Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 181115
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
515 AM CST Wed Jan 18 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 302 AM CST Wed Jan 18 2017

A large blanket of stratus covers the Midwest, with clearing
beginning from Minneapolis to Topeka. The stratus is lifting
northeast, and shows some signs of subsidence with a few holes in
the flow over southern Iowa and Missouri. Temperatures are going no
where, as we are still holding in the lower to mid 30s.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 302 AM CST Wed Jan 18 2017

The clearing of stratus will be the main challenge today. Models
move it out quickly, but that seems unlikely given the time of year,
the inversion developing, and the current stratus deck expanse.  The
flow increasing from the southwest at the surface has helped mix out
the low level RH some, and we are seeing both visibilities increase
and ceilings lift some. Thus, we will hold onto stratus through mid
morning, and show a decrease through the early afternoon. With this
cloudier than models forecast, I`ve gone a few degrees under
guidance for highs. As with all stratus waa days, this could bust
both ways, so this is seen as a least error forecast. Highs in the
lower 40s north to upper 40s southwest are forecast. Should clearing
occur quickly this morning, we could reach the lower 50s south.

Tonight, initial clear skies should allow for lows to drop the upper
20s northeast to lower 30s southwest. Clouds should arrive at mid
and upper levels again by late evening.

ERVIN

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 302 AM CST Wed Jan 18 2017

Long forecast warm up with spring like temperatures is still on
track for the extended.  Temperatures are still forecast to be 10 to
20 degrees above normal through the long term.  Sporadic chances for
precip will be possible through the extended.  With the exception of
the end of the long term period, thermal profiles are warm enough
for all rain across the area.

Thursday, upper level low that is slowly lumbering across the
central United States will lead to S flow at H5.  This will help to
usher in warmer air.  With the low in the area, skies will be mostly
cloudy and could impact overall warming.  Half of the guidance
brings in QPF on Thursday as the vort max rotates north through the
area. The best chance for rain will be later during the day and
through the overnight into Friday morning. Temperatures on Thursday
and Friday could be slightly over done due to cloud cover and
potential precip. Late Friday, the wave finally moves through the
area.

Active flow into next week brings numerous chances for precip.  A
system and associated surface low will track west of the CWA on
Saturday. At this time overall QPF looks to be low. Another
shortwave is forecast through the area on Monday and will quickly
move out of the area leading to another chance of rain.  Midweek
next week, the GFS and ECMWF brings a H5 low over the area, while
the GEM advertises a ridge across the area.   Overall confidence in
the system next week is low and is expected to change.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
ISSUED AT 511 AM CST Wed Jan 18 2017

Very low stratus continues to stream northeast from Missouri, with
a short term clear area working through southeast Iowa as of 11Z
today. The main question is visibility, as the stratus will sweep
back into the area around 12Z. Missouri visibilities are very low,
around 1/4 mile, with sunrise arriving soon, and light wind flow
from that direction, it appears we should not see low visibilties
over eastern Iowa/northwest Illinois. Thus, a slow clearing trend
later this morning should result in VFR weather finally returning
to the region after several IFR days.

&&

.HYDROLOGY...
Issued at 302 AM CST Wed Jan 18 2017

With unseasonable January rainfall amounts and subsequent run-off,
combined with ongoing ice action, flood warnings have been issued
for some forecast points on the Rock River. Joslin was adjusted
upward to moderate flood stage, with some historical events with
similar precip/ice during this time of year suggesting very quick
rises up close to major flood stage possible over the next few days.
Moline on the Rock may be getting, or eventually will get some input
from the ice jammed up waters of the lower Green River.

On the Mississippi, latest river stages show both sites in flood
rising.  The runoff from yesterdays rain event along with the ice
jam will likely lead to continued rises on the Mississippi.  Once
the ice jam frees, expect the levels in the river to drop noticeably.

Recent rainfall/run-off combined with ice action also producing
rises near or to flood stage at some sites on the Iowa and English
River in Iowa. A few other Iowa rivers approaching action stage.
And a localized areal flood warning ongoing west of the official
forecast point of Geneseo IL on the Green River for a reported ice
jam producing flooding.  A flash flood watch has been issued for
Henry County, in case there is a breach in the levee near Colona.
The rivers will have to be watched area-wide for more ice action and
jams possibly producing additional flooding during the upcoming week
of unseasonably mild weather.
..12/Gibbs..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...Flash Flood Watch until 9 AM CST this morning for Henry IL.

MO...NONE.
&&

$$

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


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