop is thoroughly unappealing for this late in April.

Worst. Winter. Ever.

[Dave]

I won't be surprised to see a small high risk area for IL & IN sometime tomorrow and a possible PDS to match it. Just waiting now...some light thundershowers to my west but those are riding along a stationary front at this time. Nothing big in them at all. I was outside most of tonight and we're holding at or near 70 degrees but the dew point is still low at 48. I saw a projection of 60+ dewpoints tomorrow and that's trouble for this region, esp if we get a lot of sunshine in between. Going to be interesting more than likely.

Waiting for the 0600Z updates now.

[WeatherGuesser]

Yup. Watching that mid-day heating that could really escalate things.

[Dave]

MESOSCALE DISCUSSION 0466
NWS STORM PREDICTION CENTER NORMAN OK
1141 PM CDT MON APR 18 2011

AREAS AFFECTED...CNTRL MO THROUGH SWRN IL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 190441Z - 190615Z

THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY
INTO THE EARLY MORNING ACROSS CNTRL MO INTO SWRN IL. ISOLATED LARGE
HAIL WILL BECOME POSSIBLE WITH THE STRONGER STORMS. OVERALL THREAT
DOES NOT APPEAR TO BE PARTICULARLY ROBUST...AND NEED FOR A WW IS
UNCLEAR AT THIS TIME...BUT WILL ULTIMATELY DEPEND ON CONVECTIVE
TRENDS.

EARLY THIS MORNING A QUASI-STATIONARY FRONT EXTENDS FROM THE OH
VALLEY WWD THROUGH S-CNTRL MO INTO NRN OK. A RESERVOIR OF STRONG
2000-3000 J/KG MUCAPE EXISTS FARTHER SOUTH IN WARM SECTOR WHERE
STEEP MID-LEVEL LAPSE RATES HAVE OVERSPREAD LOW 60S BOUNDARY LAYER
DEWPOINTS. ADVECTION OF HIGHER THETA-E AIR ALONG A STRONG SLY LLJ
WILL CONTRIBUTE NWD DESTABILIZATION ABOVE THE STABLE SURFACE LAYER
WITH MUCAPE INCREASING TO 1500-2000 J/KG. ELEVATED CONVECTION IS
ALREADY BEGINNING TO DEVELOP IN W-CNTRL MO. AS THE ATMOSPHERE
DESTABILIZES NWD...ACTIVITY COULD INTENSIFY AND POSE A THREAT FOR
ISOLATED LARGE HAIL.

..DIAL.. 04/19/2011


ATTN...WFO...LSX...SGF...EAX...

[WeatherGuesser]

Dave, did you pick up on the TOR in south central IN?




125 AM EDT TUE APR 19 2011

THE NATIONAL WEATHER SERVICE IN INDIANAPOLIS HAS ISSUED A

* TORNADO WARNING FOR...
NORTHERN DAVIESS COUNTY IN SOUTHWEST INDIANA...
SOUTHEASTERN GREENE COUNTY IN SOUTHWEST INDIANA...
NORTHEASTERN KNOX COUNTY IN SOUTHWEST INDIANA...
NORTHWESTERN LAWRENCE COUNTY IN SOUTH CENTRAL INDIANA...
NORTHERN MARTIN COUNTY IN SOUTHWEST INDIANA...

* UNTIL 215 AM EDT

* AT 120 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED 11 MILES NORTHWEST OF WASHINGTON...OR 16 MILES
NORTHEAST OF VINCENNES...AND MOVING EAST AT 30 MPH.



I don't normally post individual warnings, but since this could be considered the first of this event, I'll make an exception.

[RL3AO]

SPC has 10% tornado risk. MDT for hail angle wind.

