503
FXUS63 KDVN 041919
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
219 PM CDT Fri Sep 4 2026

.KEY MESSAGES...

- Dangerous heat continues through Saturday, with peak heat
  indices of 100 to 110 degrees. Extreme heat warnings and heat
  advisories are in effect and have been extended.

- There remains a low risk (<15%) for isolated showers/storms
  this afternoon and Saturday afternoon/evening. There is a
  Marginal (level 1 of 5) risk for an isolated severe storm
  north of Hwy 20.

- Less humid Sunday/Monday, before heat and humidity returns
  mid-week. The overall pattern has a 55-70% probability of
  above normal temperatures through mid-September.


&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 214 PM CDT Fri Sep 4 2026

Another hot and humid day is unfolding with 2pm temperatures in
the upper 80s/low 90s and dewpoints in the low to mid 70s,
similar to values 24-hrs ago. As a result, heat indices are
above or nearing 100 degrees area-wide. Just to our northeast in
southern WI, temperatures are in the 70s/low 80s thanks in part
to the showers/storms this morning. In our area, a few isolated
showers/storms occurred north Hwy 20 and along an outflow
boundary in northwest IL that has since stalled just west of
Sterling/Rock Falls.

Mostly dry and warm conditions are expected for most if not all the
area the rest of the afternoon and evening. Widely scattered
showers and isolated storms have developed in central and
northeast IA in a weak 850-750mb convergent axis. CAM solutions
are struggling with this activity as is often the case in weakly
forced environments. The RAP would suggest some of this to reach
our northwest counties, before we begin to lose instability
after sunset and have added some slight chance PoPs for this. A
brief heavy downpour and lightning will be the primary risks. If
we had a stronger trigger, our 18z sounding showed a favorable
environment for a couple strong to severe storms. All this said,
weak deep layer flow, warm temps aloft, and meager mid level
lapse rates will preclude a severe threat.

Overnight, some patchy fog will be possible along and north of
Hwy 20 as winds go calm and clouds clear. Mild lows in the low
70s are forecast.

Saturday, hot and humid conditions will once again be seen for
much of the area. A backdoor cold front will push through the
CWA from northeast to southwest, finally bringing some relief to
the heat. Models differ on when this front will be through the
area and ahead of it, the heat will remain. For this reason and
that this will be Day 6 of this oppressive heat and its
cumulative effects, have extended the Extreme Heat Warning and
Heat Advisory until 7pm Saturday south of a Independence, IA to
Sterling, IL line. Remember to practice heat safety and drink
plenty of water if outside for any holiday events. Regarding
storm chances, all model solutions are largely dry but with a
weak cool front moving through and any residual outflow
boundaries left over this afternoon can`t rule out some isolated
showers/storms much like today occurring. No severe weather is
anticipated.


&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 214 PM CDT Fri Sep 4 2026


Saturday night through Thursday Assessment...very high (>80%)
confidence on above normal temperatures.

The upper level ridge retrogrades briefly into the Plains for the
second half of the holiday weekend but will then push back east for
the middle of next week. Thus after a brief reprieve from the heat
Sunday/Monday, heat and humidity will surge back into the area
Tuesday/Wednesday with heat indices approaching 100.

By late next week the overall flow pattern aloft de-amplifies
slightly. This will allow temperatures to be closer to but still
above normal.

Any rain chances the first half of next week are low (10-25%) and
are confined to areas along/north of I-80. Thus there will be many
hours of dry weather.

The models are attempting to bring a front into the area Tuesday
night into Wednesday with the front progged to stall and wash out
across the area. The proximity of the front has the model consensus
giving slightly higher rain chances (30-50%) for late Tuesday night.

Once the front stalls and washes out across the area, its remnants
would then provide the focus for rain chances the remainder of the
week. However, even with a near daily chance of rain, the rain
chances remain low (20-30%) with the better forcing remaining across
the northern Plains and upper Midwest.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1226 PM CDT Fri Sep 4 2026

VFR conditions to persist through the TAF cycle at all terminals
except DBQ. An outflow boundary to track southwest through
northwest IL over the next 1-2 hours, but is expected to wash
out before reaching MLI. A few isolated VFR showers will be
possible this afternoon north of Hwy 30 dissipating prior to
sunset. Clearing skies and calm wind in a moist environment to
promote MVFR/IFR fog development primarily at DBQ overnight. A
northerly wind shift will be seen Saturday, with a very low risk
of shower activity just beyond this period.

&&

.CLIMATE...
Issued at 558 AM CDT Thu Sep 3 2026

The Quad Cities (MLI) has had two days to start this month with
95 degree highs. If a third happens today, it would be the
longest such stretch in September since September 4-6, 1990.

Record Warm Low Temperatures:

September 3:
KDBQ: 73/1939
KMLI: 76/1939

September 4:
KDBQ: 71/1912
KMLI: 74/2018

September 5:
KDBQ: 76/1881
KMLI: 76/1925

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 7 PM CDT Saturday for IAZ040-051>053-066.
     Heat Advisory until 7 PM CDT this evening for IAZ041-042-054.
     Extreme Heat Warning until 7 PM CDT Saturday for IAZ063>065-
     067-068-076>078-087>089-098-099.
IL...Heat Advisory until 7 PM CDT Saturday for ILZ009.
     Heat Advisory until 7 PM CDT this evening for ILZ001-002-007.
     Extreme Heat Warning until 7 PM CDT Saturday for ILZ015>018-
     024>026-034-035.
MO...Extreme Heat Warning until 7 PM CDT Saturday for MOZ009-010.

&&

$$

SHORT TERM...Gross
LONG TERM...08
AVIATION...Gross
CLIMATE...12