605
FXUS63 KDVN 141113
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
613 AM CDT Mon Sep 14 2026

.KEY MESSAGES...

- Active pattern this week with numerous rounds of showers and
  storms with heavy rain.

- There is a Marginal Risk, Level 1 out of 5, for severe storms
  this evening into tonight for the western portions of the
  outlook area. Primary hazards will be heavy rain and isolated
  damaging winds.

- An elevated flash flood risk may develop mid-week with
  repeating rounds of storms. There is a moderate chance
  (50-70%) for parts of the area to see over 2 inches of
  rainfall with localized areas of 4+ inches possible (5-15%),
  leading to rises on area creeks and streams.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 145 AM CDT Mon Sep 14 2026

Today appears to be a rinse and repeat of yesterday with
scattered showers (30-60% coverage) moving in late morning from
the west along a WAA band north of an approaching warm front.
There will be a small amount of instability in the form of
250-750 J/kg of MUCAPE which should support a few rumbles of
thunder, but the overall severe potential is low (less than 5%).
These showers and isolated storms are expected to exit the area
to the northeast by the late afternoon as the low-level WAA
weakens.

By tonight, the closed heights center over south-central Canada and
its accompanying mid-latitude cyclone occludes and pushes a cold
front southward into northern Iowa. Widespread storms (80-100%
coverage) are forecast to develop along the boundary and
propagate southeastward into our CWA. A 50-knot mid-level jet
over the area will enhance the effective bulk shear, but the
lack of steep mid-level lapse rates will keep the instability
tame at 250-750 J/kg of MLCAPE. Therefore, the overall severe
threat is once again low with these overnight storms. Still, there
remains a Marginal Risk, Level 1 out of 5, for severe storms
along and west of the I-380 corridor with isolated damaging
winds as the primary threat.

The remaining storms are expected to decrease in coverage and
intensity heading into Tuesday as the cold front inches its way
southward towards the Iowa-Missouri border. As the severe
threat with these storms diminishes, attention starts to turn
towards the flooding potential, especially across east-central
Iowa, as storms could train over the same area resulting in
flash flooding. Latest CAM guidance is suggesting 1-2 inches
tonight through Tuesday evening across northwestern Illinois and
areas along and north of I-80 in Iowa with swaths of 3+ inches
possible (10-20% chance). The WPC does have a Slight Risk,
Level 2 out of 4, for excessive rainfall across the entire
outlook area during the same time period.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 145 AM CDT Mon Sep 14 2026

By Tuesday night, the cold front will stall out across northern
Missouri and central Illinois and act as the focal point for
rounds of showers and storm to redevelop late week. A nearly
stationary longwave trough over the western CONUS and ridging
over the Southeast will keep our upper-level flow out of the
southwest through Thursday as weak shortwaves are pulled
northeastward into the Midwest. This will keep PoPs around
Tuesday night into Thursday as scattered showers and storms fire
along and north of the stationary front. With PWATS over 1.75
inches likely (70-90%) area-wide through Thursday, the flooding
threat will remain elevated, especially after the heavy
rainfall tonight and Tuesday. There is a moderate chance
(50-70%) of storm totals in the 2-3-inch range across eastern
Iowa through Thursday with localized areas of 4+ inches possible
(5-15%). Rises on area creeks and streams are likely.

Heading into Friday, a Front Range low in Colorado is forecast
to form due to forcing from a lobe of mid-level vorticity pulled
northward from the subtropics. This will introduce a more
southerly component to the low-level flow as the stationary
front finally converts to a warm front and moves northward into
Iowa. The upper-level flow is expected to become zonal and force
the Front Range low eastward Friday night into Saturday. The
increased surface convergence will support another round of
storms before the same boundary is left behind for Sunday,
keeping PoPs around.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 612 AM CDT Mon Sep 14 2026

VFR conditions to start the period ahead of a lifting warm front
across eastern NE through central MO. A line of showers and
thunderstorms ahead of this front to track eastward across IA
through the day along with extensive mid level clouds. Brief
MVFR vsbys are possible in any shower over a terminal.
Otherwise, increasing winds aloft mixing down to the surface
along with an increasing pressure gradient to result in gusty
southeasterly winds over 20kts late morning through much of the
evening hours.

A strengthening LLJ after 15.02z will bring a risk of LLWS to
the terminals through the rest of the overnight hours along with
developing showers and thunderstorms over central IA pushing
east northeast through the end of the TAF cycle. Thunder
probabilities are high enough to warrant PROB30 mention at the
end of the period at CID/DBQ/MLI. These will likely continue for
MLI and BRL just beyond the period Tuesday morning. In addition,
lower cigs are forecast to drop southward near DBQ around
sunrise Tuesday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Delaune
LONG TERM...Delaune
AVIATION...Gross