Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 292109
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
309 PM CST Tue Nov 29 2016

.SYNOPSIS...
Issued at 308 PM CST Tue Nov 29 2016

The latest sfc analysis was indicating the main low pressure center
occluding over north central MN, with a trailing trof embedded in
cyclonic flow down into the west central plains. Secondary weak low
and trof system was noted in the southeastern DVN CWA, and will
propagate east-northeast into east central into NE IL this evening
where sfc pressure falls are increasing. Aloft, main closed upper low
center was noted over southern into central MN, while deep
troffiness extended down into northern Mexico. Locally, the 88D was
getting returns off bands of AC and elevated fall streaks.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 308 PM CST Tue Nov 29 2016

Tonight...Late this afternoon and early evening, there will be a
chance for isolated to wdly sctrd showers and storms in a small
instability swath and shear zone just east of the local area from
east central into northeastern IL. May be another case for small
spin-up tornadoes in these areas, but not quite as a favorable set-
up that occurred yesterday in central into eastern IA. Will keep
Bureau and Putnam Counties dry though the evening, but a few
convective allowing models develop a few cells close to the eastern
border of these counties. Other models barely develop anything at
all. Then, as the MN upper low slowly gyrates eastward toward
northwestern WI by Wed morning, the upstream wrap-around cloud
shield acrs MN and the northwestern half of IA will sweep in from
the west this evening and into the overnight. Ongoing dry subsidence
streaking is still impeding it though, and it may not make it much
east of the MS RVR until just before dawn Wed. With the period of
mainly clear skies for much of the night before the clouds arrive,
will keep with the low temps of lower 30s to around 30 in much of
the fcst area. Also will keep any embedded light precip in the cloud
deck off to the northwest through 12z Wed.

Wednesday...The above mentioned cloud shield will continue to engulf
the rest of the area from the west during the morning, and will have
some embedded mainly light precip (like what is currently occurring
acrs eastern SD into southwestern MN) spiral in acrs the area as the
day progresses...highest coverage during the afternoon and along and
north of the I80 corridor. As for precip types, the 12z GFS is
milder and is mainly rain and sprinkles, while the colder NAM
vertical profiles keep it mainly snow with some periods of mix even
during the late morning and afternoon. For now will bring it in as
all snow into the northwest by mid morning, then transition it
diurnally to a mix or even all light rain during the afternoon...
especially the southern flank of the precip shield closer to I80.
Still rather warm ground from previous mild spell and time of day,
should melt most of the wet snow on impact(where wet snow manages to
fall for a period). As for high temps, with clouds and precip in
mind will play cooler side of guidance with widespread highs around
40 or in the low 40s...a few northern areas may have trouble getting
out of the upper 30s.    ..12..


.LONG TERM...(Wednesday Night through next Tuesday)
ISSUED AT 308 PM CST Tue Nov 29 2016

Forecast focus on an active weather pattern later this weekend and
next week with the potential for an intense winter storm around the
middle of next week.

Wednesday night: Will continue chance pops as vort max rotates
around the main upper level trough. Precipitation amounts will be
light and there could be a mix of rain and snow. Lows should be in
the lower 30s.

Thursday through Saturday: A dry period as heights rise as the broad
upper level trough shifts into the northeast United States. Skies
will remain mostly cloudy through Friday then partly cloudy on
Saturday. Chilly air will be locked in place with highs in the upper
30s to lower 40s and lows in the 20s. These readings are near normal
for early December.

Saturday night through Tuesday:  The ECMWF has backed off on showing
a rather strong system tracking from the southern Plains to the Ohio
Valley. By not having a strong lead system this allows for much more
energy available for the more intense system by mid week. Anyway,
the ECMWF brings a weak wave across the cwa late Saturday night into
Sunday with some light snow, possibly mixed with rain. However, the
GFS keeps the system south of the cwa with no precipitation in our
area. Due to the inconsistency of the models have kept chance pops
going. Then the models are fairly similar in bringing another wave
across the Midwest early next week. This would also spread rain or
snow into the dvn cwa but too early for specific details. Not much
change in the overall airmass with highs mainly in the upper 30s to
mid 40s and lows in the upper 20s to mid 30s.

Around the middle of next week the ECMWF/GFS are latching onto
strong jet energy coming into the central United States spinning up
an intense winter storm. The track/intensity of this system will
determine the impacts for the dvn cwa but this remains to be
determined and is still over a week away. Stay tuned!

HAASE

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1146 AM CST Tue Nov 29 2016

VFR afternoon with southwesterly sfc winds of 5-15 KTS. Then will
have to time the MVFR deck of wrap around stratocu currently acrs
NW IA/MN this evening and into the overnight. CID and DBQ will be
first t get under the deck from the northwest by mid evening.
Lighter southwest winds 5-10 KTS tonight, becoming west to southwest
and increasing to 10-15 KTS by late Wed morning. Cigs will look to
lower into the lower MVFR category especially north of I80 as Wed
morning progresses, and light precip of wet snow or a rain-snow
mix may try to get into the VCNTY of CID and possibly DBQ by late
Wed morning.   ..12..

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Haase
AVIATION...12


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