Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 142353
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
553 PM CST Sun Jan 14 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 335 PM CST Sun Jan 14 2018

A wing of elevated warm advection ahead of a clipper system in
the northwest flow was producing light snow over much of the
forecast area this afternoon. At 20z, the surface low was over
northwest MN with an axis of 5 mb/3 hour pressure falls over
northern IA into southeast MN. In the upper levels, a deepening
shortwave was evident on water vapor imagery moving into eastern ND
and western MN. As this wave continues to deepen and dive south-
southeast, the clipper system will move through the forecast area
tonight, preceded by widespread light snow. In its wake, a strong
cold front will introduce a period of strong winds, then bitter
cold temperatures and potentially dangerously cold wind chills
late Monday into Tuesday.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 335 PM CST Sun Jan 14 2018

A winter storm advisory has been issued for tonight through early
Monday morning for expected light snowfall, then a period of
drifting and possibly blowing snow through midday Monday. This
covers roughly the area east of a line from Dubuque through Mount
Pleasant into Van Buren County in Iowa and all of our IL an MO
counties.

At the surface, the clipper system is on track to move
through the center of the forecast area between midnight and 6
am. The track of the main vort max has shifted to the center or
even southern half of the forecast area in the 12z models. Also,
at the same time, the left exit region of a 140 kt plus upper
level jet diving southeast out of western Canada will enhance lift
over the area, especially during the evening hours. The resulting
axis of forcing suggests a southwest shift in heavier snowfall
potential from previous forecasts, with widespread 2 to 4 inches
now possible over the entire forecast area overnight. The snow
will exit out of all but our far northwest IL counties Monday
morning as reinforcing arctic cold front punches into the area. A
period of 20 to 30 plus mph winds will kick up the fluffy snow for
areas of drifting snow, if not pockets of blowing snow,
especially before noon. Our east central IA counties not included
in the advisory may still see several inches of fluffy snow, then
a period of drifting and possible blowing snow Monday morning and
will continue to watch trends closely. Temperatures in the teens
to lower 20s tonight will fall sharply following the front early
in the day, then remain steady to slowly falling through the
single digits during the day.

The combination of falling temperatures and strong northwest winds
will drive wind chills well below zero and into advisory range
over a Wind Chill Advisory has been issued for east central IA
counties, just west of the Winter Storm Advisory, starting at
12z Monday morning. As temperatures continue to fall from west to
east, the advisory then extends into much of the remainder of the
forecast area at 5 pm.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 335 PM CST Sun Jan 14 2018

Headlines for wind chill will be in effect for the area Monday night
through Tuesday morning.

Monday night into Tuesday morning it now appears cloud cover will
prevent temperatures from getting too cold. The proximity of the
upper low and disturbances rotating around it will help generate
flurries and light snow across the area. Given the high snow/rain
ratios, some minor accumulations are expected, especially north of a
Manchester, IA to Sterling, IL line.

Tuesday night through Thursday quiet and dry conditions will be seen
across the area as arctic high pressure moves through the Midwest
toward the east coast. Return flow developing Wednesday night will
help bring much warmer temperatures to the area for Thursday.

Thursday night on...

Quiet and dry conditions will continue Thursday night through Friday
night with temperatures climbing above normal. There is a weak
disturbance moving through the flow aloft Thursday night into Friday
but moisture is quite limited so only an increase in clouds are
expected.

Next weekend the global models agree that another storm system will
affect the Midwest. However, there is considerable disagreement upon
the timing and track of the storm system. Part of this disagreement
appears to be related to a weak disturbance that moves through the
Midwest late Friday night into Saturday.

Right now the model consensus has slight chance to chance pops on
Saturday for rain with possibly a rain/snow mix in the morning.

Saturday night the model consensus has chance pops with chance to
likely pops on Sunday. The track of the storm will be very important
in regards to precipitation type. Right now it currently appears
that rain will chance to snow Saturday night and then change back to
a mix or all rain on Sunday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 550 PM CST Sun Jan 14 2018

00z TAFS focused on timing and intensity of snow with clipper
system moving through the area tonight. Peak coverage/intensity
will be between 02z-12z from west to east, with 1sm visibilities
common. Ceilings should be mostly MVFR with brief periods of IFR
possible. Monday morning, strongest winds and best chance for BLSN
will be at KCID.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory until noon CST Monday for Cedar-Clinton-
     Des Moines-Dubuque-Henry IA-Jackson-Jones-Lee-Louisa-
     Muscatine-Scott-Van Buren.

     Wind Chill Advisory from 5 PM Monday to noon CST Tuesday for
     Cedar-Clinton-Des Moines-Dubuque-Henry IA-Jackson-Jones-Lee-
     Louisa-Muscatine-Scott-Van Buren.

     Wind Chill Advisory from 6 AM Monday to noon CST Tuesday for
     Benton-Buchanan-Delaware-Iowa-Jefferson-Johnson-Keokuk-Linn-
     Washington.

IL...Winter Weather Advisory until noon CST Monday for Bureau-Carroll-
     Hancock-Henderson-Henry IL-Jo Daviess-McDonough-Mercer-
     Putnam-Rock Island-Stephenson-Warren-Whiteside.

     Wind Chill Advisory from 5 PM Monday to noon CST Tuesday for
     Bureau-Hancock-Henderson-Henry IL-McDonough-Mercer-Putnam-
     Rock Island-Warren-Whiteside.

MO...Winter Weather Advisory until noon CST Monday for Clark-Scotland.

     Wind Chill Advisory from 5 PM Monday to noon CST Tuesday for
     Clark-Scotland.

&&

$$

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



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