Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

000
FXUS63 KDVN 220442
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1142 PM CDT Mon Aug 21 2017

...06z AVIATION UPDATE...

.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 06Z TAFS through 06Z Tuesday Night)
ISSUED AT 1136 PM CDT Mon Aug 21 2017

Light to some pockets of moderate rain is expected into the overnight
at MLI, CID and BRL with embedded thunder mainly vicinity of BRL.
DBQ looks to be mainly north of the best forcing and mostly dry
outside of a few sprinkles or stray shower. All precipitation
should taper off from west to east after 09z through 13z as a cold
front pushes through the region. I have kept with previous shifts
trend and also recent guidance of lowering ceilings into MVFR for
a few to several hour period around the frontal passage. During
the day on Tuesday expect northwest winds to become gusty and
usher in drier air. This should lead to an improvement to VFR
conditions with decreasing clouds. NW winds should diminish at or
below 10 kts with sunset.

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.