April 18-20th Severe Weather

[Hoosier]

This may be a dumb question to alot of you but could someone explain what a hodograph is? I've got the skew-t's down, I just always see the hodo and cant quite interept what its showing. Thanks!

It shows how the winds change direction and speed with height. The ones on the wxcaster site are very easy to interpret. Basically, a long curved/looping structure suggests good low/mid level shear which may favor tornadoes. More of a straight line means that the wind profile is more unidirectional which would be more favorable for damaging winds or splitting cells.

[cyclone77]

This may be a dumb question to alot of you but could someone explain what a hodograph is? I've got the skew-t's down, I just always see the hodo and cant quite interept what its showing. Thanks!

This is a question that Ocean or BI could answer a lot better than me, but basically for tornadoes a long and clockwise looping hodograph is favorable.

[snowlord81]

This is a question that Ocean or BI could answer a lot better than me, but basically for tornadoes a long and clockwise looping hodograph is favorable.

Well it makes pretty good sense now that I've got the basic defintion. Thanks Hoosier.

[JoMo]

This may be a dumb question to alot of you but could someone explain what a hodograph is? I've got the skew-t's down, I just always see the hodo and cant quite interept what its showing. Thanks!

Short answer with examples:

http://www.theweatherprediction.com/habyhints/275/

[JoMo]

SPC WRF has updated

http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/

Tues Eve

[Hoosier]

Check out these parameters. Filthy. Cap almost gone at this point.

[Chicago Storm]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1228 PM CDT MON APR 18 2011

VALID 191200Z - 201200Z

..THERE IS A MDT RISK OF SVR TSTMS FROM NRN AR/MO

NEWD ACROSS

MUCH OF IL INTO IND/NWRN KY...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM

NRN TX/ERN OK INTO OH/WRN PA...

...A SIGNIFICANT SEVERE WEATHER EVENT IS EXPECTED FROM EASTERN

OKLAHOMA INTO THE OH VALLEY TUESDAY - INCLUDING THE THREAT FOR

TORNADOES AND DAMAGING WIND/HAIL...

AN ACTIVE MID-HIGH LEVEL JET WILL CONTINUE ACROSS THE LOWER 48

DURING THE DAY2 PERIOD. THIS HIGH MOMENTUM AIRSTREAM WILL REMAIN

PROGRESSIVE WITH A STRONG SHORTWAVE TROUGH EXPECTED TO TRAVERSE THE

CNTRL ROCKIES ACROSS THE CNTRL PLAINS INTO THE MID MS VALLEY DURING

THE EVENING HOURS. IN RESPONSE TO THIS FEATURE LEE CYCLOGENESIS

WILL BE DISPLACED OFF THE HIGH PLAINS ALONG THE KS/OK BORDER EARLY

BEFORE SHIFTING INTO SWRN MO BY 19/18Z. OF PARTICULAR CONCERN IS

THE SUSTAINED WLY FLOW ALOFT THAT WILL ENSURE VERY STEEP LAPSE RATES

WILL OVERSPREAD THE WARM SECTOR AND ADJOINING COOLER BOUNDARY LAYER

JUST NORTH OF A WELL DEMARCATED WARM FRONT. THIS STEEP LAPSE RATE

PLUME WILL LIKELY INHIBIT PRE-FRONTAL CONVECTION EARLY IN THE PERIOD

AS SFC TEMPERATURES WILL NEED TO WARM CONSIDERABLY BEFORE THE CAP

CAN BE REMOVED. AT THIS TIME IT APPEARS ANY MEANINGFUL THREAT FOR

SFC-BASED STORMS WILL NOT MATERIALIZE UNTIL LOW LEVEL CONVERGENCE

SHIFTS INTO SERN KS/ERN OK/SWRN MO.

