June 26-29 Severe Threat

[snowlover2]

New day 1.

Quote

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1259 AM CDT FRI JUN 26 2020  
 
VALID 261200Z - 271200Z  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF  
EASTERN IOWA...SOUTHERN WISCONSIN...NORTHERN ILLINOIS...NORTHERN  
INDIANA AND SOUTHERN LOWER MICHIGAN...  
   
..SUMMARY  
 
A LINE OF SEVERE THUNDERSTORMS IS EXPECTED TO MOVE FROM NORTHEAST  
IOWA ACROSS SOUTHERN WISCONSIN AND NORTHERN ILLINOIS INTO SOUTHWEST  
LOWER MICHIGAN THIS AFTERNOON AND EVENING. ADDITIONAL STRONG TO  
SEVERE STORMS ARE POSSIBLE FROM THE MID MISSOURI VALLEY TO THE  
CENTRAL HIGH PLAINS.  
   
..GREAT LAKES/UPPER MISSISSIPPI VALLEY/MID MISSOURI VALLEY  
 
A SHORTWAVE TROUGH WILL MOVE EAST-SOUTHEASTWARD ACROSS THE UPPER  
MISSISSIPPI VALLEY TODAY AND INTO THE WESTERN GREAT LAKES REGION. AT  
THE SURFACE, A COLD FRONT WILL ADVANCE SOUTHEASTWARD INTO THE MID  
MISSOURI VALLEY AND UPPER MISSISSIPPI VALLEY. AHEAD OF THE FRONT, A  
MOIST AIRMASS WILL BE IN PLACE WITH SURFACE DEWPOINTS GENERALLY IN  
THE UPPER 60S TO NEAR 70 F. AS SURFACE HEATING TAKES PLACE TODAY,  
MODERATE INSTABILITY IS EXPECTED TO DEVELOP AHEAD OF THE FRONT  
ACROSS MUCH OF THE MOIST SECTOR. ALTHOUGH THERE IS SOME SPREAD IN  
THE MODEL GUIDANCE, MODEL CONSENSUS SUGGESTS THAT CONVECTION WILL  
FIRST INITIATE FROM SOUTHERN MINNESOTA SOUTHWARD INTO IOWA EARLY  
THIS AFTERNOON. THIS CONVECTION IS FORECAST TO MOVE QUICKLY  
EAST-SOUTHEASTWARD INTO SOUTHERN WISCONSIN AND NORTHERN ILLINOIS BY  
EARLY AFTERNOON REACHING SOUTHERN LOWER MICHIGAN BY LATE AFTERNOON.  
IT APPEARS THAT A LINEAR MCS WILL DEVELOP AS THIS CONVECTION  
ORGANIZES AND MOVES QUICKLY EAST-SOUTHEASTWARD ACROSS THE REGION.  
 
ALTHOUGH THE SCENARIO IS STILL FAR FROM CERTAIN, THE SETUP SHOULD  
BECOME FAVORABLE FOR A FAST-MOVING LINE SEGMENT THIS AFTERNOON.  
MLCAPE IS FORECAST TO REACH THE 1500 TO 2500 J/KG RANGE ALONG A  
CORRIDOR FROM EASTERN IOWA INTO NORTHERN ILLINOIS. CONVECTION SHOULD  
MOVE JUST SLIGHTLY TO THE SOUTH OF DUE EAST, ALONG THE INSTABILITY  
GRADIENT FROM NORTHEAST OF DES MOINES TO NEAR CHICAGO AND THEN  
EASTWARD TO NEAR DETROIT. THE NAM IS FORECASTING A 40 TO 50 KT  
MID-LEVEL SPEED MAX TO MOVE EASTWARD TO NEAR CHICAGO BY 21Z. THIS  
FEATURE, ALONG WITH AN ASSOCIATED SPEED MAX AT LOWER LEVELS, SHOULD  
ACT AS A REAR INFLOW JET TO THIS CONVECTIVE COMPLEX. THIS WILL HELP  
ANY LINE SEGMENT TO OBTAIN BOWING CHARACTERISTICS AND ENHANCE THE  
WIND POTENTIAL. NAM FORECAST SOUNDINGS ALONG THE EXPECTED TRACK OF  
THE MCS SHOW VEERED LOW-LEVEL WINDS TO THE SOUTH-SOUTHWEST AND VERY  
STEEP LAPSE RATES IN THE BOUNDARY LAYER. THIS SHOULD BE FAVORABLE  
FOR WIND DAMAGE ALONG THE LEADING EDGE OF THE LINE. SOME UNCERTAINTY  
EXISTS CONCERNING THE NORTH-TO-SOUTH EXTENT OF THE WIND DAMAGE  
THREAT BUT HAVE USED MODEL CONSENSUS TO PLACE AN ENHANCED RISK IN  
THE AREA WITH THE GREATEST PROBABILITY OF SEVERE. ALTHOUGH ISOLATED  
LARGE HAIL WILL ALSO BE POSSIBLE, THIS SHOULD BE THE LESSER OF THE  
TWO THREATS. THE SEVERE THREAT WITH THIS LINEAR MCS SHOULD REACH  
SOUTHEAST LOWER MICHIGAN AND NORTHERN OHIO BY EARLY EVENING.  
 