[WeatherGuesser]

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 153
NWS STORM PREDICTION CENTER NORMAN OK
315 AM CDT TUE APR 19 2011

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

CENTRAL AND SOUTHERN ILLINOIS
NORTHERN AND EASTERN MISSOURI

EFFECTIVE THIS TUESDAY MORNING FROM 315 AM UNTIL 1100 AM 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 65
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST
SOUTHWEST OF CHILLICOTHE MISSOURI TO 30 MILES EAST NORTHEAST OF
SALEM ILLINOIS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

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...TSTMS...MOST OF WHICH SHOULD BE SLIGHTLY
ELEVATED...EXPECTED TO INCREASE IN COVERAGE AND POSSIBLY INTENSITY
OVER PARTS OF MO/IL DURING THE NEXT SEVERAL HOURS AS WAA STRENGTHENS
ON LEADING EDGE OF ENE-MOVING EML. PRESENCE OF EML...INCREASING
MOISTURE PROVIDED BY 40-50 KT SWLY LLJ...AND MODERATE CLOUD-LAYER
SHEAR SUGGEST A POTENTIAL FOR SUSTAINED STORMS AND A FEW SUPERCELLS.
SVR HAIL SHOULD BE THE MAIN SVR THREAT...ALTHOUGH LOCALLY DMGG WIND
ALSO COULD OCCUR...MAINLY IN SRN PART OF WW.

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 500. MEAN STORM
MOTION VECTOR 24035.


...CORFIDI

[WeatherGuesser]

[GCANE]

Wow, HRRR is showing a very deep development of CAPE later today.

http://rapidrefresh.noaa.gov/hrrrconus/jsloop.cgi?dsKeys=hrrr:&runTime=2011041905&plotName=cape_sfc&fcstInc=60&numFcsts=16&model=hrrr&ptitle=HRRR%20Model%20Fields&maxFcstLen=15&resizePlot=1&domain=full&wjet=1

Cap seems to break around 18:00Z east OK thru north AR and south MO.

Looks like a squall line may quickly form at that time starting around the OK/KS/MO/AR corner.

It will drive ENE and a high significant-tornado-potential (STP) will be setup SE IL & SW IN about 6 hrs later.

I think capping will be setup in IN at that time.

So, IMHO most significant tornadoes could occur around St Louis and southern IL.

That is not to say at this time some tornadoes could occur in IN but chances diminish further into the night.

[GCANE]

Good solid moisture advecting from the GOM.

Solid dryline thru mid OK and TX with triple point at OK / KS border.

http://www.hpc.ncep.noaa.gov/html/sfclo ... loopb.html

[GCANE]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
402 AM CDT TUE APR 19 2011



THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND
CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT

SEVERE THUNDERSTORMS ARE LIKELY THIS MORNING WITH THE MAIN THREAT
BEING LARGE HAIL.

THEN BY THIS AFTERNOON...A SIGNIFICANT OUTBREAK OF SEVERE
THUNDERSTORMS IS EXPECTED OVER MUCH OF THE AREA THAT WILL PERSIST
THROUGH THE EVENING HOURS BEFORE COMING TO AN END. THE STRONGEST
THUNDERSTORMS WILL BE CAPABLE OF PRODUCING STRONG TORNADOES...HAIL
LARGER THAN GOLF BALL SIZE AND DAMAGING STRAIGHT LINE WIND GUSTS.
LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
449 AM CDT TUE APR 19 2011

.DISCUSSION...
/449 AM CDT TUE APR 19 2011/

...SIGNIFICANT SEVERE THUNDERSTORM OUTBREAK THIS AFTERNOON AND
EVENING...

DEALING WITH SEVERE ACTIVITY EARLY THIS MORNING...SO WILL SEND OUT A
BRIEF DISCUSSION ABOUT TODAY AND TONIGHT. LATEST SURFACE ANALYSIS
SHOWS SURFACE FRONT REMAINS STALLED JUST SOUTH OF I-70. STORMS HAVE
BEGUN TO FIRE EARLY THIS MORNING ON NOSE OF LOW LEVEL JET...OVER
CENTRAL MO AND ARE MOVING TO THE NORTHEAST. NUMEROUS REPORTS OF
LARGE HAIL WITH THESE STORMS.

