March 26-28 Severe Threat

[IMADreamer]

Can't see the sun yet but the storm that just rolled through has cleared out the fog and I can actually see clouds instead of just gray.  Hopeful signs I think. 

[MNWX]

Southeast Iowa is about to be prime. En route from Minnesota.

[RyanDe680]

N IL will have this moisture linger until at least noon until 1.  We would have needed clearing by then. It’s imperative in these setups - we’ve seen this over and over.  The northerly flow is a big determining factor.  That and an over worked atmosphere. 
 

not saying that there won’t be storms, but perhaps not moderate risk worthy IMO and if so, further south 

[bdgwx]

The radar returns on that convective complex are starting to wane. It's possible this lays out a boundary that backs the surface winds and enhances the critical angle on the hodographs. It's more of a low probability and speculative scenario, but the 14Z HRRR does kind of hint at that. Instability would still have to materialize of course. If it happens just right the MO/IA/IL border area might still be a prime spot.

[Quincy]

It’s an ever-evolving setup, but I see two main areas to watch based on morning trends:

1. Eastern Iowa closer to the surface low. While low-level moisture and surface heating may be less impressive than areas further south, steeper mid-level lapse rates and stronger low-level shear should compensate. 

2. West-central/central Illinois on the southern flank of lingering convection. Here, dew-points are likely to be in the mid to upper 60s. Despite less impressive lapse rates than points NW, stronger surface heating and quality low-level moisture should yield moderate to seasonably large instability. Low-level shear is a bit of a grey area, as models show less here, but one wonders if a reinforced warm frontal boundary in the wake of ongoing convection may help with locally enhanced SRH. 

[janetjanet998]

winds may veer some under that dryslot  and clear area in N MO...meanwhile more east.... skies may remain more party cloudy and winds remain backed more SE

the result may be a convergence line with supercells

HRRR picking up on this with supercells along the MS river 3-4pm 

 

 

 

 

[jpeters3]

This is the inflow sounding to one of the HRRR projected cells in western IL.  All of you who think this will be a bust are totally fried.

 

[nrgjeff]

Synoptic WF appears to have made it as far north as I-80/88; however, outflow farther south in central Illinois is obvious on the surface chart (10am Central Time). I figure the rouge cells ahead advertised on some CAMs will go on that OFB. Given how sharp the WF is up north, I'd favor the OFB. Note I have a strong personal bias toward OFB.

Still could be chaser's choice. I'm also not in the field today; so, with a virtual chase I can afford to take forecast risks. Still I have to like 1-2 cells east of where the OFB intersects the Pacific front / quasi-DL. Good luck, and be safe!

[WeatherMonger]

Just started raining here, based on radar could have 3 back to back bouts of heavier rains. Going to take a lot for the atmosphere to recover I would think. Finally heard my first rumble of thunder about 2am as the obernight complex moved through.

 

[janetjanet998]

If I recall correctly on 4-19-1996 we had morning storms over IL and it didn't clear out here until around noon

and higher dewpoints were delayed until mid-late afternoon when they surged north just ahead of the MS river pearls

is that being used as any analog or is it too old?

 

 

 

[WeatherMonger]

Went warned to my south

 

[Hoosier]

10 minutes ago, janetjanet998 said:

If I recall correctly on 4-19-1996 we had morning storms over IL and it didn't clear out here until around noon

and higher dewpoints were delayed until mid-late afternoon when they surged north just ahead of the MS river pearls

is that being used as any analog or is it too old?

 

 

 

Went back and looked at radar from that day.  Looks like there was a bit of morning activity but not much.  I don't know what the cloud situation was.

[janetjanet998]

Just now, Hoosier said:

Went back and looked at radar from that day.  Looks like there was a bit of morning activity but not much.  I don't know what the cloud situation was.

 Looks like there was a bit of morning activity but not much

 

found the old SAT data ....there were indeed clouds and some precip but basically only over me (PIA) 

[andyhb]

All of that convection in AR and MO is probably going to have some say in whether better moisture can make it far enough north in time. Mesoscale trends aren’t exactly looking favorable for a bigger event at this time.