PRIOR TO THIS DEVELOPMENT...STRONG LOW LEVEL WARM ADVECTION WILL

LIKELY DRIVE AN ELEVATED MCS ALONG COOL SIDE OF WARM FRONT ACROSS

THE MID MS/OH VALLEY. FORECAST SOUNDINGS SUGGEST AMPLE INSTABILITY

FOR HAIL...SOME OF IT MAY APPROACH OR EVEN EXCEED SEVERE LEVELS.

WITH TIME THIS ACTIVITY WILL SPREAD DOWNSTREAM OF INSTABILITY

SUPPORTIVE OF MEANINGFUL UPDRAFTS AND THE SEVERE THREAT SHOULD

DECREASE ACROSS MOST OF UPSTATE NY.

LATEST MODEL GUIDANCE IS FAIRLY CONSISTENT REGARDING THE PRIMARY SFC

FRONTAL POSITION AT 18Z...BOTH THE WARM FRONT...IN AN E-W FASHION

DRAPED FROM NRN MO INTO OH ALONG THE I-70 CORRIDOR...AND THE SURGING

COLD FRONT SWWD FROM A SFC LOW INTO THE SRN HIGH PLAINS. FORECAST

SOUNDINGS SUGGEST THUNDERSTORMS...DEEPLY ROOTED WITHIN THE BOUNDARY

LAYER...SHOULD EMERGE BY 21Z ACROSS SWRN MO INTO ERN OK. THIS

ACTIVITY WILL INITIALLY BE SUPERCELLULAR IN NATURE AS SBCAPE VALUES

SHOULD EASILY EXCEED 3000 J/KG WITHIN A STRONGLY SHEARED

ENVIRONMENT. ANY STORMS THAT MANAGE TO EVOLVE AHEAD OF THE COLD

FRONT WILL POSE AN ENHANCED TORNADO RISK...ESPECIALLY FOR CONVECTION

ACROSS MO/NRN AR INTO IL AHEAD OF SFC LOW. IN FACT...ENVIRONMENTAL

CONDITIONS FAVOR THE POTENTIAL FOR STRONG TORNADOES WITH ACTIVITY

THAT CAN REMAIN ISOLATED AHEAD OF STRONGLY FORCED COLD FRONT. WITH

TIME STRONG CONVERGENCE ALONG THE COLD FRONT WILL CERTAINLY FORCE AN

UPWARD EVOLVING SQUALL LINE. THIS LINE OF STORMS WILL MATURE WITHIN

A STRONGLY SHEARED AND VERY UNSTABLE AIRMASS OVER THE MID MS VALLEY

WHICH SHOULD ENHANCE THE LIKELIHOOD FOR BOWS AND LEWPS. GIVEN THAT

STRONG LARGE SCALE SUPPORT WILL OVERSPREAD THE LOWER OH VALLEY

DURING THE OVERNIGHT HOURS THIS ACTIVITY SHOULD PROGRESS RAPIDLY

DOWNSTREAM ACROSS IL/IND/OH. EVEN THOUGH A STRONGLY FORCED LINE IS

EXPECTED ACROSS THIS REGION AN ENHANCED TORNADO THREAT WILL EXIST

ACROSS MO/IL/IND AHEAD OF SFC LOW WHERE LOW LEVEL SHEAR WILL BE

MAXIMIZED. VERY LARGE HAIL WILL ALSO ACCOMPANY SUPERCELLS DURING

THE EVENING HOURS ACROSS THE WRN HALF OF THE OUTLOOK WHERE LAPSE

RATES WILL BE MAXIMIZED.

