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
FXUS63 KDVN 062336

Area Forecast Discussion
National Weather Service Quad Cities IA IL
536 PM CST Wed Dec 6 2017


Issued at 336 PM CST Wed Dec 6 2017

Steady westerly winds continued today with E Iowa/NW Illinois
situated between a large high over the Northern Rockies and a 985mb
sfc low over the Hudson Bay region. Gusts today were between 20-30
mph. Otherwise, aside from areas of flurries and sprinkles across
the southern CWA, the weather was quiet with temps in the 30s.


.SHORT TERM...(This Evening through Thursday)
ISSUED AT 336 PM CST Wed Dec 6 2017


Brief period of showers this evening across the far SW forecast
area as a zone of 925-850mb frontogenesis slides through on a WNW
to ESE trajectory.

Temps are in the upper 30s in this area right now, so the
showers could come in the form of rain and snow. As temps cool
past sunset the trend would be toward all snow.

For areas that receive showers, brief reductions in visibilities can
be expected, with possibly a dusting of snow. The sfc observation
in Atlantic, IA reported a visibility down to a half mile shortly
after 2 PM in the heavier snow showers. For our CWA, the best
chance for scattered rain and snow showers is SW of a line from
Keosauqua to Keokuk. Uttech


After a cold start in the teens and wind chills in the single
digits, we`ll only manage to reach the 20s for highs. Forecast 850mb
temps around -13 C are about 5 C colder than they were today
(Wednesday), which is certainly in line with Thursday being the
coldest day of the week. Luckily, the winds won`t be as strong,
generally between 10-20 mph. Temps then fall back into the teens
at night.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 336 PM CST Wed Dec 6 2017

Friday and Saturday

After a quiet day in the 30s, attention turns to a clipper system
that will be diving southward out of north-central Canada, which
could be the first +1" snowfall for parts of the CWA. And the
first event with snow accumulation on the roads.

The strength and expansiveness of the upper ridge over western North
America will actually guide the clipper all the way north of
Alaska across the southern Arctic Ocean before diving abruptly to
the SSE into the north-central U.S.

Current model blend forecast has around 1" of snow across the far
eastern counties with a taper to a dusting near the Quad Cities.
The most likely timing is either late Friday night or early
Saturday morning. Since this is several days away and swaths of
snow associated with clippers are relatively narrow, there is
still plenty of time for the forecast details to change. In
addition to the snow, 20-30 mph NW winds later Saturday morning
into the afternoon would lead to some minor drifting of the
powdery snow.

The GFS and NAM are on the wetter side with 0.15-0.20" of QPF across
the far E/NE. SLRs of 15-20:1 would yield snow amounts closer to
2-3" there. However, due to model discrepancies, do not have the
confidence in these solutions to trend any higher than the current
forecast which is around 1" in the east.

Sunday On

Brief warm up Sunday and Monday into the 30s and possibly 40s SW/S.
For early next week, trended max temps below the SuperBlend because
the bias corrected models seem way too warm and are likely
influencing the blend. Clippers are possible from time to time
next week, but confidence on timing and exact tracks of the
individual storms is low at this lead time. Uttech


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 531 PM CST Wed Dec 6 2017

An upper level disturbance and attendant surface cold front will
pass through the region tonight. This will be accompanied by a
period of low clouds with low VFR and MVFR ceilings along with
bouts of light snow and flurries with visibilities mainly 3-6sm
from roughly 02z through 09z from north to south. Winds will
become gusty from the northwest at 15 to 25 kts during this time
as well. High pressure will build in on Thursday bringing mainly
clear skies. Winds will remain gusty at times at 10-20 kts on




LONG TERM...Uttech
AVIATION...McClure is the U.S. government's official web portal to all federal, state and local government web resources and services.