Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 181200

Area Forecast Discussion
National Weather Service Quad Cities IA IL
600 AM CST Sat Nov 18 2017


Issued at 330 AM CST Sat Nov 18 2017

Patchy light rain continued across the area overnight, while
a few showers and thunderstorms occurred in parts of western and
central Illinois. Low clouds and light fog persisted overnight,
but an increasing north breeze helped keep dense fog from
developing. Early morning temperatures ranged from the upper 30s
near U.S. Highway 20, to the low 50s in the Keokuk and Macomb


.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Sat Nov 18 2017

Precipitation types/amounts, isolated storms, and strong
northwest winds are the main forecast challenges in the short term

The far southern counties are in the SPC day 1 marginal risk area,
with marginally severe hail this morning the main threat given
the steep mid level lapse rates and sufficient deep layer shear.

A band of strong frontogenetical forcing will sweep eastward
through the forecast area today. This system has a similar look to
the recent event, which resulted in brief periods of heavy
dendritic snow and minor accumulations on grass and elevated
surfaces. Snow growth/Fgen diagnostics and Bufr soundings support
a 1-2 hour period with sufficient dynamic cooling to result in a
change over to all snow across areas along/north of Interstate 80.
The complicating factor with this event will be an increasing
northwest wind gusting over 35 mph, which will contribute to brief
periods of lower visibilities. Will continue to highlight this
potential in the Hazardous Weather Outlook and later shifts can
elevate messaging as needed. Fortunately, road temperatures
remain too warm for any significant accumulations. Sustained wind
speeds and gusts are expected to remain slightly below advisory

Tonight, expect a clearing sky and a gusty northwest wind. Lows
will dip into the 20s, with wind chill values dropping into the
single digits and teens after midnight.

.LONG TERM...(Sunday through Friday)
ISSUED AT 330 AM CST Sat Nov 18 2017

Generally dry in the longer term with variable temperatures.
Sunday and Monday, dry northwest flow aloft will dominate the
central US. Warm low level advection Monday will push highs back
into the 50s. Tuesday, a dry cold front will bring another surge
of cold air, dropping highs back down in the 30s by Wednesday.

Next weather-maker is late Friday into Saturday as a cold front with
decent forcing crosses the midwest.  Have increased temperatures
Friday above guidance due to progged warm air aloft and strong warm
advection ahead of the front.


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
ISSUED AT 552 AM CST Sat Nov 18 2017

Broad area of rain and snow this morning will result in IFR to
LIFR ceilings and MVFR to IFR visibilities. Embedded thunderstorms
mainly south of Highway 34 may affect BRL, but are otherwise not
expected to impact area TAF sites directly. Precipitation will
exit the area from west to east during the afternoon, giving way
to clear skies. Surface winds from the north will become
increasingly gusty today, gusting to 45 mph by this afternoon and
shifting to northwesterly.




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