FURTHER TO THE WEST ACROSS THE MID MISSOURI VALLEY, A POCKET OF  
STRONG INSTABILITY IS EXPECTED TO DEVELOP BY AFTERNOON. AT THE  
SURFACE, A COLD FRONT WILL MOVE SOUTH-SOUTHEASTWARD IN THE MID  
MISSOURI VALLEY BY MID TO LATE AFTERNOON. ALTHOUGH DEEP-LAYER SHEAR  
SHOULD BE RELATIVELY WEAK, STEEP LOW-LEVEL LAPSE RATES SHOULD BE  
SUFFICIENT FOR A WIND DAMAGE THREAT WITH MULTICELLS ALONG AND SOUTH  
OF THE FRONT.  

 

[cyclone77]

Man, Broyles is everywhere.  What, does he work like 70hrs a week?  lol

 

[Hoosier]

They didn't really go into detail about the potential for more than one round.  I had been thinking the better threat would probably not arrive here until after dark but will have to watch the afternoon.

[snowlover2]

Marginal for most of the southern sub on new day 2.

Quote

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0101 AM CDT FRI JUN 26 2020  
 
VALID 271200Z - 281200Z  
 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN OHIO  
TO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND COASTS...  
   
..SUMMARY  
 
SCATTERED AFTERNOON THUNDERSTORMS MAY POSE A RISK FOR MAINLY  
DAMAGING WINDS ACROSS MUCH OF PENNSYLVANIA AND PORTIONS OF  
SURROUNDING STATES ON SATURDAY.  
   
..SYNOPSIS  
 
GRADUAL AMPLIFICATION OF THE UPPER FLOW FIELD OVER THE U.S. IS  
EXPECTED SATURDAY, AS SHORT-WAVE TROUGHING DIGGING SOUTHEASTWARD OUT  
OF THE GULF OF ALASKA LEADS TO A LARGE EXPANSION OF CYCLONIC FLOW  
OVER THE WESTERN U.S. THROUGH THE PERIOD. AS A RESULT, DOWNSTREAM  
RIDGING WILL INCREASE OVER THE NORTH-CENTRAL U.S. AND CENTRAL  
CANADA, STILL FURTHER EAST, SOME AMPLIFICATION OF TROUGHING IS  
EXPECTED OVER EASTERN CANADA AND INTO THE NORTHEASTERN CONUS.  
 
MEANWHILE, SEVERAL VORTICITY MAXIMA ARE FORECAST TO SHIFT EASTWARD  
IN A TRAIN-LIKE MANNER, FROM THE CENTRAL HIGH PLAINS ACROSS THE  
MIDWEST/OHIO VALLEY AND INTO THE MID ATLANTIC REGION/SOUTHERN NEW  
ENGLAND THROUGH THE PERIOD.  
 
AT THE SURFACE, A VERY WEAK/ILL-DEFINED BAROCLINIC ZONE IS PROGGED  
TO EXTEND FROM THE LOWER GREAT LAKES REGION WEST-SOUTHWESTWARD  
ACROSS THE MIDWEST/OHIO VALLEY STATES AND THEN WESTWARD TO THE  
CENTRAL HIGH PLAINS. IN THE WEST, A STRENGTHENING COLD FRONT WILL  
SHIFT SOUTHEASTWARD ACROSS NORTHWESTERN PORTIONS OF THE COUNTRY,  
REACHING AS FAR EAST AS THE NORTHERN HIGH PLAINS OVERNIGHT.  
   
