Kirkwood, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

566
FXUS63 KLSX 130402
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1102 PM CDT Mon May 12 2025

.KEY MESSAGES...

- Isolated to scattered showers and a few thunderstorms are
  expected this evening and again Tuesday afternoon, mainly in
  southeast Missouri and southwest Illinois.

- A rapid warmup is forecast for midweek, with highs well into the
  80s to near 90 degrees. Daily records may be threatened on
  Thursday afternoon.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 225 PM CDT Mon May 12 2025

The pesky mid/upper level low is currently over the mid south early
this afternoon, with a water vapor time loop showing a movement
slightly west of due north. This feature will continue to play a
major role in our sensible weather through Tuesday before it shifts
off into the Upper Ohio Valley. Scattered showers and thunderstorms
mainly over eastern Missouri and western Illinois should gradually
wane late this evening into the early overnight hours as diurnal
instability fades after sunset. Did keep isolated showers around
though most of the night as there is weak low-level moisture
convergence in the vicinity of a subtle frontal boundary at the
surface. The coverage of showers along with a few rumbles of thunder
should uptick again by early Tuesday afternoon as instability rises.
Tuesday`s activity should shift a bit further to the east compared
to this afternoon and be focused more across far southeast Missouri
and southwest Illinois. These locations will be closer to the
track of the mid/upper level low.

After a mild night tonight with lows in the upper 50s to low 60s,
look for slightly warmer conditions on Tuesday afternoon. This is
due to lesser chances of rain shower activity along with more
pockets of sunshine. There is a bit of a caveat however as there
should be quite a bit of low stratus (and maybe even some fog)
ongoing Tuesday morning. The current expectation is for this low
stratus to rise and then scatter out during the morning hours on
Tuesday. However, if this is slower to occur than forecast, these
clouds may hamper temperatures a bit than is currently anticipated.
This does not seem like a particularly likely scenario however given
the strong sun angle of mid May and lack of widespread mid/upper
level clouds above the stratus to help limit the insolation on the
lower deck. Highs in the mid 70s to near 80 degrees are forecast,
with coolest locations in south-central Illinois where more clouds
should linger and highest chances for shower activity reside.


Gosselin

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 225 PM CDT Mon May 12 2025

(Wednesday - Thursday Night)

A surface warm front is forecast to move through the area on
Wednesday, with increasing low-level warm air advection in its wake.
Temperatures not surprisingly will climb on Wednesday, with highs in
the low to mid 80s forecast. Surface winds are expected to stay
southeasterly for a majority of the daylight hours, which is not the
ideal wind direction for anomalously warm temperatures. Therefore,
stuck pretty close to the 25th percentile of the NBM for highs.

Dry weather should continue Wednesday night, though cannot totally
rule out an isolated shower/thunderstorm across northeast Missouri
and west-central Illinois. Stronger low-level moisture convergence
stays to the north, but some elevated convection may try and from
near those locations if the warm front is a bit slower than
forecast. Otherwise, look for a very mild night with increasing
southerly surface winds. Lows are only expected to drop back into
the mid to upper 60s. These values would be 10-15+ degrees above
normal for the date.

A strong mid/upper level shortwave trough is forecast to move across
the Upper Midwest on Thursday, with a trailing (Pacific) cold front
sweeping across the mid-Mississippi Valley. This front should clear
the eastern CWA just before 0Z Friday. Ahead of the front, look for
winds to veer more to the southwest, which is a favorable wind
direction for anomalously warm temperatures. These winds downslope
off of the Ozark Plateau and aid in the warmup downstream across
portions of central, east central, and southeast Missouri. Plenty of
sunshine is also expected during the day, with increasing cirrus
from the south very late in the day likely having very little impact
on temperatures. The air mass in place ahead of the front is also
quite conducive for anomalous warmth, with 850-hPa temperatures of
+18 to +22C, above the 99th percentile of climatology and near daily
records. Deep mixing is also favored on Thursday. All in all, the
expectation is for highs to climb into the upper 80s to low 90s.
These readings would be the warmest so far this year for a majority
(if not all) of the area and may threaten daily records for the
date. Please see the CLIMO section below for more details. The main
source of uncertainty with respect to Thursday`s highs is the timing
of the front itself. A faster (slower) timing of the front could
lead to highs a couple of degrees cooler (warmer) than forecast.
However, even a faster timing won`t have huge negative implications
on highs. As alluded to above, this is a Pacific cold front. The air
mass behind it is not really much cooler at all, and the fact that
winds only veer to the west behind the boundary suggest the low-
level cold air advection in some areas at least may be offset by
downslope flow.

