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June 22-23 Severe Weather Outbreak


Stebo

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On paper, Monday certainly looks high-end based off of the model solutions, particularly the GFS and NAM.

 

With that said, there are caveats. The 00z RGEM develops an MCS over the Dakotas early Monday morning and that rolls into Wisconsin by Midday. Although you'd think that would have more of an effect on instability, the RGEM still shows strong heating across southern Wisconsin. The precip fields don't appear to show intense convection during the afternoon though.

 

Edit: The 00z GFS shows a similar MCS scenario.

 

Not making a forecast by any means, but pointing out that observation.

Even the NAM shows a pretty similar scenario just to a lesser extent.. has two MCS's developing monday morning, with one moving E toward S WI but dissipating by or before 18z (due to capping?) and causes next to no impact to instability, and another MCS moving across N WI and dumping loads of rain. Regardless it seems as though one or both of these MCS's (but probably more so the southern one) could intensify during the afternoon and still cause a significant SVR risk of damaging winds and large hail, and possibly tornadoes still depending on the exact morphology and mode of the MCS/storms and if they are or become surface based. Would also have to become concerned about the outflow this MCS would put off, as it would likely be a focus point for possible initiation of SFC based supercells and pooling of instability and even further enhance the already impressive SRH and LLVL SHR, 

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Would like to get yours and others opinions on the convective mode. To me, there's no overwhelming reason to think there will be a really quick transition to linear mode. Directional shear does become less as we go through the evening but the better forcing is well north / longer capping potential also makes one wonder about the coverage farther south.

I am not seeing a huge amount of linear forcing in the models, I think this has a good potential to remain discrete even after sunset, capping doesn't even get too huge until well after 06z. Which would make sense given the strong advection from the south-southeast.

 

As for the Day 2 MDT question, I think the answer is yes because of the multiple rounds, the morning MCS should be severe and then the afternoon stuff obviously would be explosive. I think they will word it very much in the direction of going even higher as well considering the potential.

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The 12z Euro remains more subdued with the GFS more in the middle ground, but still pretty insane with the shear.  Main difference with the EC is a weaker wind field.  It also kills lapse rates because it produces typical 6-hour global model convective QPF blobs.  FWIW, I haven't been impressed with the Euro for about a year now anyway.  Just throwing that out there.

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I am not seeing a huge amount of linear forcing in the models, I think this has a good potential to remain discrete even after sunset, capping doesn't even get too huge until well after 06z. Which would make sense given the strong advection from the south-southeast.

 

As for the Day 2 MDT question, I think the answer is yes because of the multiple rounds, the morning MCS should be severe and then the afternoon stuff obviously would be explosive. I think they will word it very much in the direction of going even higher as well considering the potential.

 

 

They were clearly toying with the idea of a day 3 moderate so I wouldn't be too surprised if the new day 2 has it.

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Parameter space remains insane for Monday.  Individual solutions aren't clarifying the picture much.  Anything from a warm sector MCS Monday evening killing the potential for the later cold front for more southern locations as in the WRF-ARW to a nasty hit for central lower Michigan along the warm front early followed by round 2 with the cold front as shown on the GEM.

 

The beauty of forecasting convection....parameters are off the charts and the forcing will be there, so we know that someone will get crushed.  But it won't be possible to know when, by what, or exactly where until the last possible second.

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SPC stayed with ENH risk in D2

...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF FAR SE  
MN...WI...LAKE MICHIGAN AND LOWER MI...  
 
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER MS  
VALLEY AND GREAT LAKES REGION...  
 
...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE NRN  
PLAINS...MID TO UPPER MS VALLEY...GREAT LAKES REGION AND NRN OH  
VALLEY...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS THE UPPER MISSISSIPPI  
VALLEY AND GREAT LAKES REGION ON MONDAY WHERE A FEW  
TORNADOES...DAMAGING WIND GUSTS AND ISOLATED LARGE HAIL MAY OCCUR. A  
THREAT FOR STRONG TORNADOES AND WIND GUSTS OF GREATER THAN 65 KNOTS  
WILL BE POSSIBLE. MARGINALLY SEVERE THUNDERSTORMS MAY OCCUR ACROSS  
THE MID MISSOURI VALLEY...MID TO UPPER MISSISSIPPI VALLEY AND  
NORTHERN OHIO VALLEY.  
   
