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Area Forecast Discussion (AFD)

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

FXUS63 KEAX 201730

National Weather Service Kansas City/Pleasant Hill MO
1230 PM CDT Tue Aug 20 2019

Issued at 415 AM CDT TUE AUG 20 2019

Satellite and radar imagery this morning show a subtle shortwave 
trough zipping east across the northern Plains, with storms 
developing in Iowa on the nose of the nocturnal jet; much like every 
other night for the past several. CAMs are struggling with the early 
morning convection, with the operational models looking to have the 
better handle on the storm solutions. That said, expectations are 
that the activity in Iowa will congeal through the early morning 
hours, with an organized cold pool pushing stormy activity southeast 
from Iowa across north central and eastern Missouri this morning. 
However, if the cold pool does not get organized, then storms will 
likely stay north of the Missouri border, which will need 
monitoring owing to how that would effect temperatures later 
today. Otherwise, some of the early morning storms may be a bit 
strong, with gusty winds and torrential rain owing to the strong 
instability aloft. Any storms that wander south will take the edge
off the heat across areas from north central to central Missouri 
this morning, but there is enough time in the day for temperatures
to recover; so expect a hot and steamy afternoon either way, and 
thus will leave the Heat Advisory as is.

For tonight into Wednesday morning...we will be watching as a more 
significant trough axis swings into the northern Plains. This will 
have the duel effect of focusing tonight's nocturnal jet across 
southern Nebraska and Iowa, while also inducing a more meridional 
flow across the northern Plains. Expect the nocturnal jet to spark 
storms across southern Nebraska and Iowa early Wednesday morning,
spreading southeast as the cold pool develops and interacts with 
the nocturnal jet. This will also likely result in a weak frontal 
boundary, and/or effective front from the storms cold pool, laying
out across northern Missouri on the southern edge of a surface 
high that will be rolling across the northern Plains in response 
to the more meridional flow. Expect much of this activity to stay 
north of the Missouri border till almost sunrise Wednesday 
morning. What storms do make it into northern Missouri will 
likely include a decent chance of large hail, damaging winds, and 
torrential rain. 

Rest of Wednesday...will see the potential for storms to hang around 
as a whatever-kind-of-boundary wallows across northern Missouri. As 
a result, many models advertise ongoing showers and thunderstorms 
through the day Wednesday; but forecast thoughts are that models are 
over doing the precipitation potential during the day, converting 
what is likely going to be cloud cover into storms. Better chance 
for storms looks to arrive Wednesday night into Thursday morning as 
the nocturnal jet, on the south side of the trough axis swinging 
into the northern Plains, focusing across eastern Kansas and 
western Missouri. Will need to keep an eye out for late night 
severe potential as these storms will have plenty of instability 
to pull form aloft, and might have some organizing shear around 
any weak boundaries. 

For the rest of the work week, of note will be the cooler 
temperatures that will prevail staring Wednesday, with many 
locations across northern Missouri likely to see afternoon highs 
stay in the 70s Thursday through Saturday. There will be a small 
ongoing chance for more storms, but next widespread chance for 
storms does not return until next work week.


.Aviation...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1230 PM CDT TUE AUG 20 2019

Convection is the main concern for this TAF period, with a line of
storms hanging on along HWY 36. This is expected to slowly move
southeast/dissipate as the afternoon goes on. So far, visibility
has remained above 6 SM with ceilings still VFR. As of now, VFR
conditions are expected to remain for this TAF period. Things
should quiet down by the evening with clouds thinning out. Then
another round of convection is expected early Wednesday morning,
with the nose of the LLJ further west than this morning, making
northwest MO and northeast KS the initial target area. There is still
some uncertainty where exactly convection will initiate, but 
right now expect convection will be in the vicinity of STJ before 
sunrise and then the KC metro terminals after sunrise. Storm 
chances are expected to then continue throughout the day tomorrow.


KS...Heat Advisory until 8 PM CDT this evening for KSZ025-057-060-

MO...Heat Advisory until 8 PM CDT this evening for MOZ001-011-020-021-