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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
638 am CST Tuesday Dec 1 2015

issued at 330 am CST Tuesday Dec 1 2015

At 3 am CST...surface low pressure was located near Sioux Falls
with a warm front stretching across southern Wisconsin into
northeast Illinois. Relatively mild air remained in place across
the area...with early morning temperatures in the middle 30s to low
40s. A west/SW breeze was gusting over 20 miles per hour at some locations.
Patchy drizzle persisted in far eastern Iowa and northwest


Short term...(today and tonight)
issued at 330 am CST Tuesday Dec 1 2015

Patchy drizzle is expected to taper off early this morning. Look
for a gusty west/SW wind...near 30 miles per hour this afternoon. Forcing from
the upper level low will continue to impact the forecast area
today...with steep low level lapse rates indicated by bufr
soundings this afternoon. This is an ideal set-up for convective
snow showers...with the highest coverage along and north of the
Interstate 80 corridor. This scenario has support from high
resolution models...including the hrrr and nmm. Afternoon maximum
temperatures near I-80 may be warm enough for some partially melted snow
or rain to mix in at times. Some areas affected by the snow
showers might pick up a light dusting on grassy surfaces...but the
main impact will be sudden bursts of snow that reduce visibility.
Snow showers will continue tonight as forcing associated with the
upper low increases. Again...minor accumulations will be possible

Long term...(wednesday through monday)
issued at 330 am CST Tuesday Dec 1 2015

Wednesday...chance for light snow showers and flurries in the
morning as large upper-level low/vorticity maximum tracks through the
upper Mississippi Valley and western Great Lakes. An enhanced
vorticity. Lobe is forecast to rotate around the upper-low leading to
development of a new surface low over NE Illinois which will
eventually track into lower Michigan. Moisture on the backside of
the upper-low will advect into east Iowa/west Illinois today and last
into Wednesday. Weak positive vorticity advection...and convergence attendant to a subtle
surface pressure trough should be sufficient to produce a period of
snow showers during Wednesday morning when models are painting
quantitative precipitation forecast of a hundredth or two. Surface temperatures will be below freezing
through the middle the upper 20s to lower
minor snow accumulations of a trace to a few tenths are possible.

NAM/nmm forecast soundings show marginal surface-based instability
during Wednesday afternoon...could see some flurries redevelop. Highs
are forecast in the middle to upper 30s.

Thursday and Friday...high pressure expanding over the southern U.S.
With an extension into the Midwest will result in SW winds and
warm air advection. By Thursday night...850mb temperatures are projected to increase by
approximately 16 c. Highs will reach the lower to middle 40s on
Thursday then middle to upper 40s by Friday. Plenty of sunshine will
make it feel very nice by early December standards.

Saturday through Monday...mild/above average temperatures continue.
Highs remain in the 40s with 1000-500mb thickness near 552 dam and
850mb temperatures near 5 c. Saturday will likely be the warmest
day with highs in the upper 40s/lower 50s.

Potential southwest U.S. Shortwave may reach the Midwest by Monday
or Monday night...but only have a slight chance for rain showers
this far out. Uttech


Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 629 am CST Tuesday Dec 1 2015

Expect scattered convective snow showers this afternoon...with the
highest coverage at kcid/kdbq. MVFR visibilities and ceilings will be
common...with brief periods of IFR visibilities possible in pockets of
higher intensity snow showers. Additional show showers favored
after midnight tonight as upper level low pressure moves into the
area. A west/SW wind will gust at or above 20 kts this afternoon...then
diminish below 10 kts this evening.


Dvn watches/warnings/advisories...


Synopsis...rp Kinney
short term...rp Kinney
long term...uttech
aviation...rp Kinney

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