Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 211736
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1136 AM CST Wed Feb 21 2018

...18z AVIATION UPDATE...

.SYNOPSIS...
Issued at 223 AM CST Wed Feb 21 2018

Skies are clearing from the northwest with some high clouds as
high pressure moves in. Area temperatures have dropped into the
mid teens far NW to the lower 20s in the southwest. Next short
wave in the Pacific Southwest will arrive late tonight and Thursday
with more light mixed precipitation chances.

&&

.SHORT TERM...(Today)
ISSUED AT 223 AM CST Wed Feb 21 2018

Short term forecast confidence assessment...good or above average
with little sensible weather issues. Area high temperatures should
be within 3 degrees of the forecast.

Today...Mostly sunny to sunny with some high clouds in the southern
skies. Highs in the upper 20s north to the middle 30s far se sections
with a northerly wind of 10 to 15+ mph.

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 223 AM CST Wed Feb 21 2018

While there will be periods of quiet weather, an active weather
pattern will remain in place through the end of the month.

Quiet and dry conditions will be seen Wednesday evening as the the
next storm system approaches the area.

Late Wednesday night the first piece of energy from the storm system
arrives. Once the atmosphere saturates and cools, light snow will
develop and spread north through sunrise. Interestingly, the models
suggest a wedge of dry air that may keep much of the area dry
through sunrise. Thursday morning, light snow will be seen across
the entire area once the atmosphere saturates.

However, as warmer air works into the area the snow will mix with
freezing drizzle and then eventually drizzle for areas south of
highway 30. This change over looks to impact the morning commute
south of an Ottumwa, IA to Galesburg, IL line.

Thursday night into Friday morning could be very interesting as the
second part of the storm system arrives. Atmospheric profiles
indicate the drizzle will change over to freezing drizzle or
freezing rain for much of the area and continue into Friday morning.
The potential is there for an eventual headline event.

Friday night the next storm system moves into the area. The models
offer different opinions in regards to timing and storm track. Storm
track will be very important in regards to precipitation type. Right
now the model consensus has mainly chance pops for the area.
Precipitation type runs from rain to snow with a nasty mix,
including ice, in the transition area.

Saturday on...

On Saturday, the model consensus has chance to categorical pops for
the entire area. Depending upon the track of the system, the wintry
mix may change over to all rain by mid day as warmer air moves into
the area.

Sunday through Monday night the model consensus has quiet and dry
conditions for the area as high pressure moves through the Midwest.
Temperatures will average above normal.

On Tuesday, a weak system will move through the Midwest. Moisture is
limited and there are differences between the models regarding
timing and track. Right now the model consensus has slight chance to
chance pops for mainly rain northwest of a Dubuque to Williamsburg,
IA line.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1128 AM CST Wed Feb 21 2018

VFR conditions for most of the TAF cycle with overrunning high
clouds over departing high pressure ridge. North winds of 8-12
KTs becoming northeast overnight. CIGs will lower from the south
late tonight and especially Thu morning, as a precip-making
system pushes toward the area. This system may eventually produce
a wintry mix of freezing rain and snow along and west of the MS
RVR by mid Thu morning, first impacting the BRL site by around 14
or 15z.   ..12..

&&

.HYDROLOGY...
Issued at 223 AM CST Wed Feb 21 2018

Area rivers are continuing to respond to the widespread .5 to 1.5+
inch rains yesterday with over a dozen forecast points now in
flood, mainly for minor to moderate flooding. Several points are
in the process of cresting the next 6-12 hours. The Rock River has
the most significant rises with major flooding forecast at Moline
later this week. No additional significant rains are expected
this week which will allow most rivers to fall below flood stage
by this weekend except for the Rock River.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...16
SHORT TERM...16
LONG TERM...08
AVIATION...12
HYDROLOGY...08/16



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