Leisure Lake, Iowa Weather Forecast Discussion

260
FXUS63 KDVN 191917
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
217 PM CDT Fri Sep 19 2025
.KEY MESSAGES...
- On and off periods of showers and thunderstorms are expected
  through the weekend and the first half of next week. The
  threat for severe thunderstorms remains low.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 217 PM CDT Fri Sep 19 2025
A large upper level low pressure system is currently centered
near the SD/NE boarder, with multiple embedded spokes of energy
rotating around it through much of the Midwest. Each of these
embedded waves is leading to flare ups of showers and
thunderstorms as mid and upper level lift act on a still moist
and occasionally unstable environment.
In the very near term, today`s sun has led to greater
instability across eastern Iowa and western Illinois just as the
next embedded wave is rotating through from the west. Latest
mesoanalysis shows surface based CAPE has risen to over 1500 and
may yet go a bit higher. Because of this we do expect additional
thunderstorms to initiate over the next few hours as has already
been seen across portions of Missouri and Iowa along this wave.
Thankfully the overall wind flow around this upper low is not
very strong, with 500MB winds only about 20 to 25 KT and fairly
unidirectional shear even less than that. So storms that do form
won`t have a lot of shear to work with. However, given the
instability available, we couldn`t rule out some gusty winds
from the strongest storms. This activity likely peaks in the
late afternoon and early evening before decreasing and shifting
eastward overnight. If we`re able to get some clear skies
overnight, then cooling toward the dewpoint may lead to some
patchy fog. This is especially the case in areas that get rain
in the evening.
The upper low opens up a bit and moves east toward the
Minneapolis area tomorrow. In the meantime, we still see spokes
of energy rotating around it serving as the focus for additional
rounds of showers and embedded thunderstorms into the day on
Saturday. In these type of scenarios, it becomes increasingly
difficult to time and track each of the embedded waves beyond
about 12 to 24 hours. At the moment, most model guidance is
honing in on a wave tracking near the Iowa/Missouri border on
Saturday being the primary area for showers and storms. But we
can`t rule out rain just about anywhere so long as this big
upper trough remains nearby. In most cases it`s not a total wash
out, and not everyone will get wet. But we do expect the periods
of showers and storms to continue. Areas that see more sun will
have the potential to rise into the 80s, though that kind of
warmth would fuel instability for more thunderstorms. Areas that
remain more cloudy will stay considerably cooler.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 217 PM CDT Fri Sep 19 2025
The upper trough remains over the Upper Midwest on Sunday before
finally pushing into the Great Lakes on Monday. Guidance has
backed off a bit on the potential for showers and storms in our
area Sunday and Sunday night with another trough axis moving
through. The focus seems to be more on embedded waves just to
our north and just to our south. That said, the trough is still
around and we still have a moist environment from which it can
pull, so we can`t in good conscience put out a dry forecast. And
although guidance currently favors other areas for better rain
chances, we again can`t assign too much confidence in that as
each of these embedded waves feeds on each other and is enhanced
by convection making them less predictable with each round. So
in the end, Sunday is pretty much like Saturday with perhaps a
bit better chance that we see some sun (and thus a bit warmer
temperatures).
Although much of the focus locally is on the upper trough whose
spokes of energy are bringing our rounds of showers and storms,
further north we see a ridge extending well north through
Canada which has for the time being shut off access to cooler,
drier Arctic air. So although we have troughing locally,
there`s not a lot of cool air being dragged in with it. In fact,
we don`t see much change in air mass at all with dewpoints
remaining above normal for this time of year. So while our
current trough does finally move east, another trough digs into
the Northern Rockies on Monday and then out into the Midwest
this week. With plenty of moisture still lingering this trough
will produce additional rounds of showers and storms as it moves
through the region. Guidance still varies considerably on the
track and timing of the trough and of course on any embedded
waves. Because of that, the official NBM forecast continues to
maintain chances of rain every period through at least midweek.
In reality we`ll probably see a few rounds of showers and storms
with dry time in between. We just don`t have a lot of
confidence to say when the dry times will be vs the wetter
times.
By the end of the week, though, guidance is getting into better
agreement that the new trough will gradually shift eastward. The
ridge over Canada breaks down a bit and at the surface, high
pressure sinking south into the Great Lakes brings some drier
air into the region. So there is an end in sight to our
persistent period of wet weather, although future model runs
will likely give us better confidence on when that occurs.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1211 PM CDT Fri Sep 19 2025
Although it`s clear now, we do expect additional showers and
thunderstorms to develop this afternoon as instability
maximizes. This is most likely across the northern half of our
forecast area, but could occur at any terminal. Activity likely
decreases and shifts east in the evening. If we get some
clearing overnight we could see some fog, especially in areas
that get evening rainfall.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz

NWS DVN Office Area Forecast Discussion