Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 120941
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
341 AM CST Fri Jan 12 2018

.SYNOPSIS...
Issued at 325 AM CST Fri Jan 12 2018

Arctic high pressure is moving into the upper midwest with clearing
skies and brisk northwest winds. Temperatures are in the single
digits to lower teens south and east. Northwest flow will continue
with arctic high pressure with a disturbance bringing chances of
light snow this weekend. Temperatures will be 15 to 20 plus degrees
below normal into the middle of next week.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 325 AM CST Fri Jan 12 2018

Short term forecast confidence assessment...fair to good or average
to above average due to little sensible weather issues. Main challenge
will be highs and lows which should tend to be mostly within 3 degrees
of forecast.

Today...mostly sunny and cold with brisk Northwest winds of 15 to 25
mph. Area highs will be in the teens to lower 20s far southeast. Area
wind chills will range from -10 to +5 degrees today.

Tonight...mostly clear and very cold with northwest winds of 5 to 15
mph. Area lows will fall to around 5 below northwest to upper single
digits far southeast with again very low wind chills of +5 to nearly
-20F far NW toward daybreak.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 325 AM CST Fri Jan 12 2018

Potent clipper system to bring accumulating snow Sunday into Monday.

Saturday and Saturday night: High pressure will bring clear skies
and cold temperatures to the area. Where there is snow cover in our
nw counties readings will be colder compared to the rest of the
area. Look for highs to range from the single digits nw to the teens
se. Lows Saturday night dipping to the single digits below zero nw
to the single digits above zero se.

Sunday through Monday: Global models similar in tracking a potent
clipper system into the Midwest. An impressive deepening upper level
trough will provide large scale ascent and strong dynamics. Models
develop a band of warm air advection snow across the area on Sunday,
then followed by the main snow event Sunday night into Monday
morning. While moisture is somewhat limited (mixing ratios of only ~
1.5 g/kg) SLR`s will be around 20:1 due to the very cold airmass in
place. In addition, forecast soundings indicate saturation and omega
in the DGZ with the potential for at least moderate snow and low
visibilities at times. At this point in the game accumulations
appear to be 2 to 4 inches in our northern counties, with up to one
inch in our south.

In the wake of the clipper, a strong 1052 mb arctic high will be
building southward into the northern Plains on Monday. A tight
pressure gradient will develop across the cwa creating strong
northwest winds gusting to 30 to 40 mph. This will easily cause
considerable blowing and drifting of the fluffy newly fallen snow.
Highs will be in the teens and 20s on Sunday but only in the single
digits and teens on Monday. At least a winter weather advisory will
be needed for this event, but if the system comes in stronger a
winter storm watch/warning may need to be issued.

Monday night and Tuesday: Another round of brutally cold
arctic airmass with 850 mb temperatures dropping to -20 to -25c.
With fresh snow cover expected I have lowered temperatures from the
consensus model by several degrees. Lows will be 5 below to 10 below
zero with highs of 5 to 15 above, but this still may be too warm.
Wind chills will dip to at least 25 to 30 below, possibly colder. A
wind chill advisory/warning will be needed for this scenario.

Mid to late next week: A warming trend as the upper flow becomes
zonal allowing for Pacific air to arrive. Highs should push well
into the 30s to around 40 by Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
ISSUED AT 1117 PM CST Thu Jan 11 2018

MVFR conditions in low clouds will give way to decreasing clouds and
return of VFR conditions overnight into Friday AM. Gusty northwest
to north winds of 10-20 kts expected through much of Friday, with
winds diminishing in the evening as high pressure begins to build into
the region.

&&

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

&&

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...Haase
AVIATION...McClure



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