Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDVN 131725
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1125 AM CST Sat Jan 13 2018

...18Z AVIATION UPDATE...

.SYNOPSIS...
Issued at 318 AM CST Sat Jan 13 2018

Arctic high pressure remains entrenched over the upper midwest with
generally fair skies and temperatures mostly in the single digits.
Northwest winds will continue at 5 to 15 mph becoming light tonight
with low wind chills. A disturbance will arrive late Sunday bringing
light snow accumulations mostly in the 1 to 3 inch range. Then arctic
air will continue into midweek with well below normal temperatures.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 318 AM CST Sat Jan 13 2018

Short term forecast confidence assessment...good or above average.
Quiet weather with little sensible weather issues. Area highs and
lows should be within 3 degrees of forecast with mostly clear to
clear skies.

Today...generally sunny skies with, as mentioned above, northwest
winds of 5 to 15 mph. Wind chill advisory will expire at 9 AM in
far northwest. Area highs 8 to 18 degrees, or over 15 degrees below
normal.

Tonight...generally clear with light winds. Area lows tonight should
be mostly 5 below to 5 above or once again, over 15 degrees below normal.
Some low lying areas may experience lows 2 to 3 degrees colder.

.LONG TERM...(Sunday through Friday)
ISSUED AT 318 AM CST Sat Jan 13 2018

Potent clipper system to bring accumulating snow Sunday into Monday.

Sunday through Monday: Global models consistent 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. 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 1 to 4 inches
across the cwa.

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 due to the combination of the cold, the
snow and blowing snow. Highs will be in the single digits and teens.
A wind chill advisory will need to be issued for most of the cwa on
Monday.

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.

Wednesday through Saturday: A warming trend as the upper flow
becomes zonal allowing for Pacific air to arrive. Highs should push
well into the 30s to lower 40s by Friday, and well into the 40s on
Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
ISSUED AT 1126 AM CST Sat Jan 13 2018

Cold high pressure moving over the region will provide VFR
conditions throughout with mostly clear skies and light surface
winds. Winds will back around to the south Sunday morning ahead of
a clipper system that will bring snow late Sunday through Sunday
night, just beyond the current forecast period.

&&

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

$$

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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.