Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 052344

Area Forecast Discussion
National Weather Service Quad Cities IA IL
544 PM CST Mon Dec 5 2016


Issued at 300 PM CST Mon Dec 5 2016

What a difference snow cover makes! Across the dvn cwa low stratus,
fog and temperatures in the 30s due to snow melt moisture trapped
below an inversion at 900 mb. In western IA and into KS with bare
ground and sunshine readings were in the 50s!

Skies were clearing in portions of our far sw counties but expect
this to fill back in with stratus by late afternoon after peak heating.


.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 300 PM CST Mon Dec 5 2016

Forecast focus on clouds, fog and possible light pcpn mix followed
by a cold front on Tuesday.

Tonight: With snow melt into this evening low stratus and areas
of fog (advection) on southerly winds will continue through tonight.
The question will be how widespread and dense the fog may get overnight
so will let the next shifts monitor the trends and any need for a
dense fog advisory. Some sensible weather guidance suggest dense
fog others do not. A trough digging southeast into the Midwest
later tonight, and deepening cyclone in northern MN, will bring a
band of forcing into our far nw cwa. However, moisture is limited
so will continue slight pops for a mixture of light precipitation.
Minimum temperatures should range from the upper 20s to lower 30s.

Tuesday: This forcing will lift quickly northeast away from the
cwa early in the morning followed by a cold front pushing southeast
across the cwa. Brisk west to northwest winds and gradually falling
temperatures can be expected, especially in the afternoon. Highs
will be in the 30s before beginning to fall. We will mention areas
of fog in the morning ahead of the front. However, with the colder/drier
airmass and brisk winds with the passage of the front, any low stratus
and fog should scour out rather quickly.

.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 300 PM CST Mon Dec 5 2016

Tuesday Night: Cold air advection with westerly sfc winds and a
period of clear skies will allow temps to fall into the 20s and 10s.
Early morning wind chills on Wednesday are forecast as cold as the
single digits roughly in the counties along and north of I-80 with
teens further south.

Wednesday and Wednesday Night: 850mb temps continue to fall dropping
to -10 C by the afternoon. Expecting an increase in cloud cover from
the early morning on. Current forecast highs are in the mid 20s
north to lower 30s south. For precipitation, have a slight chance
for light snow or flurries (15-20%) across the southern tier or two
of counties. GFS/NAM are completely dry. If ECMWF/Canadian trend
drier, will be able to remove chances. For now, looks like a dusting
or nothing. Overnight lows from model consensus are in the teens and
min wind chills are near zero.

Thursday and Friday: Cold to round out the work week in the upper
teens to mid 20s (850mb temps -12 C to -14 C and 1000-500mb
thicknesses between 510-516 dam); coldest overnight to morning wind
chills are forecast near zero. Cyclonic mid-level flow, steep low-
level lapse rates, and with vorticity maxima rotating through, could
have periods of flurries or light snow showers. However, forecast is
dry right now because threat for measurable precipitation, 0.01
inches or more, is low.

Friday Night: Deep warm air advection/isentropic lift could initiate
a band of light snow in the Upper Midwest. Of course, model
consistencies exist at this lead time. POPs are low in the 20-30%
range, favoring our north half. Overall, moisture is limited in
the models for this period.

Saturday and Sunday: Another shortwave may impact the Midwest. The
GFS/GFS ensemble/Canadian are cold enough for mainly snow, the ECMWF
is the outlier being warmer and further north with the precip. Stay
tuned to future updates as a lot can change with respect to
strength/timing/impacts. Model blend temps warm into the 30s CWA-
wide by Sunday. Uttech


.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
ISSUED AT 544 PM CST Mon Dec 5 2016

Widespread IFR to LIFR conditions due to low ceilings and fog are
expected to further deteriorate overnight. Fog is expected to
thicken this evening, and with similar conditions that lead to
widespread, persistent VLIFR conditions last night through much of
Monday, will have a pessimistic transition to 1/4SM and 100 foot
ceilings in the latest forecasts by midnight. Little improvement
is expected overnight until a cold front sweeps through the
region after 12z Tuesday morning. This will likely bring a rapid
improvement to VFR conditions and winds shifting to the west and
gusting 20 to 25 knots through the afternoon.




LONG TERM...Uttech
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