Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 161151
AFDDVN

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

.UPDATE...
Issued at 541 AM CST Mon Jan 16 2017

As of 530 AM, wet bulb temperatures are 32 or colder north of
Washington IA, to Muscatine, to Galesburg line. South of this
line, patchy icing remains possible, but the widespread threat may
have ended, despite a steady rain currently occurring there. The
winter weather advisory may be cancelled early in that area, and
could be replaced by a dense fog advisory if trends continue.

&&

.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 12Z TAFS through 12Z Tuesday Morning)
ISSUED AT 541 AM CST Mon Jan 16 2017

Freezing rain, very low CIGs, and low visibility will continue
this morning across eastern Iowa, and northwest Illinois, and
change to rain by mid to late morning. Rain, with a thunderstorm
possible will continue through tonight, with fog potentially
becoming widespread. Light east winds will switch to northwest
late tonight, as the low pressure system goes by. Expect IFR/VLIFR
conditions through the period.
&&

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

     Winter Weather Advisory until 9 AM CST this morning for Des
     Moines-Henry IA-Jefferson-Keokuk-Lee-Van Buren-Washington.

     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-Mercer-Putnam-Rock Island-Whiteside.

     Winter Weather Advisory until 9 AM CST this morning for Hancock-
     Henderson-McDonough-Warren.

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

MO...Winter Weather Advisory until 9 AM CST this morning for Clark-
     Scotland.

&&

$$

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



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