Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 292013
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
313 PM CDT MON AUG 29 2016

.SYNOPSIS...
Issued at 300 PM CDT Mon Aug 29 2016

18Z surface data has high pressure over the Great Lakes while a cold
front ran from northern Minnesota into northwest Nebraska. Dew
points were in the 60s and 70s from the Ohio Valley into the Plains
with 40s and 50s across the northern Plains.

&&

.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 300 PM CDT Mon Aug 29 2016

Isolated to scattered convection will persist through late
afternoon. Due to the slow movement of the storms, locally heavy
rainfall is likely from the stronger storms. If these storms move
across areas that were hit with heavy rain last night, then
localized flooding will be possible.

The convection will persist into the evening hours and the threat of
locally heavy rainfall will continue through midnight. As the sun
sets, the showers and thunderstorms will slowly weaken.

After midnight, the showers and thunderstorms will continue to
decrease in areal coverage. At the same time patchy fog will begin
to develop due to light winds and high moisture levels in the lower
atmosphere. Although not certain, the possibility does exist for the
fog to become locally dense toward morning.

Tuesday, the cold front is forecast to move through the area. Patchy
fog will be possible shortly after sunrise but should dissipate by
mid-morning.

Isolated to scattered showers and some thunderstorms will slowly
increase in areal coverage during the late morning and afternoon
hours.

As new convection develops Tuesday afternoon, the possibility will
again exist for brief funnel clouds. The funnels will be most likely
during the initial updraft development of the new convection.

.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 300 PM CDT Mon Aug 29 2016

Tuesday Night and Wednesday...Scattered showers and storms are
possible at least through Wednesday morning before a cold front
finally pushes south into Missouri and southern Illinois. Weak
0-6 km shear of less than 25 kts and PWATs near or exceeding
1.75" are conducive for slow moving storms capable of producing
1-2"/hr rain rates, thereby posing a localized flash flood threat.

Rain coverage and timing: Since areal coverage should stay
isolated to scattered, there will likely be many areas that
receive little to no rainfall. The higher chances for rain by
Wednesday morning into the early afternoon are to the south of
I-80 ahead of the sfc front.

Wednesday Night through Saturday...Large Canadian high pressure
forecast to cross through Manitoba into Ontario and the Great
Lakes region. For E Iowa/NW Illinois, northeasterly winds will
advect in much drier air. Expect comfortable humidity levels for a
change and nice late summer/early fall weather - highs in the
70s/lows in the 50s.

Saturday Night through Monday...Sfc winds respond to increasing
pressure gradient over the Midwest by increasing out of the south.
This will be the first sign of a pattern change to more humid
conditions and chances for showers and storms. Although, chances
are fairly low until Monday when a cold front approaches from the
west. Forecast highs are in the 80s, dewpoints are well into the
60s or low 70s. Uttech

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1237 PM CDT Mon Aug 29 2016

VFR conditions should be seen through 03z/30 but pockets of MVFR
conditions will be possible from diurnal clouds. If a TSRA affects
a TAF site then a period of MVFR/IFR conditions will be possible.
After 03z/30 conditions will slowly deteriorate to MVFR as patchy
fog develops across eastern Iowa/northern Illinois. The
possibility does exist for pockets of IFR/LIFR conditions prior to
sunrise Tuesday. After sunrise Tuesday, conditions will slowly
improve back to VFR.

&&

.HYDROLOGY...
Issued at 300 PM CDT Mon Aug 29 2016

Flood Warnings: Steady river level rises the past several days
have increased confidence in reaching minor flood stage at three
sites. Flood Watches were upgraded to Flood Warnings at Conesville
on the Cedar River, and at Gladstone and Burlington on the
Mississippi River.

Flood Watches: Lower confidence exists for other sites where the
forecast to reach minor flood stage is beyond 24 hours. Continued
the Flood Watch for Keithsburg and issued a new Flood Watch for
New Boston LD17, both on the Mississippi River.

On the Wapsipinicon River, decided not to issue a watch for
Dewitt because we are anticipating a river level fall to occur
before the rise that may bring it to minor flood stage toward the
end of this week. Uttech

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...Uttech
AVIATION...08
HYDROLOGY...Uttech



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