October 21st Storm Front

A spring-like weather system brought a good mid-autumn dousing to the region Saturday evening, October 21st, one week (almost to the hour) following the damaging micro-burst storm of October 14th.

22:00Z 500mb.gif

The 7 PM 500 MB upper air chart shows a nice, full latitude upper trough approaching.   There are signs of a split in the trough as a new upper low center starts to develop in the area where New Mexico and the panhandles of Texas meet.

22:00Z 250mb.gif

At jet stream level, a very strong jet is on the back side of the trough, causing the southern part to start to split off and slowing the eastward progress of the system.  A split jet structure is ahead of the trough over eastern Kansas, causing divergence aloft and additional lift for the storms.

22:00Z 700 mb.gif

At 700 MB (about 10,000 ft ASL), a good flow of moisture just ahead of the trough as a strong upper high over the east coast helps push plenty of  moisture northward  from the Gulf of Mexico.

22:00Z 850mb.gif

At 850 MB (about 5,000 ft ASL) huge quantities of moisture are pushing northward from the Gulf of Mexico between the strong trough over eastern Kansas and the upper high centered off the east coast.

g13.2017294.2045_ICT_vis.jpg

Saturday, October 21st at 3:45 PM: Storms explode in a spring-like fashion across eastern Kansas along a slow-moving frontal boundary.  Lots of low clouds east of the storms indicated plenty of available moisture.

20171021_210610_BREF1_gray.png

At 4:06 PM, a line of storms develops from Wichita to just west of Topeka to Falls City, Nebraska.

 

2017102120_metars_ict.gif

4 PM surface plots show a well defined cold front triggering the storms as it moves into very rich air (moist and unstable) over our region.

20171021_212836_BREF1_gray.png

At 4:30 PM, the storms grow as they progress ever so slowly eastward.

g13.2017294.2145_ICT_vis.jpg

At 4:45 PM the the satellite image shows the storms growing very rapidly along and ahead of the front.

20171021_220142_BREF1_gray.png

At 5 PM storms cells are moving into Topeka as the line of storms continues to grow.

g13.2017294.2215_ICT_vis.jpg

Last good visual image at 5:15 PM shows many ‘overshooting tops’ indicating intense updrafts with the stronger storm cells.   The storm tops now cast a shadow on the low cloud deck east of the storms.  A rather spectacular image, I would say.

20171021_222924_BREF1_gray.png

At 5:30 PM, the storms are past Topeka and intensify as they approach Lawrence.

20171021_225728_BREF1_gray.png

At about 6 PM, a good solid line of storms moves into west Lawrence.  The first hundredth tipped my weather station bucket at 6 PM.  Temperatures were in the mid 70s and the dew point in the mid 60sunder low overcast skies from 2 PM until the storms hit at 6 PM.   Just ahead of the storms the barometer bottomed out at 29.75 from 4:53 to 5:33 PM.  By the time the storms hit at 6 PM the pressure had risen to 29.81.

2017102122_metars_ict.gif

Surface plots for 6 PM.  Winds were stiff out of the south before the storms hit but became very light as the storms moved in.

20171021_230304_BREF1_gray.png

6:03 PM radar image.

20171021_233309_BREF1_gray.png

6:33 PM – Can’t ask for much better than this at the end of the third week of October.

20171022_000054_BREF1_gray.png

7:01 PM.  The bucket on my weather station has recorded 76 hundredths in the roughly one hour since the storms began.

 

20171022_002721_BREF1_gray.png

7:27 PM – Storms are back-building a bit over Lawrence as a new area of rain with embedded thunder develops west of Topeka.  This is a function of the splitting upper trough that is slowing down the front as the storms continue to grow.

20171022_005923_BREF1_gray.png

At 8 PM, Lawrence is still on back end of the storms with moderate rain and embedded thunder now extending back west to Manhattan.

20171022_015927_BREF1_gray.png

At 9 PM light rain in Lawrence now but heavier moderate rain lies to the west.  The storms are only now completing a push across the KC Metro Area.

20171022_025901_BREF1_gray.png

10 PM – A good area of moderate rain with embedded thunder has developed behind the line of storms over the local area from Topeka, on across Lawrence and into the west KC Metro Area.

