Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 131135
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
535 AM CST Mon Nov 13 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 320 AM CST Mon Nov 13 2017

06Z surface data has high pressure from the Great Lakes into the
lower Mississippi Valley. Dew points were in the 20s across the
upper Midwest and northern Plains with 30s and higher from the Great
Lakes to the Gulf Coast.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 320 AM CST Mon Nov 13 2017

Through sunrise, the fog will continue to slowly expand across the
area. The current advisory looks good and data currently suggests no
need to expand it but that could change.

After sunrise, the fog will slowly dissipate through mid-day.
However, given the light winds across the area and the low sun angle
for the time of year the possibility does exist that the fog may not
completely lift.

Tonight, RAP trends indicate the low clouds will slowly move back
into the area from the west. Atmospheric profiles are pointing to
the potential for drizzle not long after the low clouds move back
into the area. The unanswered question is whether or not there will
be fog development. There will be a steady light wind around 5 mph
so that may be enough to prevent fog from developing. However, I
would not be surprised to see patchy fog develop in low lying areas
given the damp ground from the rain/snow of Sunday.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 320 AM CST Mon Nov 13 2017

An upper level shortwave seen swirling in water vapor images off the
NW coast is progged to push eastward, passing well to our north Tue
night into Wed. This sends a cold front through the forecast area
triggering showers and possible thunderstorms. A strong southwest
return flow and associated warm advection will enhance a low
level inversion already in place. This will result in a deep layer
of moisture near the surface favorable for stratus and drizzle
Tuesday. Temperatures will gradually rise into the 40s through the
day with favorable south to southeast winds. This process
continues into Tuesday night, continuing light rain or drizzle
into the evening, transitioning to scattered showers with the
developing modest upper level forcing and surface cold frontal
passage. Will keep a slight chance for thunderstorms going in the
far south and east where mid level lapse rates could result in
some elevated thunderstorms.

Wednesday and Thursday still looks dry with near normal temperatures
as a surface high crosses the area. Wed night looks to be the
coldest night of the week, with lows in the 20s under the high.

The next system is likely to affect the region Friday or Saturday,
with continued low confidence due to model differences. The GFS
remains the faster solution with the upper level trough and
surface low and cold front pushing through Friday. The ECMWF and
Canadian models have slower timing, closer to Friday night, along
with differing surface low tracks. For now, a low confidence
blended solution will result in continued precipitation chances
from Thursday night into Friday night. This will likely be in the
form of rain with at least a low potential for thunderstorms and
an even lower confidence mention of snow on the back side as the
system exits. Friday`s highs in the 50s could potentially reach
into the low 60s, especially in the south as suggested by the GFS.
All have the front through the region with cold advection that
follows Saturday and Sunday limiting high to the 30s and 40s with
overnight lows back into the 20s, and potentially as low as the
teens.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
ISSUED AT 531 AM CST Mon Nov 13 2017

LIFR conditions will be fairly widespread across eastern Iowa and
northern Illinois due to fog. Outside of the LIFR, conditions
varied from IFR to VFR. Frost development due to the fog is
possible on aircraft that remain outside. The LIFR conditions will
slowly improve to MVFR/VFR through 20z/13. After 00z/14 IFR/LIFR
conditions with drizzle are expected to overspread eastern Iowa
and eventually northern Illinois.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 10 AM CST this morning for Benton-
     Buchanan-Cedar-Clinton-Delaware-Dubuque-Henry IA-Iowa-
     Jackson-Jefferson-Johnson-Jones-Keokuk-Linn-Louisa-
     Muscatine-Scott-Van Buren-Washington.

IL...Dense Fog Advisory until 10 AM CST this morning for Carroll-Jo
     Daviess-Rock Island-Stephenson-Whiteside.

MO...NONE.
&&

$$

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



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