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April 15-19th Severe Weather


Chicago Storm

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Man... That is ALOT of rain over the Midwest heading this way. How in the world are we going to get surface based instability tomorrow.....?

I see lower to mid 60's under cloudy skies all day for some reason. I'll be relieved to the see the updated SPC outlook with SWMI still included. I think it may shrink south some below the IN border. That is just a lot of rain and debris clouds, but I guess a lot can happen in 12-16 hours right?

How did the hi-res models do on today's convection? (Been busy all day never got to check)

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Man... That is ALOT of rain over the Midwest heading this way. How in the world are we going to get surface based instability tomorrow.....?

I see lower to mid 60's under cloudy skies all day for some reason. I'll be relieved to the see the updated SPC outlook with SWMI still included. I think it may shrink south some below the IN border. That is just a lot of rain and debris clouds, but I guess a lot can happen in 12-16 hours right?

How did the hi-res models do on today's convection? (Been busy all day never got to check)

 

How is it possible to get real supercells into SWMI in April?  It seems like instability is always eaten off by previous day convection leaving half-eaten leftovers.  Somehow it used to happen in the 70s and 80s.

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Well, there's no way I'll have time to drive all the way down into central Indiana tomorrow.  Is the stupid ass convection blob over northern Missouri supposed to stay stationary all tonight and all day tomorrow?

How is it possible to get real supercells into SWMI in April?  It seems like instability is always eaten off by previous day convection leaving half-eaten leftovers.  Somehow it used to happen in the 70s and 80s.

It's definitely moving NE, but it should overshoot our area and go North along the warm front. As the storm deepens, the warm front will literally surge northward and the rain should follow... So there is SOME light for us at the end of the tunnel.

I'd say a situation like tomorrow, but with definitive instability we would get ATLEAST some supercellular storms ahead of the QLCS. Time will tell. Keep an eye on the latest HRRR and WRF 4KM. Both seemed to handle some of today's convection pretty well, more so the WRF.

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That doesn't do much when the CAPE is 50 J/kg.

CAPE is more like 500-1000 J/kg in the areas I'm looking at (NE IL/W IN)

Overall I'd say the directional shear is lacking just a bit for my taste...in terms of getting a big tornado outbreak...but I would expect some.

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I'm hoping and expecting models are underdoing instability a bit.  Temps shown in the low 70s over southern and eastern IL seem a bit low to me considering how warm the warm sector got today.  Hell, even now temps over that area are still in the mid 70s. Granted there was more sun today for temps to get that warm, but any amount of sun tomorrow will quickly vault temps above 75 I would think.  Really don't think southern/far eastern IL will have complete cloud cover tomorrow afternoon.  Should see at least partial sunshine.  This combined with established deep moisture should push cape values over 1000j/kg IMO.  With the incoming strong vort and strong shear profiles I think there's a decent chance for some tornadoes.  Like I said earlier we're gonna shoot for the intersection of the outflow/differential heating boundary and the incoming cold front/dry line.  Target starting point will be Litchfield IL, but will probably adjust depending on how the boundaries/fronts evolve. 

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CAPE is more like 500-1000 J/kg in the areas I'm looking at (NE IL/W IN)

Overall I'd say the directional shear is lacking just a bit for my taste...in terms of getting a big tornado outbreak...but I would expect some.

I am looking at that area too. I was sort of making a joke. My point is that the CAPE looks skinny and the profile looks quite wet. I expect a squall line will be in that area in Indiana. The severe weather with that squall line could be wind gusts to 80mph and short-lived tornadoes. If it doesn't destabilize much, then maybe it will be a "cool" squall line, with a few wind gust reports.

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It's way too early to be worried about crapvection. Besides, the WF will surge north as the LP deepens. Not to worry, MI crew. 

 

As long as all tonight's crapvection doesn't change the track of the low itself.  Guess I just have to wait.  The 850 mb 10 degree dewpoint isotherm is still south of where it was six hours ago and it's being a b**ch to budge north.  Right now it feels like it's getting colder out rather than warmer.