20171022_035743_BREF1_gray.png

11 PM – Rain and thunder keep on going, extending west to about the radar site west of Topeka (TWX).  West of the radar is a ground clutter pattern.

20171022_045930_BREF1_gray.png

At midnight, moderate rain continues from Topeka eastward.  What a slow-moving douser!

20171022_055542_BREF1_gray.png

At 1 AM – More moderate rain has fallen over the past hour around Lawrence.  The back edge of the rainfall is at Topeka (TOP).

 

20171022_065728_BREF1_gray.png

At 2 AM, the back edge of the rain approaches Lawrence.

20171022_075658_BREF1_gray.png

At 3 AM, the rain has just cleared Lawrence – finally.  The last tip of my automated rain bucket in southwest Lawrence was at about 2:20 AM.   My rain total in the manual gauge was 2.39 inches.

20171022_085616_BREF1_gray.png

At 4 AM – The she goes, the back end of the rain now pushing into the KC Metro Area.

GetMap-1.gif

Douglas County Rainfall reports from the CoCoRaHS network:  The Lawrence Airport automated site (LWC) came in with 2.30 inches.  A six-station Lawrence city average came in at 2.41 inches.   (Since I was out of town, my 2.39-inch report came in late and did not make the map, but I averaged it in.  One station that normally reports from east Lawrence is missing for this event.)  Note the very high amounts across eastern Douglas County – well over three inches with a 3.78 inch report at Eudora.  Clinton Lake came in with 2.49 inches and Ottawa with 2.60 inches.  An excellent late season dousing!  This later season charge of water has got to help the plants and trees for the colder months ahead, and I imagine the upcoming spring as well.

GetMap-2.gif

Shawnee County and Topeka came in with quite a bit less, as the storms developed quite a bit in the slow trek to the east.  Topeka Billard Airport (TOP) came in with 0.98 inches and Topeka Forbes Field (FOE) came in with 1.35 inches.

GetMap-3.gif

Amounts on the Kansas side of the KC Metro Area came in at over two inches everywhere and close to three inches near Bonner Springs and Leavenworth.  Johnson County Executive (OJC) came in kind of low with 1.79 inches (considering several neighboring reports of around 2.1 to 2.3 inches).   Olathe New Century (IXD) reported 2.28 inches, which looks right in there with the CoCoRaHS neighboring amounts.

GetMap-4.gif

On the Missouri side of the KC Metro Area, the northland did better but everybody received high amounts.  KCI (MCI) came in with 2.93 inches.  That was the highest of all NWS reports on the Missouri side of the KC Metro, and agreed closely with the southern Platte County amounts.  The downtown airport (MKC) came in looking kind of low looking with 1.50 inches.  Looking at neighboring CoCoRaHS reports, it should have come in around 2.25 inches.   In the past, the downtown airport site has been notorious for low readings or missing reports.

That was an excellent storm event for so late in the growing season.  Too bad I missed it!

Let’s have a final look from space on the evolution of this thing on the large scale looking at three water vapor images.  These images show the upper level system evolving.  Orange is dry air.

g13.2017294.2345_US_wv.jpg

At 6:45 PM a line of storms extends from Oklahoma across Iowa. The upper trough is digging down across eastern New Mexico (darker area) into northwest Texas where individual storms are developing in the high energy area east of the developing low to the south of the Texas Panhandle.

g13.2017295.0245_US_wv.jpg

At 9:45 PM the line of storms has made little progress eastward due to the digging southern part of the upper trough slowing down the entire system.  The new developing upper low is now over west-central Texas (small orange area) with energetic storm development in the strong upper dynamics to the east.

g13.2017295.0545_US_wv.jpg

At 11:45 PM, the new upper low center is moving slowly eastward toward north central Texas.  Most of the storm energy is closer to the developing low over Texas and especially eastern Oklahoma where more moisture is available, and on into southeast Kansas.  The storms are decreasing in intensity in our area as seen with the higher topped clouds now to our south (blue).   The upper level energy driving the storms is concentrated closer to the developing  upper low over west-central Texas (in the vicinity of the small orange spots). This splitting upper trough caused the storms to slowly weaken at our latitude as the pushed eastward into Missouri.

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s