FOR THIS MORNING...WILL CONTINUE TO SEE ONGOING ACTIVITY INCREASE IN
COVERAGE AND INTENSITY THROUGH THE MORNING HOURS...BEFORE
DIMINISHING TOWARDS NOONTIME. THEN MORE SIGNIFICANT ROUND OF STORMS
EXPECTED TO FIRE UP THIS AFTERNOON AS STRONG AREA OF LOW PRESSURE
LIFTS NORTHEASTWARD THROUGH MO...WITH IT NEAR KSTL AROUND 21Z.
MODELS COMING INTO BETTER AGREEMENT WITH FASTER MOVEMENT THROUGH
REGION THIS AFTERNOON AND EVENING...AND PCPN COMING TO AN END BY 06Z
MOST LOCATIONS.

SPC HAS KEPT SOUTHEASTERN HALF OF CWA IN A MODERATE RISK FOR THIS
AFTERNOON AND EVENING...WITH THE MAIN THREATS BEING STRONG
TORNADOES...HAIL LARGER THAN GOLF BALL SIZE AND DAMAGING STRAIGHT
LINE WIND GUSTS. SO DESPITE STRONG CAP TO DEVELOP OVER REGION AFTER
INITIAL ROUND OF ACTIVITY...STRONG ASCENT TO OVERSPREAD THE REGION
HELPING STORMS TO INITIATE BETWEEN 19Z AND 22Z. EXPECT EPISODE TO
START OFF AS SUPERCELLS THEN EVOLVE INTO A SEVERE LINEAR MCS DURING
THE EVENING AS IT PROGRESSES FURTHER EAST...EXITING THE CWA SHORTLY
AFTER 06Z.

[Dave]

000
FXUS63 KIND 191050
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
650 AM EDT TUE APR 19 2011

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...AN ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE
ACROSS CENTRAL INDIANA TODAY AND TONIGHT AS A LOW PRESSURE SYSTEM
IS EXPECTED TO APPROACH INDIANA AND PUSH NORTH TO THE GREAT LAKES
TONIGHT. A COLD FRONT TRAILING FROM THE LOW IS EXPECTED TO PASS
ACROSS INDIANA LATE TONIGHT...GENERATING MORE STORMS...SOME OF
WHICH COULD BE SEVERE. HIGH PRESSURE IS THEN EXPECTED TO BUILD
ACROSS THE AREA ON WEDNESDAY AFTERNOON AND THURSDAY PROVIDING DRY
WEATHER.

ANOTHER LOW TAKES SHAPE IN THE PLAINS LATE IN THE WEEK AND HELPS
ESTABLISH A FRONTAL BOUNDARY THAT REMAINS IN THE REGION THROUGH
THE END OF THE FORECAST PERIOD...PROVIDING NEARLY CONSTANT SHOWER
AND THUNDERSTORM CHANCES THROUGH MONDAY.

&&

.NEAR TERM /TODAY AND TONIGHT/...

SURFACE ANALYSIS EARLY THIS MORNING SHOWS A WARM FRONTAL BOUNDARY
ACROSS SOUTHERN INDIANA STRETCHING WEST TO LOW PRESSURE OVER THE
OKLAHOMA PANHANDLE. WATER VAPOR IMAGERY SHOWS ABUNDANT MOISTURE
STREAMING ACROSS THE PLAINS STATES AND MISSISSIPPI VALLEY IN THE
NEARLY ZONAL FLOW. SOUTHERLY FLOW ON THE SOUTH SIDE OF THE WARM
FRONT WAS ADVECTING WARM AND MOIST AIR TOWARD CENTRAL INDIANA WITH
DEW POINTS IN THE MIDDLE 60S ACROSS SOUTHERN ILLINOIS AND WESTERN
KENTUCKY. MEANWHILE ON THE NORTH SIDE OF THE FRONTAL BOUNDARY
NORTHEAST WINDS CONTINUED TO PREVAIL ALONG WITH TEMPERATURES AND
DEW POINTS IN THE 40S.

MAIN FORECAST CHALLENGE TODAY WILL BE POPS AND SEVERE THREAT TIMING.

