Fike Cemetery, Illinois Weather Forecast Discussion

121
FXUS63 KLSX 260728
AFDLSX
Area Forecast Discussion
National Weather Service Saint Louis MO
228 AM CDT Fri Sep 26 2025
.KEY MESSAGES...
- Dry and seasonably warm conditions continue for the entire 7-day
  forecast.
&&
.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 225 AM CDT Fri Sep 26 2025
Broad surface high pressure centered in the Southern Plains has
brought a seasonably dry air mass to the entire region and is
blocking Gulf moisture well to the south. Looking aloft, the
northern jet stream is well to the north in southern Canada while
two notable cut off lows exist, one over southern California and the
other over the Deep South. The result for our weather is largely
clear conditions in a subsident northwest flow on the back of the
southeast US low. Plenty of sun and dry air leads to good warming
today, and with the influence of the southeast low decreasing we`ll
see temperatures warm a few degrees over yesterday`s values. Most
areas top off in the low 80s. With Gulf moisture shut off and a
largely stagnant flow locally, we`ll keep the seasonably dry
dewpoints around, in the mid 50s. This offers the ability to cool
off nicely at night with some valley fog in the morning.
Kimble
&&
.LONG TERM...  (Saturday Night through Thursday)
Issued at 225 AM CDT Fri Sep 26 2025
Over the coming days the southeast trough continues to shift slowly
to the east or southeast, getting tangled with a potential tropical
system emerging over the Bahamas. In its wake, ridging slowly builds
through the middle of the country leading to a gradual uptick in
temperatures through the mid 80s this weekend into next week.
A trough moving through the northern jet stream Friday into Saturday
does push a cold front through the Upper Midwest, but this front
loses its southward push as it moves into the expanding ridge. The
surface high associated with this air mass, notably drier than our
current one, moves east through the Great Lakes. Thus it is unlikely
that this front will get far enough south to have any notable impact
on our weather. Instead we`ll maintain our current air mass, just
adding a few degrees to the daytime highs as the ridge takes hold.
Guidance does have dewpoints ticking upward a few degrees over the
coming days as well, though this may be a bit overstated. The Gulf
remains cut off and any moisture increase locally will have to be
through evapotranspiration. While we have finally had some rain
recently, long term dryness continues. And since we`re past the
equinox our nights are longer than our days at this point, so
moisture gained during the day will be counteracted by deposition
and condensation via dew and fog at night. So we`ll continue to see
seasonably cool nights, in the 50s, even as daytime temperatures
warm into the mid 80s, nearly 10 degrees above normal for this time
of year.
Our 7-day forecast remains dry at this point. Our best hope of rain
on the horizon would be related to the previously mentioned
developing tropical system over the Bahamas. There`s a lot of
uncertainty on how this system develops and interplays with the
southeast US trough (as well as current Tropical Storm Humberto
further east). Some guidance, notably the 00Z operational GFS, pull
this system inland over the southeast US and sling some moisture as
far westward as our area late next week. Other guidance holds this
system near the Carolina coast (such as the 00Z operational ECMWF)
or curl it back into the Atlantic (00Z operational CMC). So among
the possible solutions, few lead to rain near our area. Of the 12Z
ensemble guidance, less than 20 percent of members bring measurable
rain into our forecast area through Thursday.
Beyond this, guidance is in better agreement on the eventual
breakdown of the ridge late next week. A trough emanating out of the
Pacific Northwest next Thursday into Friday moves toward the middle
of the continent by Friday into Saturday and would represent another
potential for rainfall on the horizon for our area depending on how
it evolves. Those chances would increase particularly if moisture
from that tropical system were to reach our area before the incoming
trough and cold front move through. Otherwise dryness persists for
the foreseeable future.
Kimble
&&
.AVIATION... (For the 06z TAFs through 06z Friday Evening)
Issued at 226 AM CDT Fri Sep 26 2025
Light winds and clear skies are the general rule for the
foreseeable future. The only exceptions are for morning fog in
valley locations. Longer nights with lights winds and modest
humidity will continue to keep the potential for fog mainly at SUS
and potentially JEF and CPS as well. Any fog burns off within 2
hours of sunrise returning to VFR conditions.
Kimble
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX

NWS LSX Office Area Forecast Discussion