Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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185
FXUS63 KDVN 160847
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
347 AM CDT Sat Sep 16 2017

.SYNOPSIS...
Issued at 330 AM CDT Sat Sep 16 2017

More amplified pattern, including increasingly active
southwesterlies streaming up the plains and upper MS RVR Valley,
will ensure another very warm day today before a frontal system
sweeps in from the west late tonight into Sunday morning. This
system to also bring about a chance for showers and storms later
tonight into Sunday morning, before the front gets laid out along
and south of the region into early next week. Then occasional
chances for more rain as this feature tries to retreat north early
to mid next week.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Sat Sep 16 2017

Today...elongated vort lobe embedded on eastern edge of
southwesterly steering flow, along with another round of elevated
wing of rather subtle convergent warm air advection driving bands
of showers and even some embedded thunder acrs central IA into
eastern MN. The majority of this activity will miss us just to the
west and northwest, but do expect an eastern band of sctrd
showers to lift up acrs the western into north central CWA through
mid morning, possibly in a decaying fashion. Will keep/adjust low
to moderate POPs for this process until vort lobe lifts north.
Then another day where mid level clouds erode diurnally for partly
to mostly sunny skies and ongoing southerly pre-frontal wind flow
increasing acrs the area. Although fcst soundings don`t mix as
deep as Friday, as long as we get adequate sunshine with warm
airmass in place, we should warm back up into the upper 80s to
around 90 acrs much of the area. Somewhat higher sfc dpts
maintaining in the low to mid 60s will make for heat index
readings into the lower 90s to keep in mind for afternoon
activities.

Tonight...LLVL front slated to migrate eastward acrs IA as the main
upstream short wave trof rolls up acrs the central Rockies and up
into the northern plains/upper MS RVR Valley by Sunday morning.
Deeper shear and forcing patterns with llvl frontal placement to the
steering mid level flow pattern support the more widespread precip
along and post-frontal with incoming frontal passage process. Thus
while a few showers and storms may skirt acrs the western and
northwestern CWA before midnight in pre-frontal convergent WAA
wings, the bulk of more significant showers and storms will look to
occur from acrs eastern KS, western and central IA, into south
central and southeastern MN through midnight/1 AM CDT.

As the main llvl front progresses into the DVN CWA from the west
after midnight and not pushing acrs the MS RVR until probably around
12z Sunday morning, ongoing mainly post-frontal precip regime and
time of day, suggest that as the showers with embedded thunderstorms
push east into the local area late tonight, they may do so in a
decreasing fashion. Areas northwest of a line from Dubuque, to south
of Iowa City may have the best chance to receive at least a quarter
inch of rain, before the activity wanes as it pushes east toward
dawn Sunday. Concerned that areas along and east of the MS RVR may
not get much at all through 12z Sunday as incoming rain dries up.
Some signs of a secondary moisture convergent zone on the incoming
front may also help for areas in southeastern IA and northeastern
MO(west and southwest of Burlington) to possibly get in on 0.10 to
0.20 tenths of an inch of rainfall by 12z Sunday. All in all, hardly
a drought buster expected through tonight, and many areas may not
get much rain at all over the next 24 hrs while northeastern KS into
central IA get beneficial strips of much higher rainfall amounts Sat
evening. Elevated post-frontal regime and higher deep shear lag
behind front limit much of any severe strom threat for the local
area tonight. Seasonably mild lows in the low to mid 60s for most
areas...some areas east of the MS RVR held up in the upper 60s.
  ..12..

.LONG TERM...(Sunday through next Friday)
ISSUED AT 330 AM CDT Sat Sep 16 2017

Broad southwesterly flow dominates the extended forecast, with summer
like temperatures, moderate levels of humidity, and low confidence
forcing. This is certainly a departure from the large diurnal dry
air that we`ve been in the past several weeks. The biggest take away
from the subtle forcing and questionable timing of it needs a stand
alone sentence that could easily be missed in our direct forecast.

Rain chances are plentiful, but with drought conditions, but this
should not be viewed as a wet week with significant rainfall.

Like a typical summer pattern, models are highly varied as the
timing of the weak features, and this is only complicated by two
possible tropical systems near the CONUS in the next 10 days. The
previous days had shown a progressive cold front as the deep western
trof shifts east, but now, with tropic interactions slowing up the
pattern shift, The mid week cold front and it`s good rain chances
may never arrive (at least until sometime late in the month). Thus,
highs in the 80s and lows in the 60s are forecast until further
notice after Sunday and Monday`s brief cool down into the mid 70s to
mid 80s.
ERVIN

&&

.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 330 AM CDT Sat Sep 16 2017

Record Highs for today 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...12
SHORT TERM...12
LONG TERM...Ervin
AVIATION...McClure
CLIMATE...12



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