GFS 300K ISENTROPIC SURFACE SHOWS STRONG ISENTROPIC LIFT CONTINUING
OVERNIGHT BEFORE ADVECTING NORTHWARD AS THE WARM FRONT PUSHES
NORTH THIS AFTERNOON. GIVEN THE MOIST AIR MASS AND THIS UPGLIDE
AHEAD OF THE LOW....WILL CONTINUE TO EXPECTED SHOWERS AND SCT
THUNDERSTORMS ACROSS CENTRAL INDIANA OVERNIGHT BEFORE TAPERING OFF
LATER THIS MORNING.

FORECAST SOUNDINGS ACROSS THE FORECAST AREA SHOW A LINGERING LOWER
LEVEL INVERSION IN PLACE IN MOST AREAS LONG AND NORTH OF THE WARM
FRONT. ABOVE THE INVERSION...MUCH BETTER INSTABILITY LOOKS TO BE
IN PLACE AS STEEP LAPSE RATES ARE PRESENT. FURTHERMORE ACROSS THE
AREA VERY FAVORABLE WIND SHEAR IS PRESENT AS STORM RELATIVE
HELICITY IS IN EXCESS OF 300 M2/S2 FOR MUCH OF THE DAY. THUS ANY
CONVECTIVE DEVELOPMENT THAT DOES OCCUR WILL HAVE A VERY FAVORABLE
ENVIRONMENT IN WHICH TO SPIN.

ONGOING TIMING THOUGHTS REMAIN SIMILAR TO PREVIOUS RUNS AS INITIAL
THREAT WILL BE THIS AFTERNOON ACROSS SOUTHERN PARTS OF THE
FORECAST AREA...SOUTH OF THE WARM FRONT WHERE LIFTED INDEX
READINGS WILL BE LESS THAN -6. GFS SHOWS A STRONG LLJ NEAR 50 KNTS
PUSHING NORTH ACROSS INDIANA LATE THIS AFTERNOON AND
EVENING...HELPING TO PUSH THE WARM FRONT NORTH ALONG WITH THE
WARM...MOIST AND UNSTABLE AIR. THUS EXPECT ONSET MAINLY THIS
AFTERNOON AND CONTINUING INTO THE EVENING HOURS...SPREADING FROM
SOUTH TO NORTH AS THE LLJ WIELDS ITS INFLUENCE. THUS ALTHOUGH A
COMPLETE SOAKER OF A DAY IS NOT EXPECTED...WILL TRY AND FOCUS HIGH
CATEGORICAL POPS MAINLY DURING THE AFTERNOON HOURS.

SECOND ROUND OF STORMS WILL COME LATE TONIGHT AS MODELS PUSH THE
LOW TOWARD MICHIGAN AND THE COLD FRONT IS DRAGGED ACROSS INDIANA.
BY THIS TIME...ANY DAYTIME HEATING WILL BE LOST...HOWEVER A
NEGATIVELY TILTED UPPER SHORT WAVE WILL BEGIN TO INFLUENCE THE
SYSTEM AND FORECAST SOUNDINGS CONTINUE TO SHOW FAVORABLE
INSTABILITY WITH CAPE IN EXCESS OF 2000 J/KG AND FAVORABLE
HELICITY VALUES FOR ROTATING STORMS. THUS AGAIN WILL AIM FOR
CATEGORICAL POPS TONIGHT.

GIVEN THE WARM AND MOIST AIR IN PLACE AND THE EXPECTED DYNAMICS
SEVERE SEVER WEATHER THREATS WILL BE POSSIBLE...INCLUDING FLASH
FLOODING...TORNADOES...LARGE HAIL AND DAMAGING STRAIGHT LINE
WINDS. WILL MENTION ALL OF THESE IN THE HAZARDOUS WEATHER OUTLOOK.

WILL LEAN TO THE WARMER SIDE OF THE MAVMOS TEMPERATURES FOR HIGHS
TODAY AS STRONG WARM AIR ADVECTION IS EXPECTED AS THE WARM FRONT
LIFTS NORTHWARD LATE IN THE DAY.

