Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 220351

Area Forecast Discussion
National Weather Service Quad Cities IA IL
951 PM CST Sat Jan 21 2017

Issued at 941 PM CST Sat Jan 21 2017

So far any dense fog has been confined to areas south of I-80
south of the stratus deck with light winds and abundant moisture.
Satellite and obs are showing the stratus continuing to erode from
the west/southwest and do anticipate dense fog developing into
areas north of Hwy 30 late evening and overnight. Given the trends
and after coord with DMX have expanded dense fog advisory to include
nearly all of eastern IA counties. Confidence is low on dense fog
trends between stratus and increasing mid/high clouds from the
storm system to our south. The latter clouds may keep dense fog
from getting out of hand over west central IL and northeast MO and
the reason I`ve kept the dense fog advisory out of there for now.
Potential also for some light rain chances in these areas
overnight into Sunday morning as moisture ripples up along 850 mb


Issued at 338 PM CST Sat Jan 21 2017

Low clouds covered most of eastern Iowa into far northwest
Illinois this afternoon. Under the cloud cover, afternoon
temperatures were mostly in the 40s. Across west central
Illinois, where the sky was mostly sunny, temperatures rose into
the low to mid 50s. Some patchy fog lingered along the Highway 20
corridor and points to the north.


.SHORT TERM...(This Evening through Sunday)
ISSUED AT 338 PM CST Sat Jan 21 2017

The main forecast issue in the short term period is the potential
for more dense fog development tonight into Sunday morning.

In the near term, low stratus covers the northwest 2/3 of the
forecast area, with a mostly sunny sky in west central Illinois.
Lowest visibilities of 1 to 3 miles are located along the Highway
20 corridor. After collaboration with neighboring offices, have
opted to go with a dense fog advisory along and north of Highway
30, where visibilities are likely to drop the soonest tonight.
Periods of dense fog are also likely to the south, but with
uncertainty on timing and coverage, will let later shifts re-
evaluate and expand advisory as needed. Will run the advisory all
the way until 18z Sunday, and it can be cancelled early if needed.

An upper level low may support some isolated light rain in the
extreme south late tonight into Sunday morning. Otherwise, the
period will be dry. For Sunday, expect another unseasonably mild
day, with highs in the 40s.

.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 338 PM CST Sat Jan 21 2017

Forecast focus on trending toward colder temperatures and wintry mix
later next week.

Sunday night and Monday: Potent storm system currently impacting the
southern Plains and Gulf Coast States will eventually move into the
Ohio Valley by Monday. ECMWF/GFS similar in keeping the
precipitation south and east of the dvn cwa. Temperatures should be
just a tad cooler in the wake of this system, but readings will
still be well above normal. Highs on Monday should be in the lower
40s at most locations.

Tuesday and Wednesday: The next potent storm system currently in the
eastern Pacific will be slamming into CA on Sunday. This system will
then track into the Midwest by Tuesday. A 986mb cyclone will be
pushing into northeast KS by late Tuesday with the main area of
precipitation to the north and west of the track, where deeper
saturation will be occurring on the cold conveyor belt side. Ahead
of the cyclone, in the warm sector, ridging in the Gulf will prevent
Gulf moisture being transported northward initially. Therefore, the
better rain chances look to be in our western cwa. On Tuesday night
the low will push across eastern IA and then into southern WI, and
on Wednesday into Lower MI. Rain or snow will gradually turn to all
snow as colder air wraps around the backside of the low. As of now,
minor accumulations of snow is possible in our nw cwa, with the
heavier snow amounts to the west and north of the dvn cwa. Of
course, this will depend on timing of the changeover to snow and the
exact track of the low.

Thursday through Saturday: This system buckles the jet and allows
for a northwest to northerly flow aloft. This will bring colder air
into the cwa, with temperatures returning to more normal levels for
late January. Highs are expected to be in the upper 20s to lower 30s
with lows dipping into the teens to lower 20s. Can`t rule out some
snow showers or flurries periodically across the area. However, low
confidence this far out in timing/track of these individual waves in
the flow.


.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
ISSUED AT 550 PM CST Sat Jan 21 2017

Generally mvfr to ifr conditions expected at the terminals. Anticipate
some dense fog overnight into early Sun am, but confidence is low on
extent of dense fog and lifr/vlifr conditions. For the 00z tafs I
have left 1/2sm fg mention at all sites, but delayed until after 06z
through 14z.


Issued at 338 PM CST Sat Jan 21 2017

Rock River: Rapid fluctuations in the river level of 1 to 3 feet
either up or down are occurring due to ice movement. This situation
will continue through the weekend.

Mississippi River: At Burlington, the river has fallen below major
category and water was moving well with very little ice in the

Other sites: Recent and forecast rainfall/run-off, combined with ice
action is also producing significant rises on portions of the Skunk,
Wapsipinicon and Pecatonica Rivers, and flooding on portions of the
Iowa River and English River. With the ongoing mild weather, area
rivers in general will still have to be watched this weekend for
more ice action and jams possibly producing additional flooding.


IA...Dense Fog Advisory until noon CST Sunday for Benton-Buchanan-
     Cedar-Clinton-Delaware-Des Moines-Dubuque-Henry IA-Iowa-
     Muscatine-Van Buren-Washington.

IL...Dense Fog Advisory until noon CST Sunday for Carroll-Jo Daviess-



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