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As long as all tonight's crapvection doesn't change the track of the low itself.  Guess I just have to wait. 

WF is lifting Northward as we speak, you can see the whole band of convection is lifting NE as the individual showers/storms move E.

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As long as all tonight's crapvection doesn't change the track of the low itself.  Guess I just have to wait.  The 850 mb 10 degree dewpoint isotherm is still south of where it was six hours ago and it's being a b**ch to budge north.  Right now it feels like it's getting colder out rather than warmer.

 

Warm air is on the way frostfern!

 

NAM hires says mid 70s for your area. Lots of warm air fuel.

 

temp17.gif

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WF is lifting Northward as we speak, you can see the whole band of convection is lifting NE as the individual showers/storms move E.

 

I see it surging north over lower MI now but upstream in Illinois it just seems to be training.  Over Kansas, Missouri, and Iowa the convection is building back west behind the surface front.  Maybe that's the incipient strengthening low.  Hopefully.

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The cell west of Crawfordsville that will eventually head up towards southeastern LAF is the one I'd be watching.  Starting to get sort of a kidney bean shape to it.

 

We were on this for a while.  Sat in Danville, IL waiting for the cell coming NE out of Effingham to get into an area with better roads, but it really fizzled by the time it hit I-74.  Then all of a sudden that guy near Crawfordsville looked pretty good.  We only had about 20 minutes of viewing before we lost daylight, but it had some really impressive scud/lowering, and a distinct wall cloud for at least a few minutes.  Countless CG strikes too.

 

Have my eyes on that one. Of course, me being on the southeast side of LAF...

 

Also cells that went through N IL merging with ones moving/and developing north through central IN. Kinda cool radar image.

 

 

Warning cancelled/expired for Tippecanoe county. Still should be a rather quality thunderstorm...

 

Was at least a lot of rain, I hope?

 

Must've been.  I almost sunk my car on US-41 a few miles north of I-74 when I hit some pretty deep ponding at the bottom of a hill.  And even after that I had to deal with several wash-overs all the way up 41.

