Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 140925
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
325 AM CST Sat Jan 14 2017

.SYNOPSIS...
Issued at 325 AM CST Sat Jan 14 2017

A cut off upper level low was located over the Baja of California.
This system, along with high pressure off the east coast of the
CONUS was leading to SW to zonal flow across the central CONUS. Early
this morning high pressure was in place across the eastern Great
Lakes. Winds were from the east across the area. This was leading
to drier air across the area. On the radar scope, freezing rain
was just south of the CWA moving east. This area of rain was
slightly drifting to the north through time. By daybreak, some of
this freezing rain may make it into the area. Little to no ice
accumulation is expected this morning.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 325 AM CST Sat Jan 14 2017

Most of the short term period will be quiet with the exception of
the very beginning and again at the end. A mix of precip is
possible, mainly across the far southern CWA during these two
periods. This morning, hires guidance and the current radar
trends suggests that patchy freezing rain will move into the far
south early this am. At this time, it appears that any ice
accumulation will be minimal and likely on raised surfaces. This
area of rain looks to be focused on isentropic upglide that is
well depicted on the 305K level. Guidance suggests that this
upglide moves east of the area by 15z this am. As such, POPs drop
off at this time.

The rest of today looks to be quiet across the area until later
tonight when WAA and weak H5 waves moves more moisture and ascent into
the area. In response to this precip will form south of the area.
This precip will try to move north, into drier air. This drier air
will likely delay the onset of any precip until near of after 12z
across the far southern CWA. Guidance has started to buy into this
idea as QPF has been lowered with recent runs. The ECMWF is the
only model that brings QPF into the area by before 12z Sunday. As
a result, low end POPs are kept in the forecast for early Sunday
morning. Overall impacts tomorrow morning of any snow or freezing
rain will likely be very limited. Currently have low confidence in
the occurrence of any precip tonight.


.LONG TERM...(Sunday through Friday)
ISSUED AT 325 AM CST Sat Jan 14 2017

The long awaited complicated storm looks to hold off for another day
for most of the area Sunday, as is often the case with closed lows
moving northeast with a strong high in place upstream. This will
force a delay in our headlines for the northern 2/3rds of the watch,
as dry conditions last most of the day, if not well into the evening
hours Sunday. The dry conditions will also allow for warmer highs in
the lower to mid 30s Sunday. The far south should be near the edge
of light freezing rain, possibly falling as sleet as well Sunday. I
will keep the watch going there beginning at 12Z Sunday.

The main freezing rain hazard will be Sunday night through mid
morning Monday. That timing is growing in confidence now. The
amounts of ice should be under 1/4 inch, and in most locations a
tenth to 0.15 of ice is probably much more likely. Thus, I believe
this event will end up verifying as an freezing rain or winter
weather advisory. However, at 24 to 36 hours out, the watch is still
the preferred product to have in effect, and will keep that for now.
It makes sense that the day shift issue an advisory with more exact
timing likely begin lay out within that headline compared to the
broad time frame of the current watch.

Rain amounts of 0.50 northeast to 0.75 southwest are forecast for
the entire event. This is not likely to bring run off problems as
despite frozen soils, the recent dry weather should have some local
water retention in low spots. In any case, the sustained warm up in
the extended should bring a shallow thaw of the soils, and is likely
to release some of the jammed ice on area rivers.

The extended appears mainly dry, at least until late week. Highs in
the upper 30s to mid 40s early this week, will rise to the upper 40s
to mid 50s for late week. Those daytime highs will be paired with
overnight lows in the mid 30s to mid 40s, which should begin to
soften ice on river and lakes.

ERVIN

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
ISSUED AT 1136 PM CST Fri Jan 13 2017

Primary concern is potential for lower mvfr ceilings at the
terminals overnight into Saturday morning. As 925 mb flow
shifts from the south overnight ahead of an approaching trough,
I anticipate advection of these lower mvfr ceilings into the
terminals before 925 mb winds turn westerly toward daybreak into
mid morning Saturday allowing drier air and a return of vfr cigs.
DBQ may be too far north and timing may not allow them to reach
before 925 mb winds turn westerly, but several pieces of guidance
show the clouds there and have put in tempo there. The other
concern is potential for showers containing sleet and freezing
rain south of I-80 overnight attendant to wing of isentropic lift.
Have handled with vcsh wording at BRL and left out at MLI for now.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Storm Watch from Sunday afternoon through Monday morning
     for Benton-Buchanan-Cedar-Clinton-Delaware-Dubuque-Iowa-
     Jackson-Johnson-Jones-Linn-Muscatine-Scott.

     Winter Storm Watch from Sunday morning through late Sunday night
     for Des Moines-Henry IA-Jefferson-Keokuk-Lee-Louisa-Van
     Buren-Washington.

IL...Winter Storm Watch from Sunday afternoon through Monday morning
     for Henry IL-Rock Island.

     Winter Storm Watch from Sunday morning through late Sunday night
     for Hancock-Henderson-McDonough-Mercer-Warren.

MO...Winter Storm Watch from Sunday morning through late Sunday night
     for Clark-Scotland.

&&

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Ervin
AVIATION...McClure



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