..EASTERN OHIO TO LONG ISLAND  
 
CONVECTION IS EXPECTED TO BE ONGOING AT THE START OF THE PERIOD,  
WHICH CONTINUES TO COMPLICATE THE FORECAST, WITH RESPECT TO  
DIAGNOSING THE THERMODYNAMIC QUALITY OF THE AIRMASS. STILL, GIVEN  
ENHANCED LOW- TO MID-LEVEL FLOW ACROSS THE AREA, AND WEAK COLD FRONT  
MOVING ACROSS THE LOWER GREAT LAKES, SCATTERED THUNDERSTORMS --  
POSSIBLY IN MULTIPLE EPISODES -- WILL LIKELY OCCUR ACROSS THE REGION  
THROUGH THE EVENING. RISK FOR LOCALLY DAMAGING WINDS REMAINS  
APPARENT, AND THUS WILL MAINTAIN 15%/SLGT RISK FOR WIND ACROSS THIS  
REGION.  
   
..OHIO AND MID MISSISSIPPI/LOWER MISSOURI VALLEYS  
 
AS SEVERAL MID-LEVEL DISTURBANCES EMBEDDED IN MODERATE WESTERLY  
MID-LEVEL FLOW TRAVERSE THIS REGION, SCATTERED THUNDERSTORMS ARE  
EXPECTED TO DEVELOP IN A DESTABILIZING AFTERNOON AIRMASS -- IN THE  
VICINITY OF A WEAK/DIFFUSE BAROCLINIC ZONE LYING ACROSS THE AREA.  
AN AMPLE COMBINATION OF CAPE AND SHEAR IS EXPECTED ACROSS THE REGION  
TO SUGGEST THAT A FEW STRONGER STORMS WILL BE CAPABLE OF PRODUCING  
LOCALLY DAMAGING WINDS, AND MARGINAL HAIL, SUPPORTING THE  
INTRODUCTION OF 5%/MRGL RISK ACROSS THIS REGION.  
   
 

 

[Solidsting]

1 hour ago, Hoosier said:

They didn't really go into detail about the potential for more than one round.  I had been thinking the better threat would probably not arrive here until after dark but will have to watch the afternoon.

hmm you got a good point. but with the uncertainty in the models it looks like another not so straight forward event. pretty dynamic atmosphere going on like june 10th. if the first batch dont stabilize too much i do wonder also if maybe a secondary MCS would come along?

[purduewx80]

Nice discussion from LOT this morning:

Quote

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
312 AM CDT FRI JUN 26 2020

.SHORT TERM...
312 AM CDT

THROUGH SATURDAY...

AN ACTIVE PERIOD OF WEATHER IS EXPECTED THROUGH THIS EVENING, WITH 
POTENTIALLY MULTIPLE ROUNDS OF THUNDERSTORMS, INCLUDING A SEVERE 
WEATHER THREAT THIS AFTERNOON AND EVENING.

ONGOING STRONG ISENTROPIC ASCENT ON THE NOSE OF 925-850 HPA LLJ IN 
THE 305-310K LAYER IS FORCING A LINE OF CONVECTION FROM EAST-CENTRAL 
IOWA INTO WEST-CENTRAL ILLINOIS AS OF 3AM. THIS LINE WILL BEGIN TO 
OUTRUN BETTER MID-LEVEL LAPSE RATES AND LIKELY GRADUALLY LOSE 
INTENSITY, ESPECIALLY AS THE LLJ WEAKENS AROUND AND AFTER SUNRISE. 
HOWEVER, EXPECTATIONS ARE THAT THE LINE WILL CONTINUE TO LIFT ENE 
ACROSS THE CWA THROUGH MID-MORNING, WITH THE HIGHEST COVERAGE AND 
STRONGEST STORMS FAVORED ACROSS NORTH-CENTRAL ILLINOIS AROUND AND 
SHORTLY AFTER DAYBREAK. EVEN WITH POOR LAPSE RATES, THE COMBINATION 
OF EFFECTIVE SHEAR AROUND 30 KNOTS AND DECENT SYNOPTIC FORCING COULD 
ALLOW A STRONG STORM OR TWO TO PRODUCE SMALL HAIL.

OF ADDITIONAL CONCERN IS A WELL-DEFINED MCV WITH CONVECTION THAT HAS 
MAINTAINED ITSELF ACROSS NORTHERN IOWA SINCE LAST EVENING WITH 
ASSISTANCE OF THE LLJ. THE TRAJECTORY OF THIS MCV AND ASSOCIATED 
CONVECTION IS ROUGHLY ALONG OR JUST NORTH OF THE WI STATE LINE FROM 
6-7AM AROUND ROCKFORD TO 8-9AM AROUND WAUKEGAN. LIKE WITH THE BAND 
OF CONVECTION TO THE WEST, THE COMPLEX WILL ENCOUNTER AN 
INCREASINGLY LESS FAVORABLE ENVIRONMENT WITH EASTWARD EXTENT. GUSTY 
WINDS CAN BE EXPECTED FOR WITH ANY CONVECTION ASSOCIATED WITH THIS 
FEATURE GIVEN ANTECEDENT DRIER AIR AND RESULTANT HIGHER DCAPE. WHAT 
WILL ALSO BE OF NOTE IS A POTENTIAL REMNANT OUTFLOW BOUNDARY AND ITS 
ROLE IN CONVECTION LATER IN THE DAY.

