June 26-29 Severe Threat

[snowlover2]

New day 2 maintains a large slight risk from MI southwest to SE NE/NE KS. They mention that if enough destabilization can occur after morning activity, a more organized bowing type wind threat could evolve requiring an upgrade to wind and categorical risk.

Quote

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1254 AM CDT THU JUN 25 2020  
 
VALID 261200Z - 271200Z  
 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER  
GREAT LAKES REGION SOUTHWESTWARD TO THE MIDDLE MISSOURI VALLEY...  
   
..SUMMARY  
 
SCATTERED POSING A RISK FOR DAMAGING WINDS AND HAIL ARE EXPECTED  
FROM THE CENTRAL PLAINS EAST-NORTHEASTWARD ACROSS THE MIDWEST TO THE  
GREAT LAKES FRIDAY AFTERNOON AND EVENING.  
   
..SYNOPSIS  
 
GRADUAL EVOLUTION OF QUASI-ZONAL FLOW ALOFT WILL OCCUR FRIDAY, AS  
EASTERN U.S. TROUGHING SHIFTS OFFSHORE. A POSITIVELY TILTED,  
LOW-AMPLITUDE SHORT-WAVE TROUGH WITHIN THE WESTERLIES WILL CROSS THE  
CENTRAL PORTION OF THE COUNTRY THROUGH THE PERIOD.  
 
AT THE SURFACE, A COLD FRONT INITIALLY STRETCHING FROM MINNESOTA TO  
WESTERN KANSAS WILL BECOME ELONGATED IN A MORE  
NORTHEAST-TO-SOUTHWEST MANNER, AS FRONT MOVES EASTWARD ACROSS THE  
GREAT LAKES REGION, WHILE LINGERING OVER KANSAS. MEANWHILE, A  
SECOND COLD FRONT IS FORECAST TO WORK ITS WAY INLAND/ACROSS THE  
PACIFIC NORTHWEST, AHEAD OF A MID-LEVEL SHORT-WAVE TROUGH DIGGING  
SOUTHEASTWARD OUT OF THE GULF OF ALASKA.  
   
..MID MO/MID MS VALLEYS TO THE GREAT LAKES  
 
SCATTERED THUNDERSTORMS ARE FORECAST TO BE ONGOING ACROSS PORTIONS  
OF THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES REGION  
AREA AT THE START OF THE PERIOD, AHEAD OF THE ADVANCING COLD FRONT.  
AS DIURNAL HEATING DRIVES AFTERNOON DESTABILIZATION, NEW STORM  
DEVELOPMENT IS EXPECTED NEAR THE ADVANCING COLD FRONT, FIRST OVER  
THE WISCONSIN VICINITY AND THEN STRETCHING SOUTHWESTWARD ALONG THE  
COLD FRONT INTO KANSAS.  
 
FLOW ALOFT THROUGH THE LOWER AND MIDDLE TROPOSPHERE ACROSS THE  
REGION WILL BE SUFFICIENT FOR ORGANIZED STORMS -- LIKELY EVOLVING  
LOCALLY INTO FAST/EASTWARD-MOVING BANDS. ALONG WITH HAIL POTENTIAL,  
DAMAGING WINDS WILL LIKELY TO BE THE FAVORED SEVERE RISK. DEPENDING  
UPON DEGREE OF DESTABILIZATION WHICH CAN OCCUR ACROSS THE GREAT  
LAKES AREA IN THE WAKE OF EARLY-PERIOD CONVECTION, A MORE  
ORGANIZED/BOWING-TYPE WIND RISK COULD EVOLVE, WHICH COULD REQUIRE  
HIGHER WIND PROBABILITY/GREATER CATEGORICAL RISK IN LATER FORECASTS.  
 
CONVECTION SHOULD CONTINUE THROUGH THE OVERNIGHT HOURS -- SPREADING  
AS FAR EAST AS PARTS OF PENNSYLVANIA AND NEW YORK, BUT  
WITH SEVERE RISK LIKELY WANING GRADUALLY AS THE AIRMASS STABILIZES  
WITH TIME.  
   

 
..GOSS.. 06/25/2020  

 

[A-L-E-K]

should be solid, bonus points for friday evening 

[snowlover2]

Enhanced area added on updated day 2.

Quote

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1227 PM CDT THU JUN 25 2020  
 
VALID 261200Z - 271200Z  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS  
SOUTHEAST WI AND CENTRAL/SOUTHERN LOWER MI...  
   
..SUMMARY  
 
A LINE OF SEVERE THUNDERSTORMS IS EXPECTED FROM SOUTHERN WISCONSIN  
INTO LOWER MICHIGAN FRIDAY AFTERNOON AND EVENING. ADDITIONAL STRONG  
TO SEVERE STORMS ARE POSSIBLE FROM THE MID MISSISSIPPI VALLEY  
THROUGH THE CENTRAL PLAINS INTO THE CENTRAL HIGH PLAINS.  
   
