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998
FXUS63 KDVN 221745
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1245 PM CDT Thu Jun 22 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 251 AM CDT Thu Jun 22 2017

A warm front extended from southern Minnesota, through far
northeast Iowa, into northern Illinois during the overnight hours.
An area of strong thunderstorms continued to developed and move
into northeast Iowa and southern Wisconsin. Warm and muggy
conditions persisted into the early morning hours, with
temperatures in the 70s area-wide.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 251 AM CDT Thu Jun 22 2017

The main forecast issues in the short term period are convective
coverage and intensity tonight.

In the near term, strong storms continue just to the north of the
forecast area, in the 850mb moisture transport axis. Some CAMS
have some of this activity barely skirting the far northern
counties through daybreak. Have made some short term adjustments
to pops. Some heavy rain, small hail, and gusty winds would be the
main issues, especially over northern Buchanan, Delaware, and
Dubuque counties. Most areas will remain dry early this morning,
as well as through the afternoon hours. Expect a hot and humid day
with highs 85 to 90 and afternoon heat indices from 90 to 95.

Looking ahead to this evening, timing among the various CAMS and
synoptic models is similar in bringing storms into the far
northwest near or shortly after 00z. Vertical shear profiles favor
a linear storm mode as widespread storms push southeast along an
advancing cold front. All but the far southern counties are in the
day 1 slight risk area for a hail/damaging wind threat. Corfidi
vectors indicate potential for some back-building/repeat
thunderstorms, with PWAT values over 2 inches, so isolated flash
flooding cannot be discounted.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 251 AM CDT Thu Jun 22 2017

Forecast focus on below normal temperatures and no significant rain
expected through this extended period.

Friday: I will maintain a chance for showers and thunderstorms in
our far se cwa early in the morning, as the cold front continues to
make progress to the southeast. Otherwise, much of the day will be
dry as dewpoints steadily fall throughout the day, on a rather brisk
northwest wind.

Friday night through Tuesday: Northwest flow aloft will dominate our
weather through this period. Deep upper level trough (for the end of
June) will remain anchored in the Great Lakes region, as the heat
dome bakes the Desert Southwest. Temperatures will be unseasonably
cool with highs in the 70s and lows in the 50s. 850 mb temperatures
drop as low as +4c Sunday and Monday. There is the potential for our
northern cwa to have even lower readings than currently forecast in
the grids. Meaning highs could be in the 60s and lows in the 40s,
depending on cloud/wind trends, for later shifts to monitor.

Rainfall: Little if any rain is expected during this time frame but
Saturday afternoon offers the possibility of scattered showers,
possibly an isolated thunderstorm, mainly in our northeast cwa. This
is when an upper level disturbance in the flow will drop into our
area. The grids will have chance pops based heavily on the GFS, but
the ECMWF is dry, keeping the showers to our north.

Mid to late next week: Flow becomes zonal again with a series of
disturbances/low pressure systems tracking across the Corn Belt.
Warm, moist and unstable airmass will return with periodic episodes
of showers and thunderstorms. However, predictability of severe
weather is too low this far out.

&&

.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...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Haase
AVIATION...Cousins