Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 121017
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
417 AM CST Thu Jan 12 2017

.SYNOPSIS...
Issued at 335 AM CST Thu Jan 12 2017

At 3:30 AM cold arctic high pressure is moving in with a last area of
mixed precipitation producing light amounts in our southeast to exit
the region by daybreak. Cold conditions and dry weather will last through
Friday before a system in the southern plains affect parts or all of
the region this weekend with a mixture of mainly light precipitation.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 335 AM CST Thu Jan 12 2017

Short term forecast confidence assessment...good or above average. Limited
sensible weather issue beyond highs and lows and timing of clearing
from north to south next 12 to 18 hours.

Today...any lingering light precipitation should move east by mid morning
if not earlier. With clearing north to south by early afternoon to fair
skies. Highs should be in the 18 to 28 degree range with a north wind
of 10 to 15+ MPH.

Tonight...high clouds to move back in from the west for partly cloudy
skies and continued cold with light north winds. Lows single digits
north to the mid teens in the south.


.LONG TERM...(Friday through next Wednesday)
ISSUED AT 335 AM CST Thu Jan 12 2017

Friday into Sat morning...With a time crunch, will just generalize
the latest 00z run medium range models over the weekend and into
early next week with respect to the potential rounds of wintry mixed
precip, with emphasis on the 00z GFS and ECMWF. Siding with the 00z
GFS and ECMWF for now, expect most of Friday dry thru 00z except an
elevated band of light snow and flurries into the northwestern CWA
by late afternoon. This light snow to skirt east along and north of
HWY 30 Fri evening and may trend toward mainly flurries as it
encounters drier air from high pressure source acrs the GRT LKS. The
latest GFS and ECMWF are picking up on the strength of the GRT LKS
ridging and barely allow any freezing rain or sleet mix to creep up
into the southern CWA now thru 12z Sat. The NAM is a more bullish
outlier and spreads a wintry mix of sleet and freezing rain up to
I80 Fri night, with light snow north of I80 but will through this
model out for now or just go slight chc for a wintry mix further
north as happy medium for now. The same favored 00z run GFS and
ECMWF are then mainly dry the rest of Sat and Sat evening, with Sat
highs in the mid 20s north to the lower 30s in the south.

Saturday night...The 00z GFS is stronger with llvl northeasterly
flow an is dry even in the south through 12z Sunday...and holding
the ongoing ice storm at bay acrs KS, MO and southern IL. But the
00z ECMWF has more of northward push aided by increased elevated
warm moist conveyor, spreading a freezing rain and sleet mix up to
I80 by dawn Sunday morning with at least advisory ice accums
possible. For now will make a mean average of these two solutions
and spread slight CHC to CHC POPs north acrs the southern third of
the CWA thru 12z Sunday.

Sunday into Monday...Both the 00z GFS and Euro suggest the first
good wing of WAA induced wintry mix to spread north acrs the CWA as
Sunday progresses, with snow/sleet/freezing rain Sunday morning
becoming primarily freezing rain with some sleet Sunday afternoon
and evening. The intensity and placement of heavier bands may vary
and wane from time to time, but there may be a decent chance for
some localized swaths approaching ice storm warning criteria by late
Sunday night, and other areas a solid advisory. This even taking
into account marginal afternoon temps around or a degree or two
above freezing Sunday afternoon. Both models lift the main low
northeastward acrs western into central IA Mon into Tue, with the
GFS a bit more progressive.

Both solutions would have the local area more under the influence of
this system`s warm sector Mon and Mon night, with wintry mix early
Mon morning trending over to all rain almost CWA wide as Monday
progresses. The GFS is much warmer with highs on Monday in the 40s
and even some 50s, while the ECMWF has highs only in the mid 30s to
near 40. Again a blend will be used with likely to Categorical POPS
for Mon. Will trend freezing rain in the morning to all rain by
afternoon. Rain into the evening, and depending on speed of passing
system allowing llvl cold conveyor to wrap into the backside of the
system, some chance for a wintry mix again to spread in from the
northwest late Mon night into Tue morning. Stay tuned for the
ongoing saga of new model runs and changes with this complex
scenario shaping up for the weekend and into early next week. Too
early for any headlines such as winter storm watches yet this far
north with the uncertainties.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1131 PM CST Wed Jan 11 2017

Some local IFR cigs will linger next couple hours vicinity of MLI
otherwise mainly MVFR cigs expected overnight into Thu AM. An
upper level disturbance will pass quickly late tonight until mid
morning Thu bringing light snow to portions of northeast IA, with
DBQ having best chance of some light accums where IFR is possible
with the snow. Meanwhile, CID will likely be on the southern
fringe of any snow. Further to the south some light showers or
pockets of light freezing rain/drizzle and perhaps some sleet will
be possible at MLI and BRL between 08/09z until around 12z, and
have handled with vcsh wording for now. In wake of disturbance
expect conditions to return to VFR by late Thu AM into early PM.
Northerly winds will be sustained around 10-15 kts for most of the
period and gust at times 20-25+ kts overnight through mid morning
Thu.

&&

.HYDROLOGY...
Issued at 335 AM CST Thu Jan 12 2017

An ice jam remains in place just downstream of Burlington, Iowa,
along the Iowa side of the river channel on the Mississippi. This
jam is producing minor to moderate flooding from near Fort Madison,
IA up to Gladstone, IL with high water upstream to Keithsburg, IL.
This situation is expected to persist for the remainder of the week.

Another ice jam has formed just downstream of Joslin that is causing
minor flooding upstream. Ice action will continue to produce rises
on a few other forecast points as well, such as further downstream
on the Rock at Moline.

&&

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

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...12
AVIATION...McClure
HYDROLOGY...12



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