FARTHER SOUTH...VERY HOT AFTERNOON TEMPERATURES ACROSS TX WILL

REMOVE THE CAP ALONG THE DRYLINE FROM DFW...SWWD TOWARD AUS. IT/S

NOT ENTIRELY CLEAR HOW MUCH ACTIVITY WILL EVOLVE ALONG THIS BOUNDARY

BUT ANY STORMS THAT DEVELOP WILL DO SO WITHIN A VERY UNSTABLE

AIRMASS AND MORE THAN ADEQUATE DEEP LAYER SHEAR FOR SUPERCELL

DEVELOPMENT AND A THREAT FOR LARGE HAIL AND DAMAGING WINDS. IF IT

BECOMES MORE CLEAR THAT STORMS WILL DEVELOP INTO CNTRL TX THEN A

SLIGHT RISK WILL BE EXTENDED SWWD TO INCLUDE THIS SCENARIO.

..DARROW.. 04/18/2011

[B-Rent]

From IND. On board with dual significant events. They've also posted a web brief I cant view mobile. Probably just the same text as the HWO though from experience.

TUESDAY AND TUESDAY NIGHT STILL LOOK LIKE A SIGNIFICANT SEVERE EVENT FOR CENTRAL INDIANA. COULD SEE TWO WAVES WITH THIS EVENT. THE FIRST WOULD BE IN THE AFTERNOON TO EARLY EVENING ALONG AND SOUTH OF THE WARM FRONT THAT WILL BE MOVING NORTH THROUGH THE AREA. PRETTY MUCH ALL SEVERE PARAMETERS ARE POINTING TOWARD THE POTENTIAL FOR SUPERCELLS DURING THIS TIME WHICH WOULD BRING WITH THEM THE THREATS OF TORNADOES...VERY LARGE HAIL...AND DAMAGING WINDS.

THEN DURING THE OVERNIGHT HOURS THE THREAT WILL TRANSITION TO ONE OF THE QLCS/BOW ECHO VARIETY AS CONVECTION FORCED NEAR THE COLD FRONT TO OUR WEST RACES EAST AND CONGEALS INTO A LINE. LOW LEVEL HELICITY VALUES AND TORNADO PARAMETERS ARE STILL FAVORABLE SO TORNADO THREAT WILL CONTINUE THROUGH THE OVERNIGHT HOURS BUT THINK DAMAGING WINDS MAY TAKE OVER AS THE MORE PREVALENT THREAT AT THAT POINT.

ALSO OF NOTE FROM TONIGHT THROUGH EARLY WEDNESDAY MORNING IS THAT RAINFALL TOTALS IN THE VARIOUS MODELS ARE FROM A WIDESPREAD INCH TO WELL OVER 2 INCHES.

WITH THE FRONT MEANDERING ACROSS THE AREA AND ISENTROPIC LIFT IN PLACE THE WHOLE TIME AS WELL AS SHORTWAVES MOVING THROUGH AND PRECIPITABLE WATER OVER AN INCH MUCH OF THE TIME ALSO POINTS TO THE POTENTIAL FOR A FLOODING/FLASH FLOODING THREAT AS WELL.

Sent from my HTC Thunderbolt using Tapatalk.

[Indystorm]

My hunch that I-70 in IL and IN looks to be active continues. Good continuity with svr parameters for the Effingham to Terre Haute area Tuesday evening.

[csnavywx]

Ehhhh... not sure I like where these trends are going with the surface winds, appear to be coming in more veered as we get closer to the event, especially ahead of the cold front. My bet is that most of the tor potential is going to have to be rooted near or on the warm front. No doubt there's a big hail and wind threat, but the tornado side of the equation seems to be quite a bit more localized.

[thewxmann]

Not much to say that hasn't already been said. Cap will hold initiation off till 0Z down in OK, where LCL's, linear forcing, veered sfc flow, and temporal/spatial limits of quality environment will preclude an outbreak (among others, this is just a quick list right now). Along the WF, elevated convection and/or stratus north of it will hold off its northward progression, and the cap will not break till after 0Z. The sharp nature of the front disfavors maturation of mesocyclones in a high helicity environment prior to becoming elevated. So I don't see a tornadic supercell outbreak there either.