..UPPER MIDWEST/LOWER GREAT LAKES  
 
A WARM FRONT IS FORECAST TO EXTEND FROM NORTHERN IL NORTHWESTWARD  
ACROSS SOUTHWEST AND WEST-CENTRAL WI INTO EAST-CENTRAL/NORTHEAST MN  
EARLY FRIDAY MORNING. SCATTERED THUNDERSTORMS, AIDED BY ENHANCED  
LOW-LEVEL FLOW THROUGHOUT THE EASTERN PERIPHERY OF AN APPROACHING  
UPPER TROUGH, WILL LIKELY BE ONGOING ALONG AND NORTH THIS FRONT,  
NEAR AN ATTENDANT SURFACE LOW/TRIPLE POINT. THE WARM FRONT OVER THE  
REGION IS EXPECTED TO MOVE NORTHWARD/NORTHEASTWARD THROUGHOUT THE  
DAY AS THIS WEAK LOW MOVES EAST-NORTHEASTWARD, BRINGING MID TO UPPER  
60S DEWPOINTS IN TO CENTRAL/SOUTHERN WI BY EARLY AFTERNOON AND INTO  
CENTRAL/SOUTHERN LOWER MI BY THE LATE AFTERNOON. ADDITIONAL  
THUNDERSTORM DEVELOPMENT (OR POSSIBLY JUST REINVIGORATION OF THE  
EARLY PERIOD STORMS) IS EXPECTED AS THE LOW ENCOUNTERS THE MORE  
MOIST AND UNSTABLE BOUNDARY LAYER DOWNSTREAM. MESOSCALE FORCING FOR  
ASCENT WILL BE PROVIDED BY THE SURFACE LOW, WITH THE APPROACHING  
UPPER TROUGH PROVIDING ADDITIONAL LARGE-SCALE ASCENT.  
 
EXPECTATION IS FOR THIS FORCING TO RESULT IN QUICK THUNDERSTORM  
DEVELOPMENT ONCE THE AIR MASS DESTABILIZES. LINEAR CHARACTER TO THE  
FORCING FOR ASCENT COMBINED WITH THE PRESENCE OF MODERATE TO STRONG  
WESTERLY FLOW ALOFT IS EXPECTED TO PROMOTE QUICK UPSCALE GROWTH INTO  
AN ORGANIZED CONVECTIVE LINE. CONSEQUENTLY, A CORRIDOR OF HIGHER  
WIND GUST POTENTIAL IS EXPECTED ALONG AND JUST SOUTH OF THE WARM  
FRONT. BASED ON CURRENT GUIDANCE, THE CORRIDOR APPEARS TO BE MOSTLY  
LIKELY FROM SOUTHEAST WI INTO CENTRAL/SOUTHERN LOWER MI.  
ADDITIONALLY, THE MODERATE TO STRONG MID-LEVEL FLOW WILL RESULT IN  
ENOUGH LOW-LEVEL VERTICAL SHEAR TO SUPPORT TRANSIENT/BRIEF  
LINE-EMBEDDED/QLCS TORNADOES. HAIL IS ALSO POSSIBLE, PARTICULARLY  
WITH ANY EARLY, MORE CELLULAR STORMS OR AS A RESULT OF STORM  
MERGERS/INTERACTIONS WITHIN THE LINE.  
   
..MID MS/MID MO VALLEYS INTO THE CENTRAL PLAINS  
 
MODERATE INSTABILITY IS FORECAST TO BE IN PLACE FROM THE MID MS  
VALLEY INTO THE CENTRAL PLAINS AHEAD OF THE APPROACHING COLD FRONT.  
VERTICAL SHEAR WILL WEAKEN WITH SOUTHWESTWARD EXTENT, BUT ABUNDANT  
LOW-LEVEL MOISTURE (I.E. DEWPOINTS IN THE UPPER 60S/LOW 70S) AND  
STEEP MID-LEVEL LAPSE RATES (PARTICULARLY ACROSS THE CENTRAL PLAINS)  
WILL HELP SUPPORT STRONG UPDRAFTS CAPABLE OF BOTH LARGE HAIL AND  
DAMAGING DOWNBURST WINDS.  
   
 
   

 
..MOSIER.. 06/25/2020

 

[hawkeye_wx]

The morning models have sped up the front and are now firing the storms farther south.  The UK and Euro now have nothing here.  The CAMs fire the storms just barely in time.

[frostfern]

Hope this will be a good show.

[madwx]

1 hour ago, hawkeye_wx said:

The morning models have sped up the front and are now firing the storms farther south.  The UK and Euro now have nothing here.  The CAMs fire the storms just barely in time.

the HRRR has been trending slower all day and its been the quickest model.  Hoping the trend continues so storms erupt in our area

[Chicago Storm]

I’ll have more later, but *if* everything works out, could see a moderate risk needed across portions of NE IA/N IL/S WI/W MI for tomorrow. I’m big on the wind potential.