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DTX

IN ADDITION TO THE FLOOD POTENTIAL...SEVERE WEATHER IS A MAJORCONCERN TODAY AND THIS EVENING. WITH THE WARM FRONT SURGING NORTHTHE HIGH SURFACE DEW POINTS WILL ALLOW SURFACE BASED CAPE VALUES TORISE TO 1.5 TO 2 J/G DURING THE AFTERNOON WITH MUCAPE VALUESREMAINING NEAR 1 J/G INTO THE EVENING HOURS. HIGH WINDS ARE A REALTHREAT FROM CONVECTION THAT DEVELOPS AS WINDS MEET OR EXCEED 60KNOTS AS LOW AS 3500 FEET. HODOGRAPHS ARE ALSO QUITE IMPRESSIVE WITHSURFACE TO 1 KM HELICITY VALUES OF 250 TO 300 WITH SHEAR VALUES OF20 TO 25 M/S. THE ONE SEVERE WEATHER PARAMETER THAT IS NOT TOOIMPRESSIVE IS THE FREEZING LEVEL...WHICH IS 11-12K FEET ALONG WITHTHE LONG SKINNY CAPE WHICH ARE NOT VERY CONDUCIVE FOR LARGE HAIL. ITAPPEARS THE MAIN THREAT WILL BE DAMAGING WINDS...WHICH IT WILL NOTTAKE MUCH TO BRING TO THE SURFACE GIVEN THE STRONG WINDS JUST OFFTHE DECK. THERE WILL ALSO BE AN ELEVATED TORNADO THREAT GIVEN THEHODOGRAPH AND HIGH AMOUNT OF SHEAR IN THE LOWEST LEVELS OF THEATMOSPHERE AS WINDS TURN FROM SOUTH AT 25 KNOTS TO SOUTHWEST AT 60KNOTS AT 3500 FT. THE MAIN FACTOR AGAINST TORNADO DEVELOPMENT IS THELACK OF LOW LEVEL CAPE. HOWEVER THE SOUTHERN CWA IS MOST ATRISK...ESPECIALLY IF THERE IS A BREAK IN THE CONVECTION AND SOMEAFTERNOON SUNSHINE CAN GENERATE LOW LEVEL CAPE AND ENHANCE EHIVALUES WHICH GET TO AROUND 2 JUST TO OUR SOUTHWEST.
IN ADDITION TO THE FLOOD POTENTIAL...SEVERE WEATHER IS A MAJORCONCERN TODAY AND THIS EVENING. WITH THE WARM FRONT SURGING NORTHTHE HIGH SURFACE DEW POINTS WILL ALLOW SURFACE BASED CAPE VALUES TORISE TO 1.5 TO 2 J/G DURING THE AFTERNOON WITH MUCAPE VALUESREMAINING NEAR 1 J/G INTO THE EVENING HOURS. HIGH WINDS ARE A REALTHREAT FROM CONVECTION THAT DEVELOPS AS WINDS MEET OR EXCEED 60KNOTS AS LOW AS 3500 FEET. HODOGRAPHS ARE ALSO QUITE IMPRESSIVE WITHSURFACE TO 1 KM HELICITY VALUES OF 250 TO 300 WITH SHEAR VALUES OF20 TO 25 M/S. THE ONE SEVERE WEATHER PARAMETER THAT IS NOT TOOIMPRESSIVE IS THE FREEZING LEVEL...WHICH IS 11-12K FEET ALONG WITHTHE LONG SKINNY CAPE WHICH ARE NOT VERY CONDUCIVE FOR LARGE HAIL. ITAPPEARS THE MAIN THREAT WILL BE DAMAGING WINDS...WHICH IT WILL NOTTAKE MUCH TO BRING TO THE SURFACE GIVEN THE STRONG WINDS JUST OFFTHE DECK. THERE WILL ALSO BE AN ELEVATED TORNADO THREAT GIVEN THEHODOGRAPH AND HIGH AMOUNT OF SHEAR IN THE LOWEST LEVELS OF THEATMOSPHERE AS WINDS TURN FROM SOUTH AT 25 KNOTS TO SOUTHWEST AT 60KNOTS AT 3500 FT. THE MAIN FACTOR AGAINST TORNADO DEVELOPMENT IS THELACK OF LOW LEVEL CAPE. HOWEVER THE SOUTHERN CWA IS MOST ATRISK...ESPECIALLY IF THERE IS A BREAK IN THE CONVECTION AND SOMEAFTERNOON SUNSHINE CAN GENERATE LOW LEVEL CAPE AND ENHANCE EHIVALUES WHICH GET TO AROUND 2 JUST TO OUR SOUTHWEST.
 
 
 
