Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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189
FXUS63 KDVN 150512
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1112 PM CST Sat Jan 14 2017

...AVIATION UPDATE...

.UPDATE...
Issued at 908 PM CST Sat Jan 14 2017

No significant changes to previous forecast needed based on latest
model runs and forecast soundings. Winter Weather Advisory remains
in effect Sunday into Monday morning for all but the far northeast
counties. Anticipating snow/sleet/ice accumulations will pose some
travel difficulties, but will not be enough to cause significant
impacts to trees and power lines.

&&

.SYNOPSIS...
Issued at 328 PM CST Sat Jan 14 2017

1035mb sfc high over the Midwest keeping the area dry and
seasonably cool this afternoon in the 20s to lower 30s. The 850mb
0 C isotherm is analyzed right through the central section of the
forecast area; a sign of "warm air" aloft and potential for mixed
precip with the next weather system set to move in from south to
north mainly Sunday afternoon into Sunday night.

&&

.SHORT TERM...(This Evening through Sunday)
ISSUED AT 328 PM CST Sat Jan 14 2017

This Evening and Tonight:

With sfc high overhead, it will be dry and winds will be light.
Lows are forecast in the low 20s south to low 10s far north.

Sunday Morning through Sunday Afternoon:

Winter Weather Advisories are in effect across portions of the
southern forecast area. Please see advisory product for county
specific beginning and ending times and expected wintry precip
amounts.

Trend in the models is for slower arrival of light mixed precip.
Best chance for measurable precip from the mid morning through
the afternoon is across the southern tier of counties: Scotland,
Clark, possibly southern Lee, Hancock, and McDonough. Have 20-40%
PoPs further north toward highway 34 (west of Galesburg), but low
confidence on precip actually occurring in this region due to
degree of dry air that must first be saturated.

Precipitation Type:

In the area where precip is most likely, forecast soundings and
time-heights indicate increasing weak omega, collocated with
increasing positive sfc-700mb theta-e advection, and max wetbulb
temps aloft squarely in the 1-3 C wintry mix range. General
thinking is for showery precip starting as a light snow/sleet/FZRA
mix to quickly transition to a mix of light sleet/FZRA or just
straight light FZRA. Again, this is referring to the far southern
CWA through the late afternoon.

Potential Impacts:

Be prepared for slippery roadways and other paved surfaces from
a combination of sleet and a light glazing of ice.

.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 328 PM CST Sat Jan 14 2017

Forecast focus is on the early week storm system slowly lifting up
from the southwest, spreading a wintry mix, freezing rain, rain and
even possible thunderstorms before exiting Tuesday.

Headlines: Will be rolling the winter storm watch over to a winter
weather advisory, beginning in the south midday Sunday, the evening
in the central and north and ending over the entire area Monday
morning. The precipitation looks likely to start out as snow or
sleet, transitioning to freezing rain for a period before warm
advection transitions the precipitation to all rain in a south to
north fashion late Sunday night into Monday morning. While snow and
sleet accumulations will be light, ice accumulations from a light
glaze coating northeast to just under a quarter inch in the far
southwest, will combine to create a period of hazardous travel
conditions, especially overnight.

Latest forecast models were narrowing in on a more similar storm
track, lifting the surface low from OK Sunday night N-NE overhead
through east central IA Monday night. Saturation and precipitation
development continues to be delayed with subsequent model runs, due
to the anticipated slower timing of the upper level low lifting out
of the southwest and the effects of the dry low level easterly flow
out ahead over the local area. Moisture looks rather impressive with
the system, with a feed of high precipitable water pushing .75 to 1
inch or 200 to perhaps 300 percent of normal, fortunately reaching
the area with a warm enough column to support all rain Monday into
Monday night. Have introduced a slight chance for thunderstorms over
the southeast half late afternoon into Monday evening as mid level
thetae and temperature lapse rates are sufficiently steep, in
combination with strong forcing ahead of a compact vort max and
shortwave passing overhead.

Tuesday, will have to watch for a possible need to increase
precipitation chances, as hinted by the GFS, as there may be an
additional round of upper level forcing from a possible deepening
mid level shortwave in the northern stream that follows on the heals
of the exiting surface low. At this time, there is not much cold air
to follow to present much of a wintry precipitation threat.

Tuesday night through the rest of the week looks dry with above
normal temperatures under a split flow aloft that keeps arctic air
bottled up well to the north.  The next system arrives toward the
weekend with low chances for what looks like rain Friday night
into Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
ISSUED AT 1103 PM CST Sat Jan 14 2017

Have delayed timing of precip onset slightly through the day
Sunday. Now expect a -SNPL mix and MVFR cigs/vsbys around 21z at
KBRL, with a change to -FZRA around 02z. A wintry mix will
approach KMLI around 01z and KCID around 03z. KDBQ will likely
stay dry through 06z.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory from 9 PM Sunday to noon CST Monday for
     Benton-Buchanan-Cedar-Clinton-Delaware-Dubuque-Iowa-Jackson-
     Johnson-Jones-Linn-Louisa-Muscatine-Scott.

     Winter Weather Advisory from 3 PM Sunday to noon CST Monday for
     Des Moines-Henry IA-Jefferson-Keokuk-Van Buren-Washington.

     Winter Weather Advisory from 9 AM Sunday to 9 AM CST Monday for
     Lee.

IL...Winter Weather Advisory from 9 PM Sunday to noon CST Monday for
     Henry IL-Mercer-Rock Island.

     Winter Weather Advisory from 3 PM Sunday to noon CST Monday for
     Henderson-Warren.

     Winter Weather Advisory from 9 AM Sunday to 9 AM CST Monday for
     Hancock-McDonough.

MO...Winter Weather Advisory from 9 AM Sunday to 9 AM CST Monday for
     Clark-Scotland.

&&

$$

UPDATE...RP Kinney
SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...Sheets
AVIATION...RP Kinney



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