089
FXUS63 KEAX 161809
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
109 PM CDT Wed Apr 16 2025

.KEY MESSAGES...

* Warmup today and Thursday
  - Today: Mainly low to mid 70s
  - Thursday: Upper 70s to 80s.

* Active pattern provides multiple opportunities for showers/storms
  thru the weekend.
  - Best strong to severe chances...
    - Thur AM: SPC Marginal Risk
    - Thur PM: SPC Marginal to Slight Risk
    - Fri: SPC Marginal to Slight Risk

* Possible flooding concerns Friday into weekend with potential
  for multiple rounds of moderate to heavy rainfall.
  - WPC Day 3 and 4 Excessive Rainfall Outlooks over
    southern/southeast portions of the region

&&

.DISCUSSION...
Issued at 403 AM CDT Wed Apr 16 2025

Surface high pressure dominated conditions overnight, keeping it
quiet with light winds. Combination of clear skies, light winds, dry
air mass, and drying soils, cooling was extremely efficient. A
number of locations, mainly rural/outside of urban heat islands, had
approached or surpassed originally forecast lows by 2-3am. No
guidance had latched onto this, so have adjusted "best" guidance
downward a few degrees to accommodate. With surface high
slinking SE, far western Missouri into Kansas already seeing
return of southerly flow, limiting peak cooling. No real
consequences, aside from a bit chillier start to the morning.
Rest of today will be highlighted by increasing southerly flow
in response to building low pressure over the western High
Plains as a northern stream wave/trough drops out of Canada.
Broadly speaking this opens up the Gulf for strong moisture
return into the central Plains as well as advects in a warmer
air mass. On the nose of this activity today may be some weakly
convective, highly elevated showers rooted around 700mb. Can
see the beginnings of this currently over south central Kansas
with building cloud cover. Increased clouds probably the main
result with very dry air below as better low level moisture lags
westward. Activity mainly expected south of I-70 and sliding
eastward through the day. Winds increase through the day with
the building surface low, likely to around 20mph sustained and
gusts to 30mph Temperatures too will begin to drive warmer in
response to the increasing southerly flow, pushing into the 70s.

By later tonight, High Plains surface low starts to move out into
the central Plains and fill as the northern stream upper trough digs
SE and begins to interact with southern stream closed upper low.
Concurrently, a secondary surface low will develop and begin to push
off the Colorado Front range. This will direct moisture plume and
strong WAA more directly toward/over the area. Back west along dry
line in western OK/KS a few storms likely initiate in the evening,
and with strengthening LLJ overnight, expectation remains across
guidance for elevated storms to develop above a stout cap/EML and
track into the area around/after 3am. Profiles are nothing to get
too excited over with sub-par wind fields through the effective
layer and marginal MUCAPE (largely <500 J/kg). Any threat would
be for small to marginally severe hail with the strongest
updrafts, and likely transient. Activity continues to slide
eastward and weaken through the morning. SPC Day 1 Outlook
highlights this risk with western areas under a Marginal Risk.
This too bleeds into the SPC Day 2 given the 12z/7am Thursday
transition between the two outlooks.

On the heels of Thursday morning activity, progression of previously
mentioned northern/southern stream troughs will continue to
interact/phase and work to elongate Colorado Front Range surface low
in a SW to NE fashion across the central Plains. There remains some
discrepancies in exactly geography of the elongated surface low, but
broad agreement is for a strong cap to setup and is likely to keep
most of the area quiet Thursday evening/night. Best guess area for
convective initiation Thursday evening remains northward into
eastern Nebraska and western Iowa where the triple point is most
likely to reside. Uncertainty is largely whether initiation will
more southward in/around Grand Island/Lincoln, NE or more northward
toward Norfolk, NE. Additional convection may be seen along the warm
front, but again, should be displaced well north over northern
Iowa/southern Minnesota. Should the more southerly solutions
prevail, it is not out of the question for convection to clip
northern Missouri. Initially surface based convection would carry
the threat of all modes with an environment yielding MLCAPE
>1500 J/kg, effective bulk shear >45-50 kts, good hodograph
curvature and shape. Tornadic threat questionable though with
very high LCLs. Otherwise, large hail and damaging winds in
play. As activity slides eastward through the evening, expected
to become more elevated in nature and transition to primarily
large hail threat within potential MUCAPE environments >1500
J/kg with ongoing moisture advection and increasing LLJ. SPC
Day 2 highlights this risk, with Slight Risk roughly from
Highway 36 northward, accounting for some of geographic
uncertainty noted above. But again, risk currently appears
greatest over eastern Nebraska into Iowa.

Surface low shifts NE overnight Thursday in response to the
positively tilted western CONUS trough. Phasing depictions vary
some among the deterministics and their ensembles, but the
result locally is largely unchanged with surface front expected
to hang up across Missouri. Not much change potential location
by Friday afternoon, from roughly NE corner of Missouri
southwestward toward Butler, MO. Ahead of this front air mass
will remain moist and unstable, with depictions of a weakening
EML. This should allow for more expansive convective potential
along and ahead of the front by Friday evening. Model point
soundings suggest effective bulk shear >45-50 kts and SB/MU CAPE
values >2000 J/kg possible, yielding hail and wind threats.
Severe threat is likely short lived/confined to the first few
hours as upscale growth is likely with mean winds/storm motions
more parallel than orthogonal to the front. So as the severe
threat wanes, concerns may turn to flooding if there is little
to no frontal progression (as expected) with potential/likely
training of storms. As has been highlighted in previous AFDs,
local amounts in excess of 2" to 3" may be seen and result in
localized flooding or subsequent river flooding. For now, little
change overall to risk area, generally over the S/SE portions
of the CWA and on into the Ozarks. WPC EROs too reflect this
with Day 3 and 4 Marginal to Slight risks clipping the area.

Into the weekend, deterministic guidance continues to struggle a bit
with the degree of phasing of the northern/southern steam troughs
and how they eject into the central Plains. Suffice it to say,
shower/thunder chances carry on into/through the weekend, but with
prevailing solutions keeping the area on the cool side of the
developing surface low strong/severe risks are not expected at this
time.

After temperatures peak in the 80s on Thursday, they fall back
toward the 60s if not mid to upper 50s through the weekend. Upper
level height rises/ridging and more zonal flow overall will allow
some rebounding next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1241 PM CDT Wed Apr 16 2025

Breezy southerly winds are expected to persist through the
period, with gusts ranging from 22-28 knots. Showers are likely
and a few rumbles of thunder will be possible (along with MVFR
VIS/CIG) between 9z and 12z Thursday morning, otherwise dry
conditions and VFR conditions are likely.

&&

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

&&

$$

DISCUSSION...Curtis
AVIATION...BMW