Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 160445
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1145 PM CDT Fri Sep 15 2017

...06z AVIATION UPDATE...

.SYNOPSIS...
Issued at 250 PM CDT Fri Sep 15 2017

18z surface data has low pressure over central Nebraska and high
pressure over the Ohio Valley. A front ran northeast from the low
into eastern Lake Superior. Dew points were mainly in the 60s across
the Midwest with some 50s across eastern Iowa.

&&

.SHORT TERM...(This Evening through Saturday)
ISSUED AT 250 PM CDT Fri Sep 15 2017

Very warm and dry conditions will be seen through sunset. After
sunset the dry conditions will continue through midnight. Attention
then turns to the late night time frame.

After midnight, the RAP model has a layer of unstable air aloft,
that, when combined with some weak forcing and moisture generates
some elevated convection. This situation occurred last night and
resulted in showers and a few thunderstorms.

So, based on this persistent signal from the RAP, slight chance to
low chance pops have been introduced for areas west of a Manchester,
IA to Williamsburg, IA line. The rain from the elevated convection
will fall through a dry layer that is around 10 kft deep. So, while
the nocturnal convection may look impressive on radar, the amount of
rain at the surface may just barely wet the pavement.

The nocturnal convection that develops late tonight will dissipate
around mid morning Saturday. Once the clouds break up, very warm
conditions will be seen across the area with high temperatures
ranging from the mid 80s to the lower 90s. Dew points will drop
during the day but heat index readings are still expected to be in
the upper 80s to lower 90s.

Refer to the climate section for record highs for September 16th.

.LONG TERM...(Saturday Night through Friday)
ISSUED AT 250 PM CDT Fri Sep 15 2017

Long term forecast highlights are unseasonably warm temps through
next week, along with potential for some relief from the recent dry
spell.

A well-advertised cold front will finally arrive Saturday night into
Sunday. Highest rain coverage is favored along/west of the
Mississippi River. Areal averages should be less than 1/4 inch, with
isolated pockets of heavier rain with isolated storms. This will not
provide much relief for the drought conditions across southeast
Iowa. Weak deep layer shear and forcing should preclude any
organized severe weather threat. Clouds and a south breeze will keep
lows Saturday night well above normal, mainly in the 60s.

Sunday, expect scattered showers and a few storms to linger as the
front pushes south of the area. A cooler and drier air mass will
overspread the area, with afternoon highs in the mid 70s to around
80.

Early next week, there is more favorable model consensus regarding
the arrival of another short wave trough embedded in southwest flow,
along with a warm front across the forecast area. This scenario
could yield some more widespread significant rain Monday and/or
Monday night, although confidence in details remains low.

Looking ahead, expect highs warming into the 80s Tuesday/Wednesday.
The ECMWF and GFS are both advertising more rain for Wednesday.
Temps will remain above normal through Friday, with additional late
week chances of showers and thunderstorms. Model blend pops indicate
at least some potential for rain every period. This is overdone, but
no period can be reliably ruled out at this point.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
ISSUED AT 1127 PM CDT Fri Sep 15 2017

VFR conditions will continue to dominate the TAF cycle. Setup still
offers potential for some elevated convection overnight through
mid morning Saturday over portions of eastern IA within warm/moist
advection and weak impulses lifting up in SW flow aloft. I have
continued with VCSH wording at KCID after 10z until 16z as this
terminal has best potential of being impacted by a SHRA, with a low
risk of TSRA and very brief period of MVFR visibility. There is a
chance for additional showers and storms Saturday evening into
eastern IA but being late in TAF period and lower confidence will
not have any mention with 06z TAFs.

&&

.CLIMATE...
ISSUED AT 250 PM CDT Fri Sep 15 2017

Record Highs for September 16...

Moline.........92 in 1931
Cedar Rapids...98 in 1931
Dubuque........96 in 1931
Burlington.....95 in 1906

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...RP Kinney
AVIATION...McClure
CLIMATE...08



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