Jefferson City, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

619
FXUS63 KLSX 101836
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
136 PM CDT Tue Jun 10 2025

.KEY MESSAGES...

- Warm and dry conditions are expected tomorrow and likely
  Thursday, and some areas may touch 90 degrees for the first
  time this year.

- A showery pattern remains likely to develop Thursday night and
  continue through the weekend. The potential for hazards besides
  lightning remains generally low.

&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 135 PM CDT Tue Jun 10 2025


As expected, today has been downright pleasant thanks to the
infiltration of dry northwest flow. With temperatures on their way
to about 80 degrees, dewpoints in the 50s, light winds, and mostly
sunny skies all in place (aside from a few wisps of high level
wildfire smoke), it should be a busy afternoon in area parks.
Overnight tonight, winds will once again become nearly calm, and
another round of patchy valley fog will be possible throughout the
Ozark river valleys. Otherwise though, expect mostly clear skies and
effective radiative cooling that should allow temperatures to drop
into the 50s yet again.

For tomorrow, an upper level ridge is expected to begin building
east and into our area, and light southerly flow will resume. As
such, temperatures remain likely to climb to slightly above average
values by mid afternoon, with widespread values in the upper 80s
expected. Meanwhile, some places like St. Louis will have a
reasonable chance to hit 90 degrees for the first time this year.
Meanwhile, higher humidity air will begin to arrive from the south,
but this should only amount to some increasing high level cloud
cover late in the day.

BRC

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 135 PM CDT Tue Jun 10 2025

By Thursday, the axis of the previously mentioned upper ridge is
likely to slide just to our east, and moisture will continue
marching northward ahead of a weak subtropical low pressure
system. This will begin a transition to a more humid and showery
pattern across the area, although the richest moisture likely will
not arrive until the following day. This leaves Thursday in a bit
of a transition period, and exactly what transpires will depend
on whether enough moisture can reach the area for precipitation to
develop. Model guidance continues to suggest that we will be dry
in most areas for a majority of the day, but nonetheless still
suggest a low (20-30%) chance of afternoon/evening showers or weak
thunderstorms. Early model soundings suggest deep, dry sub-cloud
layers as mid-level moisture works into the area from the south,
with modest instability stunted by poor lapse rates aloft. If we
do manage to squeeze out a few showers, there is a slight
preference for central and northeast Missouri. Meanwhile, another
warm day is likely, although much will depend on how far east the
subtropical low makes it by then, and also how much cloud cover
arrives by peak heating hours.

On Friday, though, ensemble guidance is in better agreement that the
subtropical low will gradually transition into an open shortwave and
very slowly move east through the area. This will help to draw
richer moisture northward, with ensemble mean PWAT values near the
90th percentile. The combination of this and weak forcing from the
upper wave should increase shower chances, although this will likely
not be equal throughout the area. Current track projections keep
both the best forcing and moisture across our southern areas, so
precipitation chances continue to be maximized south of I-70. In any
case, wind shear projections remain marginal, with 90th percentile
values only reaching near 30 kt thanks to some very modest mid-level
flow associated with the upper wave. While there will be sufficient
instability in place, the lack of a strong forcing mechanism and
modest wind shear will significantly limit the potential for strong
or severe thunderstorms or prolonged heavy rainfall. As such, run of
the mill thunderstorms to perhaps a cluster or two are more likely,
with only low chances for more significant hazards. I am hesitant
to say that these chances are "zero" given the presence of
moderate instability and at least a weak upper level wave, not to
mention rich moisture and the resulting potential for at least
briefly efficient rain rates. However, the currently forecast
parameter space and synoptic setup are not particularly favorable
for severe weather hazards.

Over the weekend, ensemble guidance continues to push the primary
shortwave to our east, but does maintain some weak troughing across
the area. Meanwhile, the lack of a strong synoptic cold front means
that high humidity air is likely to linger across the area at least
through the weekend. As such, shower and thunderstorm chances do
persist through the weekend and possibly into early next week,
particularly along and south of I-44 (MO) and I-70 (IL).

It should be noted that throughout this whole period, precipitation
chances appear to be maximized across the Ozarks and most of
Illinois. Likewise, the northern half of Missouri and west-central
Illinois may end up being in a local minimum of precipitation
throughout the forecast period, and probabilities for substantial
rain totals are not very high here. In fact, NBM precipitation
probabilities in this area never really reach above 50% during any 6
hour period through Tuesday, and are much lower than that from
Sunday onward. So, while these areas may still see a few showers at
times, widespread and prolonged rain is not particularly likely.

BRC

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 101 PM CDT Tue Jun 10 2025

VFR conditions are expected throughout the 18Z TAF period. Light
to occasionally breezy west winds will become nearly calm
overnight, and another round of patchy valley fog will be
possible. However, confidence is low that local terminals will be
impacted, as only very brief periods of shallow fog were observed
at SUS/CPS this morning under very similar conditions.

BRC

&&

.CLIMATE...
Issued at 348 AM CDT Tue Jun 10 2025

St Louis has still not seen 90 degrees yet in 2025. The average
first 90 degree reading is May 20. The most recent late 90-degree
start was June 10, 2021. With 90 degrees being highly unlikely
today (June 10), this is the latest first 90 degree day since at
least 1995 (June 19). The latest date of first 90 degrees on
record was July 4 in both 1961 and 1912.

Columbia has also not yet seen a 90 degree reading in 2025, however
the average first date is much later (May 31). The latest date of
first 90 degrees on record was July 14, 1904.

Quincy reached 90 degrees on May 15 of this year, about 3 weeks
earlier than their average first 90 degrees (June 2).

Kimble/MRB


&&

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

$$

WFO LSX