Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 292002
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
302 PM CDT THU SEP 29 2016

.SYNOPSIS...
Issued at 300 PM CDT Thu Sep 29 2016

18Z surface analysis has high pressure from the upper Great Lakes
into the southern Plains while a cut off upper low was over the
lower Ohio Valley. Dew points were in the 40s and 50s from the
Plains into the Ohio Valley.

&&

.SHORT TERM...(This Evening through Friday)
ISSUED AT 300 PM CDT Thu Sep 29 2016

Through sunset, mainly clear skies will be seen across much of the
area with clouds and isolated showers/sprinkles across the far
eastern parts of the area. After sunset and through much of the
evening, isolated sprinkles/showers will gradually decay across the
far east.

The upper low over Kentucky will remain there through Friday. Trends
with the RAP and other models indicate another surge of low clouds
will spread west again after midnight with widespread cloud cover
over the eastern two thirds of the area around sunrise Friday.

On Friday, several additional upper level disturbances will rotate
through the area. These disturbances will slowly spread isolated to
scattered rain showers west across the area during the day.

The initial dryness of the air indicates some chilly temperatures
are possible tonight, especially those areas that remain clear.

On Friday, cloud cover/precipitation will make temperatures very
interesting. High temperatures should eventually get into the 60s at
some point during the afternoon.

.LONG TERM...(Friday Night through Thursday)
ISSUED AT 300 PM CDT Thu Sep 29 2016

Forecast focus on chance of showers early in the extended then
chance of thunderstorms about the middle of next week.

Friday night through Saturday: Vertically stacked upper low in KY
will track slowly northward into northern Indiana. The cyclonic
flow/cold pocket around the low will bring a mostly cloudy sky to
the dvn cwa, along with scattered showers. The higher pops (40-50
pct) will be kept roughly along and east of the MS River, closer to
the low. In our far western counties pops will be in the 20-30 pct
range. Highs on Saturday should range from 65 to 70 due to the
extensive thick cloud cover.

Saturday night through Tuesday night: A pleasant stretch of weather
expected, dry with a warming trend. The upper low will be shifting
into the eastern Great Lakes during the weekend, while ridging aloft
builds into the cwa. Highs will be in the upper 60s to lower 70s on
Sunday, warming well into the 70s by Tuesday. Lows will be mainly in
the 50s.

Wednesday through Thursday: Low confidence due to potential Tropical
Storm or Hurricane Matthew moving up the East Coast (GFS) vs the
system still near the Bahamas (ECMWF). Both models sweep a negative-
tilt trough/strong cold front into the Midwest, accompanied by
showers and thunderstorms. So, there are two scenarios 1) the
tropical system slows the approaching trough or 2) the trough sweeps
to the east and merges with the tropical system. As of now, the ECM
with the slower movement to "Matthew" sweeps the cold front across
the cwa on Wednesday. On the other hand, with the tropical system
moving up the East Coast the GFS is about 24 hours later with the
arrival of the front. The consensus model has chance pops to cover
the two scenarios described above.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
ISSUED AT 1220 PM CDT Thu Sep 29 2016

VFR conditions will be seen through 06z/30. Some VFR cigs are
possible at KBRL/KMLI. After 06z/30 MVFR cigs will again slowly
build west to the Mississippi river and then into eastern Iowa by
sunrise Friday. After sunrise Friday, MVFR and possibly some IFR
conditions will be seen across eastern Iowa and northern Illinois
with rain showers.


&&

.HYDROLOGY...
Issued at 1224 PM CDT Thu Sep 29 2016

Mississippi River:

Latest adjustments that were made was to slightly lower crest
forecasts at most points but minor to major flooding continues to be
on track. Forecast point DLDI4 Dubuque is expected to crest right at
flood stage with major flooding still expected at New Boston,
Keithsburg,Gladstone and Burlington. Majority of the crests are
projected to occur during the Saturday through Monday time frame.
No significant rain is expected through the middle of next week.

Cedar River...

Vinton: Forecast to fall below flood stage by Friday morning.

Cedar Rapids: Forecast to fall below major flood stage by late
tonight.

Conesville: Cresting near 18.1 feet through this evening
before beginning to slowly fall.

Wapsipinicon River...

Anamosa Shaw Rd: Forecast to fall below moderate flood stage by
the late evening.

De Witt 4S: Now into major flood stage. Thinking current crest
forecast at 13.4 feet is on the upper end of possible outcomes.
Reasonably high probability the final crest is a bit lower.

Iowa River...

Marengo: Moderate flood stage is forecast by Friday afternoon or
evening.

Columbus Junction: Major flooding is occurring. Rate of rise has
slowed but is forecast to increase tonight.

Oakville and Wapello: Moderate confidence is associated with the
crest forecasts. Current thinking is crest forecasts are toward the
upper range of what is possible; observed crests may come in lower.
Please follow forecast information closely throughout this event.

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...Haase
AVIATION...08
HYDROLOGY...Haase/Uttech



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