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Area Forecast Discussion (AFD)

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

                            
000
FXUS63 KEAX 231747
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1247 PM CDT Thu May 23 2019

.Mesoscale Discussion...
Issued at 1026 AM CDT THU MAY 23 2019

Thunderstorms/outflow continue to reinforce the position of the
surface front this morning across far southern Missouri, and
starting to see CI already occurring across the southern High
Plains in response to a shortwave trough lifting out the main
upper trough across the desert Southwest. These storms will stay
south and west of the forecast area for the majority of the day, 
but will play a major role in how convection evolves this evening 
and tonight. 

Extreme instability will continue to mount across the TX panhandle
through south central KS, and will become easily uncapped through
daytime heating, spawning widespread deep convection by early
afternoon. While parameters suggest supercell morphology with
these storms, the lift may be too extensive and uninhibited to 
prevent storm mergers and a messy, progressively more linear 
storm mode across central KS. The surface warm front will begin 
to lift northward across the western half of KS but may lag a bit 
in southern Missouri where precipitation has been more widespread 
and persistent this morning; however, strong southwesterly flow 
will eventually begin to push the front northward late this 
afternoon and evening into (and eventually across) our CWA. This 
NW-SE positioning of the front, coupled with fast northeast storm
motion will quickly direct storms to the cool side of the 
boundary in KS this afternoon and evening, further promoting storm
mergers and non-discrete storm mode. Very strong winds aloft, 
unidirectional but impressive speed shear, and increasing MUCAPE 
will support MCS development and maintenance even on the cool side
of the front, which gives the most credence to the 12z NAMNest 
and NSSL WRF solutions which show a MCS-like structure moving into
northeast KS and northwest MO by this evening as storms in KS 
continue to merge and become cold pool dominant. Height rises
across the CWA in response to the shortwave trough and lesser
large-scale lift may cause storms to weaken as they move across 
MO, but it remains to be seen how much of a detriment that will be
to an ongoing, robust storm system.

A more conditional threat exists across southeast KS and southern
through central MO for redevelopment along the surface warm front
as it lifts north this afternoon and evening. CIN may hang on in 
this area with lesser surface heating and without the influence of
the shortwave trough to the west, DCI seems less likely, albeit 
possible. These storms, if they form, will move out of surface 
based instability pretty quickly and would not be as robust as 
convection further west.

&&

.Discussion...
Issued at 420 AM CDT THU MAY 23 2019

Satellite imagery this morning continues to show a large trough over 
the intermountain west; which has been responsible for the stormy 
weather of late as it ejected shortwaves across the Plains. And, the 
short version of the forecast is that this pattern will persist 
through the end of the work week and the holiday weekend, keeping 
the threat of storms coming. 

Long version of the forecast...continues to be defined by the large 
trough to our west; at least through the weekend. Temperatures will 
generally be around to above normal as the southwest flow under the 
trough out west will keep southerly winds blowing across the region. 
However, under this same southwest flow a weak frontal boundary will 
continued to wallow around, which has been, and will continue to, 
interact with any shortwave ejected by the western trough in the 
days to come. Stepping back to look at the moisture feed; a high 
pressure ridge across the Deep South has pushed a lot of the western 
Gulf moisture onshore, with LPW satellite imagery really 
highlighting this. While last nights storms did help clear some of 
the moisture from the atmosphere, the persistent south winds will 
bring that moisture rushing back later today. And, with precipitable 
water values of 1.5" just to our south, we can expect values of 1.5" 
to 2" to prevail across the region by tonight. 

Today and Tonight...We should get another daytime break from the 
storms, with temperatures spread through the 70s; but it looks like 
storms will return tonight, which will bring a quick return of 
flooding concerns. Next shortwave to eject from the southwest will 
start today; with the associated leeside low already seen across 
northern Texas. This will spark storms again today across central 
Kansas as a warm front lifts back to the north this afternoon; with 
storms spreading northeast across northeast Kansas and northwest to 
north central Missouri through the evening and overnight hours. 
Storms might be on the decaying side as they approach northeast 
Kansas, as they move away from the best instability, but there looks 
to be more than enough shear (0-6KM > 50 knots, among other shear 
parameters) to warrant keeping a careful eye on storms that move 
through northwest Missouri. As such, thoughts are that large hail 
and damaging winds are the big threats as storms move into later 
tonight, but an isolated tornado can not be ruled out. 
Additionally, with the high precipitable water values, we can 
expect river and stream flooding to be an issue, along with flash 
flooding. Will let the day shift try to pin down where any Flash 
Flood Watch may be needed for tonight.

Friday into the weekend...will see the parade of storms continue. 
It's likely that the day Friday will once again be mostly dry, 
though a few showers from Thursday nights storms may linger across 
the region into the morning, and we can't rule out some afternoon 
activity bubbling up, but the best chances for storms looks to 
arrive again Friday night into Saturday as western trough starts to 
fill and eject a significant portion of itself across the Plains 
States. This will result in periods of severe storms and flooding 
rain Friday night into Saturday morning, with another round expect 
Saturday night into Sunday. We might get a little bit of a break 
from the storms by Monday, but expect more stormy activity Tuesday.

&&

.Aviation...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1247 PM CDT THU MAY 23 2019

Stratus based around 3 kft will continue to lift north across all
TAF sites, but will bounce between MVFR and VFR as lower ceilings
move in but also attempt to mix a bit higher. Storms will become
possible by 00z but most likely to impact KSTJ versus KC-area TAF
sites. On-and-off thunderstorms are possible through the night
until after 12z, when they should start weakening and moving out. 

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Mesoscale...Laflin
Discussion...Cutter
Aviation...Laflin