000
FXUS63 KDVN 201755
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1255 PM CDT TUE SEP 20 2016

...18z AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CDT Tue Sep 20 2016

A weak front has passed across the region with little or no precipitation
yesterday. Light winds in north sections are producing areas of fog
that is locally dense north of highway 30. Temperatures at 2 AM are
ranging from the 50s far north in areas of fog to the upper 60s in the
far south. Upstream energy in the northern plains supports dry conditions
for at least the next 18 hours.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Tue Sep 20 2016

Short term forecast confidence assessment...fair or average with main
concern is the viability of a decaying convective system to move into
the northern portions of the forecast area after midnight. Evidence
is this may be overdone due to drier dewpoints tonight.

Today...fog should burn off by 9 AM, then a fair, quiet and comfortably
warm day with moderate humidities. Highs will be once again at least
7 degrees above normal ranging from the lower 80s north to the upper
80s far south. Light east winds will become southeast by dusk.

Tonight...mostly clear and warmer with lows mostly in the middle to
upper 60s. Have chance pops north 1/3 of the area after midnight with
a decaying area of showers and storms. Conditions do not support a severe
risk at this time for later shifts to reassess. rain amounts should
be mostly light to possibly some areas of moderate totals to near .75
inch, most likely in the far NW sections. This system may be delayed
and/or weaker based on upstream lower dewpoints than are forecast.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 330 AM CDT Tue Sep 20 2016

The models are now suggesting a frontal boundary will stall out
across southern Minnesota into Wisconsin Wednesday through Thursday.
Disturbances running along the front are expected to generate rounds
of showers and thunderstorms. Each round of convection has the
potential to push the front south or create a secondary boundary
that moves south into our area.

As a result, the highway 20 corridor appears to have the best chance
of seeing rain on Wednesday. Internally, the models are suggesting
the possibility of an organized thunderstorm complex Wednesday night
that could push rain as far south as I-80 and possibly as far south
as an Ottumwa, IA to Galesburg, IL line. The models do agree that
the better rain chances Wednesday night will be north of highway 30.

Thursday into Thursday night the next disturbance moves out of the
Plains and into the upper Midwest. More showers and thunderstorms
are expected generally along and north of I-80. The better rain
chances still look to be north of highway 30.

Friday on...

The models develop a fairly deep low in the southwest United States
over the weekend and then slowly eject pieces of energy into the
Plains. The models diverge on their solutions mainly in regards to
the overall timing and placement of storm systems.

The model consensus has slight chance to low chance pops north of
I-80 on Friday and north of highway 30 Friday night.

On Saturday, the model consensus has dry conditions for the area as
high pressure settles over the Great Lakes. A couple of solutions
are suggesting a potential cold front coming off Lake Michigan. If
this were to occur, temperatures could be much cooler that what is
currently forecast.

Saturday night through Monday is when most of the timing differences
show up in the models. All models indicate the main upper low in the
desert southwest ejecting into the Plains. How this system ejects
into the Plains will dictate the sensible weather for the weekend.

Right now the model consensus has slight chance pops Saturday night,
followed by chance pops for Sunday/Sunday night, and then slight
chance pops for Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1244 PM CDT Tue Sep 20 2016

A VFR afternoon and evening acrs the area with east to southeast
sfc winds of 7-12 KTS. Then the watch will be on after midnight
and possibly close to dawn Wed morning for areas of weakening
showers and thunderstorms moving down out of MN/WI and into areas
north of I80. This could put the CID and DBQ terminals at risk of
MVFR to temporary bouts of IFR conditions early tomorrow morning
if they make it down here. They are then expected to diminish and
end by late Wed morning. Besides the areas of showers/storms,
some chance for at least some MVFR fog toward dawn at most TAF
sites, but if southeast SFC winds maintain at 3-5 KTS it should
prevent IFR to LIFR level fog.   ..12..

&&

.HYDROLOGY...
Issued at 330 AM CDT Tue Sep 20 2016

Little to no rain yesterday will probably result in crests coming in
slightly lower at DEWI4, MROI4, and CNEI4. The water in the area
rivers is routed flow and is accounted for by the river models. It
now appears that most of the area will be dry for the next 18-24
hours which will place most sites closer to a crest before rain
starts falling again.

&&

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

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...08
AVIATION...12
HYDROLOGY...08