Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 252003

Area Forecast Discussion
National Weather Service Quad Cities IA IL
303 PM CDT Tue Oct 25 2016

Issued at 302 PM CDT Tue Oct 25 2016

Low pressure centered over western Nebraska is forecast to move
east through the short term period. In response to the sfc low,
sfc moisture and warmer temperatures surged north across eastern
NE and northern KS. At 2pm, 60 degree dewpoints were located from
Beatrice NE, sse to near Colombia, MO. This moisture will continue
to surge north through the short term period. ESE winds across our
area look to limit overall transport of moisture east until the
main H5 wave swings through the area. This low pressure will be
main the weather producer in the short term.


.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 302 PM CDT Tue Oct 25 2016

Overall model agreement on the timing of the H5 wave suggests a
12Z to 18Z frontal passage across the area. Models have finally
come into agreement as far as the track of the sfc low. The sfc
low will follow roughly I80. The ECMWF had this yesterday. Ahead
of this front and sfc low, a frontogenesis band will lead to rain
and possibly embedded showers and thunderstorms through most of
the overnight, especially across northern and central zones. Hires
guidance suggests pops will wane overnight before front moves
through. A glance at the large scale frontogenesis parameters this
would be supported. Near 12Z Wednesday, H85 WAA brings in the warm
sector across our area. MUCAPES, generally less than 500 J/kg will
be in the warm sector. This will lead to a chance for SCT thunder,
especially in the 12Z to 18Z time period.

Deep layer shear of 35 to 50 kts will be across the area near 12Z
to 15Z tomorrow. A look at this shear shows that nearly all of
exists in the 0-3 km level. The orientation of this vector would
be perpendicular to any line segment that might form. This is
preferential for mesovortexgenesis. It appears that the best
shear, is just ahead of the CAPE. The best chances for a strong
storm will exist in a narrow window where the CAPE and shear
overlap. That being said, there is a substantial stable layer
near the sfc, closer to the track of the low. This would limit
overall chances for severe weather.

Overall rainfall totals of half an inch to 1.5 inches look to be
possible across the area. Hires precip accums range from 1 to 2
inches across the highway 20 corridor. This is where the heaviest
rain should occur.

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 302 PM CDT Tue Oct 25 2016

Lingering showers will end well east of the Mississippi Wednesday
evening. Otherwise, expect dry conditions. Cloud cover will help
keep temperatures a little above normal.

Dry and seasonable conditions will be seen Thursday and Thursday
night across the area. Attention then turns to the next storm system.

On Friday the next storm system will remain well north of the area.
Breezy and warm conditions will develop with temperatures around 10
degrees above normal.

Friday night on...

Going on the assumption of deep mixing occurring on Friday, there
should be a fairly large swing in diurnal temperatures into Friday
night. Dry conditions are expected with low temperatures above

Saturday will see another day of breezy, dry, and warm conditions.
Temperatures will average about 10 degrees above normal.

The model consensus continues the dry conditions Saturday night
through Monday night with temperatures at or above normal. A dry
cold front is forecast to move through the area Monday night.

On Tuesday another storm system will move northeast out of the
southern Plains. The model consensus has mainly dry conditions for
the area with the exception of the the IA/MO/IL borders where there
are slight chance pops. Temperatures will continue to average above


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
ISSUED AT 1242 PM CDT Tue Oct 25 2016

Mainly VFR conditions are forecast before a cold front approaches
the area late in the period. CIGS should turn to MVFR and possibly
IFR late in the period. Have held off on the IFR for late in the
period as confidence is low in seeing that. Rain and rain showers
will be possible across the area tonight and into the morning.
Some rumbles of thunder will be possible. At this time, have not
included a LLWS threat. While this looks possible, will hold off
until it becomes more certain in later shifts. VSBYs should be
impacted tonight and into tomorrow with this rain.




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