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July 11-14 Severe Weather Event


Powerball

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4km NAM is having none of what the 12km NAM is saying. Honestly I don't know if I would buy the 12km NAM's solution it actually starts stuff near Eau Claire at 12Z and grows upscale.

Crazier things have happened with the NAM being right.. But meh. Doubt that any decent new convective development, besides maybe some showery MCS related activity preceding the line, could take place that early. However, given the jet dynamics in place, there could be ample forcing for this to occur.
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RPM for Monday morning from WGN Chicago

 

Looks nasty!

I say Milwaukee and Chicago both see some good action early tomorrow morning and likely later on too after a recovery.

 

ARX put this out just a short time ago.

 

FileL.png

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Interesting. 12km NAM has the MCS going in a more easterly motion than that. 

 

I guess they're thinking it will turn right and follow the warm front...? I would think with the higher dewpoints and instability west of here it will start to turn.

 

Outflow boundary taking shape to the northwest of Minneapolis.

 

MPX.N0Q.20150713.0228.gif

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So, the initial MCS by sunrise or so..... Then the follow up, sometime in the late afternoon.  Now is this contingent on the clearing of any remnants from the mornings storms?  

 

Any chance of this going high risk? Or for that matter happening at all?  Not trolling, asking a serious question. 

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Alek's scenario is not impossible, but it would take extensive morning convection and lingering extensive clouds to make it a greater possibility.

Well, it's happened before this year. Multiple times actually... I'm not saying it will happen again (especially with the parameters we've seen this week), but the option is always on the table with the year we've had.

I've enjoyed some of the soundings and graphs posted so far. Absurd CAPE numbers like this don't happen very often (last I remember things this jacked was 6/29/11). Saved a number of these for posterity. I think there is a definite possibility of some great severe tomorrow barring anything unforeseen.

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I guess they're thinking it will turn right and follow the warm front...? I would think with the higher dewpoints and instability west of here it will start to turn.

12km NAM has a strong easterly push of the MUCAPE gradient/warm front between 06z and 12z, and the MCS follows that. At 12z, the MUCAPE gradient is almost perfectly on the entire OH/IN border. 

