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Area Forecast Discussion (AFD)

Issued by Kansas City/Pleasant Hill, MO (EAX)

FXUS63 KEAX 170400

National Weather Service Kansas City/Pleasant Hill MO
1100 PM CDT Tue Apr 16 2019

Issued at 251 PM CDT TUE APR 16 2019

Upper level ridging and a low level thermal trough extending through 
eastern KS and western MO has allowed us to warm up quite nicely 
today into the upper 70s and even lower 80s in places. This ridge 
will start to break down overnight as a series of shortwave troughs 
move through the plains on Wednesday setting up possible severe 
weather over our area late Wednesday afternoon into the evening. 

The first shortwave trough will move into eastern KS overnight and 
progress to the NE into the morning hours. This feature will advect 
low level moisture into the region under a nice EML that has set up 
over the area. This moisture advection will help to develop a 
stratus deck over our area overnight that looks to extend into 
eastern KS as well.  This cloud deck and how long it lasts will be a 
crucial piece to the severe weather potential puzzle going into 
Wednesday afternoon. As this low pressure system moves north a cold 
front will develop over eastern NE in the afternoon. While this is 
occurring a more significant shortwave trough will enter western TX 
Wednesday afternoon which will help form another low pressure system 
over north TX. These two features will interact to provide our 
weather impacts Wednesday afternoon and overnight. 

There will be two features that will provide uncertainty to our 
severe weather potential tomorrow, the low cloud deck and when the 
cap may break tomorrow. Model guidance does not have a consensus on 
how long this low cloud deck will stick around with the NAM/RAP/ARW 
all showing this deck stick around past 18Z while the GFS has it 
clear out before 18Z. Past events lead me to believe it will last 
longer than earlier as it will have to clear out from the ground up 
and it always seem to take a little longer to get the insolation we 
need to clear out. This will have major impacts on the temperatures 
and in turn the breaking of the capping inversion potential. For the 
strong cap to break there will need to be stretching and lifting 
from above as well as warming from the surface. Mid level troughing 
does not enter the area until near 7pm so without ample surface 
heating it is possible this feature does not break north of the MO 
River. We are leaning on the clouds clearing out just in time for 
enough heating to break the cap close to 7pm forming some convection 
along the frontal boundary over northern MO for a limited time while 
the SBCAPE is in place. SBCAPE of 1500-2000 J/kg and 30-35kts of 0-
6km bulk shear so these initial storms will likely intensify quickly 
with large hail and damaging winds being the main impacts as DCAPE 
will be near 1000 J/kg. The instability along the cold front will 
decrease rapidly so this may only be a 1-2 hour event. The second 
chance for severe weather occur as the warm frontal like feature 
moves into the area from SE KS in association with the southern low. 
The mid level lifting and thermal troughing will likely break the 
capping inversion south of the MO River resulting in available 
MUCAPE of near 2000 J/kg and effective shear of near 50kts 
available. These storms will likely be elevated due them moving into 
the area after 8-9pm so the main severe weather threat will be large 
hail and possible very heavy downpours. PWAT values of 1.4" will be 
well above the climatological norms and storm motion along the 
boundary being similar which could lead to flash flooding if 
training occurred over the KC Metro, but outside of that area only 
localized flooding is a threat do to higher flash flood guidance. 
Overall QPF looks to be 0.25-0.5" north of the MO River and 0.5-1.5" 
to the south with locally higher totals possible in convection. The 
severe threat will not last long (maybe until midnight) as the cold 
front will merge and overtake the warm front undercutting the 
boundary and decreasing the MUCAPE potential quickly.

Cooler air and gusty winds near 30mph will occur Thursday on the 
backside of this cold front. High temps are only expected to get 
into the upper 50s and with the winds it will feel cooler than that. 
Upper level ridging will build into the area Friday into Saturday 
which will help us quickly climb back into warmer temperatures. 
Saturday is looking to be one of the nicest days of the year with 
temperatures in the lower 70s and dewpoint in the 40s. A quick 
moving shortwave looks to push through the area Sunday afternoon and 
could kick up some elevated showers, but severe weather doe not look 
to be an issue. 


.Aviation...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1100 PM CDT TUE APR 16 2019

MVFR ceilings will impact the Kansas City metro TAF sites near 
10Z and spread northward towards KSTJ by 12Z. MVFR ceilings will 
slowly improve to VFR levels by early afternoon. Widespread 
thunderstorms will develop as the next storm system approaches the
central Missouri near 00Z-03Z tomorrow evening with isolated 
convection near KSTJ. Winds will remain from the south near 12kts 
through the morning hours. Southerly winds will increase with 
gusts near 24kts tomorrow afternoon. By late in the TAF period, 
expect gusty north winds.