Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 282317
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
617 PM CDT Sun May 28 2017

.UPDATE...
Issued at 617 PM CDT Sun May 28 2017

A few weak showers and an isolated thunderstorm have developed
over the past hour in south central IA. These were ahead of a
weak upper level impulse and surface trough. As the associated
forcing appears to be moving out of an axis of higher CAPE and
thus better support, these should weaken, if not dissipate as
they advance eastward into southeast IA and far northeast MO early
this evening. Will update the forecast to mention isolated
evening showers along and south of the IA highway 34 corridor.

&&

.SYNOPSIS...
Issued at 356 PM CDT Sun May 28 2017

As forecast, the cold front exited the CWA early this morning, with
dry weather, lowering dewpoints, and highs in the mid to upper 70s
behind it. The 10 to 20 mph wind is actually quite pleasant in this
temperature range, and as readings cool off this evening, the wind
will also lower, thus, through sunset, it will continue to be an
outstanding day.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 356 PM CDT Sun May 28 2017

Clouds will decrease to clear skies around sunset tonight, with only
a few patches of mid clouds through the night possible in northwest
flow. AS the mixing depth decreases in this process, winds will also
drop to under 10 mph for the rest of tonight. The pressure gradient
will keep a light northwest wind going through the night, and lows
will be kept above the current dewpoints for that reason. Lows of
lower to mid 50s are solidly in the guidance blend range. Monday,
continued northwest flow will send another spoke of vorticity
southward, and this may allow for a similar uptick in cumulus by
late morning, followed by isolated to scattered showers. It seems we
will build these early enough in the day to keep the chances for
thunder quite low, and highs probably will only top out in the upper
60s north with the early cloud onset there. Farther south, with
milder air aloft, more sun is expected, and highs should once again
reach the mid 70s.
ERVIN

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 356 PM CDT Sun May 28 2017

The trof over Quebec that has been a mainstay for a while will
continue to hold on.  Keeping us in an active weather pattern.
Guidance suggests that this will change the end of next week as a
deep trof moves on shore across the western US.

Long term sensible weather will be a continuation of Monday without
the chances for precip.  This is expected to continue through at
least Thursday morning, when the GFS and GEM suggest a wave through
the northwest flow.  This wave will help to advect in decent low
level moisture and our next chance for thunderstorms.  Guidance
suggests a summertime setup for nocturnal MCS with a LLJ and
instability Thursday morning through Friday morning.  The track of
any potential MCS will likely change before the day actually comes.
This is important to keep in mind.  If you have something to do
where you need dry conditions, get them done before Thursday.

Into the weekend, the flow becomes zonal to southwest.  This will
usher in warmer and more moist conditions and the chance for showers
and thunderstorms again.  Differences in model solutions lead to low
confidence at this time.  The GEM and ECMWF have NW flow across the
area, whereas the GFS is southwest with a compact wave moving into
the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 617 PM CDT Sun May 28 2017

VFR conditions will be the rule throughout as a dry airmass moving
into the area on gusty west winds will eliminate the potential
for fog and low ceilings. Isolated showers and thunderstorms over
south central IA are expected to dissipate before reaching the BRL
terminal this evening. There will be another round of at least
isolated showers Monday afternoon. These appear to be too
isolated to include in the forecasts at this time.

&&

.HYDROLOGY...
Issued at 356 PM CDT Sun May 28 2017

Added Keokuk to a flood watch as latest guidance takes it just above
flood.  Also decided to keep BLVI4 at a watch as confidence that the
river will flood there is still suspect.  The ensembles have nailed
upstream crests and continue to keep BLVI4 below flood.  With this
low confidence decided to keep it at a watch.  The rest of the river
forecasts remain unchanged.

&&

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

$$

UPDATE...Sheets
SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...Gibbs
AVIATION...Sheets
HYDROLOGY...Gibbs


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