Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 302355
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
555 PM CST Wed Nov 30 2016

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 300 PM CST Wed Nov 30 2016

The latest sfc analysis was indicating the main occluded low center
acrs the U.P. of MI, with trailing trof extending back acrs southern
MN. Large stratocu field with embedded areas of mainly light rain
and snow continue to rotate to the south of it acrs the local area.
Aloft, the current water vapor imagery loop was indicating large
multi-centered upper low complex spiraling acrs MN/WI/northeastern
IA, with 150+ KT upper jet streak streaming to the lee of it up the
central/eastern GRT LKS. This will draw the upper low northeastward
into Thu morning.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 300 PM CST Wed Nov 30 2016

Tonight...With a more vigorous vort spoke continuing to rotate
around the upper low and down acrs the northeastern half of the CWA
out of southeastern MN this evening, expect rounds of light precip
to continue mainly along and north of I80 through Midnight. But
there may be also more spotty areas of sprinkles or flurries
transitioning to all flurries south of I80. With cold air just
aloft, diurnal boundary layer melting effect will diminish after
dark and expect mainly wet snow and flurries north of I80 as the
evening progresses. Again with lingering mild ground temps, don`t
expect much in the way of any accumulation...maybe a wet dusting
mainly on elevated surfaces after dark thru midnight in these
northern areas. With ongoing cloud cover, precip boosted sfc DPTs,
mixing winds of 10-20 MPH overnight, will keep the previous shift`s
minimal diurnal drop-off from afternoon highs for low temps
tonight...generally lower to mid 30s for most of the CWA. As the
main vort departs, expect the more organized areas of precip to
transition more into scattered flurries late tonight into early Thu
morning.

Thursday...As the main cyclone complex pushes east acrs the GRT LKS
this period, it will continue to whirl a substantial cloud deck acrs
the area. Another weaker and more channeled vort lobe will still
look to wring out flurries and sprinkles acrs at least the
northeastern third of the CWA Thu morning into early afternoon,
before propagating off to the east. High temps similar to today
mainly in the upper 30s, with a few spots tickling 40 in the south
especially if some late afternoon breaks in the cloud cover can
occur.    ..12..

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 300 PM CST Wed Nov 30 2016

Overview: Quiet and near average temperatures to start this extended
forecast period. Then, becoming increasingly active from Saturday
night into next week with large temperature swings possible along
with several separate rounds of precipitation.

Thursday Night through Saturday:

Cool but seasonable in the 30s and 40s for highs, 20s and 30s for
lows. WNW flow aloft should keep conditions mainly dry through this
period.

Saturday Night through Sunday Night:

First decent chance for light precipitation is from Saturday night
into midday Sunday. Fast moving, low amplitude trough progged to
force a zone of warm air advection and DCVA through E Iowa/NW
Illinois.

Chance for Light Rain or Snow...Moisture is limited because closed
low along the Western Gulf Coast will restrict moisture advection to
the southern states. Locally, 850mb temps of -2 to -4 C appear cold
enough for light snow; however, sfc-925mb ambient temps and sfc wet-
bulb temps are warmer making either rain or a rain/snow mix more
likely along/south of I-80. Best chance for a period of all snow is
probably along/north of highway 30. Again, near sfc temps are
marginal at this time for any snow accumulation and total precip
amounts should be light. For these reasons, not anticipating much in
the way of travel impacts from this system.

Monday Night through Tuesday Night: Next system has more Gulf
moisture associated with it as it pulls northeastward out of Texas.
850mb temps, max wetbulb temps aloft, and sfc wetbulb temps all
would favor mainly a rain event. This could change some in future
model runs if there is more dry air than the models are currently
resolving.

Wednesday on: Potential for the strongest of the three systems to
affect the Midwest as longwave trough and anomalously strong upper
jet both strengthen over tight baroclinic zone across the Central
U.S. As expected at this lead time, run-to-run intra- and inter-
model consistency is lacking. The GFS is further NW through Central
Minnesota and weaker than the ECMWF which tracks the sfc low through
W Wisconsin. Not much can be said about the details this far out
except that there is potential for a strong, rapidly deepening low
in the Midwest next week.  The track will likely remain uncertain
through this week or weekend as the models continue to jump around
with the evolution and positioning of key kinematic features. What
does look probable is a change to much colder temperatures on the
back side of the low. Uttech

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 530 PM CST Wed Nov 30 2016

A mix of light rain and snow will transition to all light snow
this evening, mainly impacting KDBQ and KCID. Scattered flurries
are expected at KMLI with little or no precipitation at KBRL.
Expect periods of IFR ceilings at KDBQ/KCID overnight into
Thursday morning, mainly MVFR at KMLI/KBRL.

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Uttech
AVIATION...RP Kinney



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