Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 161747
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1147 AM CST Mon Jan 16 2017

.UPDATE...
Issued at 1146 AM CST Mon Jan 16 2017

Temperatures continue to slowly climb late this morning, with all
reporting sites above 32 as of 11 am. Area radar mosaic shows a
large arc of higher reflectivity north and northeast of the upper
low, across SE NEB through central IA, curving southeast through
southeast IA into western IL. This will continue to lift
northward through early afternoon with dewpoints and wet bulb
temperatures well above 32 ending the threat of additional
freezing precipitation.

Will thus allow the bulk of the winter weather advisory to expire
as scheduled at 18z, and reassess the remaining far northern
tier, north of the highway 20 corridor, for possible early
expiration as air and pavement temperatures continue to climb.
Fog has so far remained light across the area, but once the upper
level dry slot punches through later this afternoon and surface
winds decrease with the approaching low, there is a greater
likelihood of dense fog and an advisory may be needed.

&&

.SYNOPSIS...
Issued at 256 AM CST Mon Jan 16 2017

Freezing rain, with possibly a bit of sleet northwest, covers nearly
all locations as of 2 AM, northwest of a Keokuk, to Sterling line.
This is creating slick conditions, especially in the western
counties were wet bulb temperatures are in the upper 20s. This is
not true in the southeast, where most locations are 32 degrees, with
dewpoints of 32 as well. Dense fog is developing in adjacent parts
of Missouri and western Illinois, indicating that dew points will
likely rise another degree soon. That would end the freezing rain
threat if that trend continues by around sunrise in the south.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 256 AM CST Mon Jan 16 2017

Freezing rain will be ongoing in most spots at 6 AM, and will end
from south to I-80 by mid morning, and from I-80 to our northern
border from 10 AM to 1 PM. This is blending current conditions with
the RAP diurnal trends, and I have rather high confidence in that.
This is important, and the ice accumulations will be greatly limited
in the southern 1/2 of the CWA using this trend, and the efficiency
of ice accumulation in the northwest will also decrease with time.
Thus, with around 0.10 expected by sunrise in the west, and an
additional 0.05 to 0.10 in the northern 1/2 through Noon, our
amounts have been slightly lowered again from the evening update.
However, the impacts are nearly identical, and our forecast will
focus 100% on impact from this point forward today.

By 1 PM, wet bulb temperatures >32 will be found over the entire
area, and this ice event will have concluded. However, the fog and
moderate rainfall event, with possible thunder will continue through
late evening, before deformation zone light rain is forecast to
develop as cold advection develops behind the low. The fog may be
dense enough for an advisory today and tonight, but with the ongoing
freezing rain and additional rainfall expected to develop, will
hold off on issuing a product to keep the forecast focused on the
most critical hazard at this time.

Something to consider today, when viewing our forecast, is that we
will be updating nearly every hour for current conditions. Expect a
day where updates will be critical in addressing the hourly changes
in hazardous weather.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 256 AM CST Mon Jan 16 2017

Main story in the long term forecast is the warm up with
temperatures well above normal this week. The pattern turns to a
more spring like pattern with rising temperatures reaching the 50s
for the weekend.  Before this, the remnants of the ice storm will
bring a mix of freezing drizzle and rain as it moves out of the area
on Tuesday.

Tuesday, wrap around moisture could lead to light precip mainly
across the far northeast CWA.  The best chance for the precip will
be close to 12z when thermal profiles favor freezing rain or
drizzle.  As temperatures warm, this will turn to rain or drizzle
across the northeast.  Little to no impacts are expected from this
freezing precip.

Tuesday night on, H5 ridging will drive warmer air into the area.
Surface high pressure south of the CWA will usher in 6 to 8C H85
temps for later in the week.  This will lead to high temperatures
possibly 20 degrees or more above average.  Late week, a wave from
the south attempts to move north.  This will be the next chance for
precip across the area.  Later in the period into next weekend,
another wave moves onshore across the west.  Models suggests this
ejects out of the SW into the Plains bringing a more appreciable
chance for precip.  However, with the active weather pattern, expect
timing and placement of systems to change in future iterations of
the numerical guidance.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1146 AM CST Mon Jan 16 2017

Widespread LIFR conditions due to low clouds and fog will be the
rule throughout the forecast as a large storm system lifts through
the region from the plains. Precipitation out ahead in the form
of freezing rain will transition to rain at CID and DBQ early this
afternoon as warmer air moves into the area. Widespread rain will
than transition to drizzle during the afternoon. There is a low
potential for thunderstorms, but confidence and possible coverage
is too low to include in the TAFS. Overnight, widespread drizzle
and dense fog will result in LIFR to VLIFR, with only minor
improvement Tuesday morning as winds shift to the northwest and
lead to gradually improving visibilities.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory until noon CST today for Benton-Cedar-
     Clinton-Iowa-Jackson-Johnson-Jones-Linn-Muscatine-Scott.

     Winter Weather Advisory until 3 PM CST this afternoon for
     Buchanan-Delaware-Dubuque.

IL...Winter Weather Advisory until noon CST today for Bureau-Carroll-
     Henry IL-Putnam-Rock Island-Whiteside.

     Winter Weather Advisory until 3 PM CST this afternoon for Jo
     Daviess-Stephenson.

MO...NONE.
&&

$$

UPDATE...Sheets
SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...Sheets


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