 
GRR
 CONSENSUS OF LATEST 00Z SHORT RANGE GUIDANCE CONTINUES TO SUGGESTPOTENTIAL FOR SEVERE WX LATER TODAY... PARTICULARLY THIS AFTERNOON ANDEARLY EVENING. THIS AS A STRENGTHENING LOW PRESSURE TRACKS NE TONEAR MKE BY 00Z THIS EVE.IT DOES SEEM OVERALL GUIDANCE CONSENSUS DOES NOT SHOW AS MUCHINSTABILITY AS EARLIER MODEL RUNS DID... NOW GENERALLY SHOWING SBCAPES MAY ONLY REACH 500-1000 J/KG THIS AFTN. EVEN SO THIS ISCERTAINLY SUFFICIENT ENOUGH/COMPENSATED FOR TO GET SEVERE WX WHENCOMBINED WITH ROBUST DEEP LAYER SHEAR VALUES AND STRONG UPPERDYNAMICS AND VERY STRONG WINDS ALOFT ALONG WITH STRONG LLJ.LATEST SPC SREF (041721Z RUN) CRAVEN BROOKS SIG SVR PARAMETERSUGGESTS AREAS FROM IN/OH FURTHER SOUTH WOULD BE THE GREATESTCONCERN FOR SIG SVR LATER TODAY. ON THE OTHER HAND IT IS NOTED THATTHE SUPERCELL COMPOSITE PARAMETER RAMPS UP SIGNIFICANTLY OVER OURAREA THIS AFTN AND THE SIG TOR FCST PARAMETER DOES REACH 1-2 BY THISAFTN/EARLY EVE. SO THE OVERALL SETUP STILL LOOKS FAVORABLE FORPOTENTIAL SEVERE WX MAINLY THIS AFTN/EARLY EVE.IN ADDITION THE SVR WX THREAT MAY COME SOONER RATHER THAN LATER WITH00Z 4KM WRF-NMM SIM Z GUIDANCE SHOWING POTENTIAL FOR A SQUALL LINETO COME ONSHORE SHORTLY AFTER NOON TODAY AND THEN SWEEP ACROSS OURENTIRE FCST AREA FROM AROUND 1 PM THROUGH 4 PM THIS AFTERNOON. THISNOTION IS SUPPORTED BY THE 4KM NSSL-WRF SIM Z GUIDANCE AS WELL.ALTHOUGH WE WILL STILL HAVE POTENTIAL FOR STRONG TO SEVERE STORMS INTHE LATE AFTN/EVE TOO... THE HIGHER RES GUIDANCE SUGGESTS THEGREATER SVR WX THREAT THIS EVE MAY BE MAINLY SOUTH OF OUR AREA FROMIN/OH SOUTHWARD WHERE THERE WILL BE GREATER INSTABILITY. OUR SVR WXTHREAT SHOULD BE OVER BY 06Z TONIGHT (AND PROBABLY SEVERAL HOURSSOONER) WHEN THE COLD FRONT WILL BE CLEARING OUR EASTERN FCST AREA.
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mcd0518.gif

      MESOSCALE DISCUSSION 0518   NWS STORM PREDICTION CENTER NORMAN OK   0725 AM CDT THU APR 18 2013      AREAS AFFECTED...ERN IL...MUCH OF INDIANA...SWRN LOWER MI      CONCERNING...SEVERE POTENTIAL...WATCH LIKELY       VALID 181225Z - 181400Z      PROBABILITY OF WATCH ISSUANCE...80 PERCENT      SUMMARY...LINE OF THUNDERSTORMS WILL ADVANCE EWD ACROSS ERN IL INTO   INDIANA AND SWRN LOWER MI THIS MORNING...WITH SVR THREAT EXPECTED TO   INCREASE WITH TIME. ALTHOUGH A WW IS NOT IMMEDIATELY NECESSARY...ONE   WILL LIKELY BE ISSUED LATER THIS MORNING.      DISCUSSION...SURFACE LOW PRESSURE CONTINUES TO ADVANCE NEWD ACROSS   THE MID MS VALLEY THIS MORNING AHEAD OF A SHORTWAVE TROUGH EJECTING   OVER THE CNTRL PLAINS. LINE OF THUNDERSTORMS OCCURRING AHEAD OF THE   SURFACE LOW IS CURRENTLY MOVING EWD ACROSS CNTRL IL WITHIN A WEAKLY   UNSTABLE AIRMASS. HOWEVER...LATEST SURFACE OBSERVATIONS AND   OBJECTIVE ANALYSIS GUIDANCE INDICATE INCREASING THETA-E VALUES AHEAD   OF THE LINE OVER ERN IL AND WRN INDIANA. IN ADDITION...EARLY VISIBLE   SATELLITE IMAGERY SHOWS MAINLY CLEAR SKIES ACROSS INDIANA...WHICH   WILL FURTHER AID IN BOUNDARY LAYER DESTABILIZATION WITH CONTINUED   DAYTIME HEATING. GIVEN THE PRESENCE OF 60+ KT OF DEEP-LAYER SWLY   FLOW OVERSPREADING THE AREA...THE THREAT FOR DAMAGING WIND GUSTS AND   A COUPLE OF TORNADOES IS EXPECTED TO INCREASE THIS MORNING.      ..GARNER/HART.. 04/18/2013
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New day one outlook.

