Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 301727
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1227 PM CDT FRI SEP 30 2016

...AVIATION UPDATE...

.UPDATE...
Issued at 1050 AM CDT Fri Sep 30 2016

Persistent cloud cover is helping to keep temperatures in check.
Slightly drier air over the area is eroding the precipitation down
to drizzle/sprinkles as it moves west.

Radar trends would support better rain chances this afternoon
moving in from the east.

The forecast has been updated to lower temperatures slightly and
to better reflect the precip chances.

&&

.SYNOPSIS...
Issued at 327 AM CDT Fri Sep 30 2016

The latest sfc analysis was indicating a low pressure center acrs
the KY portion of the OH RVR Valley, with cyclonic flow and embedded
trofs circulating it northwestward to the MS RVR Valley. A
seasonably strong ridge axis was located to the northwest of the
cyclone from the southwestern plains, up acrs MN and toward the
James Bay region. Latest IR satellite loop was indicating associated
stratocu deck trying to whirl westward toward the local area from
the southwestern GRT LKS.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 327 AM CDT Fri Sep 30 2016

The upstream clouds will continue to propagate westward and overtake
the area, but may be more ragged at times west of the MS River for
portions of the day with drier air entrainment seen on the water
vapor loop from north of the GRT LKS. But this feed will get
squeezed/pinched off with cyclone retrograde by mid to late
afternoon and expect a cloud shield to cloak the entire CWA into the
evening. Just spotty light showers or sprinkles tying to make it
into the eastern CWA at times today with the same problem battling
dry air, but like the clouds, coverage to increase from the
northeast by late afternoon and into the evening.

Several of the 00z model runs vary on extent of coverage that these
light showers can make it acrs the local area even by this evening,
from mainly dry to likely coverage by this evening and into the
overnight. For now will keep low to moderate POPs mainly acrs the
eastern third and toward the MS RVR today, and expand into far
eastern IA into tonight. Most areas that manage to get some showers
will get only a few hundredths of an inch or a trace, except acrs
far northwestern IL and down into the I80 corridor east of the Quad
City area, where higher coverage and a bit more low to mid level
saturation may allow for a few areas to get up to a tenth of an inch.

As for temps, cloud cover to limit highs to the mid to upper 60s,
but some potentail for the far west if they remain partly cloudy
longer to get back to 70. Sfc winds and clouds to keep temps u
tonight in the mid to upper 50s.   ..12..

.LONG TERM...(Saturday through next Thursday)
ISSUED AT 327 AM CDT Fri Sep 30 2016

Upper low to keep cloudy, cool and unsettled weather going through
Saturday, then pattern shift to SW upper flow to bring warmer
temperatures and next rain chances toward the middle of next week.

Saturday, the lingering nearly stacked surface and upper low over
IL/IN will provide another day of cloudy skies with scattered light
rain showers over especially east of the MS river, where highest
chance pops are maintained. Temperatures will only rise into the
60s.

Saturday night into Sunday, model consenus has a deepening low
moving into the western U.S., inducing downstream ridging that
nudges the Great Lakes/Ohio Valley low northeastward. This will
bring a warming trend Sunday through Tuesday with highs returning
above normal into the mid to upper 70s by Tuesday. As the upper low
moves into the Rockies, a deep southerly flow brings a return flow
of moisture northward into the plains and then MS River valley,
possibly resulting in at least isolated showers Tuesday night.
Steepening mid level lapse rates may then result in thunderstorms
Wed into Wed night.  Forecast confidence decreases from Thu onward
due to differences in how models lift the upper low through the
Northern plains and the associated vort maxes rotating around its
base over the local area. Chance pops for showers are maintained
through Thu, where the timing of a cold front will be critical to
highs, which for now are held in the upper 60s to lower 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
ISSUED AT 1223 PM CDT Fri Sep 30 2016

Widespread MVFR conditions will be seen through 18z/01 as an upper
low remains stationary across northern Kentucky. Light rain and
drizzle will slowly increase in coverage, especially after
00z/01. The possibility does exist that IFR conditions may develop
after 06z/01.

&&

.HYDROLOGY...
Issued at 1213 PM CDT Fri Sep 30 2016

Many area rivers are near crest now, and will begin falling within
the next 36 hours. This is true for all of the tributary rivers in
flood at this time.

Wapsipinicon...
The stage at near DeWitt remains near crest, as 13.78 feet, which
is about the 4th highest crest on record. It should remain near
that level through tonight, and possibly Saturday before beginning
to fall quickly.

Cedar into Iowa...
The levels remain at major flood stage from near the confluence
on downstream. In addition, it appears all sites on the lower Iowa
are near crest now, and should only vary by a tenth or so through
the crest today and tonight.

Mississippi...
Generally, the routed flow supported dropping most crests by about
a tenth to two tenths of a foot today. This has kept the forecast
consistent within flood category, except at Dubuque LD11 where the
warning is now dropped and at Keokuk were Moderate flooding is
dropped to Minor flooding. Major flooding remains forecast for New
Boston, Keithsburg, Gladstone, and Burlington.

ERVIN

&&

.DVN Watches/Warnings/Advisories...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...12
SHORT TERM...12
LONG TERM...Sheets
AVIATION...08
HYDROLOGY...Ervin


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