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AREA FORECAST DISCUSSION  NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL  946 PM CDT SUN JUL 12 2015     UPDATE    946 PM CDT    CONVECTIVE TRENDS...BOTH TO OUR NORTHWEST...AND OVER NORTHERN  ILLINOIS...WILL BE THE MAIN CONCERN LATER TONIGHT INTO EARLY  MONDAY.    WATER VAPOR IMAGERY EARLY THIS EVENING DEPICTS A RATHER STOUT WEST-  SOUTHWESTERLY UPPER LEVEL JET ACROSS WY AND SD...WEDGED BETWEEN A   LARGE SUBTROPICAL RIDGE CENTERED OVER TX AND A DISTURBANCE OVER   SOUTHEASTERN SASKATCHEWAN. THE EVENING 00 UTC RAOBS INDICATE THAT   THIS JET IS AROUND 90 KT AT 300 MB...PER KUNR REPORT. SEVERE   CONVECTION CONTINUES TO DEVELOP WITHIN THE LEFT EXIT REGION OF THIS   UPPER JET OVER NORTHERN MN. THIS CONVECTION IS BEGINNING TO SHOW   SIGNS OF BUILDING UPSCALE AND BECOMING COLD POOL DOMINATED. AS   SUCH...THE 850MB TO 300 MB THICKNESS AND THE INSTABILITY GRADIENT   SUGGESTS THIS ACTIVITY WILL LIKELY BECOME A FORWARD PROPAGATING MCS   TOWARDS THE SOUTHEAST...IN THE VICINTY OF A WARM FRONTAL   BOUNDARY...WHERE THE ENVIRONMENT IS VERY UNSTABLE. CURRENT TIMING   WOULD NOT BRING THIS AREA OF CONVECTION INTO THE AREA UNTIL AFTER 3   TO 4 AM. STRONG DAMAGING WIND GUSTS WOULD BE THE PRIMARY CONCERN   WITH THESE STORMS OVER NORTHERN ILLINOIS AROUND OR A COUPLE HOURS   PRIOR TO DAYBREAK.     ADDITIONAL SCATTERED STORMS MAY ALSO TRY TO DEVELOP OVER THE   AREA...WITHIN THE VICINTY OF THE WARM FRONTAL BOUNDARY OVER THE NEXT   COUPLE OF HOURS. THE 00 UTC SOUNDINGS AT KILX AND KDVN BOTH INDICATE   VERY UNSTABLE CONDITIONS WITH UPWARDS OF 4000 J/KG SBCAPE   VALUES...AND LITTLE TO NO CAPPING. WITH THIS IN MIND...AND THE FACT   THAT THERE IS A VERY HIGH THETA-E AIRMASS NEAR THE SURFACE   BOUNDARY...IT WILL LIKELY NOT TAKE MUCH TO GET SOME ELEVATED   ACTIVITY TO DEVELOP. VARIOUS CAMS (CONVECTION ALLOWING MODELS)  SUGGEST THAT SCATTERED DEVELOPMENT WILL OCCUR OVER THE  AREA...AHEAD OF THE MAIN MCS...LATER THIS EVENING AND OVERNIGHT AS  WARM AIR ADVECTION AND ASCENT OCCURS ATOP THE SURFACE BOUNDARY.  THIS ACTIVITY COULD POSS A THREAT OF ISOLATED LARGER HAIL GIVEN  THE PRESENCE OF STEEP MID-LEVEL LAPSE RATES. HOWEVER...OF MORE  CONCERN IS THE HEAVY RAIN THREAT...ESPECIALLY CONSIDERING THERE IS  ALREADY ONGOING FLOODING OVER PORTIONS OF THE AREA. PWATS ARE  SITTING RIGHT AROUND 1.8" PER THE 00 UTC RAOBS AT KDVN AND  KILX...SO THIS WILL CERTAINLY ALLOW ANY STORMS TO PRODUCE  TORRENTIAL DOWNPOURS...POTENTIALLY TO AROUND...IF NOT OVER...2  INCHES PER HOUR.    AS FOR THE SEVERE THREAT LATER MONDAY INTO MONDAY   EVENING...UNCERTAINTY STILL EXISTS AS TO HOW THE EARLY MORNING  ACTIVITY WILL EVOLVE. THIS WILL PLAY A BIG ROLE IN THE MESOSCALE  ENVIRONMENT...DETAILS WHICH CANNOT REASONABLY BE RESOLVED AT THIS  DISTANCE. SYNOPTICALLY IT STILL APPEARS IT WILL BE A VERY  FAVORABLE ENVRIONMENT FOR BOTH HP SUPERCELLS WITH ATTENDENT LARGE  HAIL...DAMAGING WIND...TORNADO...AND FLOODING RAIN THREAT AS WELL  AS BOW ECHOS WITH DAMAGING WINDS ON MONDAY AFTERNOON AND EVENING.  THEREFORE...GIVEN THE MESOSCALE UNCERTAINTIES AT THIS TIME...THE  CURRENT THINKING HAS NOT CHANGED WITH RESPECT TO THE POTENTIAL FOR  SOME SIGNIFICANT SEVERE THUNDERSTORMS OVER OR NEAR THE AREA.    KJB  
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0z 4km NAM breaks a cell off from the QC line tomorrow night. Naturally it passes close to IKK.

 

attachicon.gifoutput_FNNQIy.gif

 

 

Another look, with county outlines

 

 

post-14-0-81600200-1436756651_thumb.png

 

 

Noticed some interesting things in the model fields.  Check out the localized strong 850 mb winds near that cell.  Also, the model tries to back the low level flow out ahead.

 

 

post-14-0-98431300-1436756700_thumb.png

 

 

post-14-0-81148100-1436756710_thumb.png

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A bit OT, but love when WFO's do mesoscale discussions either the night before, or morning of a potentially big severe event just to give a good update of the situation. LOT seems especially good at doing this as well.

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A bit OT, but love when WFO's do mesoscale discussions either the night before, or morning of a potentially big severe event just to give a good update of the situation. LOT seems especially good at doing this as well.

They do a lot of things really well when it comes to severe and winter wx ops.

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Seems SPC will go high risk if there's enough clearing. Tornado outbreak not out of mind either. They'll probably go high risk with a 60% for wind/hail and a 15% risk for tornadoes unless the cells are a lot more discrete in central IL. But my tornado area would be Central IL with very high instability and efficient shear and a 80 Knot mid-layer flow. 

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