FOCUS THEN SHIFTS TO THE TRAIN OF MCVS UPSTREAM IN THE CENTRAL GREAT 
PLAINS EARLY THIS MORNING. AFTER THE EARLY TO MID-MORNING CONVECTION 
CLEARS THE CWA, AN INCREASINGLY UNSTABLE ENVIRONMENT SHOULD DEVELOP 
AS LOW-LEVEL MOISTURE AND MID-LEVEL LAPSE RATES INCREASE. RESIDUAL 
OUTFLOW BOUNDARIES AND UPSTREAM CONVECTION LIMIT CONFIDENCE ON THE 
NORTHWARD EXTENT OF THE MORE FAVORABLE ENVIRONMENT, BUT CURRENT 
INDICATIONS ARE THAT AREAS AT LEAST AS FAR NORTH AS THE I-88 
CORRIDOR (AND POTENTIALLY THROUGH THE REMAINDER OF THE CWA) = SHOULD 
BECOME PRIMED FOR CONVECTION THIS AFTERNOON AND EVENING. THE ONE 
CONCERN THAT COULD DERAIL THE FORECAST BEYOND LATE THIS MORNING IS 
WHAT APPEARS TO BE A PAIR OF MCVS OVER NORTHEAST NEBRASKA TRACKING 
EASTWARD EARLY THIS MORNING. TIMING OF THE FEATURES INTO THE CWA 
FOCUS IN THE LATE MORNING TO EARLY AFTERNOON PERIOD. IT IS ENTIRELY 
POSSIBLE THAT THESE MCVS COULD INITIATE CONVECTION IN NORTHERN 
PORTIONS OF THE CWA AND SHIFT THE LOCATION OF ANY EFFECTIVE OUTFLOW 
BOUNDARY FARTHER SOUTH WHILE ALSO CARRYING AN INCREASING SEVERE RISK 
FOR DAMAGING WINDS.

A MID-LEVEL (AROUND 700 HPA) SPEED MAX WILL DEVELOP IN CONCERT WITH 
A PASSING RIGHT-ENTRANCE REGION OF AN UPPER JET LATE THIS AFTERNOON 
AND ESPECIALLY EARLY TO MID EVENING. MEANWHILE, A COLD FRONT WILL 
TRACK SOUTHEAST INTO THE CWA THIS EVENING. IN AREAS NOT AFFECTED BY 
THE AFOREMENTIONED POTENTIAL CONVECTION FROM THE MCVS, ROBUST DEEP 
CONVECTION IS EXPECTED TO DEVELOP NORTHWEST OF THE AREA BY LATE 
AFTERNOON AND SHIFT SE INTO THE AREA EARLY TO MID-LEVEL AS EITHER A 
SOLID LINE OR MULTIPLE WAVES/BOWING SEGMENTS (LEWP). 

ANY CONVECTION WILL BE CAPABLE OF DAMAGING WINDS, ESPECIALLY WITH 
BOWING CLUSTERS. WHILE A RELATIVELY LOW RISK, CONDITIONS ARE 
FAVORABLE FOR BRIEF TORNADOES GIVEN THE POTENTIAL QLCS/LEWP 
EVOLUTION OF CONVECTION AND MODEST LOW-LEVEL SRH. 

IN ADDITION TO THE SEVERE THREAT, LOCALLY HEAVY RAIN IS ALSO 
POSSIBLE WITH GENERALLY BOUNDARY PARALLEL FLOW AND PWATS NEARING 2". 
WITH THE APPROACHING COLD FRONT, OVERALL CONVECTION SHOULD BE 
PROGRESSIVE ENOUGH TO LIMIT THE FLASH FLOOD RISK, ESPECIALLY GIVEN 
THE OVERALL DRY WEATHER OVER THE PAST MONTH. THE AREA OF MOST 
CONCERN WILL BE ACROSS THE NORTHERN TWO TIERS OF COUNTIES LATE THIS 
AFTERNOON THROUGH MID-EVENING BEFORE THE COLD FRONT AND DEVELOPING 
COLD POOL OUTFLOWS FOSTER MORE SOUTHWARD PROPAGATION WITH 
CONVECTION. CONVECTION SHOULD THEN CONTINUE TO GRADUALLY SHIFT SOUTH 
THROUGH THE CWA THROUGH THE REMAINDER OF THE NIGHT.