AS FOR LOWS WILL LEAN TOWARD THE WET BULB TEMPERATURES AS RAIN IS
EXPECTED AND THE BEST COLD AIR DOES NOT ARRIVE UNTIL AFTER 12Z
WEDNESDAY.

[Dave]

000
FXUS63 KLMK 191126
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
726 AM EDT TUE APR 19 2011

...UPDATED AVIATION DISCUSSION...

.SHORT TERM (TODAY AND TONIGHT)...

...SEVERE WEATHER EPISODE EXPECTED LATE THIS EVENING AND OVERNIGHT
WITH DAMAGING WINDS...LARGE HAIL...SCATTERED TORNADOES AND PLENTY OF
HEAVY RAINFALL...

06Z SFC ANALYSIS REVEALED AN AREA OF LOW PRESSURE OVER NW OKLAHOMA
THIS MORNING WITH A QUASI-STATIONARY FRONTAL BOUNDARY EXTENDING FROM
THE LOW NORTHEASTWARD INTO THE LOWER-MID OHIO VALLEY. THE BOUNDARY
WAS LOCATED NORTH OF THE OHIO RIVER AND SLOWLY MAKING PROGRESS TO
THE NORTH. NOCTURNAL LOW-LEVEL JET AXIS IS IMPINGING ON THE AREA
FROM THE SOUTHWEST WHICH IS PROVIDING GOOD MOISTURE TRANSPORT INTO
THE REGION WHICH IS HELPING MAINTAIN THE LARGE AREA OF CONVECTION
JUST TO OUR NORTH. LATEST HIGH RESOLUTION MODELS SHOW THIS AREA OF
CONVECTION CONTINUING TO PULL OFF TO THE NORTHEAST THIS MORNING AS
THE BOUNDARY MOVES NORTHEASTWARD AND AWAY FROM THE REGION. SOUTH OF
THE BOUNDARY...A FEW SCATTERED THUNDERSTORMS HAVE CONTINUED TO MOVE
NORTHEASTWARD ACROSS CENTRAL AND EAST-CENTRAL KY. THESE STORMS WILL
CONTINUE TO MOVE ACROSS BLUEGRASS REGION OVER THE NEXT FEW HOURS.
TEMPERATURES REMAIN QUITE MILD EARLY THIS MORNING WITH MOST
LOCATIONS STILL IN THE MID-UPPER 60S WITH SOME UPPER 60S TO LOWER
70S STILL NOTED ACROSS FAR SOUTHERN KY.

FOR TODAY...SFC FRONTAL BOUNDARY IS EXPECTED TO MOVE SLOWLY
NORTHWARD AND AWAY FROM THE AREA. SKIES ARE EXPECTED TO CLEAR OUT A
BIT WITH PARTLY TO MOSTLY SUNNY SKIES EXPECTED THROUGH MUCH OF THE
DAY. UNDER A STIFF SOUTHWESTERLY WIND FLOW...TEMPERATURES ARE
EXPECTED TO WARM INTO THE LOWER 80S ACROSS THE REGION. THE STRONG
SOUTHWESTERLY FLOW WILL CONTINUE TO PUMP RICH/MOIST GULF AIR INTO
THE REGION WITH SURFACE DEWPOINTS EXPECTED TO RISE INTO THE
MID-UPPER 60S DURING THE AFTERNOON HOURS. WOULD NOT SURPRISE ME TO
SEE SOME 70 DEWPOINTS AS CLOSE AS FAR SW KY/NW TN.

