Office: DMX
FXUS63 KDMX 191129
AFDDMX
Area Forecast Discussion
National Weather Service Des Moines IA
629 AM CDT Fri Apr 19 2024
...Updated for the 12z Aviation Discussion...
.KEY MESSAGES...
- Breezy conditions today, perhaps windy at times over northern
Iowa.
- Freezing temperatures possible tonight north and west but low
potential for frost. High chance for area wide frost Saturday
night.
- Next chance for precipitation arrives Monday/Monday night.
&&
.DISCUSSION...
Issued at 336 AM CDT Fri Apr 19 2024
Ridge of high pressure is extending from Montana and into southwest
Iowa early this morning and as expected, temperatures have fallen
into the 30s as of 3 am. Expect a few areas to reach the upper 20s
in the next few hours over north central Iowa and into the
Nishnabotna Valley over the west. Despite the presence of the
surface ridge over the southwest, some clouds based around 12 kft
are passing across that area with radar echoes showing up as well
with mid level forcing passing by. Very dry air in the sub cloud
layer though is evaporating any hydrometeors upon descent.
Good mixing will occur today to near 800 mb. Mixed layer winds will
vary with a peak near 20 kts over southern Iowa to 35-40 kts over
northern Iowa. These peak mixed layer winds will not be realized at
the surface with a weaker pressure gradient and the lack of strong
cold advection, but wind gusts over 35 mph are possible over
northern Iowa. An upper level system and surface cold front will be
approaching Iowa from the north today and will reach north central
Iowa by mid to late afternoon. The differential cold advection which
will be not as strong at the surface, will result in deeper mixing
initially and should negate any surface cold advection impacts on
temperatures. It will however keep the gusty wind in place over the
north into the early evening before decoupling occurs. An area of
showers is expected to develop this afternoon behind the boundary in
Minnesota but there is a quick drop off in available moisture into
Iowa so while some puffy cumulus could develop, much of the cumulus
will be quite shallow and at this time, no precipitation is expected.
The Frost and Freeze headlines may still be needed tonight and again
Saturday night. In collaboration with all surrounding offices, the
plan is to allow the current headlines to expire then have any new
headlines be issued on the day shift each day. For tonight, The wind
will remain breezy at times despite the eventual decoupling. This
may limit or prohibit frost formation in addition to the drier air
in place leading to lower relative humidity values. Therefore, any
headlines may be limited to below freezing areas. Lighter winds and
a greater potential for radiational cooling and frost development
occurs Saturday night and that will likely be the coldest night
during this stretch. Saturday itself will be on the cool side with
highs in the upper 40s to low 50s. Sunday and beyond will be warmer
with high temperatures in the 60s more common with overnight lows
staying above freezing.
The next system to impact Iowa arrives on Monday. As it arrives, the
large surface high pressure will be moving into the southeastern
CONUS. The timing of this movement and how strong the ridging
remains west into Texas, will have a big impact on how quickly Gulf
moisture returns north on the backside of the highs to interact with
the system moving across Iowa. Shower and thunderstorms will move
across the state. Greater instability will occur if the Gulf
moisture arrives, especially into southern Iowa but at this time,
the overall instability looks meager with a low severe threat. Of
greater interest is the end of next week and into next weekend as a
strong system moves into the western CONUS leading to good southwest
flow aloft into Iowa. There is still a lot to unpack with that
system including lead short waves ejecting out ahead of the primary
system then the eventual primary system lifting into the Midwest.
These systems tend to be delayed from guidance this far out but this
is a severe weather setup for somewhere in the region.
&&
.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 625 AM CDT Fri Apr 19 2024
The wind will increase this morning and will become gusty from
late morning and into the afternoon. Gusts over 35 kt are
possible over northern Iowa. The wind will diminish this
evening. Otherwise, VFR conditions will persist. Clouds will
increase over northern Iowa mid to late afternoon with cigs
around 6 kft. Mid-level cloudiness will pass across southern
Iowa today as well.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 8 AM CDT this morning for IAZ004>007-
015>017-023>028-033>038-044>046-057-070.
Frost Advisory until 8 AM CDT this morning for IAZ039-047>050-
058>062-071>075-081>084-092>095.
&&
$$
DISCUSSION...Donavon
AVIATION...Ansorge
Office: DVN
FXUS63 KDVN 191048
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
548 AM CDT Fri Apr 19 2024
.KEY MESSAGES...
- Active pattern keeps wave after wave moving through the area.
Most of these waves will result in clouds and wind. Precip
returns to start next week.
- Frost and freezing overnight lows are expected through the
weekend as temperatures dip into the 20s across portions of
the area.
- Additional frost and freeze advisories and warnings will
likely be needed for the next couple of nights.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 300 AM CDT Fri Apr 19 2024
A large upper level low will lumber to the east through the
short term. This low will aide in bringing colder temperatures
into the area today. This low will also bring windy conditions
to the area with gusts approaching 30kts this afternoon. The
clear skies we have right now may see some CU redevelopment
today. Otherwise, expect clear skies tonight and temperatures
dropping off tonight. Lows in the upper 20s across the north and
mid 30s across the south are expected. While there is some
uncertainty about frost development due to the winds tonight,
lows will be near freezing so additoinal frost and freeze
products are likely needed. With an advisory out for this AM,
have opted to for this advisory to expire before we issue
another one.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 300 AM CDT Fri Apr 19 2024
Active period persists the active flow regime remains. Saturday,
the coldest air of this incursion is expected. H92 temps barely
get above freezing. Luckily for us, it should be clear, so
warming should lead to temperatures in the upper 40s to low 50s.
The HRRR depicts some showers underneath the cyclonic flow of
the upper level low. Think that the llvls will likely be rather
dry and any 'showers' that develop will likely result in just
virga. Saturday night looks like the coldest for the area with
lows at or below freezing across most of the area. We will
likely need more frost/freeze products for this as well.
To start next week, a strong clipper will move into High Plains
and translate over the upper Mississippi River valley into
Tuesday. Deep moisture is expected to be pulled north with this
system and likely lead to precipitation across the area. This
precipitation looks tied to two surface boundaries with this
clipper. Mainly rain is expected, however some thunder cannot be
ruled out. Guidance is not in good agreement with the timing of
these boundaries and thus precip chances. We will need to keep
an eye this timing difference this weekend as the slower models
have fropa during the day on Tuesday during peak heating.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 546 AM CDT Fri Apr 19 2024
VFR conditions are expected through the period with winds
starting to pick up this morning. Gusts this afternoon will
approach 30 kts. After the sun sets, expect wind gusts to ease
and sustained winds in the upper single digits.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Frost Advisory until 8 AM CDT this morning for IAZ040>042-
051>054-063.
IL...None.
MO...None.
&&
$$
SHORT TERM...Gibbs
LONG TERM...Gibbs
AVIATION...Gibbs
