Drizzle on your Parade

November 11th and 12th:

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From the Lawrence Journal World:  “Veterans on motorcycles ride down Massachusetts Street in the Veteran’s Day parade on Saturday, Nov. 11, 2017.”  Photo by Mike Yoder.

Veterans Day (Saturday, November 11th) brought the first widespread precipitation event of November as a ‘soaking drizzle’ fell across the area Saturday afternoon and evening.  When the measurable precipitation was done at about 9:30 PM, an average tenth of an inch of precipitation had accumulated across town, with individual amounts ranging from 0.07 to 0.13 inches.  At the Lawrence Airport, 0.08 inches was measured.  Temperatures were hovering in the mid 40s during the event with a light east breeze.  The high was 49, just before noon, and the low 35, resulting in a mean temperature that was four degrees below normal for the date.

Low-level ‘cold air advection’ on Sunday, the 12th, kept a low overcast across the region, though the sun made a few attempts to peer through at times around noon.  The high again reached 49 at about noon with a mid morning low of 45.   However, clearing shortly after sunset and subsequent radiational cooling allowed the temperature to drop to 31 at the Lawrence Airport by about 10 PM, resulting in a daily mean of five degrees below normal for the date.  The midnight to midnight range at my residence in southwest Lawrence was 50 and 37, averaging out to only 1.5 degrees below the normal daily mean of 45 degrees.

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Satellite image at 2:45 PM Saturday, during the height of the drizzle event. Low clouds blanket the area with band of higher clouds over the local area as well, making for a low-light day indeed, along with the drizzle.   

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Color Infrared image at the same time as the above visual image:  The layered clouds are clearly seen here with the low cloud tops at 0 degrees C (light orange) and mid to high level clouds in a band above (-10C to -30 degrees C cloud tops).    

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250 MB Chart (jet stream level) at 6 PM Saturday:  The upper wave over the plains states moves in, bringing enough lift for the drizzle.  Note the very strong jet streak over northeast Kansas of 110 knots, which helps provide lift as well.

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The 6 PM Saturday Topeka weather balloon sounding data shows that the saturated layer was limited to below 700 MB (10,000 feet ASL) by this time, with mainly dry air above.  Thus the very light precipitation, as only this low-level moisture was lifted by the incoming wave, wringing out  mainly drizzle, mixed with a bit of small-dropped light rain.

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The Saturday evening 850 MB chart (about 5,000 feet ASL) shows the extensive moisture at this level over the local region with a weak trough also seen moving across Kansas.

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The Saturday evening 700 MB chart (about 10,000 ft ASL) clearly shows the mid-level wave traversing eastern Kansas.   However, the computer has mis-drawn the 0-degree Celsius isotherm at this level, as Topeka shows a -2C reading.  So, the solid blue line should dip south of Topeka, not swerve north.  Just goes to show you – computer analysis can be a bit goofy on these charts!

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Satellite image at 4:15 CST on Sunday, October 12th:  The clearing advanced almost but not quite to Lawrence by the last hour of the day.

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The snags in the distance at Clinton Lake at 4:56 PM Sunday – 13 minutes before official sunset time.  Low overcast skies continued with just a hint of the advancing clearing seen in lighter skies along a strip above the northwest horizon.  So, under rather dark gray skies, I zoomed in on the mid-lake perches and west shore of the lake.  The turkey vultures are still hanging out on the perches, along with the occasional gull and pelican.  Some color is still vaguely seen on some of the west-shore trees, as well. 

$$

 

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