Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 170431
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1131 PM CDT Sun Apr 16 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 244 PM CDT Sun Apr 16 2017

Weak high pressure from the northern plains is bringing cooler and
drier air into the region today. Temperatures are mostly in the
mid to upper 60s at 2 PM CDT. Fair skies with temperatures slightly
above normal will continue through Monday as the high pressure
system moves slowly southeast.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 244 PM CDT Sun Apr 16 2017

Short term forecast confidence assessment...good or above average
with no sensible weather issues. Forecast highs and lows should be
within 3 degrees of forecast with favored low lying areas tending
to be a couple of degrees cooler than forecast north of I-80.

Tonight...Skies will become mostly clear to clear north with partly
cloudy skies due to high clouds in the south with winds becoming light
and variable toward morning for good radiational cooling support
some lows near 40 degrees north of I-80.

Monday...Continued mostly sunny skies with winds becoming light southerly
by afternoon. Highs should be in the 70 to 75 degree range with low
dewpoints for a splendid mid April day.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 244 PM CDT Sun Apr 16 2017

Main potential impacts for the long term period are the chances
for heavy rain midweek and again next weekend along with
continued river flooding through the period. There is a chance for
thunderstorms on midweek. SPC has our southern CWA in a Day 4 15%
severe weather risk outlook.

Progressive H5 wave is forecast through the CWA on Wednesday into
Thursday night. Differences in the overall wave structure and
positioning of the wave are main model differences. Regardless
with boundary layer moisture just stalled south of the area, this
wave should be able to bring moisture north fast on Wednesday.
GFS brings the surface low across Iowa and drapes a warm front
across the CWA. Forecast sfc winds are out of the east along and
south of this boundary. Deep layer shear of near 50kts
perpendicular to the forcing boundary favors supercells as main
storm mode. Low level shear will be high near the surface boundary
across our CWA. Forecast CAPE near to just over 1000 J/kg is
forecast. Current limiting factor is that guidance suggests
precip along the warm front Tuesday night into Wednesday. Remnant
cloud cover could limit overall destabilization on Wednesday
across the area. This would throw a wrench into what happens on
Wednesday across the area. That said, confidence is increasing for
severe weather this Wednesday. If current forecast holds true,
all types of severe weather are possible. Pay attention to
upcoming forecasts for midweek.

Another system is forecast late week and into the weekend. Overall
instability is lacking. Moderate rainfall is expected from these
showers. With the rainfall this week and again this weekend,
expect area rivers to run high and could have additional rivers
reach flood stage.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
ISSUED AT 1130 PM CDT Sun Apr 16 2017

Clear and calm conditions can be expected overnight, with high
pressure shifting east by morning, with winds turning to the
southwest, but remaining light and under 10 kts. Skies should be
clear to high level overcast with unlimited visibilities.
ERVIN

&&

.HYDROLOGY...
Issued at 1032 AM CDT Sun Apr 16 2017

Heavy rainfall from overnight has lead to rises on area rivers.
Marengo has been upgraded to moderate flood and is rapidly rising.
While confidence is medium in the river reaching moderate flood
stage, it is forecast to do so in less than 24 hours. DeWitt has
also risen rapidly, as such a warning for moderate flood stage was
issued.

On the Rock River, low confidence on routed flow kept MLI and CMO
in the watch category. If forecast trends are correct through the
day today, then warnings would be needed for these sites.

On the Cedar and Iowa rivers, watches have been issued for WAPI4
and CNE as routed flow forecast takes these sites to minor.
Confidence is low in these sites reaching flood stage.

Another round of heavy rain is forecast in the extended. This rain
could lead to more rises on local rivers into later this week.

&&

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

$$

SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...Gibbs
AVIATION...Ervin
HYDROLOGY...Gibbs



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