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000
FXUS63 KDVN 131142
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
642 AM CDT Sun Aug 13 2017

...12Z AVIATION UPDATE...

.SYNOPSIS...
Issued at 315 AM CDT Sun Aug 13 2017

Early this morning cirrus from convection over Nebraska filtered
into the area. High pressure remained across the area.
Temperatures dropped into the low and mid 50s shortly before
midnight as the cirrus moved in. This cirrus kept temperatures
warmer across the western CWA this morning. The sfc high is prog
to move out of the area today, with it the return of deep moisture
and the chances for rain later in the short term.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 315 AM CDT Sun Aug 13 2017

From a sensible weather perspective, today will be another
gorgeous day more reminiscent of Fall then middle August across
the area. The main forecast challenges will be the temperatures
and then chances for rain late in the period. Potential for the
cirrus to lead to lower highs today looks possible across the
area. Current blend temps take highs from the upper 70s to low 80s
across the SW. The ECMWF seems to be the highest guidance for
temps.

Later in the period, the upper level low over ND this morning will
move east to the north of the area. Advection of moisture into
the area today and tonight will lead to warmer lows than the past
few nights. Current thinking is that convection looks to fire
across Nebraska. This convection will slowly move towards the
east tonight. The better forcing will be north of the area and
the CAMs suggest the best chances for precip will be tied to the
wave. However. as deeper moisture is advected north, enough
moisture convergence could lead to these showers and storms
making it to the far NW by 12Z Monday. As a result, have added
schc to chc pops before 12z.

.LONG TERM...(Monday through Saturday)
ISSUED AT 315 AM CDT Sun Aug 13 2017

The first half of the week will contain a good chance for widespread
rainfall over the entire area, though the exact timing and details
are far from certain. A developing warm front over Iowa and
Illinois will be in place Monday, with continued moisture
transport into the region. This will bring a chance for scattered
showers and thunderstorms over the CWA from Monday afternoon
through Tuesday, and organized showers and thunderstorms over the
region for Wednesday and Wednesday night. Model differences on
timing are rather large, with the GFS and GEM showing the best
forcing Wednesday afternoon and night, and the EC showing that
passing through Wednesday morning. Forcing for severe storms will
be weak through Wednesday morning, but we cannot rule out isolated
strong to severe storms during the afternoon hours along the warm
front, which is expected to be near I-80 Monday and Tuesday
afternoons. SPC has this threat outlined with a marginal risk in
the outlook.

Temperatures along the south of the front, will rise to the mid
to upper 80s Monday through Wednesday, so long as rainfall does
not interfere. Farther north,mainly upper 70s and lower 80s will
be found.

After Wednesday night`s cold front passage, a rather complicated
zonal flow will keep pops going for Thursday and Friday. This is not
a high confidence period, as we do not seem to have the confidence
in northwest  flow developing until Saturday while last night, this
seemed to bring drier air to the region starting Thursday.  In the
end, the air mass is no longer forecast to change greatly after
Wednesday`s cold front, and highs will remain forecast in the lower
to mid 80s, with dewpoints in the 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
ISSUED AT 640 AM CDT Sun Aug 13 2017

VFR conditions forecast through the period with little to no
aviation impacts expected. High clouds will move in later in the
period as rain and storms attempt to enter the area near 12z
Monday.

&&

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

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Ervin
AVIATION...Gibbs