616
FXUS63 KDVN 011117
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
617 AM CDT Tue Sep 1 2026

.KEY MESSAGES...

- Heat and humidity now looks to impact the area through the
  work week. The Heat Advisory has been expanded north and east
  slightly. If another extension in time to the headlines is
  needed, then we would be into the longevity aspect of the heat
  which may require an upgrade for parts of the area.

- The Storm Prediction Center has a Marginal, level 1 out of 5,
  Risk for severe storms in the Highway 20 corridor for this
  afternoon and tonight. Damaging winds are the primary risk
  with hail a secondary risk.

- There is a near daily risk of showers and storms for areas
  along and north of I-80. However, there will be plenty of dry
  hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 224 AM CDT Tue Sep 1 2026

CHANGES...

A dense fog advisory has been issued for parts of the area.

The heat advisory has been expanded to include Clinton, Whiteside
and Carroll counties.

Discussion...

Some light showers or sprinkles will persist through sunrise in the
weak lift occurring across the area. Over 95 percent of the area
will remain dry.

The high moisture content of the atmosphere and light winds have
created the ideal environment for fog development. Patchy ground fog
has already developed with visibilities bouncing from several miles
to near zero. Recent HRRR trends are now pointing toward more
widespread fog development and thus a dense fog advisory has been
issued for parts of the area. The fog will impact the morning
commute. Visibility trends will need to be watched to see if the fog
headlines need to be extended further to the south and east.

Hot and humid conditions will continue area wide today. NBM
temperatures still look a tad warm but the delta has been slightly
negative since yesterday.

Regardless, areas outside of the heat headlines will see peak
afternoon heat indices of 95 to 100. Further south, peak heat
indices will be around or just over 100 degrees.

With the heat dome building into the area, the rain chances have
been confined to the Highway 20 corridor. Warm temperatures aloft
may prevent any showers or thunderstorms from developing until late
afternoon/evening. Any storms that do develop would be capable of
producing damaging winds.

Tonight, the area looks to be mainly dry as the heat dome pushes the
storm track into Minnesota and Wisconsin. Storms are expected to
develop in South Dakota and grow upscale into a storm complex that
moves east across southern Minnesota into Wisconsin.

Outflow boundaries from this complex may push into the northern
areas and initiate nocturnal convection that may bring brief
localized relief from the heat. However, any storms to do develop
would be capable of producing damaging winds and potentially hail.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 238 PM CDT Mon Aug 31 2026

The high heat and humidity continues through at least Thursday.
Confidence in the hot conditions Wednesday through Thursday remain
high, given the latest ECMWF EFI/Shift of Tails values for high
temperatures are in excess of 0.8 to 0.9 (even some values over 0.95
in isolated spots), along with Shift of Tails values around 1. This
suggests high confidence in anomalously warm high temperatures,
although not extreme values based on the lower Shift of Tails. With
the potential for these anomalously hot conditions to last this
week, we`ve decided to extend the Heat Advisory another day (through
Thursday). It`s entirely possible for the advisory to be extended
into Friday, given LREF ensemble exceedance probabilities of 100
degree heat indices exceeding 50% across our southern two tiers of
counties. Additionally, overnight lows might not dip below 75
degrees through Wednesday night, so this would compound the
heat stress - even at night. There is potential for some record
warm low temperatures during this period. See the Climate
section below for the current records.

In terms of thunderstorm activity for mid- to late-week, with the
strongest part of the heat building for Wednesday, seems like the
storm track will stay to our north. However, there is a signal for
the edge of the heat dome to sink slightly southward Thursday and
Friday, generating more active conditions during this time frame.
NBM consensus model blends seem to keep the chances of precipitation
north of the I-80 corridor (20-50% chances) for Thursday and Friday,
so the extreme heat could still be in play, even into Friday.
Uncertainty remains on the impact this activity will have on the
heat potential for the northern forecast area, so stay tuned for
updates throughout the week!

A look ahead to the upcoming weekend: the heat appears to diminish
by the weekend, although there are some signals it will be more
active, with additional chances of showers and storms. In terms of
severe weather, this potential appears to be pretty low, given the
lower probabilities from the various machine-learning severe prob
resources.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 600 AM CDT Tue Sep 1 2026

Morning fog is expected at DBQ/CID with visibilities down to
VLIFR at DBQ and MVFR/IFR at CID. After the fog gradually
dissipates through the mid morning (after 13/14Z), prevailing
VFR is expected at the terminals through today into tonight
along with light winds.

&&

.CLIMATE...
Issued at 222 PM CDT Sun Aug 30 2026

Record Warm Low Temperatures:

September 1:
KDBQ: 73/1937
KMLI: 75/1913

September 2:
KDBQ: 74/2011
KMLI: 77/1913

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

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

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 10 AM CDT this morning for IAZ040>042-
     051>053.
     Heat Advisory until 7 PM CDT Thursday for IAZ063>068-076>078-
     087>089-098-099.
IL...Heat Advisory until 7 PM CDT Thursday for ILZ007-009-015-016-
     024>026-034-035.
     Heat Advisory from 1 PM this afternoon to 7 PM CDT Thursday
     for ILZ017-018.
MO...Heat Advisory until 7 PM CDT Thursday for MOZ009-010.

&&

$$

SHORT TERM...08
LONG TERM...Schultz
AVIATION...Uttech
CLIMATE...Gross