Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 120540
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1140 PM CST Wed Jan 11 2017

...06z AVIATION UPDATE...

.UPDATE...
Issued at 859 PM CST Wed Jan 11 2017

Main issue is with potential for snow accums north late tonight
into Thu AM... and light freezing drizzle/freezing rain with
icing rest of cwa.

Precip has largely ended outside of potentially a few patches of
freezing drizzle. Main focus rest of tonight is with next low
amplitude wave migrating east from NE with attendant mid level
Fgen and band of accumulating snow from central into northeast
NE. This forcing looks to shift e/ne overnight into Thu AM and
anticipate working across northeast IA and southern WI. Signal
is increasing for some accums of snow for northern cwa roughly
nw of CID-FEP line late tonight through mid morning Thu, and have
started trend of raising precip chances and adding light accums.
Believe around an inch or so is possible, but Fgen bands can be
tricky and forcing looks decent to where I wouldn`t rule out a
narrow stripe of 2+ inches in/near cwa.

Forcing from this mid level wave will likely also cause some
expansion of light precip late tonight into Thu AM across the
southeast 1/3 or so of cwa within strong elevated baroclinic
zone. Precip type quite challenging due to strong thermal gradient
but soundings support generally freezing rain and some sleet.
Should be fairly quick shot toward 09z ending by around 12z. In
between these two main areas of concern nw/se .... rest of cwa
will likely have some concerns for freezing drizzle.

In summary expect an increase of precipitation again late tonight
into Thu AM with main areas nw cwa and se cwa, with nw being
mainly snow with potential for accums to possibly 1-2" while
elsewhere freezing drizzle and light freezing rain could result in
slick conditions for the early morning commute. Not all model
guidance is in agreement on this scenario, thus the main reason
for not issuing any headlines at this time. Could have some
expansion of slick conditions for the early morning commute
tomorrow which may necessitate headlines.

&&

.SYNOPSIS...
Issued at 312 PM CST Wed Jan 11 2017

Low pressure has moved into central MO with 3 hr pressure falls
of 6 mb in northeast MO/western IL. 4 mb rises were noted in KS. This
indicates the surface low to track into western IL by this
evening. The arctic front has sagged southeast and early this
afternoon extended from southern WI to near the Quad Cities and
into KS. Precipitation was increasing across the dvn cwa and the
low levels were finally saturating.

A warm front was moving northward along I-70 in MO with temperatures
to the south in the 60s and 70s with dewpoints well into the 50s.
To the north of the arctic front readings were in the single digits
above and below zero. There is almost a 100 degree temperature
difference with the mid 80s in sw TX and 12 below zero in northern
MT! Closer to home temperatures ranged from the upper 20s at
Independence to the lower 50s in our far southern cwa.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 312 PM CST Wed Jan 11 2017

Headlines: Freezing rain advisory and dense fog advisory in effect
until 9 pm. There is the potential if freezing drizzle develops overnight
the advisory may need to be expanded southward and extended into
the overnight hours. Will pass concerns to the evening shift to
monitor precipitation trends.

Tonight: Rain or freezing rain will gradually end from southwest
to northeast this evening as the forcing lifts to our northeast.
The arctic front will continue to sag southward allowing the
colder/drier air to filter into the cwa overnight. Forecast
soundings indicate the potential for some freezing drizzle in
portions of the cwa overnight as we lose the mid/high level
moisture. Will let the evening shift monitor trends. As this
arctic airmass builds deeper into the cwa the dense fog in our far
eastern cwa should also dissipate later this evening. The surface
low should quickly move into OH by 12z (6 am). Minimum
temperatures will range from 11 at Independence to the mid 20s
from Macomb to Princeton, IL.

Thursday: Any lingering mixed precipitation should end in the
morning but forecast soundings indicate a strong inversion at
around 850 mb trapping low level moisture below. This should keep
our skies cloudy or mostly cloudy but temperatures will be quite
cold. Highs will range from the upper teens at Independence to the
upper 20s from Macomb to Princeton, IL.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 312 PM CST Wed Jan 11 2017

Active and unsettled weather to continue to the end of this week
and into next week. Challenging forecast in extended primarily due
to precip type issues Sunday.

Thursday night-Friday...strong 1045+ mb high to slide across the
upper Midwest, keeping the CWA dry. Friday lows to be in single
digits to lower teens. RH progs suggest high clouds early Friday,
but still may see some thinning of clouds. Wind chills also will be
between -5 and -15 degrees Friday morning, especially north of
highway 30.  All 12z solutions continue to show cut off upper low
rotating over the SW CONUS with a weak 500mb wave moving east over
the northern Plains. This wave may be able to generate enough lift
for flurries north of highway 20 although it will be moisture
starved. Rest of area to remain dry Friday.

Friday night-Monday...extremely challenging time frame with main
issue being precip type.  The track of surface low will be key as to
what type of precipitation, amounts, and when it will fall. 12z GFS
shows low track from northern TX to northern MO by 00z Tues whereas
the ECMWF has the low a little further east, tracking right over the
Quad Cities by 06z Tues. These solutions are further east than their
previous runs and the GFS Ensemble Mean is also further east than
its deterministic run. Thus have sided closer to the ECMWF track
with this forecast. Plenty of moisture will be advected north ahead
of this low, with 12z NAEFS showing anonymously high PWs (up to 2
standard deviations) for the middle of January. There will be two
main waves of energy that will move through the forecast area
during this time frame. The first weaker wave will bring a light
glaze of ice to areas generally south of a Fairfield to Galesburg
line Sat night-Sun morning. The second wave will bring
precipitation to the south as early as Sunday afternoon, spreading over
the entire area Sunday night, and continue through the day on
Monday. Due to the complexity of this system, continued model run-
to-run differences, and that it is still 4 days away, have tried
to keep the weather grids simple with a chance of rain or freezing
rain on Sunday changing to all rain on Monday as forecast
soundings depict a quick changeover to all rain from southeast to
northwest over CWA, as temperatures warm aloft. Monday will be the
day where most of the QPF falls.

Looking further ahead, upper low lifts northeast over the area
Tuesday, with dry conditions and temperatures remaining above normal
through the middle part of next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
ISSUED AT 1131 PM CST Wed Jan 11 2017

Some local IFR cigs will linger next couple hours vicinity of MLI
otherwise mainly MVFR cigs expected overnight into Thu AM. An
upper level disturbance will pass quickly late tonight until mid
morning Thu bringing light snow to portions of northeast IA, with
DBQ having best chance of some light accums where IFR is possible
with the snow. Meanwhile, CID will likely be on the southern
fringe of any snow. Further to the south some light showers or
pockets of light freezing rain/drizzle and perhaps some sleet will
be possible at MLI and BRL between 08/09z until around 12z, and
have handled with vcsh wording for now. In wake of disturbance
expect conditions to return to VFR by late Thu AM into early PM.
Northerly winds will be sustained around 10-15 kts for most of the
period and gust at times 20-25+ kts overnight through mid morning
Thu.

&&

.HYDROLOGY...
Issued at 312 PM CST Wed Jan 11 2017

An ice jam remains in place just downstream of Burlington, Iowa,
along the Iowa side of the river channel on the Mississippi. This
jam is producing minor to moderate flooding from near Fort Madison,
IA up to Gladstone, IL with high water upstream to Keithsburg, IL.
This situation is expected to persist for the remainder of the week.

Another ice jam has formed just downstream of Joslin that is
causing minor flooding upstream.

&&

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

$$

UPDATE...McClure
SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Gross/Uttech
AVIATION...McClure
HYDROLOGY...Gross/Uttech



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