Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 110249
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
849 PM CST Tue Jan 10 2017

.UPDATE...
Issued at 847 PM CST Tue Jan 10 2017

Winds have decreased across eastern Iowa, northwest Illinois, and
far northeast Missouri this evening. Winds will continue to
decrease to 10 to 20 MPH overnight and for these reasons the wind
advisory has been canceled.

UPDATE Issued at 702 PM CST Tue Jan 10 2017

Have cancelled or expired the wind advisory for all but far
northeast IA and portions of northern IL roughly along/ne of
DBQ-CWI-VYS line where will leave in effect as winds continue to
tickle criteria next 1-2 hrs before sfc isallobaric max departs
allowing winds to diminish. Elsewhere in the cwa, we are already
seeing the winds let up quite a bit recently with pressure
gradient easing as the deep low continues to lift quickly into
Ontario. Updated NPW has been sent.

&&

.SYNOPSIS...
Issued at 147 PM CST Tue Jan 10 2017

As of 2 PM...Latest GOES WV imagery displayed a potent looking
cyclone tracking rapidly from IA through WI with a classic comma-
head structure. The WV loop showed a textbook example of the mid-
level theta-e ridge/TROWAL and dry slot features curling into the
center of the low. Earlier this morning and afternoon, there were
even a few lightning strikes near the Quad Cities and Burlington
when instability in the warm sector peaked. Then there was a
brief changeover to a mix of rain/snow or all snow across the far
NW, mainly NW of Cedar Rapids to Dubuque but no reports of
slippery roads. That being said, it is already down to 28 F
degrees in Independence, IA.

SPC mesoanalysis had a 987mb centered over south-central WI and an
impressive pressure gradient to the SW across E IA/NW IL. MSAS
sfc isallobaric rises of 7-8mb/3hr along the IA/MO border were
moving NE, hence the reason for the gusty westerly winds of 40-50
mph, and at times, sustained 30-35 mph.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 245 PM CST Tue Jan 10 2017

This Evening and Tonight:

Strong Winds:

Wind Advisory continues through this evening but will expire at 7
PM across the southern and western CWA and at 10 PM to the north
and east. Sustained winds around 30 mph (at times) along with
gusts of 40-50 mph will continue blowing around loose objects and
making travel difficult. High profile vehicles will be most
susceptible to the strong winds, especially on north-to-south
oriented roads.

Later tonight winds will subside as temps cool into the 20s and
10s far north.

Wednesday into Wednesday Evening:

Another mild day, relatively speaking, is in store. Forecast
highs range from the lower 30s NW to the lower 50s far south.

Since there isn`t a large sfc high building in behind the sfc low
exiting out of WI tonight (Tuesday Night), WAA raises 850mb temps
back above 0 C during the morning. The low-level baroclinic zone
is forecast to increase in magnitude through the day as another
weak wave rides along the boundary bringing chances for light rain
to most of the CWA by the afternoon.

Light Freezing Rain Possible:

As this next sfc low slides into central IL, northerly sfc winds
will increase dropping temps into the lower 30s and upper 20s over
the northern CWA by mid to late afternoon. Forecast soundings and
max wetbulb temps aloft support potential for a zone of light
freezing rain. PoPs are on the low-side right now (between 30-40%)
but could see these increasing with next forecast update. Time-
height sections indicate forcing tied to ~925mb frontogenesis and
lack of ice present aloft because saturation is below -10 C.

Main message is to be aware of potential for light icing across
the northern tier or two of counties (north of highway 30) from
Wednesday afternoon into Wednesday night. Uttech

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 245 PM CST Tue Jan 10 2017

The overall weather pattern will be unsettled into early next week.

Wednesday night into Thursday morning...

Thermal profiles of the atmosphere support a continued change from
rain to snow Wednesday night. There will likely be a period of
freezing rain and sleet during the transition period. However, that
transition period should only be 3-4 hours in any one location. By
late Wednesday night and Thursday morning, thermal profiles support
precipitation in the form of light snow instead of freezing rain.
Any snowfall amounts should be a dusting.