As many have alluded to, this will likely be a QLCS event initiating around 00-02Z. The threat for embedded supercells with tornadoes will increase during this time as low-level helicities ramp up with the LLJ, and low-level thermal profiles will have to be monitored over the course of the evening. The hodographs at around 03Z-06Z look favorable for tornadoes.

[Hoosier]

My hunch that I-70 in IL and IN looks to be active continues. Good continuity with svr parameters for the Effingham to Terre Haute area Tuesday evening.

Wind profiles may be too unidirectional with southward extent by the time of the greatest chances for convection. I think the greatest tornado threat probably sets up somewhere between US 24 and I-70.

Repost of what I posted on my blog:

We are on the eve of what I believe will be the most significant/widespread severe weather event in the state so far this year. Without wasting any time, let's dive in to the setup.

At the surface, the models are in general agreement on a deepening surface low tracking through northern Indiana. Ahead of this low, strong southerly flow will transport rich low level moisture northward. Aloft, an 850 mb jet of 50-70 knots will develop through the Ohio Valley, placing Indiana in the favorable left front quadrant. Given the aforementioned moisture transport, good heating and steep lapse rates aloft, MLCAPE should range from AOB 750 J/kg in the extreme northern part of the state to 2000-3000 J/kg in the central and southern portions.

Thunderstorms may be ongoing for much of the day in scattered fashion, but it is unclear how much of this activity will be surface based. A more widespread severe threat will develop to our west sometime Tuesday afternoon or evening before spreading east into Indiana during the evening. As forcing increases and wind profiles become more unidirectional with time, upscale growth into a linear system/QLCS is anticipated with risks for damaging winds, hail and tornadoes well into the night.

The tornado threat will be somewhat dependent on storm mode, but shear profiles suggest we can't discount the threat entirely even after a transition toward a more linear mode. The 09z run of the SREF shows a high probability of several key ingredients coming together tomorrow evening.

At this time, given the anticipated track of the surface low (best low level shear), I expect the greatest tornado threat to lie roughly between US 24 and I-70, including areas such Lafayette, Kokomo, Marion, Terre Haute, Indianapolis, Anderson and Muncie. If the surface low tracks a little farther north, then the greater tornado threat could shift up toward Route 6. Areas outside this zone certainly aren't at zero risk and everyone should be paying close attention to the weather tomorrow into Wednesday.

[weathergy]

Really hoping that I could pull a decent wind event Wednesday morning. SREF profiles keep me hopeful. A decent event for the OV nonetheless.

[hooralph]

Wind profiles may be too unidirectional with southward extent by the time of the greatest chances for convection. I think the greatest tornado threat probably sets up somewhere between US 24 and I-70.

Repost of what I posted on my blog:

We are on the eve of what I believe will be the most significant/widespread severe weather event in the state so far this year. Without wasting any time, let's dive in to the setup.

At the surface, the models are in general agreement on a deepening surface low tracking through northern Indiana. Ahead of this low, strong southerly flow will transport rich low level moisture northward. Aloft, an 850 mb jet of 50-70 knots will develop through the Ohio Valley, placing Indiana in the favorable left front quadrant. Given the aforementioned moisture transport, good heating and steep lapse rates aloft, MLCAPE should range from AOB 750 J/kg in the extreme northern part of the state to 2000-3000 J/kg in the central and southern portions.

Thunderstorms may be ongoing for much of the day in scattered fashion, but it is unclear how much of this activity will be surface based. A more widespread severe threat will develop to our west sometime Tuesday afternoon or evening before spreading east into Indiana during the evening. As forcing increases and wind profiles become more unidirectional with time, upscale growth into a linear system/QLCS is anticipated with risks for damaging winds, hail and tornadoes well into the night.

The tornado threat will be somewhat dependent on storm mode, but shear profiles suggest we can't discount the threat entirely even after a transition toward a more linear mode. The 09z run of the SREF shows a high probability of several key ingredients coming together tomorrow evening.

