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fxus63 kdvn 180615 
afddvn

Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
115 am CDT Wed Sep 18 2019

..aviation update...

Synopsis...
issued at 245 PM CDT Tue Sep 17 2019

18z surface data has high pressure over the Great Lakes with a weak
boundary across western Iowa and Missouri. Dew points were in the
mainly in the 60s with 70 dew points around the boundary in Iowa and
Missouri.

&&

Short term...(this evening through wednesday)
issued at 245 PM CDT Tue Sep 17 2019

Satellite trends indicate some diurnal cumulus developing from
northeast Missouri into southern Iowa. This cumulus may or may not
result in a couple of isolated showers/thunderstorms prior to sunset
in parts of Scotland and Van Buren counties.

Quiet and dry conditions will be seen tonight with clouds increasing
after midnight. There may or may not be some patchy fog developing
prior to Sunrise East of the Mississippi and in low lying areas
across eastern Iowa. The wind flow is progged to be a little
stronger than last night so that in combination with high level
clouds moving in late should limit any fog development.

On Wednesday the overnight storms that developed in central and
western Iowa will slowly dissipate as they move toward the area.
There may or may not be a few decaying showers that enter Buchanan
and Benton counties prior to mid day.

Diurnal heating should result in isolated showers and storms
developing by mid to late Wednesday afternoon generally west of a
line from Manchester to Belle Plaine, Iowa line.

It will feel very warm and humid Wednesday as dew points slowly
climb into the upper 60s and lower 70s. Peak heat index readings
will be 90 to 95 west of the Mississippi and 85 to 90 east of the
Mississippi.

Long term...(wednesday night through tuesday)
issued at 245 PM CDT Tue Sep 17 2019

Potential for heavy rainfall this weekend.

Wednesday night through friday: highly amplified pattern with a big
ridge in the east and deep trough in the west. This will keep our
area in the Summer-like weather with warm/humid conditions. Highs
will be in the 80s with lows well into the 60s to lower 70s.
Dewpoints will be on the muggy side around 70, quite high for mid
September. There will be chances for thunderstorms most favored
Wednesday night into Thursday as a weak disturbance arrives. In our
NW counties storms appear likely with the potential for heavy rain.

This weekend: this is when the active pattern really sets in with
periodic rounds of thunderstorms. Deep trough will slowly makes it's
way into the Midwest. This will pull copious western Gulf moisture
northward (along with Pacific moisture). In addition, enhanced
moisture from the remnants of tropical depression (possibly tropical
storm) currently off the se coast of Texas will get transported into
our area. This will be a period to watch for heavy rain as an
impressive 1.8 - 2.0" precipitable water plume stems from the western Gulf into
the upper Mississippi Valley. Naefs is already showing integrated
water vapor (iwv) transport values around 2 Standard deviations
above the mean for the middle to end of September. While it is too
soon to determine rainfall amounts or locations of the heaviest
rain, interests especially along rivers should pay attention to
later forecasts. Also, mine the severe potential. Highs will be in
the 70s to lower 80s with lows in the 60s to around 70.

Early next week: models are trending dry with high pressure over the
area. Highs should be in the 70s with lows in the mid 50s to lower
60s.

&&

Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1251 am CDT Wed Sep 18 2019

Southeast surface winds were being observed early this morning
along with some high cirrus clouds. Ample low level moisture will
likely yield reduced visibilities across the area through
Wednesday morning. As of 06z only isolated areas were seeing MVFR
visibilities, but expect that coverage to increase going through
the next few hours as the temperature/dewpoint spreads are only a
couple of degrees for much of the area. Winds are around 5-8kts so
thinking this along with the cirrus will preclude any dense fog
development this morning. Winds will not be too strong today but
could see some isolated areas with gusts to 15kts at peak heating
when the boundary layer is fully mixed.

&&

Hydrology...
issued at 819 PM CDT Tue Sep 17 2019

The only significant change to this evening's river forecast is
that the Pecatonica River at Freeport is now expected to crest just
underneath moderate flood stage at 13.9 feet tomorrow.

Observations show the Rock River at Moline is nearing its crest,
and is expected to begin falling Wednesday afternoon.

Previous discussion...

Moderate flooding continues on the Pecatonica and rock rivers.
Other rivers that are still seeing rises (including the
mississippi) are not expected to rise above flood stage at this
time. However, wet weather is expected later this week, with the
pattern looking to stay wet into October. Heavy rains are possible
this weekend as a storm system moves slowly across the area,
combined with copious Gulf moisture. Adding to the moisture will
be the remnants of a tropical low pressure currently located off
the se coast of Texas. Those with concerns on area rivers should
stay updated on the latest forecasts.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

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