Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 222023
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
323 PM CDT Thu Jun 22 2017

.SYNOPSIS...
Issued at 245 PM CDT Thu Jun 22 2017

A frontal boundary stretches from central Nebraska northeastward
into northern Iowa and into Southern Wisconsin. Scattered showers
continue north of Interstate 80. Temperatures ranged from the
upper 70s along the Highway 20 corridor to the mid 80s in
southeast Iowa and northeast Missouri. Dewpoints were in the upper
60s to lower 70s.

&&

.SHORT TERM...(This Evening through Friday)
ISSUED AT 245 PM CDT Thu Jun 22 2017

The main forecast concern this period are chances of thunderstorms tonight
into Friday morning. Large scale models are in good overall
agreement and CAMs are resolving the current features a little
better.

Models depict a cold front sliding southeastward across the region
from basically 06 utc to about 09 UTC Friday. The best lift is
slightly offset from the convergence along the front and the best
RH. Surface base CAPE is currently ranging from 1500 to 2500 J/kg
across the region. The better 0 to 6 km shear is just ahead of the
front and will probably need the arrival of the front to initiate
storms across the north and then move southeastward with the front
across the region. The main threats will be hail and winds ranging
from 60 to 70 MPH. For these reasons, there is slight risk of
severe thunderstorms across the region. The convergence of the
front and synoptic lift will be needed to overcome the CAP to our
north and develop thunderstorms that will move into our region. There
is also an isolated flash flood threat with increasing deep
moisture.


This is expected to be a progressive system with the front moving
through and high pressure building into the region for the end of
the work week. Temperatures will be slightly below normal for
Friday.



.LONG TERM...(Friday Night through Thursday)
ISSUED AT 245 PM CDT Thu Jun 22 2017

.Mainly dry, and exceptionally pleasant conditions will be found
from Friday through Monday, as a seasonally strong upper trof digs
over the eastern 1/3 of the country. This upper trof will draw down
a surface high from central Canada, with dry dewpoints in the 40s
and 50s, and highs in the mid 60s to mid 70s over the upper Midwest.
There should be a daily increase in cumulus during the afternoon
hours each day, and with some passing upper energy, some isolated to
scattered showers and weak thunderstorms are possible. However,
despite this rain threat, the days should be viewed as dry days for
the most part. Any rain should quickly evaporate within a few
minutes of falling in the dry air.

Moving on to mid week, after a period of moderation under the high,
moisture is expected to return to the Midwest for Tuesday through
Friday as a series of waves pass through in zonal flow aloft. The
GFS/GEM/and EC all hit the area with a at least 1 if not multiple
MCS during this period. With a sustained southerly flow headed into
the warm front during that period, PWAT values probably will be
seasonally high given the convergence into the upper Midwest.
Therefore, a seasonal risk for both severe weather and heavy rains
is expected in this time frame. As to what days that occur, and
whether it is multiple events, or just one, is going to have to wait
until the pattern evolves.
ERVIN

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
ISSUED AT 1236 PM CDT Thu Jun 22 2017

Made very few changes to the TAF through the forecast period. VFR
conditions are currently in place and are expected to prevail
until the arrival of thunderstorms this evening where conditions
drop to MVFR in thunderstorms. Thunderstorms will be clearing KBRL
by 9 UTC. Any remnant MVFR ceilings should be out of the region
between 12 and 14 UTC with VFR conditions prevailing afterward.


&&

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

$$

SYNOPSIS...Cousins
SHORT TERM...Cousins
LONG TERM...Ervin
AVIATION...Cousins


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