Area Forecast Discussion
Issued by NWS Des Moines, IA

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693
FXUS63 KDMX 241122
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
622 AM CDT Sun Jul 24 2016

.SHORT TERM.../Today/
Issued at 311 AM CDT Sun Jul 24 2016

A cool front has entered northwest Iowa and will gradually move
across the remainder of the state today, finally providing some
relief from the heat of last week. Upstream observations show
dewpoints falling into the low to mid-60s behind the boundary though
these may moderate a bit during the daytime as local evapotranspiration
kicks in. Showers and thunderstorms accompanying the frontal boundary
in Minnesota are expected to remain north of our area this morning.
However, during the afternoon as the frontal boundary hangs up near
the Iowa/Missouri border it is expected that there will be additional
thunderstorm development. Most of this will be across northern Missouri,
but it may affect the southern row or two of counties in our area
and have maintained slight chance POPs there accordingly. Otherwise
no sensible weather of consequence is anticipated and it will be a
partly to mostly sunny day, still somewhat warm but certainly more
comfortable than the previous four or five days.

.LONG TERM.../Tonight through Saturday/
Issued at 311 AM CDT Sun Jul 24 2016

Few concerns the next couple of days. Boundary transitioning into
southern Iowa tonight with lingering convection near or just south
of the border from 00z to 06z prior to most moving south of the
forecast area. Airmass will slowly transition to cooler with less
moisture...especially north. However for southern Iowa temperatures
will settle into the mid to upper 60s for lows by tonight.  Weak
ridge of high pressure will move across Iowa from Monday through
Tuesday providing for quiet and pleasant more seasonal summer
conditions.

As the center of the our current hot airmass aloft at H500 migrates
toward the southwest US by Friday...the ridge will flatten and allow
a series of northern stream short waves to deepen slightly east of
the Rockies. This will result in a more normal temperature distribution
across the region and increased chances for thunderstorms from late
Tuesday night through next Saturday. Model consensus suggests the
most active days will be Wednesday with another peak around Friday
...though the stronger of the two systems and more abundant moisture
should occur with the first system. Temperatures meanwhile will
top out in the upper 70s to lower 80s from Wednesday through Saturday
after a two day stretch of 80s to near 90 highs Monday and Tuesday.
Lows will fall into 60 to 65 range expect for Wednesday night when
overcast conditions and a brief push of warmer air will bring uncomfortable
lows back into the picture...mid to upper 60s with higher levels
of humidity into Thursday morning. Overall the best chance for any
organized heavier rainfall will occur with the first system Wednesday
night into Thursday. Though wind fields are meager and chances for
much severe weather look limited at this point...precipitable water
is forecast to rise to 1.5 to 2 inches Wednesday night through Thursday
morning concurrently with warm cloud depths above 12 kft and weak
but persistent 0-3km CAPE. A progged warm front and developing surface
wave should assist in the potential for a up to 1-2 inch rainfalls
in the 36 hour period. Toward the weekend a trend toward lesser organized
convection is expected.

&&

.AVIATION.../For the 12Z TAFS through 12Z Monday morning/
Issued at 622 AM CDT Sun Jul 24 2016

A cool front will move across the area this morning, causing winds
to shift from SW to NW. The front will be accompanied by a narrow
band of low clouds which will produce a brief period of MVFR
ceilings around FL012-018 for around an hour or a bit more at some
of the terminals, mainly DSM/MCW/ALO. Have handled this with TEMPO
groups as it is high confidence but short duration and
intermittent. Once this band of clouds has passed VFR conditions
are expected for the remainder of the TAF period.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

SHORT TERM...Lee
LONG TERM...rev
AVIATION...Lee



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