Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 172315
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
615 PM CDT Tue Oct 17 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 235 PM CDT Tue Oct 17 2017

18Z surface data has high pressure over the Tennessee Valley with a
surface low developing in northeast New Mexico. Dew points were in
the 40s across the Midwest.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 235 PM CDT Tue Oct 17 2017

Quiet and dry conditions will be seen through sunset Wednesday.
Winds will increase again during the day on Wednesday resulting in
breezy conditions. Temperatures should average above normal.

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 235 PM CDT Tue Oct 17 2017

A mainly quiet weather pattern with a storm system for the weekend.

Quiet and dry conditions will continue through sunset on Friday.
Temperatures should average above normal.

Friday night on...

The dry conditions will continue Friday evening. Attention then
turns to the weekend system.

Starting late Friday night some model solutions are breaking out
very light precipitation in the strong moisture return into the
area. Given how dry the atmosphere is initially, most of this
moisture should go into cloud production. However, one cannot fully
rule out some sprinkles or very isolated light rain showers
developing.

The model consensus has most of the area dry late Friday night but
does have some spotty slight chance pops.

Saturday into Sunday is where questions on timing occur with the
storm system. The large scale picture is very supportive of rain
occurring over the weekend when the front moves through the area.
Internally, the models are showing the better forcing to be along
and behind the front with very weak forcing ahead of the front.

Interestingly, the GFS and CMC have sped up the front with with the
bulk of the rain occurring Saturday/Saturday night. The ECMWF looks
a bit faster but still has the bulk of the rain occurring Saturday
night into Sunday. As a result of these differences, the model
consensus has chance to likely pops Saturday, likely to categorical
pops Saturday night, and chance pops mainly along and east of the
Mississippi on Sunday.

Sunday night dry conditions will be seen across the area as high
pressure moves through the Midwest.

Monday into Tuesday, fast west northwest flow aloft will allow at
least two upper air disturbances to move through the area. Moisture
availability is in question. However, atmospheric profiles indicate
layers of air aloft becoming unstable during daytime heating. Thus
the potential is there for diurnally driven rain showers to develop.
The model consensus has slight chance to chance pops Monday/Monday
night with slight chance pops on Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 614 PM CDT Tue Oct 17 2017

VFR conditions will be the rule tonight through Wednesday as dry
air remains in place with an increasing low level south to
southwest flow ahead of a frontal system. Decreasing surface winds
below 20 to 30 kt winds around 600 to 1200 ft agl may result in
low level wind shear conditions by late this evening. However,
forecast confidence is low that conditions will reach LLWS
thresholds and mention in the forecast has been limited to the
CID and DBQ terminals, where conditions are more favorable.

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...08
AVIATION...Sheets


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