 

 

 

 

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0736 AM CDT THU APR 18 2013

VALID 181300Z - 191200Z

...THERE IS A MDT RISK OF SVR TSTMS TODAY INTO THIS EVENING OVER
PORTIONS OF SOUTHERN LOWER MI...MUCH OF IND...CENTRAL AND SOUTHERN
IL...SOUTHEAST MO...WESTERN KY...WESTERN TN...EASTERN AR...AND
NORTHERN MS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM EAST TX NORTHWARD ACROSS
MUCH OF THE MS AND OH VALLEYS...

A LARGE UPPER TROUGH IS FORECAST TO ROTATE EASTWARD INTO THE MS
VALLEY TODAY. AS THIS OCCURS...AN EXPANSIVE SQUALL LINE THAT
CURRENTLY EXTENDS FROM NORTHERN IL INTO AR/EAST TX WILL SURGE
EASTWARD AND RESULT IN A LARGE AREA OF SEVERE THUNDERSTORM
POTENTIAL.

...MI/IL/IND...
VERY STRONG LARGE SCALE DYNAMICS WILL OVERSPREAD THE MID MS VALLEY
AND CENTRAL GREAT LAKES REGION TODAY. IN ADDITION TO THE STRONG
FORCING...LOW AND MID LEVEL WIND FIELDS WILL BECOME IMPRESSIVE
THROUGH THE DAY WITH 850MB WINDS SPEEDS OVER 60 KNOTS AHEAD OF THE
SQUALL LINE. 12Z RAOBS AHEAD OF THE SQUALL LINE SHOW THERMODYNAMIC
PROFILES FAVORABLE FOR STRONG DOWNDRAFTS REACHING THE SURFACE AFTER
JUST A FEW HOURS OF HEATING. THE END RESULT MAY BECOME A SWATH OF
RATHER WIDESPREAD DAMAGING WINDS ACROSS PARTS OF IL/IND INTO
SOUTHERN LOWER MI. ANY CELLS THAT FORM AHEAD OF THE MAIN LINE WILL
ALSO BE CAPABLE OF BECOMING SUPERCELLULAR GIVEN 0-3KM SRH VALUES OF
300-500 M2/S2. THIS WILL PROVIDE POTENTIAL FOR A FEW TORNADOES AS
WELL.

...LA/AR/MS/TN/KY...
THE SQUALL LINE WILL BE MOVING SLIGHTLY SLOWER OVER THIS REGION
COMPARED TO FARTHER NORTH. THIS WILL PROVIDE A FEW MORE HOURS OF
DIURNAL HEATING AHEAD OF THE STORMS BEFORE THEY TRAVERSE THE MOIST
AXIS. SEVERAL MODEL SOLUTIONS SUGGEST THE SQUALL LINE AS WELL AS
SEVERAL STORMS AHEAD OF THE LINE WILL INTENSIFY BY EARLY AFTERNOON.
AMPLE MOISTURE/INSTABILITY AND FAVORABLE LOW LEVEL/DEEP LAYER
VERTICAL SHEAR SUGGEST SUPERCELL AND BOW STRUCTURES WILL BE POSSIBLE
THROUGHOUT THIS REGION. DAMAGING WINDS ARE LIKELY THE MAIN
THREAT...BUT A FEW TORNADOES /SOME STRONG/ ARE ALSO A
POSSIBILITY...ESPECIALLY WITH DISCRETE STORMS THAT FORM AHEAD OF THE
SQUALL LINE.

..HART/GARNER.. 04/18/2013

 

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