Slight Risk Of Severe Weather Tonight

4 PM Update:

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A Tornado Watch was issued for northwestern Missouri later this afternoon. We will be monitoring this are closely. The main severe weather risk type is damaging winds later this evening.

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The risk is definitely there, but there are still many questions on how this will evolve. We will go over the details on 41 Action News. The timing is still about the same as issued in the previous blog below.

Previous Blog Entry:

Good morning bloggers,

Kansas City Weather Timeline:

  • Today: Sunny and hot with no chance of thunderstorms. There will be a few afternoon clouds with a southeast breeze around 10 mph.  High: 95°
  • This evening from 6 PM – 8 PM:  Dry near KC. Thunderstorms will be forming north and west of KC.  Temperatures near 92°
  • 8 PM to Midnight:  Thunderstorms track southeast with a few possibly becoming severe. Damaging winds and some hail are the main risk types near KC. The chance of a thunderstorm in your backyard is 40%.
  • Tuesday:  Mostly sunny. High:  88°
  • Wednesday: A 30% chance of early morning thunderstorms. High: 87°

It reached 95 degrees yesterday at KCI Airport.  As the heat grows stronger, concerns for drought increase.  Let me begin with the HRRR rainfall forecast ending at 1 AM tonight:

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If this model is exactly right, then thunderstorms would form and track south-southeast just west of the state line around and after sunset tonight.  There is a slight risk of severe thunderstorms, in fact, the SPC upgraded the risk to an Enhanced Slight Risk:

day1otlk_1300

From the SPC:

"...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON/EVENING FROM SOUTHEASTERN NE TO SOUTH CENTRAL KS...

   ...SUMMARY...
   Severe thunderstorms capable of producing a few tornadoes, very
   large hail, and damaging gusts are expected late this afternoon into
   early tonight from southeastern Nebraska to northwestern Oklahoma. 
   More isolated severe storms will be possible farther north across
   Iowa and southern Minnesota, as well as along the corridor from
   northeastern Missouri to North Carolina.

   ...Southeastern NE to northwestern OK this afternoon into tonight...

   A surface cold front is moving southeastward across eastern SD/NE
   and northwestern KS early this morning, in association with a
   midlevel shortwave trough crossing the northern Plains.  The front
   will continue eastward into western MN/IA and southeastern NE to
   central KS by this evening, though motion of the front will slow in
   KS this afternoon.  Meanwhile, the warm sector is demarcated by a
   convectively-reinforced baroclinic zone from central IL to western
   IA and southwestern MN, with upper 60s to near 70 F dewpoints in the
   corridor between the boundaries from eastern KS into eastern NE. 
   This moisture, combined with strong surface heating and steep
   midlevel lapse rates, will support strong buoyancy (MLCAPE in excess
   of 3000 J/kg) this afternoon along and immediately ahead of the cold
   front, which will serve as the primary focus for severe thunderstorm
   development this afternoon/evening.

   As the surface front slows across KS by this afternoon, strong
   surface heating and deep mixing will result in large buoyancy and
   steep low-midlevel lapse rates.  These profiles will favor strong
   low-level stretching of vertical vorticity along the boundary by new
   updrafts, prior to the generation of widespread convective outflow. 
   Moreover, deep-layer vertical shear will be marginally favorable for
   supercells, and aligned such that supercell motion should largely
   parallel the boundary toward the south-southwest.  The net result
   will be the potential for supercells to move along the boundary and
   produce isolated very large hail and a few tornadoes with hybrid
   characteristics, mainly in the 21-01z time frame.  Thereafter,
   thunderstorm outflow should become more pervasive, and damaging
   winds will be the main threat this evening into early tonight.  The
   coverage of storms will likely become more isolated with
   southwestward extent across OK, though any persistent/back-building
   storms will have some large hail and damaging wind potential into
   late evening.

   ...Mid MS Valley and vicinity this afternoon/evening...
   Convection is ongoing in a couple of clusters from western IA to
   central IL, in association with low-level warm advection and MCVs. 
   This convection will help reinforce the stalled front along the same
   corridor, which should focus additional storm development this
   afternoon as the boundary layer to the south destabilizes.  One or
   more clusters may cross the area from northeastern MO across
   southern IL to KY this afternoon into early tonight, with an
   attendant threat for damaging winds and isolated large hail.  "

The risk was increased this morning due to the fact that there is no cloud cover at all, and the instability levels will be quite high.  The most likely development area is north and west of the KC viewing area as you can see on these next couple of maps.

HRRR 3 PM Surface Forecast:

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This forecast map, above, shows the 3 PM forecast.  Thunderstorms are modeled to begin forming around 3 PM north and west of Omaha, Nebraska.  Once they form, conditions are favorable for them to intensify and drop south-southeast.  The potential is there for large hail and damaging winds. A tornado or two is possible way up to the north and west of KC in the Enhanced Slight Risk Area.

6 PM Surface Forecast from the HRRR Model:
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By 6 PM, the thunderstorms are forecast to be organizing over southeastern Nebraska. Hopefully they form a bit farther east and not a bit farther west. If they form just one or two counties west of this area, then KC would be missed by this system entirely. If they form a bit farther east, then KC would be a target for heavy thunderstorms around 10 or 11 PM tonight.

10 PM Surface Forecast From The HRRR Model:

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This 10 PM surface map shows the thunderstorms tracking just west of KC.  After this system goes by, there is another chance on Tuesday night-Wednesday morning.  The GFS model tracks that chance southwest of KC as well, with no rain at all here. The NAM, and other models have a pretty good chance of a complex of thunderstorms early Wednesday morning near KC. Just like during the winter, the spring versions of these chances usually end up with the model that shows not much at all.  So, I have more concerns about missing Wednesdays chance as well. Let's begin with this first chance.  During the winter, we would present three chances showing up, and then it would be strike 1, 2, 3, and your out.  We take our first swing tonight.
Thank you for spending a few minutes of your day reading the Action Weather Blog.  Go over to the Weather2020 blog to join in the conversation.  Click Here For The Weather2020 Blog

Gary
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