Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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168
FXUS63 KDVN 220241
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
941 PM CDT Mon Aug 21 2017

.UPDATE...
Issued at 930 PM CDT Mon Aug 21 2017

Still monitoring far northeast MO into portions of west central
IL for stronger storms with a low risk of isolated severe storm
over the next 1-2 hours. With cold front still to our NW may
see some redevelopment of showers and storms overnight. Greatest
chances for precip will reside near to south of Hwy 30 per
proximity of best low-mid level warm/moist advection and convergence.

&&

.SYNOPSIS...
Issued at 307 PM CDT Mon Aug 21 2017

There were a few breaks in the cloud cover during the afternoon
hours, but not ideal conditions for eclipse viewing over most of
the area. As the eclipse reached its peak coverage in the Quad
Cities, the temperature fell two degrees at the Davenport Airport.
Scattered thunderstorms continued south of the Burlington area,
and increased in coverage over northern Iowa. Early afternoon
temperatures in the area were mostly in the 70 to 80 degree range.

&&

.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 307 PM CDT Mon Aug 21 2017

The main forecast issue in the short term period is coverage,
timing and intensity of thunderstorms tonight.

Based on upstream trends across north central Iowa, and the recent
runs of the HRRR, storms should impact the northwest counties a
bit earlier this evening, potentially between 6 and 7 pm. A few of
the most intense storms may be capable of producing low-end severe
weather, but the lack of instability should be a limiting factor.
Another late night round of storms is also expected as the main
cold front and upper trough. In addition to marginal severe
weather, there is potential for heavy rain in an environment with
1.5-2 inch PWAT values. Isolated flash flooding is possible,
mainly south of Interstate 80 where heavier rain fell recently.

The front will quickly exit the area Tuesday morning, with
lingering showers and a few rumbles of thunder, mainly along/east
of the Mississippi River. Drier and cooler air will overspread the
area behind the front, with afternoon highs in the mid 70s to low
80s.

.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 307 PM CDT Mon Aug 21 2017

Quiet, and quiet pleasant weather will last through the extended,
with highs and lows running below normal through the period.
Northwest flow aloft will bring Canadian high pressure to the region
from Tuesday evening, through Friday. The result will be a benign
period of weather, with mostly clear skies. Dewpoints in the lower
to mid 50s will give a late September feel to the air until Friday
when return flow and an approaching upper trof bring a bit more
moisture to the region. This is shown on both the GFS and EC, but it
is too far out to pin point more than 20 percent pops toward Friday
and Saturday.

On thing is certain, there is no summer heat headed in our area`s
direction. The EC and GFS show a cooler than normal pattern beyond 7
days out.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
ISSUED AT 641 PM CDT Mon Aug 21 2017

Showers and storms will move across the terminals this evening, with
a secondary round possible overnight ahead of a passing cold front.
Gusty winds will be main threat from storms west of the Mississippi
River. Expect MVFR to IFR conditions in the precipitation. Late
tonight through mid morning Tuesday we may see some patchy fog and
areas of lower clouds with the frontal passage and lingering for
a few hours thereafter. Gusty northwest winds 15-25 kts developing
on Tuesday should bring in drier air and allow for improving
conditions to VFR by afternoon.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...McClure
SYNOPSIS...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Ervin
AVIATION...McClure



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