 

Edit: And think SPC will have to bring the 5% tor down into S WI and N IL more.

[purduewx80]

Tomorrow looking like a NOWCAST day in terms of severe weather to me. The upgrade to enhanced is possibly a bit premature given signs of junky WAA convection throwing a wrench in where the best destabilization occurs. Potential is certainly there for multiple swaths of wind damage, however. 

[Chicago Storm]

On 6/25/2020 at 3:59 PM, purduewx80 said:

Tomorrow looking like a NOWCAST day in terms of severe weather to me. The upgrade to enhanced is possibly a bit premature given signs of junky WAA convection throwing a wrench in where the best destabilization occurs. Potential is certainly there for multiple swaths of wind damage, however. 

I don’t think the morning WAA activity will play any role at all, but agree on the last part.


.

[Hoosier]

Timing appears to be less than ideal this far south as far as the main severe threat, but it looks like a considerable amount of instability could hang around into late evening.  Would definitely be more optimistic farther north.  My optimism locally is more middle of the road.

[cyclone77]

Timing looks pretty decent for the DVN cwa with this.  This doesn't look to be another case of withering Iowa sloppy seconds.  

[A-L-E-K]

Looking money here

[madwx]

As long as there is no festering convection in eastern Iowa in the mid morning I’m feeling prettay prettay good

 

There's even some local backing of winds through late afternoon 

[purduewx80]

1 hour ago, Chicago Storm said:

I don’t think the morning WAA wing will play any role at all, but agree on the last part.

Fair enough. I do think it'll affect what latitude is at the greater risk and agree with @A-L-E-K that the threat is probably farther south than the SPC currently expects.

[Chicago Storm]

Fair enough. I do think it'll affect what latitude is at the greater risk and agree with [mention=163]A-L-E-K[/mention] that the threat is probably farther south than the SPC currently expects.

That and the track of individual disturbances/MCV’s. 

I agree with further south than what SPC has as well...and a larger area of quality risk.

 

 

.

[frostfern]

I'm wondering if the convection won't be surface based up here in Michigan.  It will be a warm day, but rather dry.  The higher dewpoints come in from the west over the lake late in the day.

[purduewx80]

30 minutes ago, Chicago Storm said:

That and the track of individual disturbances/MCV’s. 

I agree with further south than what SPC has as well...and a larger area of quality risk.

Yes, thanks for pointing that out. Will be important to watch growth across NE the next few hours where most guidance has an MCV evolving. The general consensus on 18Z placement of that feature is in the vicinity of south-central or SE WI. Would expect PM sfc-based development to be most likely E-thru-S of that.

 

 

[Stebo]

Of course the 00z runs completely blast the current outlook.

[HillsdaleMIWeather]

4 minutes ago, Stebo said:

Of course the 00z runs completely blast the current outlook.

What're they saying?

[Stebo]

Just now, HillsdaleMIWeather said:

What're they saying?

Everything is a bag of crap.

[Solidsting]

Ahh nice to see yall again. hope this time around don,t disappoint like that moderate risk day did. would not surprise me tho

[Chinook]

1 hour ago, Stebo said:

Of course the 00z runs completely blast the current outlook.

So, how do the 00z model runs change the outlook significantly?

[Stebo]

Just now, Chinook said:

So, how do the 00z model runs change the outlook significantly?

I don't see anything worthy of the Enhanced risk right now, and I would shift everything south at least 100 miles.

[Chicago Storm]

I don't see anything worthy of the Enhanced risk right now, and I would shift everything south at least 100 miles.

Definitely still need an ENH based on 0z guidance, and definitely shifted/expanded south and southwest as well.


.

[Stebo]

Just now, Chicago Storm said:

Definitely still need an ENH based on 0z guidance, and definitely shifted/expanded south and southwest as well.


.

I don't know man, even a squall line is looking lack luster right now.

[Solidsting]

20 minutes ago, Stebo said:

I don't know man, even a squall line is looking lack luster right now.

of course things changing for the worse. one good blower for wayne county and ill shutup for the summer

[Chinook]

I think there's a possibility for a damaging squall line in SW Michigan. This model run is not really an outlier or anything like that.

[Hoosier]

36 minutes ago, Stebo said:

I don't know man, even a squall line is looking lack luster right now.

I'd keep the enhanced and then we'll see what things look like in the morning.  

[HillsdaleMIWeather]

2 minutes ago, Chinook said:

I think there's a possibility for a damaging squall line in SW Michigan. This model run is not really an outlier or anything like that.

Agreed, and the 3KM NAM still has a Lower Michigan wide one 

[Solidsting]

it dont look great for SE mich, unless its taylored to a more easterly direction and not propagating southeast