Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 160849
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
349 AM CDT Mon Jul 16 2018

.SHORT TERM.../Today through Tonight/
Issued at 346 AM CDT Mon Jul 16 2018

An upper trough currently spinning across western Ontario with a
surface low in the same vicinity. An associated cold front is draped
to the southwest across central WI and through Iowa into SE NE. This
front has pushed through much of the forecast area and will continue
to move south and east through the day and out of the state by late
afternoon. A much drier and cooler airmass will move in behind the
front with high pressure building into the state through the day
into tonight. Little moisture with this front, with only a few
isolated showers in east central Iowa currently. Any chance for
precipitation should quickly move off to the south/east early this
AM, with some residual cloud cover this morning. Otherwise dry
conditions are expected through the day into tonight with any cloud
cover moving out by early evening. Temps may still reach into the
mid 80s south of the front across far southern Iowa, but expect
highs around 80 to the lower 80s central and north. With the high
overhead tonight and a drier airmass in place expect temps to fall
into the lower 60s across the forecast area.

.LONG TERM.../Tuesday through Sunday/
Issued at 346 AM CDT Mon Jul 16 2018

We will remain in northwest flow on Tuesday with an upper ridge
building to the west and a trough over the Great Lakes.  The result
will be continued mild temps and comfortable humidity.

Wednesday and Thursday a shortwave will undercut the ridge and drop
through the Northern Plains into the Upper Midwest.  As suspected
yesterday, this shortwave will be a little stronger than models had
suggested in past runs and the set up will be a little more
conducive to thunderstorms with better moisture and instability
working into the area ahead of this for Tuesday night.  In
addition...shear is more supportive of at least marginally severe
storms for Wednesday and likely Thursday as well. PoPs were
increased during this period and we will be hitting the potential
for strong/severe storms in the HWO and weather story.

The GFS closes the wave into a low over Wisconsin on Friday and
while the Euro and Canadian still keep it a wave, they are hinting
at the potential for closing it into a low as well.  This will slow
the system and deepen it which will keep the precip potential going
for Friday, though the models vary widely on timing and just where
the best chances for precip will reside.  The good news is that the
heavy rain and severe potential will be past by then.

By later Friday through Saturday the upper ridge rebuilds and noses
into the region for dry conditions and with the flow remaining more
west to northwest, temperatures will remain in check as well with
highs remaining in the low to mid 80s.

For Sunday into Monday all the models move a low across Canada which
flattens the ridge and drives a shortwave across the region bringing
additional chances for showers and storms.  However by the end of
this forecast valid period, precip only makes it into western Iowa
and variability in the models with respect to timing and the strength
of the low moving across Canada warrants low confidence in any of
this happening and especially storm potential.

&&

.AVIATION.../For the 06Z TAFS through 06Z Monday night/
Issued at 1139 PM CDT Sun Jul 15 2018

VFR conditions across all sites, with a few clouds across central
to northeast Iowa and another larger area over far northwest
Iowa. Expect VFR conditions to persist throughout the TAF period.
Patchy fog may develop over far southeast Iowa overnight, however
do not anticipate any impacts to OTM at this time.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Beerends
LONG TERM...FAB
AVIATION...Hagenhoff



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