AS TEMPERATURES WARM AND MOISTURE CONTINUES TO INCREASE...WE WILL
SEE THE ATMOSPHERE BECOME CONDITIONALLY UNSTABLE DURING THE LATE
AFTERNOON HOURS. STEEP LAPSE RATES ALOFT...MAINLY ABOVE 700HPA WILL
RESULT IN LIFTED INDICES DROPPING TO BELOW -5 DEGREES C IN MOST
PLACES. CAPE VALUES WILL LIKELY SURGE INTO THE 2000-2500 J/KG
RANGE. HOWEVER...ALL MODELS POINT TO A LAYER OF WARM AIR ALOFT
BETWEEN 700-800HPA WHICH WILL EFFECTIVE CAP THE ATMOSPHERE FOR THE
AFTERNOON AND EARLY EVENING HOURS. GIVEN THE ANTICIPATED CAPPING
INVERSION...PRETTY MUCH ALL OF THE REGION WILL LIKELY BE DEVOID OF
ANY CONVECTION DURING THE AFTERNOON...THUS PLAN ON KEEPING SMALL CHC
POPS IN FOR THIS MORNING WITH THE LINGERING ACTIVITY AND THEN
REDUCING POPS FOR THE AFTERNOON. AS MENTIONED...WINDS WILL BE GUSTY
THIS AFTERNOON WITH SUSTAINED WINDS OF 15-20MPH AND GUSTS UP TO 30
MPH. AT THIS TIME...DO NOT FEEL THAT WE WILL REACH WIND ADVISORY
CRITERIA...BUT IT WILL BE SOMETHING TO WATCH AS THE DAY UNFOLDS.

BY LATE THIS AFTERNOON...CAPPING INVERSION IS EXPECTED TO MIX OUT
WELL TO OUR WEST. AS THIS OCCURS...VIGOROUS CONVECTIVE DEVELOPMENT
IS EXPECTED ACROSS WESTERN MO LATE THIS AFTERNOON. LONG CURVED
HODOGRAPHS SUGGEST THAT INITIAL CONVECTIVE MODE WILL BE
SUPERCELLULAR. THESE STORMS SHOULD QUICKLY MOVE EASTWARD ACROSS MO
AND INTO FAR WESTERN KY AND ILLINOIS THIS EVENING. AS THEY HEAD
EAST...THEY WILL LIKELY CONGEAL INTO A QUASI-LINEAR CONVECTIVE
SYSTEM AND THEN SURGE EASTWARD INTO SOUTHERN INDIANA AND CENTRAL
KENTUCKY LATE THIS EVENING AND OVERNIGHT. THIS QLCS SHOULD BE
REMAIN WELL MAINTAINED AS PLENTY OF INSTABILITY AND MOISTURE WILL BE
IN PLACE ACROSS OUR REGION. CURRENT THINKING IS THAT THE PRIME TIME
FOR OUR SEVERE WEATHER EPISODE WILL BE BETWEEN 10 PM AND 600 AM
EDT. GIVEN THE STRONG WIND FIELDS A LARGE DAMAGING WIND EVENT SEEMS
VERY LIKELY. IN ADDITION...LARGE HAIL AND SQUALL LINE EMBEDDED
TORNADOES ARE LIKELY. AS PREVIOUS FORECASTER MENTIONED...THE OVERALL
SETUP STILL LOOKS A LOT LIKE 4/28/2002 WHICH RESULT IN QUITE A BIT
OF WIND DAMAGE ACROSS THE REGION ALONG WITH A FEW TORNADOES.
ACTIVITY WILL LIKELY APPROACH THE I-75 CORRIDOR TOWARD THE END OF
THE SHORT TERM FORECAST PERIOD AND BE ON A GRADUAL DOWNTURN AS
INSTABILITY WILL DECREASE AS ONE HEADS EASTWARD INTO EASTERN
KENTUCKY. TEMPERATURES WILL REMAIN MILD TONIGHT WITH LOWS FALLING
INTO THE LOWER-MID 60S.

AS IF THE SEVERE WEATHER WAS NOT ENOUGH...HEAVY RAINFALL WILL BE A
PROBLEM AS WELL AS THIS SYSTEM MOVES THROUGH THE REGION. A GOOD ONE
TO AS MUCH AS TWO INCHES OF RAINFALL IS EXPECTED AS THIS SYSTEM
MOVES THROUGH THE REGION. OVERALL...FLASH FLOOD GUIDANCE VALUES
REMAIN QUITE HIGH AND MOST OF OUR RIVERS HAVE GONE BACK INTO THEIR
BANKS. ISOLATED FLASH FLOODING IS POSSIBLE...BUT GIVEN THE OVERALL
STORM TRACK...FEEL THAT THE MOST SUSCEPTIBLE AREA FOR FLOODING WILL
BE ACROSS SOUTHERN INDIANA. THE ONE TO TWO INCH RAINFALL WILL
LIKELY RESULT IN QUICK RISES ON AREA STREAMS AGAIN. SO THOSE LIVING
NEAR CREEKS/STREAMS OR IN FLOOD PRONE AREAS...SHOULD KEEP AN EYE ON
WATER LEVELS OVER THE NEXT 24 HOURS.

