000
FXUS63 KDVN 231112
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
612 AM CDT Sun Sep 23 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 310 AM CDT Sun Sep 23 2018

High pressure was centered just north of MN and was providing a
clear cool night with light to calm winds. Early morning
temperatures ranged from the mid 40s to mid 50s.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 310 AM CDT Sun Sep 23 2018

Sunny and mild today, clear and a bit warmer tonight.

Today: High pressure will bring a sunny and mild day with light
southeast winds. Model data suggests this will be warmer than
yesterday as heights rise a bit, and 850 mb temperatures warm to
+16C compared to +12 yesterday. I will forecast afternoon highs in
the mid 70s at most locations. These readings would be normal to a
couple degrees above normal for late September.

Tonight: Clear again tonight with a southeast wind at 5 to 10 mph.
This should give the area a bit warmer temperatures, with lows in
the upper 40s to mid 50s.

.LONG TERM...(Monday through Saturday)
ISSUED AT 310 AM CDT Sun Sep 23 2018

Mild fall weather continues into Tuesday, when a strong cold front
brings the next chances for showers and thunderstorms. The rest of
the week looks mainly dry with below to well below normal
temperatures.

The latest model runs have come into rough agreement with the timing
of lift ahead of a strong upper level shortwave that passes through
Tuesday night. This drives a cold front through the forecast area
Tuesday afternoon into early evening, likely triggering scattered
showers and thunderstorms. Ahead of the front, highs should again
reach the mid to upper 70s, while the far northwest may only reach
the upper 60s due to the earlier fropa. Thunderstorm coverage will
likely be greatest over northwest Illinois, far southeast Iowa and
northeast Missouri in the afternoon. If the faster timing of the
ECMWF and Canadian is maintained, further southward adjustments of
the axis of higher pops can be expected.

Wednesday through Friday, a broad upper trough carves out over the
north central U.S. At the surface, cool high pressure will dominate
outside a reinforcing cold front that pushes through Thursday. This
fropa is trending drier with each model run and pops have largely
been removed. The seasonably cold Canadian airmass will limit highs
to the 60s while overnight lows return to the 40s.

Forecast confidence remains low for Saturday, where models continue
to have poor agreement on the location of an east-west frontal
boundary setting up over the area. Rain and clouds north of the
front could hold temperatures in the 50s, while 70s would be
possible to the south. The GFS has the former, while the ECMWF
depicts the latter, or more southerly location. For now, the
forecast splits the difference with temperatures ranging from the
mid 60s north to mid 70s south along with low chances for rain. This
forecast will likely change over the next several days, once there
is greater confidence in where the front will set up.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
ISSUED AT 612 AM CDT Sun Sep 23 2018

High pressure will continue to provide VFR conditions with light
east to southeast winds and mostly clear skies through Monday
morning.

&&

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

$$

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