879
FXUS63 KEAX 220425
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1125 PM CDT Tue May 21 2024

.KEY MESSAGES...

- Storm chances will be greatly influenced by the position of
  the cold front and timing of storm initiation. Severe risk is
  significantly reduced behind the front.

&&

.DISCUSSION...
Issued at 107 PM CDT Tue May 21 2024

Short Term (Today-Tonight)

A small line of elevated storms moved across far northern MO during
the morning hours. Its concentration further north and quick
progression through the region does not look to impact the short
term forecast. Warm air and moisture advection into the region
continues ahead the approaching cold front.  This destabilizes the
atmosphere substantially  with some CAMs already projecting CAPE
values around 3000-4000 J/kg. Bulk shear above 50kts and midlevel
lapse rates greater than 8 C/km further increase confidence in the
potentially volatile environment. Storms are already beginning to
form across far SE Nebraska. Now, it is just a matter of how fast
the cold front progresses across eastern KS and how long it takes
for storms to initiate across the cold front.

Confidence is high that storms will form within the warm sector
ahead of the front; however, exactly where the front will be as
storms initiate is still in question. Short term model guidance
varies in the timing of convective initiation and the position of
the front. Citing two, the NAMnest initiates convection across
eastern KS pushing eastward into central MO through the evening.
Conversely, the HRRR suggests the front progressing further eastward
with storm initiation possible along and east of the I-35 corridor.
If the cold front progresses further eastward, those behind the
front may not see any storms regardless if there are within the
outlined risk areas.

Where models have been persistently agreeing is in the expected
storm modes and evolution of the system. Confidence is high that
storms are expected to start as discrete cells before congealing
into a line of storms across central and eastern MO. These discrete
cells are expected to bring chances for large hail (2+ inches),
damaging winds, and tornadoes. These threats are expected to
continue even as storms begin to linearize. Once the line becomes
fully organized, the primary threat transitions to damaging winds.
However, embedded brief tornadoes remain possible. Please ensure you
have multiple methods for receiving weather information; especially
during the late evening hours.

Longer Term (Extended Forecast)

The long term forecast remains persistent. A reinforcing vort
max will move through the Midwest on Wednesday, which may keep
storm chances in our southern fringes during the
afternoon/evening. More likely, though, is that storms will stay
south of the region Wednesday and Wednesday night (70 percent
chance). After the warm weather today, temperatures will be much
more seasonal on Wednesday in the wake of the system.

The pattern late this week into this weekend remains unsettled,
with general quasi-zonal or southwesterly low-amplitude flow in
place. Multiple perturbations will eject from a broad large-
scale trough in the West, leading to multiple chances for
convection through the holiday weekend. Ensembles are gradually
converging on a relatively higher threat Thursday night and
Friday as well as Sunday. With an open Gulf and relatively fast
flow in proximity to the perturbations, at least some severe
threat exists with each of these passing systems. Notably, the
CSU machine-learning probabilities provide nearly daily chances
of severe weather from Thursday through Monday for the region.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1125 PM CDT Tue May 21 2024

VFR conds are expected to prevail thru the pd with sct-bkn
clouds btn 8-10kft thru 23Z aft which clr skies are expected.
Winds will be out of the WNW around 5kts before becmg lgt and
vrb aft 23Z.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

MESOSCALE...
DISCUSSION...Pesel
AVIATION...73