[Quincy]

Ugly veer-back signature in the wind profiles right now across central Illinois. Think the early convection played a role. High res guidance does show improvement with time and that jives with mesoanalysis (better wind profiles advecting in from MO). It’s going to be a few hours before kinematics support sustained, organized severe storms in IL. 

[WeatherMonger]

Northern MO, SE IA, Western IL clearing out big time.

 

[snowlover2]

Still moderate with possible upgrade at 20z to high.

Quote

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1138 AM CDT SAT MAR 28 2020  
 
VALID 281630Z - 291200Z  
 
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS  
OF FAR EASTERN IOWA AND INTO PARTS OF CENTRAL AND NORTHERN  
ILLINOIS...  
   
..SUMMARY  
 
A SEVERE-WEATHER OUTBREAK IS EXPECTED FOR PORTIONS OF THE MIDWEST  
THIS AFTERNOON AND EVENING. A FEW LONG-TRACKED, SIGNIFICANT  
TORNADOES ARE POSSIBLE, ALONG WITH LARGE, DAMAGING HAIL AND SEVERE  
GUSTS.  
   
..SYNOPSIS  
 
A DEEPENING MID-/UPPER-LEVEL LOW -- NOW MOVING EAST-NORTHEASTWARD  
ACROSS NEBRASKA/KANSAS -- WILL ADVANCE TO WESTERN IOWA BY EARLY  
EVENING, AND WILL BE ACCOMPANIED BY AN 80 TO 100 KT SOUTHWESTERLY  
MID-LEVEL JET. THE JET STREAK WILL CROSS THE OZARKS AND LOWER  
MISSOURI/MID MISSISSIPPI VALLEYS THIS AFTERNOON, AND THEN INTO THE  
OHIO AND TENNESSEE VALLEYS OVERNIGHT, ATOP LOWER-LEVEL SOUTHERLIES  
IN THE 40 TO 60 KT RANGE. THIS VEERING/INCREASING OF FLOW WITH  
HEIGHT WILL YIELD A VERY FAVORABLY-SHEARED ENVIRONMENT OVER A BROAD  
AREA.  
 
AT THE SURFACE, A DEEPENING LOW IS ANALYZED OVER NORTHEASTERN  
KANSAS, AND WILL MOVE NORTHEASTWARD ACROSS THE MID MISSOURI VALLEY  
THIS AFTERNOON, AND THEN ACROSS IOWA THIS EVENING AND INTO WISCONSIN  
OVERNIGHT. A TRAILING COLD FRONT IS CURRENTLY CROSSING EASTERN  
KANSAS/EASTERN OKLAHOMA AND EASTERN/SOUTHEASTERN TEXAS, AND WILL  
REACH THE MID AND LOWER MISSISSIPPI VALLEY VICINITY BY EARLY  
EVENING. A WARM FRONT CURRENTLY EXTENDS EASTWARD FROM THE LOW  
ACROSS NORTHERN MISSOURI INTO CENTRAL ILLINOIS/CENTRAL INDIANA, AND  
WILL LIFT NORTHWARD WITH TIME ACROSS NORTHERN MISSOURI, IOWA,  
ILLINOIS, AND INDIANA AS THE PARENT LOW MOVES NORTHEASTWARD,  
ALLOWING WARM/MOIST/DESTABILIZING AIR TO SPREAD ACROSS THESE AREAS  
THROUGH EARLY EVENING. BY THE END OF THE PERIOD, THE LOW WILL HAVE  
OCCLUDED OVER WISCONSIN, WITH THE COLD FRONT APPROACHING THE WEST  
SLOPES OF THE APPALACHIANS AND THE WARM FRONT EXTENDING  
EAST-SOUTHEASTWARD FROM THE GREAT LAKES REGION TO THE MID-ATLANTIC  
AREA.  
   
..MID MISSISSIPPI VALLEY/MIDWEST REGION  
 
A SIGNIFICANT OUTBREAK OF SEVERE WEATHER REMAINS APPARENT FROM PARTS  
OF EASTERN IOWA AND EASTERN MISSOURI, EASTWARD INTO THE MIDWEST/OHIO  
VALLEY.  
 
