Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 121125
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
525 AM CST Tue Dec 12 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 319 AM CST Tue Dec 12 2017

06Z surface data has the cold front from northwest Ohio across
southern Iowa. The front then becomes a warm front across the
eastern Dakotas into northeast Nebraska. Dew points were in the
teens and 20s from the Great Lakes into the northern Plains with 30s
from the Ohio Valley into the central Plains.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 319 AM CST Tue Dec 12 2017

Through sunrise, winds will continue to decrease as skies clear.

Tuesday, breezy conditions will be seen for much of the day along
with dry but cold conditions. Clouds will slowly be on the increase
during the afternoon hours. Temperatures will average below normal.
Attention then turns to the next system.

Tuesday evening will continue to see dry conditions and an increase
in clouds as the next clipper type system approaches the area.
After midnight things get more interesting.

The approaching clipper system has similarities to yesterday`s
system. Right now dry conditions are expected through sunrise.
However, if the system would track further to the south and west...
the previous system did this...then there may be a potential for
some flurries or very light snow in the highway 20 corridor from
Dubuque on east.

Temperatures tonight will initially drop after sunset but will
steady out around mid-evening. After midnight temperatures should
slowly rise through sunrise Wednesday.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 319 AM CST Tue Dec 12 2017

Consistent northwest flow pattern to keep area overall dry to mostly
dry with day to day temperature changes mostly within 5 to 7 degrees
of normal climatology.

Long Term Forecast Confidence Assessment...fair to good or average
to above average, main issue is Wednesday with vigorous short wave
to bring windy conditions and probably some light to dusting amounts
of snow.  Diurnal ranges bit underdone once again an issue with
highs up to 3 plus degrees too cool most days and some lows too mild
with clear skies and light winds by 2 to 3 plus degrees.

Wednesday...a fast moving but intensifying low pressure system will
bring areas of light snow and snow showers northeast 1/2 with local
forcing tools suggesting some areas may pick up an inch or so that
will likely not be better known for at least 24 more hours.
Southwest 1/2 of area could see a rain/snow/sleet mix with little or
no snow accumulations. Winds could be big challenge with kinematic
techniques supporting by PM in western 1/2 of the region northwest
winds of 25 to 40 mph with risk of some gusts to 45+ mph which would
suggest and wind advisory possibly may be needed west of the
Mississippi River.  Highs also a challenge with once again strong
evaporative cooling and strong CAA by PM hours. Highs mostly likely
mid to late morning most locations with falling temperatures by
afternoon. Highs mid 30s to mid 40s a decent starting point but
later shifts may need to adjust downward if cold air and evaporative
cooling are faster.

Thursday through Tuesday...consistent northwest flow with passing
minor disturbances for risk of very light precipitation.  Highs
mostly in the 30s and 40s, mins mostly in the 15 to 30 degree range
with day to day high and low variances of 5 to 7 degrees expected.
Any precipitation amounts would be trace to minor, mostly in the
form of snow or flurries.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
ISSUED AT 521 AM CST Tue Dec 12 2017

VFR conditions will be seen through 06z/13 as high pressure moves
through the Midwest. After 06z/13 VFR conditions are forecast to
continue as another storm system approaches the western Great
Lakes. Although not included in the 12z TAFs, the models are
suggesting the potential for LLWS developing across eastern Iowa
after 06z/13. GFS/ECMWF/CMC models suggest the potential is
marginal. WRF model is more aggressive on developing LLWS.

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...Nichols
AVIATION...08


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