August 16 Event – and Non-event

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At 8:15 PM a line of thunderstorms has developed.   Precipitation was primarily confined to areas along and south of a a line from Wichita to Kansas City.

It looked like a potential heavy rain event setting up for August 16, as several inches of rain had fallen across much of Nebraska the previous day, mainly north of a Hastings to Omaha line, including much of the Sand Hills in the central and north-central portion of Nebraska.

Early in the morning, the ‘low-level jet’ did indeed induce a nice little thundershower that dropped anywhere from around 2 tenths of an inch in north sections of Lawrence to over 6 tenths in a narrow swath across southwest to east-central Lawrence.  This was followed by another area of showers from around 9:15 AM to 11:15AM.  These showers were decreasing in intensity they moved across the area but brought another one to two tenths of an inch.

When all was said and done with the Wednesday morning rainfall, Lawrence came in with a 7-station average of 0.51 inches. The official Lawrence Airport gauge came in with an event total of 0.41 inches, with 0.21 inches falling from the early morning shower, followed by another two tenths in the mid-morning.

Although Douglas County was in (but on the northwest edge of) a severe thunderstorm watch Wednesday evening, the Wednesday morning rainfall constituted the entire event for Lawrence, as all the new storm development in the afternoon occurred to the south and east of town.

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About 6 AM – Here comes the storm – and the main event for most of Lawrence.  Measurable rainfall started shortly after 6 AM. 

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7 AM – The storm is through west Lawrence but lingers over east Lawrence.  Kansas City from downtown southward got hit pretty good by a new cell at this time, with about an inch falling in northeast Johnson County.  Another area of nocturnal development and thunder is just west of Manhattan and moving eastward. 

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8 AM – West and north Kansas City are now in some heavy rain and thunder.   The storms to the west are now approaching Topeka, but are generally weakening as nocturnal development is prone to do by the mid-morning hours.

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9 AM – The area of precipitation is now approaching Lawrence but continues to weaken. 

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10 AM – Light rain in Lawrence but not much if anything left in the way of heavy rain or thunder.

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11:00 AM – Mainly light but some moderate rain crosses the Lawrence area, dropping one to 2 tenths of an inch or so. 

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11 AM – And that is that.  The area of rain has pretty much fallen apart.  Now we await heating and destabilization for the afternoon/evening severe event that is in the forecast. 

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Skip ahead 3 1/2 hours to 2:30 PM – Clearing behind the morning rain has allowed quick heating and destabilization of the atmosphere and ‘convection initiation’ has occurred just west and north of Wichita, with hints of incipient development in an arc to the northeast.

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At 3 PM, a mere one-half hour later, an intense storm quickly develops right over Wichita, dropping about an inch.  Hints of development to the northeast around Emporia. 

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4 PM – Scattered storms from Wichita to the south KC area.   Thick clouds are now over the local area with hints of development up the Kansas Turnpike toward Topeka, but the area to the south is stealing all the thunder, so to speak. 

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5 PM – The area of development cannot really push much north of I-35, which looks to be the dividing line between wet and dry areas.  There is a hint of development just southwest of Topeka, with a ground clutter pattern near the radar west of that.  The east edge of the ground clutter area probably marks a discontinuity in the near surface airmass, otherwise known as the ‘cold front.’

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6 PM – Thick building clouds and a few sprinkles over the Lawrence area, but skies are clearing out west toward Topeka.  Real precipitation remains confined to areas from I-35 southeastward.  The ground clutter discontinuity proceeds to the Turnpike, defining the edge of the more stable near surface air. 

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7 PM – Southern KC metro gets clipped by an outlier that had developed over the I-35 area but the line of storms is pushing southeastward.  A bit of outlier development just southeast of Lawrence, but moving eastward.  The discontinuity, still visible, is advancing across Topeka and past the Turnpike.  

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8 PM – Outlier development just north of Ottawa and over downtown KC, but movement is to the east.  Ground clutter pattern has become more ill-defined around the edges. 

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9 PM – That is all she wrote.  An ‘I-35 miss.’   (Definition: When storm development is confined to the area along and southeast of I-35 – not an uncommon occurrence!)  Settings have probably been adjusted on the radar and a normal night time ground clutter pattern now extends well out from the radar. 

 

 

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