In terms of precipitation chances, dry weather is favored for the
entire area even with this frontal passage. There are a lot of
negating factors for convective initiation, including: 1) strong
capping between 600 and 750 hPa, 2) weak surface convergence along
the Pacific cold front, and 3) strongest mid/upper level forcing for
ascent residing across the Great Lakes. All of these factors
strongly suggest that any convective initiation should not occur in
our CWA, but to our east/northeast. The "best" chance (~10%) of any
thunderstorms would be across far eastern sections of the CWA
Thursday afternoon/evening. This would also likely be contingent
upon a slower frontal passage and/or weaker cap than is currently
forecast.


(Friday - Next Monday)

Another weak cold front is expected to approach from the west on
Friday. This boundary looks to have a bit more to work with Friday
afternoon/evening than its predecessor. The cap is quite a bit
weaker with deterministic models also suggesting a subtle midlevel
shortwave trough moving out of the mid-Missouri Valley.
Six hour probabilities for measurable rainfall on the LREF are also
quite a bit higher, in the 30-50% range Friday evening in parts of
southeast Missouri and southwest Illinois. This is a period that we
will have to keep an eye on as there should be plenty of instability
(LREF probabilities for 1500+ J/kg of CAPE 40-60%) with 40-50+ knots
of deep-layer shear. So, while convective initiation along this
boundary definitely seems more likely, the question is more so
focused on the timing/speed of the front and when convective
initialization occurs. Most guidance suggests it will be across
southeast Missouri and southwest Illinois near our southeastern CWA
border. Supercells should be the primary convective mode given a
very orthogonal component to the deep-layer shear vector to the
initiating boundary. Splits may also be common given very straight
hodographs. Large hail certainly looks like the main potential
threat given very high CAPE within the hail-growth zone.

Forecast uncertainty increases substantially heading into the
weekend (and beyond) with respect to where Friday`s front stalls
out. The deterministic ECMWF (and a majority of its ensemble
members) have a stronger mid/upper level trough across the
northeastern CONUS. This allows for a more northerly component to
the mid/upper level flow across the eastern third of the country and
helps get the surface front into the mid south. This would mean
slightly cooler temperatures and mostly dry weather for our neck of
the woods. The deterministic GFS and many of its individual ensemble
members have a weaker midlevel trough with the surface front
stalling near or in the southern part of the CWA. This would mean
additional rounds of showers and thunderstorms would be possible
this weekend. A middle of the road approach seems wise at this
juncture, showing dry weather favored on Saturday with PoPs
increasing Sunday night into Monday as the front is more likely to
at least begin to wobble back north as a warm front.


Gosselin

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1050 PM CDT Mon May 12 2025

IFR ceilings and fog is expected to spread from south central and
southwest Illinois across much of the area tonight. Current
thinking is that mostly IFR fog will affect south central
Illinois, and that fog will transition to IFR ceilings farther
westward. Regardless, expect IFR conditions to prevail by 09Z-12Z.
Ceilings/visibilites will improve through MVFR to VFR through the
late morning into the early afternoon. Additionally, scattered
showers and a thunderstorm or two will be possible again on
Tuesday, primarily along and east of the Mississippi River.

Carney

&&

.CLIMATE...
Issued at 227 PM CDT Mon May 12 2025

Record maximum temperatures and warmest minimum temperatures
for May 15.

                MAY 15

ST Louis:
MAXIMUM         94 1944
WARMEST MIN     72 2013


Columbia:
MAXIMUM         90 1944
WARMEST MIN     71 1941


Quincy:
MAXIMUM         93 1944
WARMEST MIN     69 1962


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX