Coal Valley, Illinois Weather Forecast Discussion

509
FXUS63 KDVN 180826
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
326 AM CDT Thu Sep 18 2025
.KEY MESSAGES...
- The warmer than normal temperature regime will generally continue
  for the rest of the week and into early next week.
- Rain chances will continue to rather slowly increase from the
  west as the upstream upper trof out that way/northwestern
  plains migrates eastward through the weekend into the western
  GRT LKS. Sporadic rounds of showers and storms then look to be
  in store over the weekend for the local area.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 AM CDT Thu Sep 18 2025
Complex multi center upper trof complex seen on water vapor acrs
much of the central into the northwest high plains will continue to
be the focus and weather maker as it tries to edge eastward in a
blocked and slow progression pattern acrs the CONUS. The challenge
again today will be how far east the diurnal showers and storms will
develop and make it toward and into the western CWA, as well as how
warm it will get away from the precip and debris clouds. Will keep
low CHC POPs in the far western CWA for much of the day, although
think most of the area to stay dry through at least mid afternoon
with temporary upper ridge nudge back west and round of EML acrs the
local area. The lower sfc DPT gradient from east-to-west doesn`t
help precip causes making it further to the east as well. With this
drier scenario, vertical thermal profiles and mixing depths support
another unseasonably warm day acrs most of the area with highs in the
upper 80s to low 90s. Debris clouds may keep the west and northwest
more in the mid 80s.
Then a vort wing/max currently seen on WV imagery acrs the
southeast CO/southwest KS border region will pivot around the upper
trof base and head this way by late afternoon and evening. This
feature will combine with plentiful THTA-e rich air mass to produce
large clusters of thunderstorms from the southeastern plains and up
acrs much of the southwestern half of IA late afternoon and into the
evening. Will go with moderate to high CHC POPs from mid evening
into the overnight for some of this activity to make it acrs at least
the west half of the DVN CWA, but likely in a weakening and decaying
fashion as it gets away from better support and encounters the upper
ridge and drier air in place. Again areas west of the MS RVR more
favorable for this overnight activity, and would bank against much
of a chance for a stronger or severe storm in our area but there may
be some decent storms not all that far off to the west. PWAT feed is
projected to boost values to at least 1.5 inches supporting locally
heavy rainfall especially under slow moving storms. But again better
potential for this just upstream acrs central IA. May have just some
spotty areas getting 0.20-0.40 inches of rain through 12z Friday in
the western and southwestern CWA. Low temps tonight held up in the
low to mid 60s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 315 AM CDT Thu Sep 18 2025
Friday...Latest ensembles show a negatively tilting upper low/trof
acrs the Saskatchewan/Manitoba region down toward the mid MS RVR
Valley. This placement would allow for more sctrd showers and storms
to develop acrs the entire CWA by Friday afternoon, with a shift
east to northeast of any eventually evolved larger storm cluster
acrs the northeast half of IL into WI by Friday night. A few
stronger storms may occur this period along with locally heavy rain
in better effective shear profiles than what has been occurring all
week locally, but there will be less CAPE. More clouds and moisture
mean temps held down in the 70s to lower 80s for much of the local
fcst area. Sctrd storm chances continue into Friday night,
especially acrs the northeast half of the DVN CWA. The NBM has a
Likely POP at Freeport IL, and right now can`t argue with that. But
the NBM`s spotty QPF may be underdone in several areas.
Saturday and Sunday....The cooler core upper trof will look to
continue acrs the upper Midwest into the GRT LKS over the weekend,
keeping sporadic showers and thunderstorms going off and on through
this period. Plenty of dry hours mixed in with a shower/storm
cluster chasing you inside. Even under the influence of the upper
trof, thermal profiles support above normal temps over the weekend
with plenty of upper 70s to lower/mid 80s.
Next Week...The latest suite of ensembles continue to develop a
large closed off upper low somewhere over the mid CONUS and thus the
resurrection of another blocked pattern by mid next week. Low
confidence at this point of favored precip chances and areas of
occurrence next week, and temp trends all relative to the central
core placement if the feature evolves, as hinted at by the latest
medium range guidance.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1247 AM CDT Thu Sep 18 2025
Will have to watch for isolated showers and a few storms getting
into the VCNTY of the CID terminal overnight into Thu morning,
otherwise with no fog of consequence, a VFR stretch through much
of the rest of the TAF cycle. Will have to maintain the watch
for isolated to sctrd convection in the west again Thursday into
Thursday evening which again may impact mainly the CID terminal
if it makes it that far east. A few models now spread sctrd
showers/storms further to the east after mid Thursday evening
which would impact all the terminals with passing bouts of MVFR
to IFR conditions and enhanced variable wind gusts, something to
keep in mind but will keep out of this TAF issuance for now.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...12
LONG TERM...12
AVIATION...12

NWS DVN Office Area Forecast Discussion