WIDESPREAD CLOUDS, AND ONGOING SHOWERS/THUNDERSTORMS, PERSIST ACROSS  
MUCH OF THE RISK AREA AT THIS TIME -- ALONG AND AHEAD OF THE COLD  
FRONT FROM SOUTHERN MISSOURI TO EASTERN TEXAS AND NEAR/NORTH OF THE  
WARM FRONT FROM IOWA EASTWARD TO PENNSYLVANIA -- WHICH CONTINUES TO  
COMPLICATE THE FORECAST IN TERMS OF FINER-SCALE DETAILS. GENERALLY,  
SEVERE RISK ACROSS THE REGION IS EXPECTED TO OCCUR WITHIN TWO  
REGIMES:  
 
1. A GRADUAL INCREASE IN COVERAGE/INTENSITY OF THE ONGOING STORMS  
NEAR THE COLD AND WARM FRONTS, AS MODEST, LOCAL  
HEATING/DESTABILIZATION COMBINE WITH A STEADY INCREASE IN THE FLOW  
FIELD ALOFT, AND  
 
2. NEW STORM DEVELOPMENT -- INITIALLY EXPECTED FROM NORTHEASTERN  
MISSOURI INTO SOUTHEASTERN IOWA IN THE 19 TO 21Z TIME FRAME -- AS  
ONGOING CONVECTION AND CLOUD COVER SHIFTS EASTWARD/NORTHEASTWARD  
ALLOWING SURFACE HEATING/DESABILIZATION TO OCCUR BENEATH STEEPENING  
MID-LEVEL LAPSE RATES AND INCREASINGLY STRONG FLOW ALOFT.  
 
BROADLY SPEAKING, STORMS INCREASING FROM ARKANSAS AND SOUTHEASTERN  
MISSOURI, AND EASTWARD ACROSS ILLINOIS AND INDIANA WILL CONTINUE TO  
POSE AN INITIAL RISK FOR HAIL AND POSSIBLY LOCALLY STRONG WIND  
GUSTS. WITH TIME, AS BOTH THE KINEMATIC AND THERMODYNAMIC  
ENVIRONMENT IMPROVE, MORE INTENSE/ROTATING STORMS WILL GRADUALLY  
EVOLVE, POSING GREATER SEVERE POTENTIAL. GREATEST TORNADO RISK WILL  
LIKELY OCCUR WITH NORTHWARD EXTENT, NEARER THE WARM FRONT, THOUGH  
SOME POTENTIAL WILL EXPAND ACROSS AREAS AS FAR SOUTH AS PARTS OF  
TENNESSEE AND NORTHERN MISSISSIPPI THIS EVENING AS SEVERE STORMS  
SPREAD EASTWARD.  
 
GREATEST RISK FOR LONG-TRACK/SIGNIFICANT TORNADOES, ALONG WITH  
POTENTIAL FOR VERY LARGE/DESTRUCTIVE HAIL AND DAMAGING WIND GUSTS,  
STILL APPEARS TO EXIST FROM PORTIONS OF NORTHEASTERN MISSOURI AND  
ARCING NORTHWESTWARD INTO IOWA, AND THEN EASTWARD ACROSS ILLINOIS  
AND INTO INDIANA. THIS RISK WILL LARGELY EXIST WITH NEW/INTENSE  
STORM DEVELOPMENT THIS AFTERNOON IN THE WAKE OF THE INITIAL  
CONVECTION -- BUT ALSO POTENTIALLY EVOLVING WITH A FEW INTENSIFYING  
STORMS WITHIN THE INITIAL/ONGOING BAND OF CONVECTION -- ALONG/NEAR  
THE WARM FRONT INTO INDIANA. AS THE STORMS INTENSIFY RAPIDLY THIS  
AFTERNOON IN RESPONSE TO THE RAPIDLY EVOLVING ENVIRONMENT, EXPECT  
PEAK TORNADO RISK TO OCCUR THROUGH LATE AFTERNOON AND INTO EARLY  
EVENING, SPREADING FROM EASTERN IOWA/NORTHEAST MISSOURI ACROSS THE  
REMAINDER OF THE MDT AND ENH RISK AREAS. GIVEN EXISTING  
UNCERTAINTIES DUE TO ONGOING PRECIPITATION/CLOUD COVER, AND  
ANTICIPATED/RAPID CHANGES IN THE ENVIRONMENT AS THE WARM FRONT LIFTS  
NORTHWARD AND CLOUDS THIN/CLEAR FROM THE WEST, CONFIDENCE REMAINS  
TOO LOW TO DELINEATE A POTENTIALLY CONCENTRATED AREA OF GREATEST  
RISK, WHICH WOULD OTHERWISE SUPPORT HIGH RISK UPGRADE. AS THE  
SITUATION EVOLVES, A POSSIBLE UPGRADE REMAINS POSSIBLE FOR THE 20Z  
OUTLOOK UPDATE, GIVEN THE LARGER-SCALE PATTERN/ENVIRONMENT WHICH  
CONTINUES TO APPEAR FAVORABLE FOR SEVERAL SIGNIFICANT TORNADOES.  
 
