Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 111152
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
552 AM CST Wed Jan 11 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CST Wed Jan 11 2017

Fast zonal flow is pushing high pressure rapidly east with considerable
mid/high clouds moving back in with next frontal wave to arrive by mid
day. Temperatures are stalled in the 20s across the region. Pressure
falls are significant to our west and moisture pooling along convergence
zone supports spotty light precipitation may develop along and behind
the front in the area by late morning and then along weak surface low
by late afternoon and evening.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Wed Jan 11 2017

Short term forecast confidence assessment...fair or average with question
of coverage and type of spotty, very light precipitation. Trends support
amounts of a trace to a few hundredths all but far SE later today and
tonight which should all be liquid. Amount of low level moisture later
today may be overdone behind front with profiles more supportive of
drizzle and freezing drizzle far north than rain or freezing rain.

Today...Decent gradient across the region with highs in the lower 30s
NW to around 50F far SE as next frontal system arrives. Temperatures
in the north behind next front may slowly fall in the afternoon hours.
Any areas of ice behind the front will be trace to very light with almost
all areas getting above freezing for a few hours before cooler air arrives
by late morning. Still favorable for need to public be aware of slick
conditions in areas that receive light freezing rain or drizzle. POPS
are generally in the 20 to 40 percent range with amounts below to well
below 5 hundredths except far SE where a tenth or so of rain may occur.

Tonight...any precipitation should slide to the east by the overnight
hours with a light wintry mix possible along and north of I-80 corridor
before precipitation ends. Any ice once again suggested to be very
light with limited if any impacts at this time. Cold air advection will
see temperatures fall to near 10 above far NW to the mid 20s far SE
as cold high pressure moves in despite mostly cloudy to cloudy skies.

.LONG TERM...(Thursday through next Tuesday)
ISSUED AT 330 AM CST Wed Jan 11 2017

Thursday and Friday...00z run models in general agreement of
building strong cold core Canadian high down acrs the northern
plains and into the GRT LKS this period. Will have to walk out
lingering precip moving along southward pushing llvl baroclinicity
Thu morning...with changing thermal profiles suggesting freezing
rain mixing with sleet in the far east and southeastern CWA, and a
swath of light snow moving east in deeper cold air north of I80.
Both precip zones expected to be on the light side but still may
produce some localized slick spots. Then clearing and cold later Thu
into first part of Fri. Single digit lows north of I80 Thu night
and wind chills may approach 15 below Fri morning northwest of the
CID to DBQ areas.

Latest run medium range solutions dig a L/W trof and cut-off upper
low acrs the northwestern Baja of CA By Fri evening, with
tightening llvl thermal gradient and amplifying southwesterly
steering flow from the southwestern CONUS...up along and north of
the OH RVR Valley. Latest lift, thermal profiles and initial wave
propagation along the flow steering zones suggest mainly a few
bands of light snow or flurries scooting acrs the CWA from west-to-
east later Fri afternoon and into the evening. Light snow accums
possible north of I80 and especially north of Hwy 30 by Midnight.
The real mess/icing on the latest solutions take aim to the south
from OK, to central/southern MO and southern IL through Sat
morning. But will still have to carry at least CHC POPs for some
of this activity bulging up acrs the southern CWA after midnight and
into Sat morning in the form of sleet and snow changing over to a
sleet-freezing rain mix with at least a light glaze possible
especially along and south of the Hwy 34 corridor.

Saturday and Sunday...The latest run 00z medium range models,
concentrating on the GFS and ECMWF, are slowing and adjusting
south with the first wave of energy lifting out of SW CONUS upper
trof and toward lingering cold dome acrs the upper MS RVR Valley
and GRT LKS. Expect more changes and turns with the additional runs
over the next 24-48 HRS, but for now the latest runs now suggest
that after what can make it into the southern CWA Sat morning, the
rest of the day and much of Sat night may now be dry while the ice
storm continues acrs the southern plains to northern OH RVR Valley.
But again for some continuity, will have to keep at least CHC POPs
in the south for much of Sat. Late Sat night into Sunday morning the
models(especially the 00z ECMWF) suggest a better LLJ, warming aloft
and moisture push to the north may bring a wintry mix into the
southern CWA up to HWY 34 again.

 The upper low will look to roll into the southwestern plains into
Sunday night, effectively really sharpening up/amplifying upper
ridge axis acrs the northern and central MS RVR valleys. This
combined with ongoing east to northeast fetch from GRT LKS lower
level high pressure system may act as a precip inhibitor as it tries
to creep north Sunday into Sunday evening. The new ECMWF is more
bullish with this aspect and has just a few rounds of light wintry
mix in the south until better saturation and storm lift out occurs
late Sunday night and especially Monday. The 00z GFS has freezing
rain and sleet spreading up acrs most of the area Sunday afternoon
and night. The northern fringe may be more snow and sleet. With
ongoing uncertainties, will reluctantly keep high CHC to likely POPs
going after 06z Mon.

Monday...this day continues to be shaping up as the main precip
occurrence, as both the sfc and upper low lift out unseasonably to
the west acrs the MO RVR Valley and western/central IA on Tue. Both
the latest GFS and especially the ECMWF show warming profiles as
Monday progresses, switching any mixed precip or freezing rain to
mainly regular rain as the day and Monday evening progresses. The
GFS holds on to icing the longest along the western HWY 20 corridor
Thru Mon evening. For now with complexity and ongoing model run-
to-changes, will limit the weather grids to just rain or rain-snow
mix later Mon into Tue. The latest model runs even suggest that
thunderstorms may not be all that far away from the CWA Mon night
into early Tue, with dry slot and milder air feed possibly
engulfing the CWA later Tue into Tue night.   ..12..

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
ISSUED AT 546 AM CST Wed Jan 11 2017

VFR conditions with cloudy skies from mid/hi clouds this morning will
lower from north to south this afternoon behind a cold front to MVFR
conditions with a chance of light rain or possibly freezing rain at
CID/DBQ terminals. At MLI/BRL terminals, MVFR conditions will develop
this evening behind the cold front with a chance of rain. Light south
or southeast winds will shift to the north at 10 to 15+ MPH behind the
cold front.

&&

.HYDROLOGY...
Issued at 330 AM CST Wed Jan 11 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 formed on Saturday January 7th downstream of Joslin,
IL on the Rock river. The current river forecast, which is based on
ice action as well as rainfall amounts from Tuesday through today,
pushes Joslin to flood stage later today. If rainfall is less than
forecast, then the river may remain below flood stage. But ongoing
ice action may overcome lower rainfall amounts and still push the
river into minor flood stage today. As a result with the
uncertainties of rainfall amounts and ice action, a flood watch
continues for around the Joslin area for now but a warning may be
needed later this morning.

&&

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

$$

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



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