Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 220844
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
344 AM CDT THU SEP 22 2016

.SYNOPSIS...
Issued at 303 AM CDT Thu Sep 22 2016

At 3 am cdt...areas showers and thunderstorms are draped just northwest
of the region along and north of a stalled frontal system. Trends support
most or all of the most significant convection will stay to our NW
with episodes of convection making into the NW 1/3 the next 24 hours.
A backdoor cool front will arrive Friday that will tend to keep the
region drier and a bit cooler with less humidity.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 303 AM CDT Thu Sep 22 2016

Short term forecast confidence assessment...fair or average with main
concern next 24 hours if another outflow boundary impacts northern
sections today that could impact high temperatures by up to 3+ degrees
cooler. POPS in far NW 1/4 of the region also a challenge as will be
near the edge of favored rounds of convection.

Today...Generally partly to mostly sunny with some mostly cloudy skies
across the north. Chance or slight chance POPS over NW 1/3 of the region.
Highs again may be a challenge with near 80 degrees along highway 20
corridor to near 90 degrees along IA/MO border. Heat indices south 1/3
of the region may reach 90 for a few hours in the afternoon. Rain totals
of up to a half inch may be possible along the highway 20 corridor.
Strongest storms may produce gusty winds to around 40 MPH.

Tonight...Little change from the day with a slight shift south in the
rounds of convection. Additional one half inch or more of rain may be
north of highway 30. Since these areas past 5 plus days have been fairly
dry, no water issues expected. Lows still balmy for late September
in the mid to upper 60s.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 303 AM CDT Thu Sep 22 2016

Internally, the models are indicating there should be some type of
decaying convective complex across roughly the northern third of the
area Friday morning. The frontal boundary, that is projected to be
around I-80, and outflow boundaries from the convection are expected
to provide the focus for new convection Friday afternoon.

Cloud cover and precipitation along with the position of any meso
and synoptic scale boundaries does raise the possibility that
temperatures across the north half of the area `could` be much
cooler than forecast on Friday.

Friday night/Saturday dry conditions will be seen across the area as
high pressure quickly moves through the Midwest. Attention then
turns to the next approaching system.

Saturday night is interesting. The upper low will have ejected out
of the desert southwest. At the same time, energy from the remnants
of a western Pacific typhoon will top the ridge just off the west
coast. How these two pieces of energy will interact is key to the
sensible weather for the area. It is possible that the upper low may
eject out of the desert southwest slower than what the models are
indicating. If that occurs, Saturday night `could` end up being dry.

Right now the forecast has slight chance to chance pops for the
western half of the area Saturday evening with the eastern half
being dry. After midnight, all but the far east areas have a risk of
rain with the western third of the area having the best chance.

Sunday on...

There continues to be a wide disparity of the model solutions in
both timing and how energy in the northern stream interacts with the
cut off low. The GFS is quite progressive with the upper low. The
ECMWF and CMC models eject an open wave while developing another
upper low in the southern Rockies. Even with the ECMWF and CMC
models suggesting a similar scenario, both differ considerably with
the eastward movement of the system.

Right now the model consensus has a daily threat of rain for the
area from Sunday through Wednesday. There will be periods of dry
weather but there is no clear indication from the models when that
will occur.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1120 PM CDT Wed Sep 21 2016

A dry overnight with southeast winds and VFR weather is expected,
though powerful thunderstorm complex north of Waterloo will need
to be watched carefully, and it could move toward eastern Iowa
after 10Z, as it weakens. This is not confident, but has enough
potential that a vicinity shower has been included toward morning
at DBQ and CID. Otherwise, another warm and mainly dry day is
forecast for southeast Iowa and Illinois Thursday.

ERVIN

&&

.HYDROLOGY...
Issued at 303 AM CDT Thu Sep 22 2016

Over the past 24 hours, southern Wisconsin was hit hard with heavy
rain. The upper headwaters of the Rock river was partially affected
but most went into other rivers in Wisconsin that flow into the
Mississippi.

Starting yesterday afternoon and continuing overnight parts of
northeast Iowa, southeast Minnesota, and Wisconsin have been hit
with another round of heavy rain.

The headwaters of the Cedar, Iowa, and Wapsipinicon basins were hit
hard with heavy rain. The Maquoketa basin so far was not hit as hard.

Because of the heavy rainfall that has occurred, and with more heavy
rain forecast, the Cedar, Wapsipinicon, and Mississippi rivers are
projected to have significant rises on them with most points going
into flood.

There are many questions that are yet unanswered. These questions
are as follows; when, where, and how much rain will fall.
Additionally, how quickly will water run off and get into the
various river basins.

Given these uncertainties, river flood watches have been issued for
most of the Cedar and Wapsipinicon rivers, and parts of the Iowa
River. The river flood warnings for CNEI4, DEWI4, and MROI4 continue.

Additional river flood watches are possible over the next 24-36
hours for the Mississippi river.

In looking at the overall big picture, significant rises will be
occurring on the Cedar, Iowa, and Wapsipinicon rivers. The main stem
Mississippi will also see significant rises as well.

Crest forecasts for the above mentioned rivers are expected to
fluctuate considerably over the next 48-60 hours until a full
accounting of the rain and runoff is achieved.

The forecast has additional rain for the area from Sunday through
Wednesday of next week. Where this rainfall occurs and how much
falls will become very important to river basins in eastern Iowa and
possibly northern Illinois.

&&

.DVN Watches/Warnings/Advisories...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...08
AVIATION...Ervin
HYDROLOGY...08



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