Perry, Missouri Weather Forecast Discussion

712
FXUS63 KLSX 271654
AFDLSX
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1154 AM CDT Sat Sep 27 2025
.KEY MESSAGES...
- Beautiful fall weather lasts the full 7-day forecast. Warm days
  and seasonably cool nights are expected with no significant rain
  chances.
&&
.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 205 AM CDT Sat Sep 27 2025
Surface high pressure stretches from the eastern Great Lakes to
Texas and its axis crosses right through our forecast area. This has
led to light and variable winds, a mostly clear sky, and dry
weather. Looking aloft we see the jet stream far to the north over
southern Canada with two subtropical lows cut off to the south. One
over the Southwest US will aid in the development of downstream
ridging over the central US, leading to greater daytime warming over
the next few days. The other is over the Tennessee River Valley
pulling dry, subsident air behind it across our region. As far as
sensible weather goes, expect similar conditions today as were
observed yesterday, but perhaps a couple of degrees warmer. 80s will
be widespread with mid 80s common this afternoon, 5 to 10 degrees
warmer than normal for late September. Dry air (dewpoints in the low
to mid 50s) will ensure these warm temperatures remain pleasant
while also enabling strong nighttime cooling. Lows dip back into the
50s, closer to normal. We warm even further on Sunday as ridging
develops aloft over the region. The probabilistic NBM even has some
low probabilities (10 to 20 percent) of 90 degrees Sunday afternoon.
However, thanks to an exceptional late season heat spell in 1953,
even that wouldn`t be close to a record for the date.
Kimble
&&
.LONG TERM...  (Sunday Night through Friday)
Issued at 205 AM CDT Sat Sep 27 2025
As we go forward into next week we see the western trough open up
and get replaced by a trough near the Pacific Northwest. Ridging
expands through the center of the continent, even deep into Canada.
Although a cooler, drier air mass does get shoved around the ridge,
it takes aim on New England during the middle to later part of this
week. We`ll remain under the influence of the warm ridge with Gulf
moisture remaining solidly cut off and suppressed far to the south.
In fact we may get some even drier air circulating into the area
from the northeast around midweek.
The southeast US low is still the biggest source of uncertainty in
the forecast this coming week as it will play a big role in steering
a developing tropical system over the Bahamas toward the southeast
US coastline. At one point there was some hope that moisture from
this tropical system would actually get pulled westward across the
Appalachians and toward our area. But this possibility is looking
increasingly less likely. Among the 26/12Z ensemble guidance less
than 20 percent of members produce rain in our forecast area in the
48 hours ending Friday night. Just 24 hours earlier, among the
25/12Z runs, that number was 30 percent. And 24 hours before that,
among the 24/12Z runs, that number was 40 percent. So the likelihood
of any rainfall from this reaching our area this week just keeps
trending downward as guidance is coming into a little better
agreement on the interplay between this low and the incoming
tropical system. Now most guidance even keeps the system offshore of
the southeast US coast.
Now that the tropical moisture isn`t panning out, our next best hope
for rain would be when the ridge finally breaks down. The ridge does
tilt eastward late this week, with surface high pressure pushing to
our east as well. This eventually opens up a southerly flow over the
Plains and Mississippi Valley late this week into this weekend which
will begin to finally pull in Gulf moisture. This will have the
effect of buoying nighttime lows and increasing the chances of some
rainfall whenever the western US trough finally begins to nudge away
the ridge. But that`s not going to happen until early the following
week at the earliest. In other words, no rain in this 7-day
forecast.
Kimble
&&
.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1151 AM CDT Sat Sep 27 2025
VFR conditions and light winds can be expected for a majority of
the 18Z TAF cycle. Once again, the primary concern will be the
potential for redeveloping valley fog along the Missouri and
Mississippi Rivers, which has impacted JEF, SUS, and CPS to
varying degrees over the past two mornings. While coverage may be
somewhat reduced compared to this morning, fog will once again be
possible at each of these terminals overnight and early tomorrow
morning. Otherwise though, no additional weather hazards are
expected.
BRC
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX

NWS LSX Office Area Forecast Discussion