Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 132349
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
649 PM CDT Wed Sep 13 2017

...00Z AVIATION UPDATE...

.SYNOPSIS...
Issued at 331 PM CDT Wed Sep 13 2017

The remnants of what was once Hurricane Irma were rotating across
the western Ohio River Valley through the morning and afternoon.
A weak band of rain showers developed across northern Illinois
during the morning as a result of a few vort maxes rotating around
the low, but quickly died off as it encountered dry air in place
across the region. This dry air was from high pressure in place
from the Mid Atlantic northwest towards the Great Lakes, and was
fairly stagnate in nature. Temperatures across the region varied
from the lower 70s over northwest Illinois, to lower 80s over east
central Iowa.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 331 PM CDT Wed Sep 13 2017

Tonight...Expect to see mainly clear skies with only a few upper
level cirrus or cirrostratus clouds, along with light and variable
winds. These light winds and clear skies will favor development
of some areas of radiation fog, especially in the river valleys
east of the Mississippi. Guidance is trying to keep lows in the
lower to middle 50s, but do believe that some areas will see upper
40s towards Jo Daviess and Stephenson counties.

Thursday...Fog will quickly burn off in the morning hours, leaving
us with another gorgeous day of sunshine and above normal
temperatures for mid September. Upper level heights will also begin
to increase as ridging from the central Great Plains builds into the
Mississippi River Valley, setting the stage for a prolonged period
of warm weather.

.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 331 PM CDT Wed Sep 13 2017

Very warm temperatures for early fall dominate the extended
forecast. Additionally, the abnormally dry or drought conditions
will continue (depending on location in the forecast area).

Friday through Sunday:

Warming trend expected to peak on Friday and Saturday with highs in
the mid 80s to near 90 F across the forecast area. Continued trend
of going slightly above SuperBlend for max temps, giving a little
more weight to raw model guidance. Model 850mb temps in the upper
teens to around 20 C are supportive of highs in the upper 80s to
lower 90s. Forecast soundings display a dry, inverted-V sounding
and deep boundary layer mixing to around 800mb. Thus, may have to
increase a few more degrees in later updates. Temps on Sunday are
forecast about 5-10 F cooler.

Since dewpoints are forecast in the upper 50s to lower 60s on
Friday and a few degrees higher for Saturday, heat indices will
be very similar to the ambient air temps.

No changes regarding the precipiation forecast: Scattered showers
and thunderstorms are possible mainly Saturday night into Sunday
morning along and ahead of a cold front. Significant 500mb height
falls are forecast to stay well north of E Iowa/NW Illinois, so
forcing for ascent and the threat for widespread appreciable
rainfall is low.

For Monday through Wednesday, models in general agreement on
amplification of the upper ridge over the Midwest and another
warming trend well into the 80s by Wednesday. Aside for low chances
for scattered showers or isolated storms, most areas will probably
receive little to no rainfall. Uttech

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 640 PM CDT Wed Sep 13 2017

Main concern is fog potential tonight. Overall, little change is
shown from the setup which produced the patchy fog early this
morning (clear skies, near calm winds and strong radiational
cooling), thus expect redevelopment of patchy/areas of fog again
overnight dissipating shortly after sunrise. Crossover temps (dew
point during peak heating) of upper 40s to mid 50s will be close
to minimum temps tonight, thus forecasting visibilities generally
1-3 miles but there is a chance for lower visibilities. After the
fog dissipates early on Thursday will see increasing southerly
winds to around 10 kts with some mid clouds in developing warm
advection regime.

&&

.CLIMATE...
ISSUED AT 331 PM CDT Wed Sep 13 2017

Record Highs for September 16...

Moline.........92 in 1931
Cedar Rapids...98 in 1931
Dubuque........96 in 1931
Burlington.....95 in 1906

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Uttech
AVIATION...McClure
CLIMATE...Uttech



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