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Area Forecast Discussion (AFD)

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

FXUS63 KEAX 240512

National Weather Service Kansas City/Pleasant Hill MO
1212 AM CDT Fri May 24 2019

Issued at 331 PM CDT THU MAY 23 2019

Convection continues to bubble on the High Plains this afternoon,
leaving the main concern for today how storms will evolve through
the afternoon and evening as they approach the forecast area.
High-res models have come a little better in line with the idea of
an eventual transition to a linear storm mode this evening as
storms continue to merge and cold pools amalgamate; however,
timing is still a bit of a concern. Current storms across western
KS and OK are elevated and driven mainly by large scale lift from
the ejecting shortwave trough, but eventually more surface-based
and thus more robust convection is expected to develop and begin
congealing into a complex this evening through tonight. Steering 
flow is strongly to the northeast, but cold pool propagation could
allow a more west-to-east motion of the complex should it develop
into a bowing structure. The most likely scenario appears to be an
evolving MCS with a mainly southwest-to-northeast motion, perhaps
with a few segments that move more east than northeast, but
impacting mainly portions of far northeast KS and northwest MO
this evening. Arrival time could be as early as 00z but may be as
late as 06z, depending on how quickly storms evolve to the west
and how strong of a complex develops. Increased MUCAPE, strong
speed shear and overall strong flow will support MCS maintenance
should one develop, even despite height rises and a separation
from large scale lift as the system progresses further east.

Tonight's flash flood watch is contingent on storm mode, since a
progressive eastward-moving MCS would generally not support flash
flooding. However, a less organized convective complex with a
direct path across the northwestern corner of the CWA could result
in several inches of rainfall over a short period of time, causing
creeks and streams to rise. An additional flash flood watch will
likely be needed beyond Friday morning, but will address with
future forecast issuances.

Storm chances over the next several days will depend largely on
the previous night's convection and any boundaries that linger, so
timing is likely to change. On a broad scale, high dewpoints in
the upper 60s to lower 70s, diurnal increases in SBCAPE, and
continued 30-50 kts of deep layer shear will support severe
weather pretty much any time storms occur. Currently, the most
likely scenario is that the boundary which will be lifting north
overnight tonight will be temporarily shunted southward by
tonight's convection, but will then lift well north of the CWA
during the day Friday. A moisture gradient will drape northwest of
the area and could serve as a focus for convective initiation in
the evening and would then build south overnight; however, a 
separate area of storms could pop in the warm sector during the 
late afternoon and evening over the CWA, providing additional
storm/severe weather chances. Timing/placement becomes much more
uncertain beyond Friday night/Saturday morning; but again, any
storms that develop could produce severe weather.

Flooding potential will also continue due to both the repeated
nature of convection, already saturated creeks/streams, and high
PWATs. QPF forecasts are uncertain due to the convective nature 
of precipitation, but the likelihood of flooding somewhere in the
forecast area is moderate to high.

The upper trough helping to fuel continued storm chances will
reload this weekend through early next week, but is expected to
move east on Wednesday, perhaps providing a brief break from the
active pattern before possibly returning late next week.


.Aviation...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1211 AM CDT FRI MAY 24 2019

The warm front has lifted to the vicinity of the terminals.
Thunderstorms are developing along and north of the front from
northwestern MO through southwestern KS. These storms are
generally moving to the northeast. The overall area of storms 
should eventually shift south and start to impact the terminals
later tonight. Then through the day tomorrow, there is a good
chance the showers with embedded thunderstorms. It's actually hard
to find a period of time when there isn't some chance for
precipitation. Ceilings and visibility may drop to low MVFR or IFR
through the rounds of precipitation. 


KS...Flash Flood Watch until 10 AM CDT this morning for KSZ025-102.

MO...Flash Flood Watch until 10 AM CDT this morning for MOZ001-002-