..UPPER MS VALLEY/GREAT LAKES REGION
 
 
A VIGOROUS UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS THE NRN PLAINS  
INTO THE UPPER MS VALLEY ON MONDAY AS AN IMPRESSIVE 60 TO 80 KT  
MID-LEVEL JET OVERSPREADS THE UPPER MS VALLEY AND GREAT LAKES  
REGION. AT THE SFC...A LOW IS FORECAST TO MOVE QUICKLY NEWD FROM THE  
MID MO VALLEY INTO THE GREAT LAKES REGION AS A COLD FRONT ADVANCES  
SEWD INTO THE UPPER MS VALLEY. AHEAD OF THE FRONT...A VERY MOIST  
AIRMASS SHOULD BE IN PLACE WITH SFC DEWPOINTS IN THE LOWER 70S F  
WHICH SHOULD ENABLE MODERATE TO STRONG INSTABILITY TO DEVELOP ACROSS  
MUCH OF THE MID TO UPPER MS VALLEY BY AFTERNOON.  
IN ADDITION TO THE STRONG INSTABILITY...MODEL FORECASTS SHOW  
IMPRESSIVE SHEAR PROFILES AND AN UPPER-LEVEL SYSTEM THAT APPEARS  
QUITE ORGANIZED WITH A WELL-DEFINED LOW TO MID-LEVEL JET COUPLET.  
THIS COULD RESULT IN A SIGNIFICANT EVENT OCCURRING ACROSS PARTS OF  
THE UPPER MS VALLEY AND GREAT LAKES REGION ON MONDAY. CONSIDERING  
THE NAM...GFS AND ECMWF MODELS...THE NAM AND GFS APPEAR TO THE BE  
MOST AGGRESSIVE SOLUTIONS WHILE THE ECMWF IS SLIGHTLY MORE  
CONSERVATIVE CONCERNING THE AMOUNT OF INSTABILITY...SHEAR AND  
ORGANIZATION WITH THE UPPER-LEVEL SYSTEM. MANY PROBLEMS EXIST FOR  
DETERMINING THE MOST LIKELY CORRIDOR FOR SEVERE INCLUDING 1) HOW  
MORNING CONVECTION WILL IMPACT THE SETUP IN THE AFTERNOON AND 2) HOW  
FAR NORTH WILL THE CAPPING INVERSION IMPEDE CONVECTIVE DEVELOPMENT.  
 
THE CURRENT THINKING IS THAT A MORNING MCS WITH WIND DAMAGE  
POTENTIAL WILL TRACK ESEWD FROM ERN MN AND ERN IA ACROSS SRN  
WI...NRN IL AND INTO IND AROUND MIDDAY. FURTHER WEST BEHIND THE  
MORNING MCS...AN AXIS OF STRONG INSTABILITY WILL DEVELOP FROM NRN MO  
NWD INTO ERN IA WITH NEW CONVECTION INITIATING ON THE NRN END OF THE  
STRONG INSTABILITY IN FAR SE MN AND NWRN WI DURING THE AFTERNOON.  
THIS CONVECTION SHOULD MOVE EWD AND GRADUALLY GROW UPSCALE. NAM  
FORECAST SOUNDINGS AT 21Z ON MONDAY FOR MADISON WI SHOW IMPRESSIVE  
THERMODYNAMICS AND SHEAR PROFILES WITH MLCAPE ABOVE 4000 J/KG AND  
0-6 KM SHEAR FROM 60 TO 70 KT. THIS WOULD BE VERY FAVORABLE FOR  
SEVERE STORMS INCLUDING SUPERCELLS. IT SEEMS POSSIBLE THAT A CLUSTER  
OF SUPERCELLS COULD ORGANIZE DURING THE MID TO LATE  
AFTERNOON...MOVING EWD ACROSS CNTRL AND ERN WI AND CROSSING LAKE MI  
INTO LOWER MI BY EARLY EVENING. STRONG LOW-LEVEL SHEAR COULD SUPPORT  
A THREAT FOR STRONG TORNADOES AND A LONG-TRACK TORNADO CAN NOT BE  
RULED OUT. THE OTHER POSSIBILITY IS FOR A SEVERE WIND PRODUCING  
LINEAR MCS THAT MOVES QUICKLY ESEWD ACROSS WI DURING THE LATE  
AFTERNOON REACHING LOWER MI BY EARLY EVENING. DUE TO THE POSSIBILITY  
OF A HIGH-END EVENT FOR EITHER TORNADOES OR WIND DAMAGE...THE  
ENHANCED AREA WILL BE EXPANDED TO INCLUDE MOST OF WI AND LOWER MI  
WITH THE SIGNIFICANT HATCHED AREA ALSO INCLUDING SERN MN.  
 