At this time, given the anticipated track of the surface low (best low level shear), I expect the greatest tornado threat to lie roughly between US 24 and I-70, including areas such Lafayette, Kokomo, Marion, Terre Haute, Indianapolis, Anderson and Muncie. If the surface low tracks a little farther north, then the greater tornado threat could shift up toward Route 6. Areas outside this zone certainly aren't at zero risk and everyone should be paying close attention to the weather tomorrow into Wednesday.

Sweet. I'll be near Carmel.

[JoMo]

Well I'm right on the line if storms fire up they will be just west of here, on top of me, or east of me. Expecting baseball sized hail, 70+ mph winds and at the onset maybe a tornado. If it's just east of here, I could put weed n feed on my yard, otherwise I can't...... decisions, decisions.

[csnavywx]

Not much to say that hasn't already been said. Cap will hold initiation off till 0Z down in OK, where LCL's, linear forcing, veered sfc flow, and temporal/spatial limits of quality environment will preclude an outbreak (among others, this is just a quick list right now). Along the WF, elevated convection and/or stratus north of it will hold off its northward progression, and the cap will not break till after 0Z. The sharp nature of the front disfavors maturation of mesocyclones in a high helicity environment prior to becoming elevated. So I don't see a tornadic supercell outbreak there either.

As many have alluded to, this will likely be a QLCS event initiating around 00-02Z. The threat for embedded supercells with tornadoes will increase during this time as low-level helicities ramp up with the LLJ, and low-level thermal profiles will have to be monitored over the course of the evening. The hodographs at around 03Z-06Z look favorable for tornadoes.

Careful when using this as a blanket scenario. If storm motion vectors are pointed parallel (or ideally, the frontal zone is oriented slightly to the right of the mean storm motion) to the frontal zone, this favors them becoming associated directly with the boundary layer convergence along the front (e.g. April 9th in Iowa and far E Nebraska and quite a few other examples, including the famous I-70 special). If these vectors are pointed more perpendicular to the front, then your assertion definitely holds more weight. The problem I have in this scenario is similar to the one from April 9th. In this scenario, we've got a front oriented from 270-260 degrees and storm motions from about 240, or in other words, the front is only oriented 20-30 degrees to the right of the storm motions. With a prominently clockwise-curved hodograph, it won't take much rightward deviation (20, 30 degrees at most) for them to root directly on the boundary. This may only turn out to be a one or two storm scenario, but I've seen some hellacious cyclical supercells that develop that way.

Otherwise, I think you're right on the main mode being linear further south. I happen to think the cap will break between 21-22Z, but that's another topic.

[Chicago Storm]

[cyclone77]

Ahh you beat me to it. Definitely a nice jump compared to previous runs at 00z. Still think it is a little fast with the surface low, but I guess we'll see how it shakes out.

[Reed Stough]

I don't think this event is as clear cut as the last one. Dewpoints, EHI, Helcity, CAPE, are really up there, but the veering of the winds from surface to aloft is not as dramatic like this last event. Though this storm is coming somewhat negatively tilted, it stil may end up being more progressive in nature.

There are still a lot of questions still be answered.

The storm this past weekend was pretty clear cut and definitive.

[hoosierwx]

From LMK AFD:

