Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 260822
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
322 AM CDT Wed Sep 26 2018

.SYNOPSIS...
Issued at 320 AM CDT Wed Sep 26 2018

With the passage of the strong cold front which was well to our se
skies were clear early this morning. Temperatures were in the mid
40s to lower 50s.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 320 AM CDT Wed Sep 26 2018

Much cooler in the short term.

High pressure settling into the area will provide sunny skies and
much cooler weather today. Highs will be in the 60s. Clear
tonight with lows in the 40s. Winds will be rather light both
today und tonight.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 320 AM CDT Wed Sep 26 2018

Cooler, early fall weather will be the main story late week into the
weekend. Temperatures may be cool enough for frost in the north late
Friday night. A transition to much warmer weather will likely take
place early next week with temperatures possibly back in the 80s and
a return of rain and thunderstorm chances.

Thursday: A tightening surface pressure gradient and warm advection
ahead of an approaching cold front will lead to a breezy and warmer
day. Highs should reach the upper 60s to lower 70s with southwest
winds from 15 to 25 mph. The lack of moisture return, prevented by
sprawling high pressure to the south, will lead to a dry frontal
passage Thursday night.

The upper level shortwave driving the front through Thursday night
is shown digging out the broad upper trough over the region. This
leads to lowering heights and cold advection at 850 mb, where models
have temperatures dropping to around zero C across the north Friday
night. Along this 850 mb baroclinic axis, the GFS and ECMWF maintain
a ribbon of light QPF Friday afternoon into Friday night due to the
frontogenetical forcing. For now, slight chances for showers are
advertised for Friday afternoon, but these may be need to be
extended into Friday evening based on the latest ECMWF timing. All
models then have surface high pressure building overhead by 12z
Saturday morning. If skies clear sufficiently, temperatures should
easily drop into the mid and upper 30s over the northern half of the
forecast area Friday night and have introduced patchy, to areas of
frost wording mainly north of highway 30. Forecast confidence is
below average at this time due to the model timing differences in
how fast the surface high builds in and associated decreasing cloud
cover.

Saturday then looks mainly dry with temperatures in the upper 50s to
lower 60s, possibly warmer if cloud cover is thinner than models
depict. Low confidence chance pops will remain across the southwest
in the afternoon due to the potential for the wetter, more aggressive
GFS solution that ripples a wave along the stalling from to the
south.

This front is then depicted in a better model consensus
lifting northward, spreading rain chances northward Saturday night
into Sunday. This starts a more active period, where shower and
thunderstorm chances are possible along this boundary that is
maintained over the area to some extent through at least Tuesday.
Temperatures will likely be in the upper 70s to lower 80s on the
warm side of this boundary, while 60s to lower 70s would be more
common north. Returning low level moisture will return dewpoints as
high as the 60s and limit overnight lows to the mid 50s to mid 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
ISSUED AT 1254 AM CDT Wed Sep 26 2018

VFR conds as high pressure builds into the area. Northwest winds
10 to 15 knots today then variable less than 5 knots this evening.

&&

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

$$

SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Sheets
AVIATION...Haase



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