[GCANE]

Already strong STP in south MO.

Sky's look clear there, should see strong surface heating today.

IMHO, convective initiation could be explosive in eastern OK later this afternoon.

[CrazyC83]

SPC AC 191629

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT TUE APR 19 2011

VALID 191630Z - 201200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
PARTS OF ERN OK...AR...CNTRL/SRN MO...WRN TN...KY...IL...IND AND WRN
OH...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER GREAT LAKES SWWD
INTO SRN TX...

...OUTBREAK OF SEVERE THUNDERSTORMS CAPABLE OF WIDESPREAD
HAIL...DAMAGING WINDS AND A FEW STRONG TORNADOES POSSIBLE THIS
AFTERNOON THROUGH TONIGHT...

...OH VALLEY/LOWER GREAT LAKES SWWD INTO ERN OK/AR...

SHORTWAVE TROUGH OBSERVED OVER THE CNTRL/SRN HIGH PLAINS THIS
MORNING WILL CONTINUE NEWD...CONTRIBUTING TO A CORRIDOR OF 30-60 M
HEIGHT FALLS PER 12-HR AT 500 MB FROM THE CNTRL PLAINS THROUGH THE
MID MS VALLEY INTO UPPER GREAT LAKES. IN THE LOW-LEVELS...SURFACE
LOW ATTENDANT TO THIS SYSTEM ANALYZED OVER W-CNTRL MO AS OF 16Z WILL
DEVELOP NNEWD TO N OF STL BY 19/21Z...THE IL/IND BORDER NEAR DNV BY
20/03Z TO LAKE ERIE BY 20/12Z. A WARM FRONT WILL PRECEDE THE
LOW...GRADUALLY LIFTING NWD THROUGH IL/IND/OH/PA. TRAILING COLD
FRONT WILL ADVANCE SEWD...LIKELY EXTENDING FROM SURFACE LOW OVER
CNTRL IL SWWD THROUGH E-CNTRL MO...NWRN AR AND SERN OK BY 20/00Z.
THIS COLD FRONT WILL SERVE AS THE PRIMARY FOCUS FOR SEVERE
THUNDERSTORM DEVELOPMENT THIS AFTERNOON INTO TONIGHT.

12Z REGIONAL SOUNDINGS SHOWED THE PRESENCE OF STEEP MIDLEVEL LAPSE
RATES/EML IN PLACE FROM THE CNTRL/SRN PLAINS EWD THROUGH THE
MID/LOWER MS VALLEYS. THESE LAPSE RATES RESIDE ABOVE A MOIST AND
RATHER BROAD WARM SECTOR CHARACTERIZED BY PW VALUES OF 1.0-1.5
INCHES AND BOUNDARY LAYER DEWPOINTS IN THE 60S. ASIDE FROM ISOLATED
OCCURRENCES OF HAIL N OF WARM FRONT OVER THE OH VALLEY TODAY...A CAP
AT THE BASE OF THE EML IS EXPECTED TO DELAY SURFACE-BASED TSTM
DEVELOPMENT UNTIL THIS AFTERNOON.

ABUNDANT SUNSHINE...THE STEEP LAPSE RATES AND INCREASING LOW-LEVEL
MOISTURE WILL YIELD A MODERATELY TO STRONG UNSTABLE WARM SECTOR
TODAY WITH MLCAPE VALUES RANGING FROM 1000-2000 J/KG S OF THE WARM
FRONT IN THE OH VALLEY...TO 3000-4000+ J/KG AHEAD OF COLD FRONT FROM
SRN MO INTO ERN OK/WRN AR. FRONTAL UPLIFT COUPLED WITH INCREASED
FORCING FOR ASCENT ATTENDANT TO MIDLEVEL TROUGH ARE EXPECTED TO
FOSTER TSTM DEVELOPMENT BY MID AFTERNOON FROM THE VICINITY OF THE
SURFACE LOW OVER CNTRL/E-CNTRL MO SWWD TO ERN OK/WRN AR.

