Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 230947

Area Forecast Discussion
National Weather Service Quad Cities IA IL
347 AM CST Mon Jan 23 2017

Issued at 330 AM CST Mon Jan 23 2017

As of 3 AM...First night in a while without dense fog in E
Iowa/NW Illinois. Widespread stratus clouds are inhibiting sfc
cooling enough to prevent formation of dense fog. There are,
however, areas of patchy fog. The lowest reported visibility in
the CWA is near 1 mile at Independence, IA. Most other locations
are between 2-5 miles. Sfc temps are ~5 F degrees warmer than
yesterday morning, holding steady in the mid to upper 30s.


.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Mon Jan 23 2017

Today and Tonight:

"Mild" late January temps to start the work week - upper 30s far
W/NW to lower 40s elsewhere today, then around 30 F tonight.

Low-level moisture, trapped under an inversion near 850mb, has no
way of advecting out of the area today. As a result, the cloudy
skies will continue. Aside from some patchy areas of drizzle this
morning, it will stay dry because there is no upward motion in the
sfc-850mb saturated layer.

Low-level clouds may scour out overnight as sfc high gradually
lowers height of the inversion through subsidence. But as this
happens, mid-level clouds will overspread the region from the SW,
mitigating widespread fog potential. Uttech

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 330 AM CST Mon Jan 23 2017

Focus remains on a low pressure system that is forecast to lift
east-northeast through the forecast area late Tuesday and Wednesday.
There is now enough consistency from run to run among operational
models indicating the bulk of the snow from this system will track
northwest of the forecast area and winter storm watches are in place
across northern IA and southern WI. Colder weather is on track to
follow late week into the weekend, when temperatures should return
closer to late January normals.

At 00z, upper air analysis showed a very energetic pattern over the
U.S. with a 150 kt plus 300 mb jet across CA and NV around the base
of an upper low off the Pacific NW. A ridge was downstream over the
northern Rockies, while an intense upper low was over the southeast.
The advancing upper jet from the Pacific is progged to spin up a
surface and upper level low over the Central Plains Tuesday, which
is depicted spreading E-NE across KS/NE through central or southern
IA Tuesday night into the Great Lakes Wednesday. The ECMWF and
Canadian remain slightly further south and nearly 6 hours slower
with the progression of this system, which would keep precipitation
going longer over the area Wednesday. For now, the forecast remains
closest to a blend of the slightly faster GFS/NAM.

Ahead of the low, strong warm advection develops on 40 to 50 kt
winds at 850 mb, spreading moisture and steep lapse rates over the
area during the day Tuesday. At the low levels, brisk east to
southeast surface winds will develop, with initially dry air in that
layer possibly leading to a brief mix of snow in the far northwest
if precipitation develops early enough in the day before
temperatures climb well into the 30s and 40s. Otherwise, rain
showers should be the rule and at least isolated rumbles of thunder
possible with the elevated warm front lifting through. The strongest
forcing ahead of the upper low and jet exit region suggests the most
widespread showers and possible thunderstorms Tuesday evening over
east central IA into NW IL. Current QPF amounts of a few hundredths
to a quarter inch may be too low. This is followed by the passage of
a dry slot that will end measurable precipitation across the south
toward morning. Wednesday, colder air in-wrapping behind the system
should transition rain or drizzle to a rain/snow mix, then all snow
from W-NW to E-SE during the day with temperatures falling into the
lower to mid 30s by evening. Considering the lack of cold air in
place and unfavorable surface low track, at this time, any snowfall
looks to be limited to 1 to possibly 2 inches along the mainly the
IA highway 20 corridor. Snow showers will be possible in the
cyclonic flow behind the exiting system Wed night. Without a strong
influx of cold air, temperatures are expected to only cool into the
mid and upper 20s.

Thursday through Sunday still looks to be a cooler, but more
seasonable period with highs limited to the mid 20s to mid 30s. A
rather active N-NW flow aloft aloft around a large eastern Canadian
upper low will provide a threat of several rounds of very light snow
or flurries.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
ISSUED AT 1141 PM CST Sun Jan 22 2017

Stratus encompasses much of the Northern Plains and Upper Midwest
and don`t foresee much change next 24 hours given fairly light
flow, as weak high pressure builds toward the region. As a
result, expect generally MVFR to IFR conditions through the TAF
cycle as moisture remains trapped beneath subsidence inversion
and winds remain light from NNW at 4-10 kts. Weak 850 mb cold
advection and a passing mid level wave may aid in patchy to areas
of drizzle forming overnight through mid morning Monday.


Issued at 330 AM CST Mon Jan 23 2017

Illinois Tributaries: Levels continue to rise on the Pecatonica
River at Freeport and minor category flooding is forecast for the
next several days. On the Rock, levels continue to recede fairly
rapidly with gages no longer exhibiting indications of ice action
over the past 24 hours. Joslin should drop below flood stage today,
while minor flooding is forecast to continue through the week at
Moline, but current trends suggest stages could drop sooner.

In Iowa, minor flooding continues along the Cedar River at
Conesville due to ice action. The forecast currently keeps the river
above flood stage through the week due the uncertainties of ice
action. A flood watch was issued last evening for Marengo on the
Iowa, where upstream ice action well upstream may result in levels
climbing above flood stage as early as late Monday night.




LONG TERM...Sheets
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