Atchison, Kansas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

676
FXUS63 KEAX 182337
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
637 PM CDT Thu Jun 18 2026

...Updated for 00z Aviation...

.KEY MESSAGES...

- Cooler weather today with light rain showers tracking south across
  the region.

- Active weather returns late Saturday through Sunday. Some
  strong to severe storms will be possible. Primary threat
  looks to be heavy rainfall which may lead to flash flooding.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 135 PM CDT Thu Jun 18 2026

Current/Today:

Surface high pressure resides over KS and spans into MO with
cyclonic flow aloft. This morning a few impulses are rounded
through the upper level flow across northern MN. Mixing with
the mid level moisture we are saw scattered rain showers with a
few rumbles of thunder. Further south there is a stalled out
boundary across southern KS into the Ozarks. Along this boundary
there is more robust showers and storms. This boundary is
expected to stay south of the CWA with the main focus of any
precipitation being the wave aloft from this morning
transitioning south through the day. Model soundings indicate
some dry air through the low levels which will keep rain totals
light through the day. Additionally, much cooler temperatures
today with highs in the upper 70s.

Friday:

Surface high pressure slides east to encompass MO with southerly
return flow beginning in the afternoon. This push of warmer air
will lead to highs climbing into the mid 80s. Isentropic ascent
will also increase through the afternoon and evening hours
leading to 20% chance of showers. Weak instability in play could
lead to a rumble of thunder at times, but no severe weather is
expected.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 135 PM CDT Thu Jun 18 2026

Weekend:

Saturday a low develops in the lee of the Rockies and quickly
strengthens as it moves east into KS. Southerly flow increases
across the midwest picking up a fetch of Gulf moisture. Shower and
storm chances will be increasing through the day with a 20-40%
in the afternoon. Forecast trends have been slowing the progression
of the system with better dynamics for severe weather being
shifted to the west. The latest from SPC has the metro and areas
west and northwest in a marginal risk (1/5) for severe weather.
Timing for the stronger to severe storms look to have a later
arrival in the evening hours when better instability builds in
and a shortwave moves overhead.

Perhaps the bigger problem will be the potential for heavy rain late
Saturday through Sunday. The strong low out of the Rockies draws on
a deep well of PWATs with the GEFS climatology hinting at
values of 2" which would be over the 99th percentile for this
time of year. The 12Z suite of deterministic guidance still
shows a fair bit of oscillation in placement of a developing
MCS. Previously the GFS and Euro were spilt between taking the
path through IA or northern MO. There is growing agreement for
northern MO track. Over the last 4 runs the EFI has shifted out
of the IA and into northern MO with values of 0.80. Shift of
tales has also shown an increase to 1 allowing for some over
achievement possible. Taking a look at QPF plumes across the
region shows a noticeable uptick in the Euro family with
clustering now emerging within the 2" total QPF values. The
deterministic GFS continues to remain an outlier, even amongst
its other GEFS members showing values in excess of 3".

Model soundings show deep saturation throughout the whole column of
air beginning Saturday night with synoptic forcing increasing
through the early morning hours. Warm cloud depth is expected to be
over 10kft allowing for some very efficient rain production. WPC
excessive rainfall outlook has the region highlighted in a
slight risk with a moderate risk just over the tip of NW MO.
Stay tuned as this set up looks favorable for flash flooding and
river rises.

Early next week:

The heaviest rainfall is expected to push off to the east late
Sunday with some lingering precipitation chances for Monday.
However, each updated model run seems to be slowing the system
down a bit which may lead to a higher rain chances then
currently advertised in this forecast package. High pressure
should build in after the low exits providing quieter
conditions through the mid week timeframe.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 635 PM CDT Thu Jun 18 2026

Good evening! VFR conditions are expected through the TAF period.
Westerly winds 5-10 kt will turn light and variable tonight as
high pressure builds in. Took a look at the fog potential late
tonight, but dew point depressions are currently around 15+
degrees and with the solstice and shortest night just a few days
away the potential appears very low and the probabilistic
guidance for visibility <5SM mirrors this at less than 20%. On
Friday, the high pressure will shift east with S/SE winds
developing at 5-10 kt. There is a very low chance (20% or less)
for a shower near the end of the TAF period, and especially just
beyond with a passing disturbance across Iowa.

&&

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

&&

$$

SHORT TERM...Britt
LONG TERM...Britt
AVIATION...McClure