Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 162324

Area Forecast Discussion
National Weather Service Quad Cities IA IL
624 PM CDT Sun Jul 16 2017


Issued at 247 PM CDT Sun Jul 16 2017

Under northwest flow aloft, surface high pressure in the Upper
Midwest is dropping south pushing a weak, lake-enhanced cold front
into the southern part of the CWA. Scattered, generally weak
thunderstorms are developing in the vicinity of the boundary as it
moves south. Overcast conditions behind the front broke out
during the last hour or two allowing some late afternoon sunshine.


.SHORT TERM...(This Evening through Monday)
ISSUED AT 247 PM CDT Sun Jul 16 2017

The cold front and associated thunderstorms will continue moving
south-southeast and should be out of the CWA in the next few
hours. High pressure is pushing a cool Canadian air mass into the
area with dew points behind the front forecast to drop into the
50s over most of the CWA by morning. Dry and pleasant weather is
slated for tomorrow - one more day before the heat and humidity
begin a gradual return by mid-week.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 247 PM CDT Sun Jul 16 2017

An extended period of humid weather is in store for the area. How
hot it gets is extremely dependent upon where the track of the
organized thunderstorm complexes sets up. Based on what the models
are suggesting, eastern Iowa and northwest Illinois may be close to
that track.

Quiet and dry conditions will be seen across the area Monday night
as high pressure moves through the western Great Lakes. Temperatures
should be around or a little below normal. Attention then turns to
the arrival of the humid weather.

Heat and humidity will arrive on Tuesday, especially during the late
morning and afternoon hours. The morning hours look to be dry across
the area. The question for Tuesday afternoon is where will the
afternoon storms develop. The better return flow and forcing is
across western and northern Iowa, so storms should initiate there in
the afternoon.

The models have been slowly backing off regarding the areal coverage
of potential rain Tuesday afternoon. So the possibility does exist
that the afternoon may end up being dry. As of now, the model
consensus has slight chance pops west of a Belle Plaine to Dubuque

Tuesday night/Wednesday the models solutions diverge on their
respective opinions. The WRF is suggesting a potent thunderstorm
complex will move through the area and dissipate on Wednesday. The
ECMWF is not as strong with the complex while the CMC keeps any
complex well north of the area. The GFS has a weak complex grazing
the northern parts of the area.

Where this complex develops and tracks Tuesday night will determine
the sensible weather Tuesday night into Wednesday. Right now the
model consensus has slight chance to chance pops across the the
northern half of the area Tuesday night with slight chance pops
across the northeast third of the area Wednesday.

Wednesday has the potential to be quite hot if the thunderstorm
complex stays north of the area. If the complex moves across the
area and generates a pool of cool air, then temperatures could be
end up being much lower.

Wednesday night on...

Nocturnal thunderstorm complexes will be seen Wednesday night
through Friday across the Midwest. The key point to understand is
that the development and track of each complex will affect the
development of the next one. As a result, the model consensus has
chance pops across the northern half of the area Wednesday night and
slight chance to chance pops across the entire area on Thursday
through Friday.

An important note...given the near daily rain chances, not every
location will see rain. Those areas that do see rain have the
potential to easily get an inch of rain.

Saturday/ interesting dichotomy with the models develops.
The ECMWF/CMC keep the very warm and humid conditions across the
area with a risk of daily showers and thunderstorms. The GFS brings
a strong cold front through the area with cooler temperatures as the
flow aloft comes from the northwest.

Right now the model consensus has slight chance pops Saturday with
slight chance to chance pops Saturday night/Sunday. The model
consensus also has above normal temperatures.


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 614 PM CDT Sun Jul 16 2017

Moist low levels will bring a chance of fog and possibly
some low clouds late tonight and early Monday AM.
Best chances will be west of Mississippi River as drying on
easterly flow will likely limit development east. For now
confidence is greatest on fog and have tempos for mvfr visibility
at CID and BRL.




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