403
FXUS63 KEAX 082310
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
610 PM CDT Fri Aug 8 2025

...Updated 00z Aviation...

.KEY MESSAGES...

* Hot/humid conditions continue, but shifts southward a bit
  - Heat Advisory extended thru Saturday for southern areas

* Multiple rounds of storms possible, from Saturday thru Monday
  - Heavy rainfall and flooding potential, esp Sunday/Sunday night
    from northern into central Missouri, including KC Metro
  - Limited severe storm threats, primarily strong/damaging
    winds

&&

.DISCUSSION...
Issued at 336 PM CDT Fri Aug 8 2025

Hot/humid conditions have prevailed across the area thus far today,
with many locations seeing heat index values from 100-105 by 19z.
This in conjunction with gusty southerly winds, up to 30 mph gusts,
as a stronger surface pressure gradient has settled in in response
to low pressure developing and moving off the Colorado Front Range.
Much of the same will continue remainder of daytime hours with highs
topping out largely in the mid 90s, with a few upper 90s, and heat
index values to around 105 or a couple degrees warmer. With
increased southerly flow continuing this evening and overnight,
pumping in moisture and limiting any substantial decoupling,
overnight lows will remain quite warm. Expect lows in the mid 70s in
northern areas, and mainly upper 70s in the KC Metro and areas
south. Coupled with another warm/hot and humid day for southern
areas of the CWA on Saturday, have extended portions of the heat
advisory through this evening/overnight and Saturday. KC Metro area
not within this extended heat advisory with anticipation for limited
relief as mid-high level cloud cover streams into the area. There
too may be a couple of widely scattered showers and isolated thunder
this evening and again overnight in response to low-mid level
moisture advection/isentropic pushes and eventually the
increasing LLJ. This activity will be quite elevated with the
substantial EML in place and likely have weak/limited CAPE to
work with, but with an overall dry airmass below any of these
bases, there will be some enhanced downdraft potential for any
stronger updrafts. Given ongoing radar depictions and
depictions in recent HRRR runs, do have some slight mentions of
PoPs in the forecast late afternoon/evening and again late
overnight.

Large upper low will continue to glide eastward along/near the US-
Canadian border and push an associated surface front southward from
the northern into the central Plains. Unfortunately, the parent
system turns northeastward during the weekend and will allow for the
surface front to lose steam and largely stall out in a SW to NE
fashion around the Nebraska/Kansas/Iowa/Missouri border areas, if
not just a bit northward initially. This will signal the beginning
of a few days of active weather, with the potential for impactful
heavy rainfall/flash flooding/areal flooding and limited severe
weather potential. Unfortunately, given the nature of the front,
confidence in details may be limited beyond 24-36 hours out.

For Saturday, aside from the heat already mentioned, strongest and
most widespread shower/storm activity is expected northward across
central to northern Iowa and Minnesota where large scale forcing
will be strongest/deepest and the EML less substantial with mid-
level height falls. MCS strength and associated cold pools will be
the wild card with regards to how far southward they will be able to
build. Steering flow/mean winds tend to work against southward
building, but we have seen multiple times this year already strong
cool pools being able to far overachieve CAM guidance. Regardless,
activity should be on a weakening trend which is further bolstered
by the strength and depth of the EML in place, limiting
strong/severe threats. Most likely scenario appears some southward
building and weakening activity Saturday morning/early afternoon and
other lingering scattered convection into the evening primarily
capable of some heavy rainfall (PWats approaching 2") and lightning.
More widespread potential will be Saturday night/overnight as LLJ
once again cranks up and initiates widespread activity/MCS over
central/southern Iowa and to work into portions of northern
Missouri. There may be some wind potential with this activity,
dependent on MCS strength, in addition to heavy rainfall. This is
reflected well in HREF, with potential for up to a few inches near
the Iowa-Missouri border thru Saturday night, especially as you work
east of I-35. Widespread flooding not a substantial concern here,
but may be priming areas for subsequent heavy rainfall potential
Sunday evening/night. This time frame is highlighted by WPC Day 2
ERO of Slight over Northern Missouri, and Moderate right on the
doorstep.

Sunday daytime should see dwindling activity mainly over northern
areas, but evening and overnight is likely time period of most
concern, especially with heavy rainfall/flooding as the surface
boundary is expected to sag southward. Environment will be primed
for heavy rainfall with deep warm cloud layer depths >3500-4000m,
PWats around or greater than 2 inches, MUCAPE values >2000-2500 J/kg
(tho may not realize full potential). At this point, boundary may
largely stall out somewhere in the vicinity  of the I-70 and Highway
36 corridors, yielding multiple rounds of convection over a fairly
wide area. While outside of most CAM windows, larger scale guidance
is in fair agreement with this Sunday evening/overnight time frame
and its environmental depiction. This too is highlighted by the
NAEFS and ECMWF ensemble situational tables as well as the ECMWF EFI
(>0.7) and SOT overlap (higher confidence) with regards to QPF.
Certainly not out of the question to see areas/swaths of 4-5"+
rainfall during this time frame. Going forecast (NBM) QPF
understandable too low and broad at this time frame, but NBM higher
end percentiles do highlight area of concern well with NBM 50th-90th
percentile over N/NW Missouri with amounts 1.5-4". WPC Day 3 ERO
area largely highlights this well too, and in conjunction with a
collaboration call, a small Moderate area introduced over northern
Missouri and a more expansive Slight to areas S and SW, including
the KC Metro. While no Flash Flood Watch this cycle, do expect one
over the next forecast cycle or two as area is further honed in on
and seeing what transpires Saturday.

Activity dwindles Monday, but another round of moderate to heavy
rainfall possible, dependent on frontal location by this point.
Suggestions for it to sag further south, more towards central to
southern Missouri. By this point, temperatures too fall back into the
80s in response to the rain/cloud cover and gradual sagging
front.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 608 PM CDT Fri Aug 8 2025

Line of thunderstorms is moving eastward out of northeast Kansas
that may approach the STJ and MCI terminals over the next couple
of hours. Expecting this activity to weaken as we progress into
the evening. Gusty winds continue through stronger pressure
gradient in place. More precipitation activity expected Saturday
evening through Sunday but most impactful activity may occur
after 00z tomorrow at STJ and the KC Metro terminals. Therefore
that has not be placed in the 00z TAFs.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory until 8 PM CDT this evening for MOZ001>008-
     011>017-020>025-028>033-037.
     Heat Advisory until 8 PM CDT Saturday for MOZ038>040-043>046-
     053-054.
KS...Heat Advisory until 8 PM CDT this evening for KSZ025-102>105.
     Heat Advisory until 8 PM CDT Saturday for KSZ057-060.

&&

$$

DISCUSSION...Curtis
AVIATION...Krull