Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 181138
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
638 AM CDT Thu Jul 18 2019

...12z AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 AM CDT Thu Jul 18 2019

A mix of storm chances and high heat will continue into the end of
the week and start of the weekend. Then a frontal system will look to
sag through the region from the north as the upper ridge/heat dome
flattens. this will bring a break from the heat, but also possible
strong storms and heavy rain in the process late Sat or Sat night.
Then northwest steering flow and undercutting high pressure systems
down acrs the northern plains and western GRT LKS to provide nice
weather with minimal precip chances for early to mid next week.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Thu Jul 18 2019

Nocturnal low level jet(LLJ) convergent axis and instability lobe
continues to fuel elevated MCS along and north of the CWA early this
morning. Still some potential for lower level cool pool generation
to allow a portion of it to then propagate more south and
southeastward down acrs the northeast half of the DVN CWA through
mid morning, but wonder if the latest CAMs such as the HRRR have an
idea of more festering sctrd convective elements bleeding down acrs
areas mainly along and north of Hwy 30 through 14z or so and then
exiting off to the east or decaying with LLJ decrease and veering
trends. These models suggest more robust storm cells or clusters
making it down more acrs southern WI and toward the Chicago area this
morning, clipping the northeastern CWA through sunrise. Although
they will dump heavy rain where they are, if they are more sctrd and
progressive it may limit a true more widespread flash flood threat.
For now will let the Flash Flood Watch ride to mid morning
especially with a recent mesoscale precip discussion issued for much
of the watch area, but it`s looking more marginal and will assess
again over the next few hours whether to cancel it early.

After the morning storm chances, expect increasing south to
southwest boundary layer flow to breezy status help mix out/flush
away any lingering cloud debris as the day progresses. This will set
the stage for hot and humid day in the mid 90s with sfc DPTs well up
in the 70s making for headline supporting heat index readings which
have been already well advertised. Thus heat headlines to continue
through Saturday. Will keep the afternoon dry for now banking on
substantial EML acrs the area, but there is a low chance for renewed
storm development on any lingering outflow boundary or discontinuity
which would likley be along or north of I80. MCS generation
parameters again set up on the northern periphery of the subtropical
ridge tonight, from SD over acrs southern MN and into WI along brunt
of rejuvenated convergent LLJ zone. But some chance of this activity
bleeding down into the northern CWA again, which could lead to
severe weather/damaging winds with any sfc rooting by storm
clusters, and heavy rainfall-flooding potential.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 330 AM CDT Thu Jul 18 2019

Friday...Still looking like the hottest day with triple digit
potential for some of the area and near record highs. Will add the
climate section again for reference for afternoon highs and possible
record high minimum temps as well. Friday night into Sat morning it
still appears the ring-of-fire pattern still too close for comfort
and will have to keep at least low chance POPs in the north for MCS
southward propagation potential.

Saturday another hot humid day with mid to upper 90s depending on
convective debris interruption at times, and the heat warning
continues especially taking into account the multi-day accumulation
factor.

Sat night into Sunday morning...signs of upper ridge de-
amplification/flattening with a cool front arrival from the north to
break the heat. Unfortunately, like many cases with heat busters, we
may have to go through strong storms and very heavy rainfall to get
there. With repeated storm  along sagging boundary, there
may be potential for several inches of rain by Sunday morning in
localized swaths.

In the longer range...signals and upper jet patterns suggest
northwest steering flow and undercutting high pressure systems will
adjust down acrs the northern plains and western GRT LKS to provide
nice weather with minimal precip chances for the early to mid next
week period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
ISSUED AT 625 AM CDT Thu Jul 18 2019

Storms will continue this morning impacting DBQ with MVFR to local
IFR conditions for a time. A shower or storm is possible at CID
and MLI with a sagging outflow boundary. Uncertainty a bit with
storm trends this afternoon, but consensus supports main storm
initiation to our north across portions of MN/WI along warm front,
thus have no mention beyond this morning. Conditions expected to
become VFR at all sites by afternoon and remain VFR through
tonight with gusty SSW winds 10-20+ kts easing some after dark.

&&

.CLIMATE...
ISSUED AT 330 AM CDT Thu Jul 18 2019

Record Highs for July 18...

Moline.........100 in 2012(+) Cedar Rapids...101 in 1930
Dubuque........99  in 1894 Burlington.....103 in 1930

Record Warm Lows for July 19...

Moline.........80 in 2011 Dubuque........81 in 1930

Record Highs for July 19...

Moline.........101 in 1934 Cedar Rapids...103 in 1930
Dubuque........97  in 2011(+) Burlington.....107 in 1934

Record Warm Lows for July 20...

Moline.........78 in 2011 Dubuque........78 in 1930

Record Highs for July 20...

Moline.........102 in 1934 Cedar Rapids...105 in 1901
Dubuque........101 in 1901 Burlington.....107 in 1934

(+) = also occurred in previous years

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Excessive Heat Warning until 7 PM CDT Saturday for Benton-
     Buchanan-Cedar-Clinton-Delaware-Des Moines-Dubuque-Henry IA-
     Iowa-Jackson-Jefferson-Johnson-Jones-Keokuk-Lee-Linn-Louisa-
     Muscatine-Scott-Van Buren-Washington.

     Flash Flood Watch until 10 AM CDT this morning for Benton-
     Buchanan-Clinton-Delaware-Dubuque-Jackson-Jones-Linn.

IL...Excessive Heat Warning until 7 PM CDT Saturday for Bureau-
     Carroll-Hancock-Henderson-Henry IL-Jo Daviess-McDonough-
     Mercer-Putnam-Rock Island-Stephenson-Warren-Whiteside.

     Flash Flood Watch until 10 AM CDT this morning for Carroll-Jo
     Daviess-Stephenson-Whiteside.

MO...Excessive Heat Warning until 7 PM CDT Saturday for Clark-
     Scotland.

&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...12
AVIATION...McClure
CLIMATE...12



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