Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 210906
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
306 AM CST Wed Nov 21 2018

.SYNOPSIS...
Issued at 305 AM CST Wed Nov 21 2018

A weak cold front has been sinking southward into northern Iowa
overnight. Behind the front, temperatures under the clouds are
actually warmer, due to the stratus coverage, but the warming that
occurred in our area around midnight despite clear skies shows the
frontal character.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 305 AM CST Wed Nov 21 2018

The front will continue to push south today, before stalling in
northeast MO and becoming a warm front Tomorrow. The main question
today will be cloud cover, as the cyclonic flow aloft will be
limited today, and cold advection weak. The clouds are likely to
remain in place where they are at in the north and northeastern
counties all day, but may never reach the south.  This sets up a
temperature contrast from the lower 30s north, to the upper 30s to
mid 40s south. Otherwise, today will see winds switch from west
northwest to light east, then increasing east to northeast as the
front settles to the southern counties this afternoon.

Tonight clouds are likely to increase in coverage as the warm front
sets up a waa regime aloft, while seeing cool easterly flow at the
surface. Continued dry conditions are expected through the night.
Lows are expected in the lower to mid 20s in the north half, and
around the lower 30s south.
ERVIN

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 305 AM CST Wed Nov 21 2018

Long term focuses on precipitation chances for the busy holiday
weekend.  Two storm systems are still forecast for the area as well
as temperatures into the 40s and 50.

Thanksgiving will start out cold across the area before warm
advection takes over.  As noted earlier the NAM has fzdz across the
northern CWA in the AM before the WAA occurs.  Currently the NAM
remains the outlier.  That said, the GFS does seem to have a deep
enough moist layer with rising motion in it as well.  We will need
to keep an eye on this as this may impact early travel on
Thanksgiving morning.  After this threat passes temperatures should
warm into the 40s and 50s across the area.  This should melt any ice
if fzdz does occur.

Friday into Saturday, good agreement between the models on the
timing of a cold front passage through the area.  All rain is
expected with this system as WAA keeps temperatures in the low 40s
across the area, even in the evening up to fropa.  Few impacts are
expected from this storm system.  Saturday, a short refrain from
rain as WAA begins again across the area.  This should lead to temps
above freezing and into the 40s.

Sunday remains the main question in the long term as models have all
trended to a solution that makes the area wet.  While models have
similar locations of the track of the system, the small differences
in terms of 40 to 60 miles makes a world of difference as far as
impacts from this system.  The 00Z GEFS solutions vary widely and
lead to low confidence in the operational solutions.  That said,
these types of systems are usually slower and will likely feature a
low track that is further west and north of where it currently is.
If this were to occur, the entire area would see rain.  If the track
shifts east 40 to 50 miles we could be in for quite the winter
weather event.  With these differences confidence in overall
solutions and expected impacts is low.  Those traveling Sunday
especially across the region should pay attention to future
forecasts.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
ISSUED AT 1030 PM CST Tue Nov 20 2018

Can`t rule out some patchy fog late tonight/early Wednesday morning,
mainly south where winds go near calm ahead of a front sagging
through the region. Too much uncertainty with extent of decoupling
and reaching crossover temp precludes any mention at this time.
In the wake of the front winds will shift to the NW and eventually
prevail from an easterly direction by afternoon/evening, as high
pressure builds across the northern Great Lakes. Potential exists
for a period of MVFR ceilings post-frontal, especially at the
northern TAF sites, which is eventually shown by various guidance
to transition to VFR later in the period with incoming subsidence.
However, confidence on extent of MVFR ceilings and improvement to
VFR is rather low.


&&

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

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...McClure



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