Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 131727
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1127 AM CST Fri Jan 13 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 327 AM CST Fri Jan 13 2017

1041 hPa high pressure located over east central MN and NW WI this
morning lead to temperatures from 4 degrees across the northern
CWA to upper teens across the southern CWA. High level moisture
moving into the area led to a cloudy night across the area.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 327 AM CST Fri Jan 13 2017

Short term forecast focuses on a quiet day today with the
introduction some freezing rain across the very south tonight.
Impacts from any freezing rain would be very minor in nature.

Zonal H5 flow is expected to continue across the area today as SW
flow tries to move into the area. With surface high pressure north
of the area, surface winds will be easterly in nature. This
easterly wind and H5 flow will drive the weather tonight. Latest
suite of guidance has continued the trend of lower POPs and no QPF
for the area through 12z Saturday. With the exception of the NAM,
no QPF is forecast within the CWA. Hires CAM guidance also keeps
the precip south of the area. With the dry easterly flow this
makes sense for the area. However, as a nod to the NAM have
maintained schc and low end chc pops tonight. These pops may be
able to be removed by later shifts. Regardless, any impacts would
be minor if the freezing rain occurs.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 327 AM CST Fri Jan 13 2017

An exceptionally challenging storm is expected from very late
Saturday night through Monday. This storm`s track has slowed a bit
from previous runs. The precipitation type for this event will
change from snow/sleet/freezing rain to all rain, and we`re
confident in that.  The timing of this change over is poorly
confident. We have several complicating factors in play.  Initially,
mid level saturation is lacking despite good warm advection forcing.
The ice introduction aloft is not there due to this mid level dry
air. Thus, the initial precipiation very late Saturday night and
Sunday morning in the south should be freezing rain/freezing
drizzle. However, as the morning evolves ice is introduced aloft
rather rapidly. This should lead to a period of mixed sleet/snow
before changing over to freezing rain as the column warms. By Monday
morning, temperatures and dewpoints will climb above freezing from
south to north. Thus, freezing rain will change to rain.

The bulk of the precipiation for all areas should fall as rain with
this storm.  That said, a watch expansion was needed to collaborate
the threat for icy roads...and a possible low end ice storm for the
southwest 2/3rds. As far as watches go, this one is far out, and
lower confidence than normal, but with the regional focus on
outlining this threat, we have issued it.

I will include lower than normal confidence in the WSW and HWO
today. Rain amounts should be generally 0.75 or less for the event
given the delayed onset and potential for more scattered amounts
after Monday Noon.

Farther out, our forecast is a blended solution of mild conditions
in broad southerly flow. The pattern more typical of late Feb/March
than mid January after Tuesday. Moisture should return for showers
by late week.

ERVIN

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
ISSUED AT 1122 AM CST Fri Jan 13 2017

VFR conditions will be seen through 00z/15 with arctic high
pressure over the Great Lakes and a storm system moving from
Kansas into southern Illinois. There are questions as to how far
north a band of FZRA/PL will get after 00z/14. KBRL may see VCSH
of PL or FZRA 06z-12z/14. If the air is drier than expected then
KBRL would not see any precipitation.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Storm Watch from Sunday afternoon through Monday morning
     for Benton-Buchanan-Cedar-Clinton-Delaware-Dubuque-Iowa-
     Jackson-Johnson-Jones-Linn-Muscatine-Scott.

     Winter Storm Watch from Sunday morning through late Sunday night
     for Des Moines-Henry IA-Jefferson-Keokuk-Lee-Louisa-Van
     Buren-Washington.

IL...Winter Storm Watch from Sunday afternoon through Monday morning
     for Henry IL-Rock Island.

     Winter Storm Watch from Sunday morning through late Sunday night
     for Hancock-Henderson-McDonough-Mercer-Warren.

MO...Winter Storm Watch from Sunday morning through late Sunday night
     for Clark-Scotland.

&&

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Ervin
AVIATION...08



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