Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

000
FXUS63 KDVN 172332
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
532 PM CST Wed Jan 17 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 PM CST Wed Jan 17 2018

Latest sfc analysis was indicating large ridge center settling
southward acrs the mid to lower MS RVR Valley, with southwesterly
flow acrs the region in it`s northwestern flank pressure gradient. A
clipper system dives into the GRT LKS on Thu while upstream upper
ridge axis nudges acrs the plains for continued moderating temp
regime into the weekend. Then a eastern Pacific wave will strive
inland behind the ridge, and eventually lift out northeastward acrs
the Midwest sometime Sunday into Monday for the next main weather
maker for the area.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 330 PM CST Wed Jan 17 2018

Tonight...Mainly clear with ongoing sfc pressure gradient between
lower MS RVR Valley ridge and clipper digging toward the
northwestern GRT LKS out of Canada, keeping southwesterly sfc winds
of 10 to 15 MPH going overnight. Despite the mixing winds, rather
dry sfc dpts and lingering snow/ice cover will make for a lean
toward the cooler of guidance into the lower teens, with even some
single digits possible in northern deeper snowpack areas and river
valleys. Some non-diurnal trends possible at times tonight with
varying wind speeds and building inversion aloft in the H9-H7 MB
layer.

Thursday...With latest Vis loop indicating snow cover back into the
east central plains, will side with the cooler of guidance highs
again, taking into account southwesterly sfc wind fetch acrs these
snow fields limiting moderation. Enhanced H85 MB inversion aloft
will also be a player. Still most areas to make it into the 30-35
degree range Thu afternoon, with southwest winds of 10-20 MPH
putting an edge on the warming temps. Southwest wind maintaining Thu
night holding lows up in the teens or even lower 20s.

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 330 PM CST Wed Jan 17 2018

Friday and Saturday...Breezy southwest winds continue to warm air
advect on Friday, while H85 temps build into the double digits
positive aloft in ongoing inversion under flattening mid CONUS
ridge. Boundary layer fetch continuing over degrading snow cover
still warrants a lean toward the cooler of guidance highs, but much
of the area should make it up in the 40s. Backing llvl flow to a
more southerly fetch, will start to do some moisture draw up acrs
the region by late Saturday, while steering southwesterlies organize
into the plains. Sat should be a mainly dry seasonably mild day with
increasing clouds as it progresses. Developing quasi-stationary sfc
front will look to lay out ESE-to-WSW somewhere acrs the central
into northern CWA Sat night and act as a convergent focus for light
precip breaking out in the vicinity. North of the boundary sfc temps
may be at or below freezing and there may be some marginal precip
type issues. But the air will be warm aloft and don`t seem much in
the way of snow...maybe drizzle or freezing drizzle north of the
boundary if warm dry wedge aloft maintains and traps llvl moisture
layer. Regular drizzle to the south.

Sunday through next Wednesday...Main feature will be the potential
of a cyclone ejecting out northeastward up through the region/IA out
of the southern plains Sunday into Monday. Still much model
discrepancy at this point with speed, west-to-east path track and
strength. But the general trend continues for the local area to be in
the warm sector for more of a early spring like shower regime late
Sunday into Monday morning, with some wrap around snow possible on
it`s back end either Monday or Monday night, depending on the model
solutions. depends on elevated instability feed, but plenty of shear
and lift to generate some embedded thunder in at least the south
half of the DVN CWA late Sunday or Sunday night. The GFS is faster
and further west with sfc cyclone track, as opposed to the slower 12z
ECMWF and GEM. Rainfall amounts by Sunday morning could range from a
quarter inch, up to near an inch in some spots especially of there
is some convection. With still frozen ground or partially frozen sfc
layer, rain run off may produce some ponding of water in areas as
well as stream/creek rises. Will have to watch for ice jam issues as
well. Low confidence in this scenario for now.

As for snow accums on Monday or Monday night in the wrap around,
most models just produce an inch or so of wetter based snow
especially on elevated/grassy surfaces.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 531 PM CST Wed Jan 17 2018

Consistently VFR weather will continue through Thursday evening,
as high pressure remains south of the area. This will bring
southwest winds around 10 to 15 kts through the period.

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...12
AVIATION...Ervin



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.