..BROYLES.. 06/21/2015  

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It was expanded south

Think he's meaning even more S/SSW like both the NAM's show as becoming uncapped...

EDIT: Also am very surprised that we didn't see a MDT looks as though they're struggling with what the convective mode will be due to the MCS, which wont be decided until morning.. On a side note, Broyles issued the outlook, in which case he is usually pretty optimistic about setups so it surprised me even more not to see the MDT. Could see it at 1730z if things become more clear in 06Z and 12Z guidance. 

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Yep, I just find it odd they based there's on the 0Z NAM but didn't expand quite a bit into Indiana/Illinois/Ohio

Agreed! I was also confused... They talked about the NAM a bunch yet none of that was translated into the graphic... even Madison is barely in the Enhanced

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DTX's AFD is a great read covering all aspects:

 

POTENTIALLY ACTIVE CONVECTIVE EVENT LATE MONDAY INTO MONDAY NIGHT
THE MAIN FOCUS DURING THIS LONG TERM. 00Z MODEL SUITE CENTERING IN
ON THE EVOLUTION OF THE MAIN SYNOPTIC FEATURES IN PLAY THROUGH THIS
PERIOD. CLOSED UPPER LOW CURRENTLY PARKED ACROSS BRITISH COLUMBIA
WILL SHEAR INTO THE MEAN WESTERLY MID LEVEL FLOW COINCIDENT WITH A
STRONG IMPULSE AND ATTENDANT JET MAX LIFING OUT OF THE CENTRAL
PACIFIC. FAVORABLE INTERACTION BETWEEN THESE FEATURES AND THE
RESULTANT GREATER HEIGHT FALL CENTER WILL ELICIT A SOLID LOW LEVEL
RESPONSE BEGINNING TONIGHT AS THESE FEATURES SHIFT INTO THE PLAINS.
00Z NAM/GFS/CANADIAN ALL CONTINUE TO PRESENT AN EXTREMELY DYNAMIC
SOLUTION...GENERATING A 60KT LOW LEVEL JET BENEATH 80-90 KNOT 500 MB
FLOW WITHIN THE EMERGING WARM SECTOR IMMEDIATELY DOWNSTREAM OF
EFFECTIVE LOW PRESSURE FORECAST TO LIFT FROM EASTERN NEBRASKA TO THE
NEAR THE STRAITS THROUGH MONDAY EVENING.

SLOW EASTWARD RELEASE OF EXISTING SURFACE RIDGING AND BRIEF MID
LEVEL SUBSIDENCE WILL PROVIDE SOME LINGERING STABILITY LOCALLY
THROUGH THE FIRST HALF OF MONDAY. INSOLATION POTENTIAL THROUGH THIS
TIME LIKELY DICTATED BY THE EXTENT AND TRAJECTORY OF ANY CIRRUS
DEBRIS LEFT FROM NOCTURNAL CONVECTION UPSTREAM. ABSENT OF THIS...A
HIGH DEGREE OF SUN COMBINED WITH INCREASING DEEP LAYER WARM AIR
ADVECTION WILL SUPPORT HIGHS OF LOWER AND MIDDLE 80S AREAWIDE.
GREATER MOISTURE ADVECTION STILL APPEARS TO LAG SLIGHTLY...DEEPER
THETA-E PLUME TRAILING THE PRIMARY SURFACE WARM FRONT NOT EXPECTED
TO ENTER SE MICHIGAN UNTIL 21Z AT THE EARLIEST. CONVECTIVE
INITATION MAY FIRST FOCUS ALONG THIS ADVANCING BOUNDARY...SOME MODEL
GUIDANCE CENTERING THE INITIAL DEVELOPMENT WITHIN THE GROWING
INSTABILITY BUBBLE ACROSS THE SOUTHERN LAKE MICHIGAN/SW LOWER MI
CORRIDOR. THE LACK OF GREATER MOISTURE QUALITY AND LINGERING
CAPPING ISSUES SUGGESTS A GREATER LIKELIHOOD FOR DRY CONDITIONS TO
HOLD LOCALLY PRIOR 20Z...THE CAVEAT BEING SHOULD A MORE PROGRESSIVE
DOWNSTREAM PROPAGATING MCS ENTER THE PICTURE.