STORMS WILL EXPLODE TO OUR WEST TUESDAY AFTERNOON AND HEAD IN OURDIRECTION. BY TUESDAY EVENING THEY SHOULD BE ENTERING SOUTHWESTINDIANA AS A LINE OF SUPERCELLS WITH LARGE HAIL...DAMAGINGWINDS...AND SCATTERED TORNADOES. AS THEY PROCEED INTO CENTRALKENTUCKY THE STORMS SHOULD GEL INTO A SQUALL LINE. THEY WILL REMAINROOTED IN THE BOUNDARY LAYER WITH WEAK TO MODERATE SURFACE BASEDINSTABILITY REMAINING IN PLACE ALL NIGHT. LOW LEVEL SHEAR WILL WANESLIGHTLY BUT WILL BE STRONG THROUGH THE NIGHT UNDER A 60-65KT LOWLEVEL JET. WE WILL ALSO BE FAVORABLY PLACED NEAR THE RIGHT ENTRANCEREGION OF A 120KT UPPER JET ACROSS SOUTHEAST CANADA AND AHEAD OF A120KT UPPER JET MOVING FROM THE ROCKIES INTO THE CENTRAL PLAINS.TORNADIC SPIN-UPS WILL CONTINUE TO BE POSSIBLE WITH THE QLCS AS ITCROSSES CENTRAL KENTUCKY. THIS EVENT IS LOOKING SOMEWHAT ANALOGOUSTO THE APRIL 28 2002 OUTBREAK...WHICH DID RESULT IN A FEW TORNADOESOVER NORTHWESTERN SECTIONS OF THE LMK CWFA.

GFS and Nam both have Capes around 2500 during the afternoon but falling to 500-1000 by arrival time. Hopefully we can keep this thing speeding up some. I really hate these 12 am to 3 am deals but it seems to be the norm here.

[PatrickSumner]

From LMK AFD:

STORMS WILL EXPLODE TO OUR WEST TUESDAY AFTERNOON AND HEAD IN OURDIRECTION. BY TUESDAY EVENING THEY SHOULD BE ENTERING SOUTHWESTINDIANA AS A LINE OF SUPERCELLS WITH LARGE HAIL...DAMAGINGWINDS...AND SCATTERED TORNADOES. AS THEY PROCEED INTO CENTRALKENTUCKY THE STORMS SHOULD GEL INTO A SQUALL LINE. THEY WILL REMAINROOTED IN THE BOUNDARY LAYER WITH WEAK TO MODERATE SURFACE BASEDINSTABILITY REMAINING IN PLACE ALL NIGHT. LOW LEVEL SHEAR WILL WANESLIGHTLY BUT WILL BE STRONG THROUGH THE NIGHT UNDER A 60-65KT LOWLEVEL JET. WE WILL ALSO BE FAVORABLY PLACED NEAR THE RIGHT ENTRANCEREGION OF A 120KT UPPER JET ACROSS SOUTHEAST CANADA AND AHEAD OF A120KT UPPER JET MOVING FROM THE ROCKIES INTO THE CENTRAL PLAINS.TORNADIC SPIN-UPS WILL CONTINUE TO BE POSSIBLE WITH THE QLCS AS ITCROSSES CENTRAL KENTUCKY. THIS EVENT IS LOOKING SOME WHAT ANALOGOUS TO THE APRIL 28 2002 OUTBREAK...WHICH DID RESULT IN A FEW TORNADOESOVER NORTHWESTERN SECTIONS OF THE LMK CWFA.

The part I bolded, italicized, and underlined is the most interesting part of this AFD. April 28, 2002 was a significant outbreak of severe weather with widespread wind damage across a large swath and a few tornadoes...

[PatrickSumner]

From LSX...calling for long track/strong tornadoes...

ALL THE MODEL DATA THAT WE CAN GET OUR HANDS ON CONTINUES TO PORTRAY

A RAPID DECREASE IN CIN LATE TOMORROW AFTERNOON AS STRONG ASCENT

OVERSPREADS THE REGION. CONVECTIVE INITIATION IS EXPECTED TO OCCUR

ROUGHLY AROUND 21Z...WITH SUPERCELLS BEING THE INITIAL STORM MODE.

LOCAL WRF CONTINUES TO PORTRAY THE MOST WORRISOME SCENARIO...WITH

TWO DISTINCT LINES OF CONVECTION DEVELOPING. AT THE ONSET THERE

CERTAINLY COULD BE TWO NORTH-SOUTH ORIENTATED LINES OF

SUPERCELLS...ONE ACROSS WESTERN/CENTRAL MISSOURI AND ANOTHER NEAR

THE MISSISSIPPI RIVER.