..GOSS/BENTLEY.. 03/28/2020  

 

[snowlover2]

 

 

[Winter Man]

Man, this could be bad. Extra bad because we're in the middle of a pandemic.

[WeatherMonger]

Looks like only change was extending the enhanced risk a bit SE in MO

[OceanStWx]

1 hour ago, Quincy said:

It’s an ever-evolving setup, but I see two main areas to watch based on morning trends:

1. Eastern Iowa closer to the surface low. While low-level moisture and surface heating may be less impressive than areas further south, steeper mid-level lapse rates and stronger low-level shear should compensate. 

2. West-central/central Illinois on the southern flank of lingering convection. Here, dew-points are likely to be in the mid to upper 60s. Despite less impressive lapse rates than points NW, stronger surface heating and quality low-level moisture should yield moderate to seasonably large instability. Low-level shear is a bit of a grey area, as models show less here, but one wonders if a reinforced warm frontal boundary in the wake of ongoing convection may help with locally enhanced SRH. 

I like the storm motion will generally be along boundary as you move into central IL too. Maximize whatever SRH you have.

[A-L-E-K]

Cold and foggy, wf doesn't stand a chance here

[Jackstraw]

70/65 here 48/48 25 miles north.  

 

[Hoosier]

8 minutes ago, A-L-E-K said:

Cold and foggy, wf doesn't stand a chance here

imo it will get through eventually, but maybe not until evening.

[Indystorm]

8 minutes ago, A-L-E-K said:

Cold and foggy, wf doesn't stand a chance here

Saved by the lake effect!   Perhaps.

[Sydney Claridge]

Time to start watching these severe-warned storms in SE Indiana.  They are tracking towards Dayton and Cincinnati, will be potential for hail if they hold together.

 

 

[pen_artist]

How well is the RAP known to perform? still a bit novice to reading models but RAP seems to be the only one still showing something significant

[jojo762]

First TOR warning of the day, just where we all expected; 70 miles south-southwest of LSX.

[WeatherMonger]

ILX midday update, imagine there will be a few 18Z or off hour RAOB launches as well.

 

Quote

UPDATE...
Issued at 1134 AM CDT Sat Mar 28 2020

A disturbance propagating out of northern MO into west central IL
has set off a few clusters of storms late this morning. A
disorganized frontal zone is somewhat stalled roughly just south
of I-74. The strongest storm feeding off a region of over 1000
J/KG MLCAPE have been able to produce hail over 1 inch diameter
just southeast of Springfield. This disturbance should move
steadily eastward reaching the IN state line by 1 p.m. Overturning
associated with this convection could diminish the afternoon
development of stronger instability to some degree, however there
should still be plenty of heating potential this afternoon. Given
strong lift and shear associated with the deepening low moving
into IA and the upper Midwest today, and organized by the trailing
cold front, severe thunderstorm potential continues today, and all
of central/southeast IL remains in a moderate or enhanced risk
according to SPC. Large hail and tornadoes are the primary
threats, while locally damaging downburst winds are also a threat.
Consensus of CAMS models indicate this last line of storms should
form in western IL mid afternoon, 3-5 p.m. or so, and progress
eastward through the evening hours. Updates this morning center
around trends in PoPs/thunder chances, mainly due to the late
morning convective clusters.

 

[jojo762]

Feel like that small cell that popped up a bit ago, now in Morgan Co. in central Missouri could bear watching the next few hours if it sustains as it eventually propagates toward Illinois and the warm front.