Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 142033

Area Forecast Discussion
National Weather Service Quad Cities IA IL
333 PM CDT Wed Mar 14 2018

Issued at 330 PM CDT Wed Mar 14 2018

18Z surface data has a dry cold front from northeast Wisconsin into
central Iowa. Dew points were in the teens across the Great Lakes
with 20s and some 30s from the western Great Lakes into the


.SHORT TERM...(This Evening through Thursday)
ISSUED AT 330 PM CDT Wed Mar 14 2018

Late this afternoon through Thursday Assessment...
very high confidence

Quiet and dry conditions will be seen from late this afternoon
through Thursday as high pressure builds into the Midwest.
Temperatures should average close to normal.

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 330 PM CDT Wed Mar 14 2018

Thursday night into Friday...Latest suite of 12z run models suggest
a rather deep sfc low center(possibly nearing 990 MB) settling
somewhere from north central to northwest KS or into far southwest
NE by 12z Fri. A dry ridge center will look to maintain for awhile
acrs the western GRT LKS, developing a dry LLVL easterly fetch of 10-
20 KTs acrs the local area by late Thursday night into Friday. This
flow to battle elevated precip wings whirling in from the west off
the low center, and although we have light POPS in the far southwest
before 12z Fri, could see the precip being held aloft in virga form.
The latest run medium range models then continue to vary rather
largely with sfc low evolution through Fri evening, with the GFS
having the center juts southwest of Omaha by 00z Sat, the ECMWF acrs
northeastern KS, and the GEM lingering back acrs central NE. With
the stiff drying easterly flow, see only the southwestern third to
half of the CWA getting in on precip through 00z Sat, and the longer
it holds off and takes to saturate a dry 950 MB to H6 MB, the more
it may be mainly rain, although brisk evapo-cooling fetch with the
ongoing saturation make for eventual sleet or sleet mixed with rain
profiles. A few models even produce a bout of light freezing rain
acrs southeast IA into west central IL Fri morning if the precip can
make it to the surface that early(questionable), but ground temps
and sfc layer ambient air may be marginal for much of any icing.
Continued downtrend with Friday highs with values only around 40 or
low 40s...some areas held in the upper 30s.

Friday night into Saturday...Both the 12z GFS and ECMWF roll the sfc
low toward or northeast of the St Louis area by Sat morning,
filling/dampening some on the way. Current trends suggest the main
def zone precip shield off the low will move acrs the DVN CWA Friday
night mainly from 00z to around 09z Sat morning, and then start to
diminish by early Sat morning into dawn. Fcst soundings of the
models all over the place and vary in QPF amounts, but a wintry mix
of some type looks on track. The model blend and general top-down
cooling profiles make for rain changing back over to a rain-sleet
snow mix along and north of a Cedar Rapids-to Quad Cities-to
Princeton IL by 8 PM-10 PM CDT Fri evening, with mainly rain mixed
with some sleet hanging on to the south of I80 for much of the

With brisk east-to northeast sfc flow(depending on eventual low
track) and drier sfc wet bulb temp feed, there may be a ribbon of
freezing rain and sleet developing a tier of counties along and
north of I80 from late evening toward midnight, and settling south
along and south of I80 down toward Burlington into early Sat
morning. This while areas along and north of Hwy 30 change over to
wet snow and sleet with at least some light accumulations up to an
inch possible by 12z Sat morning. As for potential ice accums, a
light glaze of up to a tenth of an inch possible by Sat morning,
although ground temps may make it marginal and more light glaze
occurs on elevated objects. There may be extended periods of sleet
taking away from freezing rain and snow accumulation potential, with
sleet accums of a tenth or two or even half inch in spots. Of course
these details very subject to change, but there may be the eventual
need of a Winter Weather Advisory for portions of the area Friday
night if model trends continue.  The precip will look to wind down
probably quicker than the models give it credit for by Saturday
morning. Clouds and recent precip on/in the sfc will make for highs
in the low to mid 40s.

Sunday through next Wednesday...A dry and milder Sunday still looks
on track, before the next in line low pressure system rolls
somewhere acrs the Midwest from Sunday night into Monday. This
system may be similar to the Friday night one with a wintry mix
possible, but again medium range model variance make for low
confidence on how far north or south this system will track, as well
as thermal profiles for precip types and amounts for early next
week. But rather high POPs will have to ride for Monday taking into
account the latest model trends.  ..12..


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1220 PM CDT Wed Mar 14 2018

VFR conditions will be seen through 00z/16. A dry front will move
through eastern Iowa and northern Illinois by 03z/15 followed by
high pressure.




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