988
FXUS63 KDMX 262348
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
548 PM CST Tue Nov 26 2024

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Cold Weather Ahead
- Weak System south tomorrow as colder air dives southeast
- Another cold front arrives Thursday
- Saturday system snow chances 20 to 35% with some potential
  accumulation in the south.

&&

.DISCUSSION...
Issued at 115 PM CST Tue Nov 26 2024

.Short Term /Tonight through Wednesday Night/...

Confidence: High

Northwest flow becoming entrenched over the Midwest and east over
the next several days. Old low south of Hudson Bay will move east
while high pressure drops south into Minnesota by this evening. A
weak low over Wyoming and associated warm front east into Nebraska
and western Iowa is spreading mid to high level clouds into our area
by this afternoon and tonight. The low west of the region will
eventually see most of the energy consolidate far enough south
tonight to leave our area generally dry tonight and Wednesday, with
only a small chance (10 to 20%) of some light liquid precipitation
in the far south/southeast Wednesday as a weak inverted trough
manages to promote some weak lift in the south and east. Meanwhile,
with extensive clouds tonight and Wednesday, lows overnight will be
somewhat milder than last night and dropping to the lower 20s north
to the lower 30s in the south. Tomorrow will warm only about 10
degrees regionwide with highs in the lower 30s north to the lower
40s in the southeast.

.Long Term /Thursday through Tuesday/...

Confidence: Medium

The main theme for the remainder of the forecast is cold. Overall,
we are likely to be around 10 to nearly 20 degrees below normal over
the region through the weekend with some recovery anticipated early
next week. Thanksgiving will be cold with periods of clouds in the
morning along with some some breaks in the afternoon. A stronger,
Arctic cold front will arrive by late afternoon/early evening in the
north with another batch of clouds, uptick in northwest winds and
maybe a few flurries in the north. The cold air is expected to
spread through the region Friday and linger for most of the weekend
as high pressure slowly builds into the region into early next
week. The models have been picking up a weak shortwave embedded
in the northwest flow over the past week. This is anticipated to
drop southeast along the western edge of the strong, upper
level H500 trough. As it moves toward the Central Plains, it
will spread some weak warm advection into western/southwest Iowa
along a developing boundary. With very weak lift, light snow is
expected to develop along and south of I80. Though moisture is
limited, the system may squeeze out a tenth of an inch which
would result in around an inch of snow in the south Saturday
afternoon and evening. There has been a lack of consistency in
the placement of systems as of late and looking at the run to
run consistency of the GFS/Euro suggest that some minor
adjustments are yet to occur. The GEFS mean snowfall/qpf has
also adjusted the axis of snowfall north into southern/southwest
Iowa as of the 06z and 12z runs. The area most likely to see
more than an inch would be in the southwest. Following the
departure of the low, cold temperatures will continue to funnel
southeast as high pressure from Canada settles into the region
with a 90% or higher chance of highs being below 28F for Friday
through Monday. Lows through the period will drop to the single
digits north to the lower teens south through Monday. Following
that some recovery is expected into Tuesday with readings in the
mid 20s northeast to the lower 30s southwest as a Clipper
tracks southeast toward Lake Superior.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 532 PM CST Tue Nov 26 2024

Mid to higher level clouds will continue to move through the
area during much of the TAF period, though some breaks may occur
at times. Despite the cloud cover, VFR conditions currently
forecasted to prevail at all 5 TAF sites. There may be some
MVFR ceilings at times in far northern Iowa on Wednesday morning
or night, but remain north of KMCW as of this forecast period.
Winds out of the southeast early this evening will shift through
the night settling to be out of the northeast into Wednesday
morning. Although there are low (15-25%) rain chances in
southern Iowa during the daytime Wednesday, these are expected
to remain south of KOTM precluding any mentions in the TAF at
this time, though a brief sprinkle may be possible.

&&

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

&&

$$

DISCUSSION...REV
AVIATION...KCM