STRONGLY FORCED ASCENT WILL TEND TO ALIGN IMMEDIATELY EAST OF THE
SURFACE LOW AND NORTH OF THE ARCING WARM FRONT...THIS MAXIMUM IN
MASS CONVERGENCE AND MOISTURE TRANSPORT TENDING TO ALIGN FROM
SOUTHERN WI/NORTHERN IL NORTHEAST THROUGH SOUTHWEST AND CENTRAL
LOWER MI. THIS WILL PLACE THE TRI-CITIES DOWN THROUGH THE I-69
CORRIDOR WITHIN A MORE FAVORED DOWNSTREAM POSITION TO SEE A GREATER
COVERAGE OF CONVECTIVE DEVELOPMENT/EXPANSION 20Z-02Z. POTENTIAL
WOULD EXIST FOR THE INBOUND WARM FRONTAL EXTENSION TO ANCHOR A LOWER
COVERAGE OF CONVECTION FOR POINTS SOUTHWARD. PRONOUNCED INCREASE IN
BOTH DIRECTIONAL AND SPEED SHEAR THROUGH THIS TIME...YIELDING
CORRESPONDING HIGH MAGNITUDE BULK 0-6 KM AND LOW LEVEL VALUES OF
SHEAR/HELICITY. BACKGROUND KINEMATIC ENVIRONMENT CERTAINLY
CONDUCIVE FOR RAPID CONVECTIVE ORGANIZATION AND ROTATING
UPDRAFTS...THE MAGNITUDE/SCALE AND MODE OF DEVELOPMENT DETERMINANT
ON THE DEGREE OF INSTABILITY AND POSSIBLE UPSCALE GROWTH OF ANY
UPSTREAM CONVECTION.

DEEP THETA-E PLUME WORKS INTO SE MICHIGAN THROUGHOUT THE EVENING...
IMMMEDIATELY IN ADVANCE OF THE TRAILING COLD FRONT EXPECTED TO DIVE
ACROSS THE REGION WITHIN THE 02Z-08Z TIMEFRAME MONDAY NIGHT. BEST
DESTABILIZATION LOCALLY THROUGH THIS TIME...A NOTED INCREASE IN
DEWPOINTS WITH A STEADY STEEPENING OF MID LEVEL LAPSE RATES. THIS
WILL PROVIDE A SECONDARY WINDOW FOR CONVECTIVE GROWTH AND AN
ACCOMPANYING SEVERE WX RISK AREAWIDE WITH THE FRONTAL PASSAGE. PER
THE USUAL...A COMPLEX AND CHALLENGING SETUP FOR OUR DOWNSTREAM
LOCATION WITH A MYRIAD OF SMALLER SCALE FACTORS LIKELY TO DICTATE
THE EVENTUAL OUTCOME.

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H7 temps increase and upper level support really decreases further south. I think most of the threat stays north of the WI-IL and MI-IN borders.

 

I tend to agree.

 

Assuming the stronger/more amped solutions verify, unless there's upscale growth into a QLCS (which is possible, but not certain depending on the strength of the cap), the main threat should remain in Central Lower MI and S. WI...

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FWIW, the NAM is by far an outlier amongst the SREFs for DTW.

 

IT shows MLCAPE values between 4000 and 4500 J/G at 00z tomorrow, while the mean amongst the SREFs show only MLCAPE values around 2000-2500 J/KG...

 

You absolutely won't need 4000-4500 J/kg MLCAPE with the amount of shear being forecast tomorrow. To just see the SREF mean with 2000+ is concerning enough.

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You absolutely won't need 4000-4500 J/kg MLCAPE with the amount of shear being forecast tomorrow. To just see the SREF mean with 2000+ is concerning enough.

 

Of course. It was just something to note as the 12z run comes out.

 

The difference seems to be the NAM's assuming steeper mid-leve lapse rates (compared to the other models). 

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