AN ISALLOBARICALLY BACKED WIND FIELD AHEAD OF SURFACE LOW WILL
RESULT IN A CORRIDOR OF ENHANCED LOW-LEVEL SHEAR FROM E-CNTRL MO EWD
THROUGH CNTRL PARTS OF IL/IND. GIVEN MORE DISCRETE STORM MODES
/I.E. SUPERCELLS/...THIS AREA WILL REPRESENT THE GREATEST RISK FOR
TORNADOES /SOME POSSIBLY STRONG/ FROM LATE THIS AFTERNOON INTO
TONIGHT. OTHERWISE...EXPECT THE DEVELOPMENT OF SUPERCELLS AND LINE
SEGMENTS ALONG COLD FRONT WITH EVENTUAL UPSCALE GROWTH INTO ONE OR
MULTIPLE MCSS/QLCSS. WIDESPREAD OCCURRENCES OF HAIL AND DAMAGING
WINDS /SOME SIGNIFICANT/ ARE EXPECTED ACROSS THE MODERATE RISK AREA
INTO EARLY WEDNESDAY DUE TO THE PRESENCE OF STEEP LAPSE RATES AND
THE WIDE...UNSTABLE WARM SECTOR.

...TX...

TSTM POTENTIAL AND ATTENDANT SEVERE WEATHER THREAT IS MORE UNCERTAIN
WITH SWD EXTENT ALONG THE DRYLINE THIS AFTERNOON OWING TO WEAK OR
NEGLIGIBLE LARGE-SCALE FORCING FOR ASCENT. NONETHELESS...MORNING
VISIBLE SATELLITE IMAGERY DOES SUGGEST THAT STRONG DIABATIC HEATING
WILL OCCUR TODAY ALONG AND W OF DRYLINE...BOOSTING SURFACE
TEMPERATURES INTO THE 90S. SHOULD SUFFICIENT HEATING/CONVERGENCE
DEVELOP TO INITIATE ISOLATED STORMS...THE PRESENCE OF MLCAPE VALUES
OF 3000-4000+ J/KG AND 30-40 KT OF DEEP WLY SHEAR WILL BE SUPPORTIVE
OF SUPERCELLS CAPABLE OF LARGE HAIL. ANY STORMS THAT MAY DEVELOP
WOULD LIKELY WEAKEN BY LATE EVENING AS THE BOUNDARY LAYER BEGINS TO
COOL AND CONVECTIVE INHIBITION INCREASES.

..MEAD/SMITH.. 04/19/2011

CLICK TO GET WUUS01 PTSDY1 PRODUCT

NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
CURRENT UTC TIME: 1635Z (12:35PM), RELOAD THIS PAGE TO UPDATE THE TIME

[GCANE]

VIS is showing some wide-spread gravity-type waves indicating buoyancy is developing nicely in east OK, south MO, and AR.

Looks very unstable.

[GCANE]

Good Low-Level Jet forming in SW MO.

[Dave]

Temp has risen from 48 - 55 degrees in past 2 hours across SE Indiana. Flash flood warnings have expired, received between 2 & 4" of rain from earlier this morning. Still overcast at my location but reports of broken & scattered clouds 30 miles south of me...Northern Ky. Expecting at least broken clouds here soon. Dewpoint is 56 temp 56.

Anybody see a PDS out of this yet?

[srainhoutx]

Keeping on eye on the area S of the warm front. HRRR suggests strong storms with possible super cell structures from the Ozarks of AR/MO and points N and E. May need to watch back to the SW as well into NE TX/SE OK. My hunch is we may well see a PDS Watch near the Ozarks this afternoon. We will see.

[GCANE]

IMHO a PDS for St Louis later today.