A MAJOR SEVERE WEATHER OUTBREAK IS EXPECTED TO OCCUR AS SHEAR AND

INSTABILITY PARAMETERS ARE CONDUCIVE FOR LONG TRACK SUPERCELLS

CAPABLE OF PRODUCING SIGNIFICANT/STRONG TORNADOES...VERY LARGE HAIL

AND DAMAGING STRAIGHT LINE WINDS. WE SHOULD SEE CONVECTION CONGEAL

INTO A SEVERE LINEAR MCS DURING THE EVENING AS IT PROGRESSES FURTHER

EAST...EXITING THE CWA SHORTLY AFTER 06Z.

[cyclone77]

Turning from the surface up to about 700mb is very nice. Increasing velocities up through 700mb look great too. The backing above H6 is what I'm wondering about. Not sure how much of a big deal that will be. Certainly puts a weird loop in the hodos. I think the strong low-level shear, deeper moisture than we've seen, low LCLs, strong H7 jet, and the triple point/warm front interaction should be enough to get things spinning.

We're just gonna play the warm front out in front of the triple point and see what shakes out. Right now we're just planning on heading towards Springfield and then go from there.

[B-Rent]

IND looking at initialization along the warm front around 1900Z. From the afternoon update:

MODELS CONTINUE TO ADVERTISE THE POTENTIAL FOR A SIGNIFICANT

SEVERE WEATHER OUTBREAK ACROSS THE OHIO AND MID MISSISSIPPI

VALLEYS TOMORROW INTO TOMORROW NIGHT. FRONTAL BOUNDARY WILL LIKELY

BE NEAR THE INTERSTATE 70 CORRIDOR FOR MUCH OF THE DAY TOMORROW...WITH

FORECAST SOUNDINGS DEPICTING A SIGNIFICANTLY CAPPED AIRMASS JUST

SOUTH OF THE FRONT. DURING THE AFTERNOON...THE WARM FRONT SHOULD

BEGIN TO SHIFT NORTHWARD AS A NEGATIVELY TILTED LOW PRESSURE

SYSTEM PUSHES INTO THE GREAT LAKES.

APPEARS THAT THE POTENTIAL WILL EXIST FOR INITIAL STORM

DEVELOPMENT AS EARLY AS 3 TO 4 PM TUESDAY...AND SHOULD THIS OCCUR

IN THE AREA...SHEAR WOULD BE SUFFICIENT FOR SUPERCELLS WITH THE

POTENTIAL FOR TORNADOES...VERY LARGE HAIL...AND DAMAGING WINDS.

EXPECT THAT AS THE NIGHT GOES ON AND THE COLD FRONT APPROACHES...A

TRANSITION TO A SIGNIFICANT DAMAGING WIND THREAT...ALONG WITH HAIL

AND CONTINUED ENHANCED TORNADO POSSIBILITIES...ESPECIALLY IN THE

VICINITY OF THE WARM FRONT.

[Thundersnow12]

Is it me or have we seen a ton of 50's already this year?

[tornadotony]

IND looking at initialization along the warm front around 1900Z. From the afternoon update:

MODELS CONTINUE TO ADVERTISE THE POTENTIAL FOR A SIGNIFICANT

SEVERE WEATHER OUTBREAK ACROSS THE OHIO AND MID MISSISSIPPI

VALLEYS TOMORROW INTO TOMORROW NIGHT. FRONTAL BOUNDARY WILL LIKELY

BE NEAR THE INTERSTATE 70 CORRIDOR FOR MUCH OF THE DAY TOMORROW...WITH

FORECAST SOUNDINGS DEPICTING A SIGNIFICANTLY CAPPED AIRMASS JUST

SOUTH OF THE FRONT. DURING THE AFTERNOON...THE WARM FRONT SHOULD

BEGIN TO SHIFT NORTHWARD AS A NEGATIVELY TILTED LOW PRESSURE

SYSTEM PUSHES INTO THE GREAT LAKES.

