Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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291
FXUS63 KDVN 221212
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
612 AM CST Sun Jan 22 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CST Sun Jan 22 2017

Similar to the last several nights, light winds and sufficient
low-level moisture has led to areas of dense fog across E Iowa/NW
Illinois with visibilities less than 1/4 mile at times. The fog
has been slowest to set in over the Quad Cities area, but even
here visibilities are beginning to drop.

Areas of clearing in sky cover has allowed for more radiational
cooling, so fog likely not as vertically deep as the past few
nights. Outside the DVN WFO, it is a shallow, but dense, ground
fog. Also, it is colder early this morning with sfc temps in the
upper 20s to mid 30s.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Sun Jan 22 2017

This Morning:

Dense Fog Advisories in effect through 12 PM, but thinking many
counties may be dropped several hours early.

Sfc temps near or below freezing for many locations means the
potential is there for slick roadways and sidewalks from areas of
freezing fog - something to keep in mind if traveling this
morning. Make sure to slow down and use extra caution.

Fog across E Iowa/NW Illinois is more radiationally driven as
opposed to the past few nights which were synoptically forced.
This is corroborated by lower GOES liquid-cloud thickness
values compared to recent early mornings. Hi-res model guidance
(RAP/HRRR/NMM) and sfc obs in north-central IA suggest NW/N
sections of the forecast area may be the first to see visibilities
improve as steady NW winds develop.

This Afternoon and Tonight:

Another mild and cloudy mid to late January day on tap. Forecast
highs are in the 40s most locations. There is a slight chance for
light rain showers through midday in the SE CWA, which is on NW
periphery of a large low over the Lower Mississippi Valley.

Steady NW winds should preclude areas of dense fog overnight.
Added mention of patchy fog across the north third of the CWA.
All-in-all not expecting a significant impact. Uttech

.LONG TERM...(Monday through Saturday)
ISSUED AT 330 AM CST Sun Jan 22 2017

Main focus is the system that will lift through Tuesday and
Wednesday. Colder weather is on track to follow late week into the
weekend, when temperatures should return closer to late January
normals in the 20s and 30s.

Forecast confidence is low with the details of the early week
system. While the track of the surface low remains somewhat
consistent, from NW MO through northern IL, there continue to be
timing differences among the models that will be critical for
precipitation types. Our model blended forecast approach for
precipitation types for now results in an onset of possible snow in
the warm advection out ahead Tuesday morning over eastern IA, mixing
with rain and then changing to all rain in the afternoon as
temperatures warm into the 40s. The onset could easily be late
enough to eliminate the snow potential. Similarly, any rain or
drizzle will likely transition to light snow following the passing
surface low and advection of what looks to be sufficiently cold
strong air advection. For now this transition will be advertised
Tuesday night, with an advertised transition back to rain or
rain/snow mix, then snow again as the system exits Wed into Wed
night. The current path suggests potential snow amounts of 1 to 2
inches Tue night into early Wed, north of highway 30.

Temperatures Thursday  through Saturday cool considerably under an
active, and cyclonic N-NW flow aloft. There may be a few rounds of
flurries or very light snow in this stretch, but confidence is too
low to pin down specific timing.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
ISSUED AT 548 AM CST Sun Jan 22 2017

Little change in CIGS/VSBYS with LIFR conditions observed at all
terminals. +FG is largely driven by radiation. Therefore, we
should see a quick improvement through the mid/late morning at
KBRL/KMLI, eventually to MVFR as forecast soundings show.
Increasing VSBYS AT KCID/KDBQ will be offset by IFR CIGS through
afternoon with a lower probability for period of MVFR.

The overnight features another round of IFR CIGS. Widespread,
persistent dense fog is not anticipated. Uttech

&&

.HYDROLOGY...
Issued at 330 AM CST Sun Jan 22 2017

...Ice Action Continues on Many Area Rivers...

Rock River: It appears that the ice that was jammed yesterday in the
Joslin area has since broken up and moved downstream. Over the past
24 hours, Joslin dropped nearly 3 feet and is now in minor category
flooding. Based on most recent readings, the ice from Joslin may be
currently moving through Moline, where readings were fluctuating
around a half foot and it has briefly touched major flood stage of
14 feet. As this moves through, will need to watch for fluctuations
of a foot or more, at Moline today. Further upstream, ice action
that was in the Dixon area yesterday appears to be passing the Como
gage, where it spiked to moderate flooding last evening, but has
since dropped below flood stage. Additional ice action issues can be
expected as this ice advances downstream through Joslin and
eventually Moline over the next couple days. Forecasts are thus
low confidence and stages could easily go higher than forecast as
ice moves through the area.

Mississippi River: The large ice jam that has been restricting flow
downstream of Burlington since January 7 has broken up and the stage
was rapidly falling at both Gladstone and Burlington. Gladstone has
dropped near 3 feet in the past 24 hours and is now below flood
stage, and with no additional flooding expected the flood warning
will be dropped. Burlington is on a similar trend, with a 2 foot
drop and was now in minor category flooding. At the current rate, we
may be able to drop the flood warning there later today. Downstream,
this was resulting in rising river levels at Keokuk and Gregory
Landing, where it is expected to crest just below flood stage.

Cedar River: An ice jam was impacting the river along Conesville,
where the stage jumped 3 feet Saturday, briefly above moderate flood
stage last evening. A corresponding drop of nearly 3 feet has
occurred downstream at Columbus Junction. Rapid fluctuations of
several feet will be likely along this stretch until this ice makes
it way downstream.

Ice action continues along nearly all other eastern Iowa and
northwest Illinois tributary rivers. Continued mild weather and
channeled flow due to runoff from recent rain will continue the
threat of ice jams through at least mid week.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until noon CST today for Benton-Buchanan-
     Cedar-Clinton-Delaware-Des Moines-Dubuque-Henry IA-Iowa-
     Jackson-Jefferson-Johnson-Jones-Keokuk-Lee-Linn-Louisa-
     Muscatine-Scott-Van Buren-Washington.

IL...Dense Fog Advisory until noon CST today for Bureau-Carroll-
     Hancock-Henderson-Henry IL-Jo Daviess-McDonough-Mercer-
     Putnam-Rock Island-Stephenson-Warren-Whiteside.

MO...Dense Fog Advisory until noon CST today for Clark-Scotland.

&&

$$

SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...Sheets
AVIATION...Uttech
HYDROLOGY...Sheets



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