Dry conditions will then be seen Thursday afternoon through Friday
as high pressure moves through the Midwest. Temperatures will
average below normal.

Friday night on...

The global models are indicating two separate storm systems will
affect the Midwest over the weekend and into early next week.

Confidence on the Fri night/Saturday period

Storm system affecting the area.....Low to Moderate
Timing of storm system..............Moderate
Precipitation type..................Low to moderate

Friday evening across the area looks to be generally dry.

Late Friday night through Saturday the bulk of the first storm
system will generally move from Missouri into southern Illinois. The
models indicate some moisture and lift will move across the area
late Friday night through Saturday. Thermal profiles suggest this
storm system will produce mainly snow for the area.  However, there
is a low risk of some ice south of an Ottumwa, Burlington, to Peoria
line. It is too early to give snow amounts with any reasonable
accuracy but very early indications suggest snowfall amounts should
be under an inch.

Confidence on Saturday night through Monday period

Storm system affecting the area.........Moderate
Timing of storm system..................Low
Precipitation type......................Low

Saturday night through Monday night another storm system will affect
the Midwest. There are considerable differences between the global
models regarding the track and overall timing of the storm system.
These two variables play significantly into the eventual
precipitation type.

Saturday evening looks to be dry across the area. The model
consensus has slight chance pops for snow south of an Ottumwa, IA to
Galesburg, IL line late Saturday night. However, trends with the
models have been indicating a slower arrival of the precipitation.
Thus the potential exists that all of Saturday night could be dry.

Sunday through Monday night the storm system will move through the
Midwest. The model consensus has chance to likely pops Sunday,
likely to categorical pops Sunday night into Monday, and chance pops
Monday night. However, trends in the models have been suggesting
the possibility of a slower arrival on Sunday.

Initially, it appears that there will be cold air in place to allow
the precipitation to be all snow. Depending upon the model solution,
the snow looks like it will transition to all rain for much of the
area Sunday night into Monday and then transition back to snow
Monday night. During both transition periods there may or may not be
some sleet or freezing rain.

On Tuesday, there may or may not be some lingering snow. Currently
the model consensus has slight chance pops.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 553 PM CST Tue Jan 10 2017

Improving conditions to VFR along with decreasing winds on tap
this evening in wake of departing storm system. Overnight into
Wednesday morning will see some mid and high with winds backing
to southerly and increasing to 10-15+ kts as low pressure develops
in the Central Plains. NAM model is more aggressive with ramping
up winds around 40-45kts from SSW near 2kft agl toward morning,
which would lead to low level wind shear. Other models not as
strong with winds 1-2kft agl and thus more marginal at best for
LLWS. For now have left out any mention with model variance
leading to lower confidence, but will assess trends and data to
see if mention is needed for 06z TAFS. Wednesday afternoon, mainly
mid to late afternoon or aft 19z-20z, anticipate lower clouds
forming and possibly some drizzle or very light rain as
convergence increases ahead of approaching low and cold front
sagging down from the north. As temps drop below freezing there
could be some freezing drizzle or very light freezing rain that
could impact CID and DBQ terminals toward 00z and especially
Wednesday evening 00z-06z. Being late in the taf period I have
left out mention, but plan to address this potential with 06z
tafs.


&&

.HYDROLOGY...
Issued at 356 PM CST Tue Jan 10 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 formed on January 7th downstream of Joslin, IL on
the Rock river. The current river forecast, which is based on
forecast rainfall, pushes Joslin to flood stage in a few days. If
rainfall is less than forecast, then the river may remain below
flood stage. As a result, a flood watch has been issued around the
Joslin area.

&&

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

$$

UPDATE...Cousins
SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...08
AVIATION...McClure
HYDROLOGY...08



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