APPEARS THAT THE POTENTIAL WILL EXIST FOR INITIAL STORM

DEVELOPMENT AS EARLY AS 3 TO 4 PM TUESDAY...AND SHOULD THIS OCCUR

IN THE AREA...SHEAR WOULD BE SUFFICIENT FOR SUPERCELLS WITH THE

POTENTIAL FOR TORNADOES...VERY LARGE HAIL...AND DAMAGING WINDS.

EXPECT THAT AS THE NIGHT GOES ON AND THE COLD FRONT APPROACHES...A

TRANSITION TO A SIGNIFICANT DAMAGING WIND THREAT...ALONG WITH HAIL

AND CONTINUED ENHANCED TORNADO POSSIBILITIES...ESPECIALLY IN THE

VICINITY OF THE WARM FRONT.

This I do not buy. What is the forcing for initiation in Indiana? Now LSX, I could see them being in big trouble tomorrow if they go prefrontally.

[Hoosier]

This I do not buy. What is the forcing for initiation in Indiana? Now LSX, I could see them being in big trouble tomorrow if they go prefrontally.

Yeah, I'd have to think that whatever there is would probably be elevated.

[Chicago Storm]

Is it me or have we seen a ton of 50's already this year?

Yes...and i'm pretty sure most of them have worked out.

[patrick7032]

Wind profiles may be too unidirectional with southward extent by the time of the greatest chances for convection. I think the greatest tornado threat probably sets up somewhere between US 24 and I-70.

Repost of what I posted on my blog:

We are on the eve of what I believe will be the most significant/widespread severe weather event in the state so far this year. Without wasting any time, let's dive in to the setup.

At the surface, the models are in general agreement on a deepening surface low tracking through northern Indiana. Ahead of this low, strong southerly flow will transport rich low level moisture northward. Aloft, an 850 mb jet of 50-70 knots will develop through the Ohio Valley, placing Indiana in the favorable left front quadrant. Given the aforementioned moisture transport, good heating and steep lapse rates aloft, MLCAPE should range from AOB 750 J/kg in the extreme northern part of the state to 2000-3000 J/kg in the central and southern portions.

Thunderstorms may be ongoing for much of the day in scattered fashion, but it is unclear how much of this activity will be surface based. A more widespread severe threat will develop to our west sometime Tuesday afternoon or evening before spreading east into Indiana during the evening. As forcing increases and wind profiles become more unidirectional with time, upscale growth into a linear system/QLCS is anticipated with risks for damaging winds, hail and tornadoes well into the night.

The tornado threat will be somewhat dependent on storm mode, but shear profiles suggest we can't discount the threat entirely even after a transition toward a more linear mode. The 09z run of the SREF shows a high probability of several key ingredients coming together tomorrow evening.

At this time, given the anticipated track of the surface low (best low level shear), I expect the greatest tornado threat to lie roughly between US 24 and I-70, including areas such Lafayette, Kokomo, Marion, Terre Haute, Indianapolis, Anderson and Muncie. If the surface low tracks a little farther north, then the greater tornado threat could shift up toward Route 6. Areas outside this zone certainly aren't at zero risk and everyone should be paying close attention to the weather tomorrow into Wednesday.

I completely agree.....If I was down there I would prob setup show near KCMI. With the warm front progged to be along the 70 corridor setting up somewhere in the area you mentioned would be perfect........

[Hoosier]

I completely agree.....If I was down there I would prob setup show near KCMI. With the warm front progged to be along the 70 corridor setting up somewhere in the area you mentioned would be perfect........

I think the Springfield-Champaign-Effingham triangle is dandy. If anyone chases into Indiana, try to avoid the southern portion.