Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 282013

Area Forecast Discussion
National Weather Service Quad Cities IA IL
313 PM CDT SUN AUG 28 2016

Issued at 300 PM CDT Sun Aug 28 2016

Scattered air mass thunderstorms have formed across a zone from
NW Missouri to E Iowa/NW Illinois to N Indiana through this
afternoon. Locally, storm coverage was a little lower than areas
to the east and west. A few of the storms have produced very
heavy localized rainfall amounts. Dual-pol estimated up to 2-3
inches a few miles to the NE of Iowa City in east-central Johnson
County. For areas that have not received rain today, which is most
of the CWA, it was warm and humid with temps in the mid to upper
80s and dewpoints in the lower to middle 70s.


.SHORT TERM...(This Evening through Monday)
ISSUED AT 300 PM CDT Sun Aug 28 2016

This Evening and Tonight...Isolated storms will continue to
develop through the evening hours. Anomalously high PWATs near
~1.8 inches according to the SPC Mesoanalysis means a very moist,
tropical-like air mass is present, which is supportive of
localized heavy rainfall rates of 1-2"/hr. Shear is expected to
remain low, thus do not foresee severe weather.

For the remainder of tonight, periods of clearing and light winds
should set the stage for localized shallow ground fog formation in
low-lying areas. Lows are forecast in the middle to upper 60s.

Monday...Weak upper-level flow and stagnant warm and humid air mass
warrants mention of 20-40% POPs. Models a bit more aggressive on
the areal coverage of thunderstorms compared to today (Sunday)
within preferential zone of slightly enhanced 0-1 km convergence -
especially over the SW half of the forecast area. In this region,
lower tropospheric wind flow or streamlines appear as nothing more
than a zone of weak confluence.

Thunderstorm Threats: As mentioned, the atmosphere remains largely
unchanged. Therefore, heavy rainfall rates and localized flash
flooding are the main concerns from the strongest storms. Uttech

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 300 PM CDT Sun Aug 28 2016

Monday night into Tuesday, a weak boundary and moist airmass will
support more scattered showers and storms. Weak wind fields will
likely result in more slow moving/backbuilding storms with
localized heavy rainfall, but a low severe weather threat. Tuesday
night into Wednesday, lingering storms are favored mainly south as
the front clears out of the region.

Mainly dry weather is forecast Wednesday night into Saturday as a
large upper ridge pushes slowly east through the region. Expect
cooler and slightly below normal temperatures late Wednesday into
Friday, followed by another modest warm-up next weekend. The next
wave may bring scattered showers and storms to the area late
Saturday and Sunday.


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
ISSUED AT 1251 PM CDT Sun Aug 28 2016

Isolated showers and thunderstorms are possible through next 24
hrs, but VFR conditions will prevail. Chances for rain are low, so
either left out of TAFs or included VCSH through the afternoon.
Will closely monitor and include TEMPO groups as necessary.
Primary risks from storms are torrential rain and lightning.

Areas of localized dense shallow ground fog are again possible
tonight. Visibilities may drop to LIFR for brief periods. However,
confidence is low on this occurring at any of the terminals this
far out. Uttech


Issued at 1118 AM CDT Sun Aug 28 2016

Rises on several area rivers are forecast to continue this week
due to recent heavy rainfall. Increased confidence in the amount
of routed water and recent hydrograph trends now support issuing
flood watches for the Cedar River near Conesville, as well at the
mainstem Mississippi River at Keithsburg, Gladstone, and
Burlington. All points are forecast to rise above minor flood
stage in the next 2 to 3 days, with later warnings likely if
recent trends continue. Elsewhere, on the Wapsipinicon River near
DeWitt, the forecast rise above flood stage is not expected until
next Friday. Still do not have enough confidence to issue a watch
for this point right now, due to a history of under-performing
crests this summer.


.DVN Watches/Warnings/Advisories...


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