Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 291759
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1159 AM CST Tue Nov 29 2016

...18z AVIATION UPDATE...

.SYNOPSIS...
Issued at 318 AM CST Tue Nov 29 2016

Early morning satellite imagery and obs show the dry slot has
overspread the area to the south of a filling low over southeast
SD. In the dry slot under generally clear skies, temperatures
are running above normal and in the range of the upper 30s to
lower 40s at 2 am, which is closer to typical daytime highs due
in large part to swly winds. SD low will continue to slowly fill
and slide east across MN next 24 hours ushering in colder air
tonight. Until then, we will reside in the "warm" sector for much
if not all of today, providing us with one last day of above normal
temperatures.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 318 AM CST Tue Nov 29 2016

Temperatures are the main challenge. From a distance today has one of
those looks of being above guidance for highs with swly winds and
mainly sunny skies. However, closer inspection leads to pumping the
breaks a bit. Anticipate some mid and high cloudiness to work across
our skies a bit later today, especially the southeast half or so
attendant to downstream sharpening of mid/upper level trough and
upper level jet (140+ kts) lifting from the Southern Plains to the
Ohio Valley. In addition, the models show the front and attendant
weak surface inflection and pseudo triple point lifting up across the
cwa by 00z. This may lead to lessening of winds by afternoon decreasing
the mixing potential, which coupled with some mid/high cloudiness
and shortness of day precludes me from being overly aggressive with the
warm-up today. Nonetheless, today will be the last in the recent stretch
of generally above normal temperatures and blending observations from
yesterday and various 2m temp guidance leads me to general range on highs
from the upper 40s to mid 50s, with a few upper 50s possible far south/east
depending on amount of solar insolation.

Tonight, the front looks to exit by late evening ushering in colder air
within strengthening 925-850 mb caa. This will also be accompanied by
stratus from west to east, likely arriving after midnight and possibly
closer to daybreak over the far eastern cwa. Just looking at temps early
this morning in similar airmass supports widespread lower 30s for lows.
Shallow nature of low level moisture and lack of saturation in -10c to -20c
layer precludes any mention of flurries.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 318 AM CST Tue Nov 29 2016

An upper level disturbance on the back side of the departing storm
system will rotate through the area Wednesday/Wednesday night.

Initially, Wednesday morning will start out dry. However, by mid to
late morning a mix of rain/snow showers will move into the northwest
quarter of the area as increased forcing acts upon the limited
moisture.

A shallow layer of warm air at the surface should turn any mix over
to all rain showers Wednesday afternoon for areas along/north of I-
80. However, I would not be surprised if a mix of rain/snow showers
continues into the afternoon.

A mix of rain/snow showers will continue into Wednesday evening for
areas along/north of I-80 as the disturbance moves into the Great
Lakes. After midnight, some lingering rain/snow showers will still
be possible in the highway 20 corridor.

Since the ground is still well above freezing, no accumulation of
snow is expected Wednesday and Wednesday night.

Thursday/Thursday night another upper level disturbance will move
from Minnesota into Wisconsin. With the better forcing/moisture
north of the area, quiet and dry conditions should be seen.

Friday on...

The model consensus has quiet and dry conditions Friday through
Saturday as high pressure moves through the Midwest. Temperatures
should be close to normal. Attention then turns to the approaching
storm system for the second half of the weekend.

Saturday night into Sunday night a storm system will move through
the Midwest. However, there are disagreements among the models as to
where this storm system will track. The GFS/DGEX models have the
system much further south leaving the area dry. The CMC-global and
ECMWF have the system further north bringing precipitation to the
area.

The current model consensus has a dry Saturday evening, then slight
chance pops south of an KOTM to KGBG line late Saturday night. For
Sunday the model consensus has slight chance pops along and east of
the Mississippi. Sunday night the model consensus has slight chance
to chance pops for all but the extreme western areas.

The track and timing of the storm will determine the eventual
precipitation type. Right now it looks like a rain/snow mix at night
with all rain during the day on Sunday. Again, since the ground is
well above freezing, any snow would melt on contact.

The model consensus has mainly dry conditions for the area on Monday
as high pressure quickly moves through the Midwest. However, some
model solutions are indicating another storm system moving through
the area Monday night into Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1146 AM CST Tue Nov 29 2016

VFR afternoon with southwesterly sfc winds of 5-15 KTS. Then will
have to time the MVFR deck of wrap around stratocu currently acrs
NW IA/MN this evening and into the overnight. CID and DBQ will be
first t get under the deck from the northwest by mid evening.
Lighter southwest winds 5-10 KTS tonight, becoming west to southwest
and increasing to 10-15 KTS by late Wed morning. Cigs will look to
lower into the lower MVFR category especially north of I80 as Wed
morning progresses, and light precip of wet snow or a rain-snow
mix may try to get into the VCNTY of CID and possibly DBQ by late
Wed morning.   ..12..

&&

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

$$

SYNOPSIS...McClure
SHORT TERM...McClure
LONG TERM...08
AVIATION...12



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