Sheffield, Illinois Weather Forecast Discussion

852
FXUS63 KDVN 051904
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
204 PM CDT Fri Sep 5 2025
.KEY MESSAGES...
- Cool conditions continue this weekend, but a warm up is
  expected next week. Largely dry conditions continue.
&&
.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 200 PM CDT Fri Sep 5 2025
The pesky upper low that has brought the recent bout of cool
weather is finally exiting off to the northeast today, but it`s
not quite done with us yet. Multiple shortwave troughs continue
to rotate around the bigger trough through the Upper Midwest
over the coming days. The latest wave has sent a fresh batch of
cold advection through our region today contributing to windy
conditions and some spreading cumulus this afternoon. These
winds are expected to die off this evening as high pressure to
the west expands its influence into our region. With the cumulus
also dissipating, we`ll actually see good cooling potential
overnight. Afternoon dewpoints in the mid 40s suggest that`s
where most of us will land by morning, though the cool spots
will be a bit cooler than that. We`ll likely be just a few
degrees above record low temperatures for the date (detailed in
the Climate Section), although Burlington has the best chance of
approaching a record tonight.
On Saturday one final back side shortwave rotates out of
Minnesota into Wisconsin, initiating a fresh round of cold
advection as one more cool surface high pushes southeast out of
Canada. This will kick the winds up again tomorrow, but not as
strong as they were today. Among HREF members, less than 20
percent produce wind gusts over 25 mph tomorrow. Daytime cold
advection will again produce low level instability and afternoon
cumulus. There`s an outside chance of a sprinkle or a shower,
but this chance will be greater closer to the core of the trough
over Wisconsin. Again, less than 20 percent of HREF members
produce measurable rain in our area on Saturday, so we have kept
this out of the forecast.
It`ll be one more cold night Saturday night into Sunday morning,
though the timing of the surface high arriving in our region
Sunday morning is not as optimal for a full night of ideal
cooling. Lingering winds may prevent the nocturnal inversion
from developing until late in the night. However, areas that do
go calm will again see the temperature drop into the low 40s to
perhaps the upper 30s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 200 PM CDT Fri Sep 5 2025
Cool surface high pressure moves across the region on Sunday,
but the September sun will already be working on this air mass.
This will be the last of the really cool days, with highs in the
upper 60s to low 70s. After this, upper troughing pulls even
further to the northeast opening up at least some subtle ridging
over the Upper Midwest. The warm up will be most noticeable on
Monday as we warm some 5 to 10 degrees back up closer to normal
for early September. This warm up continues through at least
midweek when 80s become even more widespread across the region.
The greatest uncertainty in the long term forecast centers
around a shortwave trough tracking through the Upper Midwest to
the Great Lakes Tuesday into Wednesday. While all guidance
depicts this trough, there`s considerable variance on it`s
strength and track. Solutions with a stronger trough bring a
cold front through our area, knocking temperatures back a few
degrees late this week. However, solutions with a weaker trough
never fully bring that front through, instead keeping warmer
temperatures in place. This uncertainty shows up in the NBM
interquartile range (IQR) for high temperatures. Early this
week the IQR is only 2 to 3 degrees, indicating high confidence
in temperatures. By Thursday this increases to 7 to 10 degrees
reflecting that uncertainty as to whether temperatures get
knocked back a few degrees or keep warming. What`s more agreed
upon is that ridging does become more dominant over the Upper
Midwest late this week into the weekend, so even if temperatures
do get knocked back briefly, it will warm back up again. In
fact, NBM probability of 90 degrees starts to increase above 10
percent in our forecast area Friday into the weekend.
As far as rain chances this week, our only real hope is with the
shortwave trough Tuesday into Wednesday. Guidance is consistent
on favoring areas to our west and north for rain when this
passes through, as this is where the limited moisture return
occurs coincident with the passing of the trough. However, at
least some low end rain chances do extend into portions of our
area with a northwest to southeast gradient. Moisture return
remains weak and instability limited, so even for areas that do
see rain we are not expecting significant amounts. Among the 00Z
ensemble guidance, about 40 to 70 percent of members show
measurable rain in our northwestern forecast area in the 24
hours ending Wednesday morning. However, less than 25 percent
produce 0.15 inches or more indicating that even if it does rain
it won`t be that much.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1211 PM CDT Fri Sep 5 2025
Gusty west northwest winds this afternoon will diminish quickly
this evening, with most areas going near calm by morning.
Stratocumulus moving through this afternoon is expected to
remain in the VFR range and also dissipate this evening. Winds
pick up again on Saturday, but not as strong as today, with
another round of afternoon cumulus.
&&
.CLIMATE...
Issued at 101 PM CDT Fri Sep 5 2025
RECORD LOW TEMPERATURES:
               September 6       September 7
Dubuque        38 in 1988        37 in 1956
Moline         40 in 1988        39 in 1956
Cedar Rapids   40 in 1950        38 in 1986
Burlington     44 in 1988        42 in 1956
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Kimble
LONG TERM...Kimble
AVIATION...Kimble
CLIMATE...Kimble

NWS DVN Office Area Forecast Discussion