Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 062334
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
534 PM CST Sat Mar 6 2021

...Updated Aviation Discussion...

.DISCUSSION.../Tonight through Saturday/
Issued at 252 PM CST Sat Mar 6 2021

Temperatures and fire weather are the short term concerns with
precipitation/thunder chances longer term issues.  Currently,
surface boundary lies across central Iowa with readings well into
the 50s and 60s across southern Iowa. Across the northeast, there
has been some rebound in temperatures given the ample sunshine today
with reading in the mid to upper 40s. Generally clear skies are
expected to prevail into tonight with light east to southeast flow.
Readings should drop quickly with the relatively dry airmass, mostly
clear skies and light winds.  Coolest readings remain in the
northeast where quickly shrinking snowpack is holding on.  Some
increase in the pressure gradient toward morning may increase winds
in the west prior to sunrise helping temperatures become steady or
even rise a few degrees prior to sunrise.  On Sunday, strong south
to southwest winds are forecast by afternoon with thermal ridging in
the Plains edging into the state. The good mixing along with ample
sunshine should push temperatures upwards of 10 degrees in many
areas with widespread 60s and a few 70s in spots.  The breezy and
warm conditions by afternoon increases fire potential as fuels dry
during the day. Dewpoints have been lowered from guidance due to
good mixing and corresponding relative humidity values drop to
around 30 percent by mid afternoon across the southwest third or so
of the state.  While not quite red flag warning criteria, fire
danger will certainly be elevated across the southwest half of the
forecast area on Sunday afternoon and will continue to message this
concern.

A shortwave passes north of the state later Sunday into Sunday night
with cold advection grazing the northeast corner of the state into
early Monday, however reintensifying warm advection is expected by
Monday afternoon as upper ridging stays put across the central US.
The warmth persists into Tuesday ahead of the approaching shortwave
with increasing moisture across the state. Showers with isolated
storms are expected to develop near the boundary in northwest Iowa
on Tuesday night ahead of a surface wave.  This activity remains
mostly in northern Iowa before quickly moving northeast out of the
state.  As the wave passes, the surface cold front begins to
progress east across Iowa on Wednesday.  As with most early and late
season systems, there will be ample shear ahead of the front by
midday Wednesday but instability remains somewhat meager.  Recent
model trends have also been to hold off initiation until later in
the afternoon to early evening which would allow for the front to
clear much of the forecast area.  However, will continue the threat
of showers and isolated storms into Wednesday afternoon across
central and eastern areas with any activity quickly propagating
northeast given the strong flow aloft.  The front stalls south of
the state into Thursday with most of the activity associated with
the boundary remaining south of Iowa. 12Z models vary beyond this
point into next weekend with some stark differences at this
point.

&&

.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 533 PM CST Sat Mar 6 2021

VFR conditions prevail through the current TAF period. Winds
become southerly and strengthen Sunday morning into the
afternoon. Gusts in excess of 20-25kts are likely through the
afternoon hours.

&&

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

$$

DISCUSSION...Cogil
AVIATION...Martin


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