KLUBER

 

[Solidsting]

Now thats interesting.. I wonder what the next SPC outlook is going to be. Potentially a very active day ahead.

[A-L-E-K]

wish i wasn't as busy but today looks close to ideal for my tastes when it comes to summer convection

 

 

[purduewx80]

Just now, A-L-E-K said:

wish i wasn't as busy but today looks close to ideal for my tastes when it comes to summer convection

 

 

Over/under on rounds of storms - 3?

[A-L-E-K]

3 sounds about right

hoping for a nice shelf down the lake

[Chicago Storm]

This first small MCS racing east along the WI/IL border will be of no issue for later activity.

If it can sustain, it could produce in IN/MI/OH later.


.

[Chicago Storm]

HRRR has been consistent in showing the best potential in/ near the new SPC ENH.

Can’t believe I’m going to say it, but looks like good positioning by Broyles. About damn time.


.

[kevlon62]

Pre First Round aka the play-in game.

Sent from my SM-N960U using Tapatalk

[purduewx80]

47 minutes ago, Chicago Storm said:

This first small MCS racing east along the WI/IL border will be of no issue for later activity.

If it can sustain, it could produce in IN/MI/OH later.

Models overnight have not handled most of the convection out in Iowa. We’ll see how that plays into destabilization later. Plenty of time though. 

[purduewx80]

Can see our two main MCVs (X'd below) this morning on composite loops (link is time sensitive). The one in SW MN is what will drive the primary swath of severe later in the day. You can even see the faster flow in the light precip on its southern flank.

[Chicago Storm]

Models overnight have not handled most of the convection out in Iowa. We’ll see how that plays into destabilization later. Plenty of time though. 

The HRRR seems to have the best handle on thing overall currently.

As you said, still way early, and I have little to no worry as of now.


.

[A-L-E-K]

tops warmed with the stuff over IL p quick here now and the IA stuff that was festering on the nose of the llj seems next to go 

 

and speaking of jets, the inflow that the hrrr gets going with the mvc later looks prime time

[purduewx80]

KLOT radar has been down for about 20 min. Would be a crappy day to lose it.

 

[purduewx80]

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

and speaking of jets, the inflow that the hrrr gets going with the mvc later looks prime time

[NEILwxbo]

37 minutes ago, purduewx80 said:

KLOT radar has been down for about 20 min. Would be a crappy day to lose it.

 

KLOT just tweeted they have technicians working on it but no estimated time of restoration.

 

[wisconsinwx]

1 hour ago, purduewx80 said:

Models overnight have not handled most of the convection out in Iowa. We’ll see how that plays into destabilization later. Plenty of time though. 

This feels like it has to be said in pretty much every setup (the models were poor in handling the early convection).

[madwx]

Pros:  MCV barrelling down the Iowa/Minnesota border, should reach here during the afternoon, ample moisture return

Cons:  All that convection between here and the MCV

[wisconsinwx]

With all this crapvection, the current storms along the WI/IL border may be the event lol.  If we get missed south, the complaint thread may be used 

[hawkeye_wx]

It looks pretty good for southeast Wisconsin and northern Illinois, but storms may or may not fire in time for Cedar Rapids.

[RyanDe680]

I dunno... every time there is morning convection it blows it for the afternoon....  The stuff by the MI river is intensifying and robbing moisture for afternoon... could be a late evening event.

[Chicago Storm]

On 6/26/2020 at 9:19 AM, RyanDe680 said:

I dunno... every time there is morning convection it blows it for the afternoon....  The stuff by the MI river is intensifying and robbing moisture for afternoon... could be a late evening event.

Stuff along the river is fading.


.

[Chicago Storm]

This arc of activity currently moving though appears to be the expected WAA/WF storms. The small cluster earlier was tied the initial passing MCV.

Activity behind this arc, around DVN, is fading with good clearing behind it.


.

[frostfern]

28 minutes ago, wisconsinwx said:

With all this crapvection, the current storms along the WI/IL border may be the event lol.  If we get missed south, the complaint thread may be used 

I'll take non-severe if it has good lighting.  I just don't want EVERYTHING to miss way to the south.  Need the rain.  I hate these E-W oriented setups where one row of counties gets trained while others get crap.

[A-L-E-K]

hydro issues on the table across northern tier if things play out right

[tuanis]

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

hydro issues on the table across northern tier if things play out right

Luckily June has been pretty dry, but these types of orientations always get me worried.